Article

Substrate water status and evapotranspiration irrigation scheduling in heterogenous container nursery crops

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... In Europe, one of the major production areas for hardy ornamental nursery stocks is situated around the town of Pistoia in Tuscany, Italy. In Pistoia, there are more than 1000 wholesale nurseries spread on a total surface of 5400 ha: in the last decades, container cultivation has been increasingly used (covering at present approximately 1500 ha; Incrocci et al., 2014). Overhead sprinkler irrigation is commonly used for containers smaller than 5-7 L while micro-irrigation is applied to larger containers. ...
... Container hardy ornamental nursery stocks are often over-irrigated because of inaccurate scheduling, which is generally based on growers' experience; a simple time clock system (timer) is commonly used for automated irrigation. In Pistoia production area, groundwater is the main source of irrigation water for nursery industry and annual irrigation water use is more than 14 million m 3 against an urban water use of less than 8 million m 3 (Incrocci et al., 2014). Current legislation on water resources (e.g. ...
... Bulk density, porosity of the substrate, container water capacity, and plant available water were 490 kg m −3 , 80.6%, 4.4 L pot −1 , and 1.8 L pot −1 , respectively. The container available water is here defined as the difference between the water content calculated at 0 and −10 kPa matric potential at the bottom of the container itself (Incrocci et al., 2014). ...
Article
The objective of this study was to design and test a prototype fertigation controller for the management of container ornamental nursery stocks irrigated with different water sources, including saline water or reclaimed municipal/industrial wastewater. The prototype could schedule irrigation in various ways, i.e. as a time clock, or by means of a soil moisture dielectric sensor, or using a crop evapotranspiration (ET) model. The prototype also monitored the salinity in the root zone using a dielectric sensor that measured both substrate moisture and electrical conductivity (EC), or a probe measuring the EC of the water draining out of the containers. Excessive substrate salinization of the containers irrigated with saline water (containing 10 mM of sodium chloride) was prevented by the automated adoption of a series of measures: irrigation with fresh water or a mixture of fresh water and saline water; progressive increase of irrigation dose for each event, and progressive reduction of fertilizer concentration in the nutrient solution delivered to the crop. The system was tested in three experiments conducted in Pistoia (Italy) between 2008 and 2010 with two ornamental species: Photinia × fraseri Dress (a salt-medium tolerant species) and Prunus laurocerasus L. (a salt-sensitive species). When irrigation with fresh water was controlled with a dielectric sensor or an ET model, total irrigation water use and the loss of both N and P were reduced by 17% to 84% compared with the time-controlled irrigation. The sensor-based control of saline water irrigation reduced the salinity effects on dry matter accumulation in both species; however, it did not prevent the occurrence of leaf damages (leaf scorch) on Prunus plants, which were unmarketable by the end of growing season. On the contrary, no leaf damages were visible on Photinia plants irrigated with saline and/or fresh water, such that all were classified in the top quality market category. The controller developed in this work could be used in commercial nurseries to improve profitability and sustainability of container hardy ornamental nursery stock production.
... Even in soilless cultivation systems, irrigation represents a very large and potentially important loss of nutrients and a source of environmental pollution (i.e., drain to waste hydroponics systems) as a surplus of 20% to 50% of the plant's water uptake in each irrigation cycle is often recommended [12][13][14][15][16]. Indeed, annual use of irrigation water ranges from 150 to 200 mm (e.g., leafy vegetable) in soil-based greenhouse crops to 1000 to 1500 mm in soilless-grown (e.g., Solanaceae, cucurbits) [11]. ...
... For scheduling irrigation in soil or soilless greenhouses, it is essential to estimate the crop evapotranspiration and, according to the soil or substrate, the irrigation dose. In addition, as cited in Incrocci et al. [16], the irrigation dose of container growing medium could be estimated based on water potential or volumetric water content, with the use of soil moisture sensors. In the meantime, the adoption of soil moisture monitoring in vegetables has been restricted by means of sensor accuracy and price as well as labor required for installation, removal, and collection of readings [7]. ...
... Lizarraga et al. [52] evaluated the efficiency of timed scheduling, and concluded that this method does not actually meet the irrigation requirements of hydroponic tomatoes resulting in over and under irrigation during the morning and in the afternoon, respectively. Similarly, Incrocci et al. [16], working with several species of ornamentals in container nursery crops, reported an increase of the water use with timed irrigation scheduling by 20% to 40% and nutrient emissions of 39% to 74% in comparison with model-based irrigation. ...
Article
Full-text available
Precision agricultural greenhouse systems indicate considerable scope for improvement of irrigation management practices, since growers typically irrigate crops based on their personal experience. Soil-based greenhouse crop irrigation management requires estimation on a daily basis, whereas soilless systems must be estimated on an hourly or even shorter interval schedule. Historically, irrigation scheduling methods have been based on soil or substrate monitoring, dependent on climate or time with each having both strengths and weaknesses. Recently, plant-based monitoring or plant reflectance-derived indices have been developed, yet their potential is limited for estimating the irrigation rate in order to apply proper irrigation scheduling. Optimization of irrigation practices imposes different irrigation approaches, based on prevailing greenhouse environments, considering plant-water-soil relationships. This article presents a comprehensive review of the literature, which deals with irrigation scheduling approaches applied for soil and soilless greenhouse production systems. Irrigation decisions are categorized according to whether or not an automatic irrigation control has the ability to support a feedback irrigation decision system. The need for further development of neural networks systems is required.
... One of the largest HONS production centres in Europe is around the city of Pistoia, central Italy, where about 1,500 nurseries currently cultivate approximately 5,200 ha (Incrocci et al., 2014). Container cultivation is increasingly used in Pistoia nurseries in consideration of its advantages (e.g. ...
... fast plant growth, year-round marketing and easy plantation). In this cropping system, water use efficiency (WUE) is low because of overirrigation (Marzialetti and Pardossi, 2003;Incrocci et al., 2014). The leaching fraction (LF= water leached/water applied) ranges from 30 to 50%, thus resulting in water loss and pollution due to fertiliser leaching (Marzialetti and Pardossi, 2003;Incrocci et al., 2014). ...
... In this cropping system, water use efficiency (WUE) is low because of overirrigation (Marzialetti and Pardossi, 2003;Incrocci et al., 2014). The leaching fraction (LF= water leached/water applied) ranges from 30 to 50%, thus resulting in water loss and pollution due to fertiliser leaching (Marzialetti and Pardossi, 2003;Incrocci et al., 2014). Inaccurate scheduling is the main cause of over-irrigation. ...
Article
In the neighborhood of the city of Pistoia, central Italy, is located one of the largest container Hard Ornamental Nursery Stock (HONS) production centres in Europe. Water use efficiency (WUE) is one of main problem of these nurseries, mainly due to inaccurate irrigation scheduling, since almost all nurseries use simple timers to control irrigations. Plants are irrigated 1-4 times per day with irrigation events set periodically (every 1-4 weeks) by the growers based on their personal experience. This paper reports the results of a work performed to design, construct and test a simple and cost-effective irrigation control system (IRRIVIVA) for HONS nurseries. This system aims to reduce the growers’ tendency to over-irrigate and the oscillations in the substrate moisture content, thus resulting in greater WUE and better crop performance (faster growth, less susceptibility to root-borne diseases etc.). For this purpose, IRRIVIVA considers the day-to-day oscillation in reference evapotranspiration (ETo) and then crop evapotranspiration (ET). The IRRIVIVA system automatically adjusts, on a daily basis, the length of watering (i.e. irrigation dose) set by the grower on the time clock system using a correction coefficient (kET), which is as the ratio between the ETo of the previous day and the historical maximum ETo for that week of the year (EToh). In a validation experiment with container-grown red-tip photinia (Photinia x fraseri Dress) and cherry laurel (Prunus laurocerasus L.), the application of IRRIVIVA reduced seasonal water use by 27% and drainage loss by 45%, on average, with respect the timer control system, without showing significant effects of plant growth.
... There is considerable scope for improving water use efficiency of crops by proper irrigation scheduling which is governed by crop evapotranspiration [11,12]. In Ethiopia, although irrigation has long been practiced at different farm levels, there is no efficient and well managed irrigation water practice. ...
... Salient features of any improved method of irrigation is the controlled application of the required amount of water at desired time, which leads to minimization of range of variation of the moisture content in the root zone, thus reducing stress on the plants [20]. Hence, irrigation scheduling is important for developing best management practices for irrigated areas [12,21]. Therefore, this experimental study investigated the effects of different levels of water supply and application frequency on the water use efficiency of garlic on vertisol of the study area. ...
Article
Full-text available
For sustainable utilization of limited available water resources in irrigated agri-culture, accurate estimation of crop water requirements and irrigation scheduling is crucial to improve irrigation water management and crop productivity. There-fore, the objective of this activity was to evaluate the responses of Garlic to the irrigation regime (when and how much to irrigate). The field experiment was conducted at the main station of Debre Zeit Agricultural Research Center during 2016, 2017, and 2018. Five treatments for allowable soil moisture depletion le-vels (ASMDL) of Irrigation at 60%, 80%, 100%, 120%, and 140% were used. Application of irrigation water for Garlic was scheduled when 30% of the total water available in the soil profile was depleted. Treatments’ were laid out in RCBD experimental design with three replications for each treatment. From the study, it has been observed that there was a significant difference in marketable yield and water use efficiency (WUE) among treatments. The maximum market-able bulb yield (7.5 t/ha) and WUE were observed from applying irrigation water at 20% more of recommended ASMDL and followed by 40% more of ASMDL (6.7 t/ha) but the lowest (4.68 t/ha) was recorded at 40% less of recommended ASMDL. Reducing the soil moisture depletion level by 40% and 20% from the recommended fraction (0.25) has significantly increased the water use efficiency. Under irrigated Garlic a shorter frequency with a smaller amount improve yield and water productivity than irrigating with wider interval but a larger amount. Therefore, managing the soil moisture content above the allowable depletion lev-el like 60% ASMDL and 80% ASMDL was better than the recommended allow-able depletion and the other lower levels. Hence it is recommended that for high-er yield and maximum water productivity it is better to irrigate Garlic frequently. (PDF) Optimal Irrigation Scheduling for Garlic (Allium sativum L.) in the Central Highland Vertisols Areas of Ethiopia. Available from: https://www.researchgate.net/publication/352128605_Optimal_Irrigation_Scheduling_for_Garlic_Allium_sativum_L_in_the_Central_Highland_Vertisols_Areas_of_Ethiopia [accessed Nov 04 2021].
... Our results are consistent with other published studies that reported scheduling irrigation based on substrate water status or crop water requirements reduced water use without negative effects on plant growth and quality in comparison with conventional nursery irrigation systems (Basiri Jahromi et al., 2017;Grant et al., 2009;Incrocci et al., 2014;Stoochnoff et al., 2018;Warsaw et al., 2009). An increase or no changes in plant growth after biochar application was reported in different studies during container production (Dumroese et al., 2011;Graber et al., 2010;Headlee et al., 2014;Vaughn et al., 2013). ...
... Substrate solution nutrient concentrations at the end of the experiment were unaffected by biochar rates or irrigation systems (P > 0.05) ( Table 5). Incrocci et al. (2014) reported similar results, indicating that substrate water status and irrigation scheduling did not affect leachate nutrient concentrations, EC, and pH. ...
Article
Full-text available
Controlling irrigation using timers or manually operated systems is the most common irrigation scheduling method in outdoor container production systems. Improving irrigation efficiency can be achieved by scheduling irrigation based on plant water needs and the appropriate use of sensors rather than relying on periodically adjusting irrigation volume based on perceived water needs. Substrate amendments such as biochar, a carbon (C)-rich by-product of pyrolysis or gasification, can increase the amount of available water and improve irrigation efficiency and plant growth. Previous work examined two on-demand irrigation schedules in controlled indoor (greenhouse) environments. The goal of this study was to evaluate the impact of these on-demand irrigation schedules and hardwood biochar on water use and biomass gain of container grown Hydrangea paniculata ‘Silver Dollar’ in a typical outdoor nursery production environment. Eighteen independently controlled irrigation zones were designed to test three irrigation schedules on ‘Silver Dollar’ hydrangea grown in pine bark amended with 0% or 25% hardwood biochar. The three irrigation schedules were conventional irrigation and two on-demand schedules, which were based on substrate physical properties or plant physiology. Conventional irrigation delivered 1.8 cm water in one event each day. The scheduling of substrate-based irrigation was based on the soilless substrate moisture characteristic curve, applying water whenever the substrate water content corresponding to a substrate water potential of –10 kPa was reached. The plant-based irrigation schedule was based on a specific substrate moisture content derived from a previously defined relationship between substrate moisture content and photosynthetic rate, maintaining the volumetric water content (VWC) to support photosynthesis at 90% of the maximum predicted photosynthetic rate. Total water use for the substrate-based irrigation was the same as for the conventional system; the plant-based system used significantly less water. However, plant dry weight was 22% and 15% greater, water use efficiency (WUE) was 40% and 40% greater, and total leachate volume was 25% and 30% less for the substrate based and plant-based irrigation scheduling systems, respectively, than for conventional irrigation. The 25% biochar amendment rate reduced leachate volume per irrigation event, and leaching fraction, but did not affect total water use or plant dry weight. This research demonstrated that on-demand irrigation scheduling that is plant based or substrate based could be an effective approach to increase WUE for container-grown nursery crops without affecting plant growth negatively.
... Recent research suggests further water savings are possible by exploiting the area beyond − 10 kPa tension (Fields et al. 2016). Scheduling irrigation based on substrate water status or a calculated crop evapotranspiration model reduced water use without affecting plant growth and quality in comparison with timerbased irrigation (Incrocci et al. 2014). ...
... Substrate solution pH, EC or nutrient concentration were not affected by irrigation schedule (Table 6). Likewise, Incrocci et al. (2014) found that substrate water status and evapotranspiration-based irrigation scheduling did not affect leachate nutrient, EC and pH compared to timercontrolled irrigation. Leachate EC levels in all of the treatments were in the recommended range of 1.0-3.5 dS m −1 for greenhouse crops as measured by the pour-through method (Cavins et al. 2000), but higher than the recommended range of 0.5-1.0 ...
Article
Full-text available
Developing management practices that make more efficient use of irrigation is important for improving the sustainability of nursery crop production. Integrating refined irrigation scheduling with a substrate amendment like biochar can improve irrigation efficiency. The objective of this research was to evaluate the impact of biochar and need-based irrigation scheduling on gas exchange, plant water relations, and biomass gain of container-grown Hydrangea paniculata ‘Silver Dollar’ with the goal of reducing water use and maintaining or shortening production cycles. Containers were filled with pine bark and amended with either 10% or 25% by volume of hardwood biochar. Plants were automatically irrigated by one of the three irrigation schedules. The irrigation schedules were conventional irrigation, delivering 1.8 cm of water in one event each day, and two on-demand, need-based irrigation schedules. The first was based on the moisture characteristic curve for each of the three substrates developed via the evaporative method. The second was a plant physiology-based irrigation scheduling regime built on the relationship between photosynthesis and substrate moisture content. Scheduling irrigation using a plant physiology or substrate physical properties basis, in combination with biochar, reduced the water requirement for ‘Silver Dollar’ hydrangea without any negative effect on plant dry weight by maintaining sufficient plant water status and gas exchange even just prior to irrigation. Automated irrigation systems coupled with a plant physiology or substrate-based actuation and a water retentive substrate amendment have the potential to reduce nursery crops water use.
... The greenhouse horticulture industry applies more water, fertilizers, and pesticides per unit of production area than any other agricultural system (Molitor, 1990;Rouphael and Colla, 2009). Minimizing water and fertilizers requirements for greenhouse production represents a major sustainability challenge, since many growers are faced with higher fertilizers costs, decreasing availability of good quality water, as well as restrictions and regulations imposed by several European governments (Incrocci et al., 2014;Rouphael et al., 2008). A promising and effective tool to optimize fertigation and to reduce drainage water runoff from greenhouses is to adopt cultivation systems that capture and reuse the drainage solution such as closed soilless systems (Kl€ aring, 2001;Colla, 2005a, 2005b). ...
Article
Full-text available
Implementing nutrient management strategies in soilless culture, which improve water use efficiency (WUE) and limit the loss of eutrophying elements without affecting crop performance, is a priority for the floriculture industry. The aim of the current research was to assess the effect of two nutrient management strategies, based on electrical conductivity (EC) or nitrate-nitrogen (N-NO3–)concentration control on plant growth, ornamental quality, plant-water relations, mineral composition, and WUE of greenhouse Hippeastrum grown in semiclosed soilless system. The recirculating nutrient solution was discharged whenever a threshold EC value of 3.0 dS·m-1 was reached (ECbased strategy), or when N-NO3– concentration decreased below the limit of 1.0 mol·m–3 (nitrate-based strategy). There were no significant differences in terms of plant growth parameters, stomatal resistance, leaf water relations, and macronutrient composition in plant tissues between the two nutrient management strategies. In the EC-and the nitratebased strategies, the recirculating nutrient solution was flushed 10 and 5 times, respectively. The water loss (WL) and the total water use (Wuse) in the EC-based strategy were significantly higher by 261.1% and 61.5%, respectively, compared with the N-NO3–-based strategy. In contrast with the EC-based strategy, the adoption of the N-NO3–-based strategy significantly minimized the nitrate, phosphate, and potassium emissions to the environment. The effective WUE of the system (WUES) recorded in the N-NO3–based strategy was higher by 55.9% compared with the one recorded with the EC-based strategy. © 2016, American Society for Horticultural Science. All rights reserved.
... Where the Evaposensor has been used to schedule (full) irrigation, this approach has been shown to be effective for diverse species . Alternatively, coefficients (K c ) can be estimated from variables such as plant height, to use with reference evapotranspiration (ET o ) calculated from meteorological variables (Incrocci et al., 2014). ...
... In the future, competition between domestic water consumption and that required for nursery production is expected to occur, particularly on the basis of development trends in ornamental crop cultivation for urban areas over the last 10-15 years, which are predicted to continue (ARPAT, 2007). In general, in the Pistoia area, irrigation volumes range from 1000 m 3 ha −1 in soil-bound crops to 10,000-15,000 m 3 ha −1 in container crops (Marzialetti and Pardossi, 2003;Pardossi et al., 2009;Incrocci et al., 2014). These huge volumes of water can increase by 40-50% during the summer season to prevent the salinization of soils, due to the accumulation of nutrients and sodium chloride which can have particularly negative effects on salt-sensitive crops. ...
Article
The growing of ornamental plants for urban greening has significant environmental and economic implications. In particular, the intensive use of peat and high-quality water at the nursery stage is sensitive due to the problems of soil depletion and water salinization even in urban areas. In these contexts, a preference for salinity-resistant species and cultivation techniques based on the substitution of low-impact materials could be beneficial. Here, an experiment has been carried out with two ornamental plant species – cherry laurel [Prunus laurocerasus L.] which is salinity-sensitive, and phillyrea [Phillyrea latifolia L.] which is salinity-resistant – using substrates containing different amounts of biochar in place of peat. Moreover, using irrigation water at two different salinity concentrations, we assess the extent to which the biochar can mitigate salinity damage in these plant species. The results of this study showed that the addition of biochar to the potting medium had no effect on plant growth but crucially limited cherry laurel salinity damage. Tolerance to salinity was attributed to lower Na+ retention in the biochar-containing substrates. Based on these findings, we conclude that the application of biochar not only reduces the amount of peat required in growth substrates, but can also permit the utilization of low-quality irrigation water – thereby also reducing the leaching of nutrients such as K+ and N-NH4+.
... Nevertheless, the applicability of this evapotranspiration-based irrigation scheduling is difficult for growers, since it requires an exhaustive study over several years. For instance, in an experiment conducted on Forsythia intermedia, Photinia fraseri, Prunus laurocerasus L. and Viburnum tinus L. during the summer of four consecutive years (2007-2010), Incrocci et al. (2014) determined the evapotranspiration irrigation scheduling of these species according to the type of container used for the growth. Carmassi et al. (2013) determined the rate of evapotranspiration of Gerbera jamesonii grown under greenhouse conditions in a Mediterranean climate. ...
Article
Ornamental horticultural production is closely associated with a high water consumption and yet the availability of freshwater is reducing. The irrigation of ornamental plants with saline water may be an alternative, but an improvement in knowledge of the effects on salinity on species used as ornamentals is essential. In this review, considering the references from the last decade, we summarized the main effects of salt stress on growth, nutrient, photosynthetic and physiological parameters in ornamental plants. At high salinities, plants exhibit a reduction of growth parameters such as biomass or leaf area related to osmotic and ionic effects of salinity. Growth under saline conditions leads to uptake of Na⁺ and Cl⁻ by plants, which can result in a nutritional imbalance due to the antagonism between nutrients and saline ions with possible effects on the foliage. Salinity can affect water relations in plants and photosynthetic capacity by stomatal limitations. These negative effects can be counteracted by the plants through the accumulation of compatible solutes or osmolytes and the activation of antioxidant machinery. Nevertheless, the performance of these mechanisms is sometimes not enough to avoid damage to the appearance of the plant and in consequence the saleability of an ornamental species. In this review recommendations for the establishment of integrative cultivation practices for nursery growers are made; these include exogenous application of nutrients and osmolytes and enrichment with CO2, in order to mitigate the damage caused by salt stress to ornamental plants.
... The maximum plant uptake of 62.5 mmol m −2 h −1 therefore corresponds with 250 L m −2 h −1 . (B) Using experimental data we found: (1) Plant water uptake was reported to be 0.7 L h −1 m −2 around noon on a summer day for chrysanthemum (Voogt et al., 2000;Janka et al., 2013); 0.7 L h −1 m −2 around noon on a summer day for rose (Baas and van Rijssel, 2006;Incrocci et al., 2014); and 0.5 L h −1 m −2 around noon in early April for tomato (Nederhoff and De Graaf, 1993;Klaring and Zude, 2009). ...
Article
Full-text available
Growing on rooting media other than soils in situ -i.e., substrate-based growing- allows for higher yields than soil-based growing as transport rates of water, nutrients, and oxygen in substrate surpass those in soil. Possibly water-based growing allows for even higher yields as transport rates of water and nutrients in water surpass those in substrate, even though the transport of oxygen may be more complex. Transport rates can only limit growth when they are below a rate corresponding to maximum plant uptake. Our first objective was to compare Chrysanthemum growth performance for three water-based growing systems with different irrigation. We compared; multi-point irrigation into a pond (DeepFlow); one-point irrigation resulting in a thin film of running water (NutrientFlow) and multi-point irrigation as droplets through air (Aeroponic). Second objective was to compare press pots as propagation medium with nutrient solution as propagation medium. The comparison included DeepFlow water-rooted cuttings with either the stem 1 cm into the nutrient solution or with the stem 1 cm above the nutrient solution. Measurements included fresh weight, dry weight, length, water supply, nutrient supply, and oxygen levels. To account for differences in radiation sum received, crop performance was evaluated with Radiation Use Efficiency (RUE) expressed as dry weight over sum of Photosynthetically Active Radiation. The reference, DeepFlow with substrate-based propagation, showed the highest RUE, even while the oxygen supply provided by irrigation was potentially growth limiting. DeepFlow with water-based propagation showed 15–17% lower RUEs than the reference. NutrientFlow showed 8% lower RUE than the reference, in combination with potentially limiting irrigation supply of nutrients and oxygen. Aeroponic showed RUE levels similar to the reference and Aeroponic had non-limiting irrigation supply of water, nutrients, and oxygen. Water-based propagation affected the subsequent cultivation in the DeepFlow negatively compared to substrate-based propagation. Water-based propagation resulted in frequent transient discolorations after transplanting in all cultivation systems, indicating a factor, other than irrigation supply of water, nutrients, and oxygen, influencing plant uptake. Plant uptake rates for water, nutrients, and oxygen are offered as a more fundamental way to compare and improve growing systems.
... Over the past decade, the environmental information based methods for precision management have been widely applied in greenhouse practice. The ambient climate of greenhouse such as temperature, humidity, and root zone water content is monitored closely as the reference for crop management 1 . Water and fertilizer are the most important inputs for greenhouse crop because the plant growth is significantly affected by plant water and nutrition status. ...
Article
Full-text available
Plant-based sensing on water stress can provide sensitive and direct reference for precision irrigation system in greenhouse. However, plant information acquisition, interpretation, and systematical application remain insufficient. This study developed a discrimination method for plant root zone water status in greenhouse by integrating phenotyping and machine learning techniques. Pakchoi plants were used and treated by three root zone moisture levels, 40%, 60%, and 80% relative water content. Three classification models, Random Forest (RF), Neural Network (NN), and Support Vector Machine (SVM) were developed and validated in different scenarios with overall accuracy over 90% for all. SVM model had the highest value, but it required the longest training time. All models had accuracy over 85% in all scenarios, and more stable performance was observed in RF model. Simplified SVM model developed by the top five most contributing traits had the largest accuracy reduction as 29.5%, while simplified RF and NN model still maintained approximately 80%. For real case application, factors such as operation cost, precision requirement, and system reaction time should be synthetically considered in model selection. Our work shows it is promising to discriminate plant root zone water status by implementing phenotyping and machine learning techniques for precision irrigation management.
... Even though time clock scheduling is more reliable than other irrigation techniques, many times, results in a high percentage of drainage and suboptimal root conditions which negatively affect plant growth, as it not always in agreement with the crop transpiration rate values. Incrocci et al. (2014) concluded that there was considerably less water use and nutrient emission depleting into the environment when the irrigation scheduling was based either on the substrate water status or on calculated crop evapotranspiration, as opposed to time clock scheduling. Lizarraga et al. (2003) who evaluated time clock scheduling, with irrigation intervals of an hour, indicated that tomatoes growing in perlite during the afternoon hours were facing water stress conditions, even though the drainage amount was almost 46% of the daily irrigation water applied. ...
Chapter
Excess nitrate in the nutrient solution of some hydroponic crop species has attracted the attention of regulatory agencies because this form of nitrogen can be often toxic to humans, especially children. Inclusion of ammonium in hydroponic nutrient solutions can promote significant increase in productivity and thus, help meet the growing demand for safer foods. However, several factors may alter the availability of ammonium to plants, which may lead to phytotoxicity. However, silicon can mitigate abiotic stresses such as ammonium phytotoxicity, and can be used to prevent possible damage to plants from this form of nitrogen. Therefore, the objective of this review was to gather research information about the nitrogen forms used in hydroponics, their relationships and peculiarities, as well as information on the use of silicon, its available sources and role in mitigating the toxic effects of ammonium.
... The majority of common plant water status estimation methods are based either on evapotranspiration models or soil moisture sensors (Vilsack and Reilly, 2014). Many researchers have worked on these techniques to improve automated precision irrigation timing (Evett et al., 2008;Grabow et al., 2012;Gutierrez et al., 2014;Incrocci et al., 2014;Rutland and Dukes, 2014;Soulis et al., 2015;Vellidis et al., 2008). Because these methods are associated with the complicated soil-plant-atmosphere continuum relationship (Damour et al., 2010;Jones, 2004Jones, , 2014Kramer and Boyer, 1995;Saseendran et al., 2008), some researchers have worked to develop plantbased techniques. ...
Article
Plant-based sensors can potentially be an answer to mitigate the shortcomings of the common plant water status monitoring methods. In this study, leaf thickness and leaf electrical capacitance (CAP) were investigated as indicators of water stress. The experiment was conducted on a tomato plant (Solanum lycopersicum) in a growth chamber with a constant temperature of 28°C and 12 h on/off photoperiod for 11 days. The growth medium used was a peat potting mixture, with its volumetric water content (θ) measured by a soil moisture sensor. The soil water content was maintained at field capacity for the first three days and allowed to dehydrate thereafter, over a period of eight days. The daily leaf thickness variations were minor, with no significant day-to-day changes between soil moisture contents from field capacity to wilting point. However, leaf thickness changes were more noticeable at soil moisture contents below the wilting point until leaf thickness stabilized during the final two days of the experiment when the moisture content reached 5%. The CAP stayed roughly constant at a minimum value during dark periods and increased rapidly during light periods, implying that CAP was a reflection of photosynthetic activity. The daily CAP variations decreased when soil moisture was below the wilting point and completely ceased below the soil volumetric water content of 11%, suggesting that the effect of water stress on CAP was observed through its impact on photosynthesis. The results suggest that leaf thickness and CAP can be used for estimating plant water status.
... Excess irrigation is sometimes applied to leach fertilizer salts that accumulate in containerized substrates (Yeager et al., 1997;Jacobs and Timmer, 2005;Sammons and Struve, 2010). Previous studies suggest that leaching fractions (i.e., 100% − A e ) between 10% and 20% can reduce salt buildup (Moratiel and Martínez-Cob, 2013;Stanley, 2013) and best management practices recommend a 20% leaching fraction (Yeager et al., 1997)-although even higher leaching fractions have been reported in irrigation comparison studies (e.g., ∼35%; Incrocci et al., 2014). In this study, we observed a wide range of leaching fractions from 4.2% up to 41.1%. ...
... Nelle colture ortofloricole e più in particolare nelle colture fuori suolo su substrato, l'incremento dell'efficienza irrigua è una necessità importante, a causa dei loro consumi idrici molto elevati, compresi tra 5.000 e 12.000 m 3 ha -1 all'anno (Carmassi et al., 2013;Bacci et al., 2014;Incrocci et al., 2014). La bassa efficienza irrigua di queste colture si traduce in genere in un'elevata percentuale di drenaggio con conseguente spreco di acqua e nutrienti (Vox et al., 2010). ...
... Concerning the NS, while the sample of field nurseries, with the exception of F12, performed within the threshold, the average value observed for CP was 0.2 mg ha −1 y −1 , which is significantly higher than the threshold value (Grignani et al. 2003). Incrocci et al. (2014), reporting a study previously conducted in the Pistoia District, confirmed that the loss of nitrogen in the container nursery sector was more than 0.1 mg ha −1 y −1 . In addition, Chen, Huang, and Caldwell (2001) showed how fertilization rates for ornamental nursery production exceeded the needs of plants by up to 50%; this fertilizer overuse results in a pollution effect due to nitrogen leaching. ...
Article
Full-text available
Ornamental plant production exerts considerable impacts on the surrounding environment. To assess the environmental sustainability within this sector, a set of impact indicators, which refer to specific management issues in environmental terms, was selected. By comparing the indicators with sustainable thresholds, we assessed the environmental sustainability of a pool of nurseries growing plants in container production (CP) and in open field production (FP) located in the Pistoia Nursery District of the Tuscany Region. Because of their peculiar production structure, the CP nurseries impacted the environment more than the FP nurseries, and hence need more improvements to reach the minimum level of environmental sustainability.
... Since studying leachate contamination of surface and groundwater supplies is costly and time-consuming, due to the need for laboratory experiments and sampling, the use of dynamic tests, such as lysimetric tests, in conjunction with statistical approaches, appears to be a feasible option. Lysimetric experiments are carried out for different purposes, such as to assess the amount of irrigation required for cereals (Incrocci et al., 2014;Kasam et al., 2016;Ostad-Ali-Askari, 2022a;Treder et al., 2017), to indicate the composting effects on biodegradable waste (Elbl et al., 2016;Elbl et al., 2015;Plošek et al., 2017), and to simulate the performance of landfill to reveal leachate quantity and the dynamics of contaminants (Dąbrowska et al., 2019). ...
Article
Predicting leachate pollutants is of prime importance in detecting the amount of pollution in water resources adjacent to sources of leakage. In this study, Electrical Conductivity (EC) as a physicochemical water pollution parameter with the possibility of portable measurement was used as an indicator of leachate quality for the Tychy-Urbanowice operating and closed landfill complex. In order to simulate landfill conditions, two lysimeter experiments were conducted simultaneously. Using sensors mounted in the lysimeters, from the end of November 2018 to the end of December 2019, EC, waste temperature and waste moisture were measured for the open lysimeter and only waste moisture for the closed lysimeter. Additionally, meteorological data obtained from the nearest synoptic station and soil moisture and temperature acquired from the GLDAS satellite were employed as external data to analyze various conditions. Thereafter, Artificial Neural Network (ANN), Neuro-Fuzzy Inference System (ANFIS), and Emotional ANN (EANN) models were developed to determine the parameters affecting the EC value recorded for the open lysimeter and subsequently, predict the missing EC parameter of the closed lysimeter by employing the transfer learning method. Following that, in order to improve the precision of EC predictions, ensemble techniques were applied to the outputs of the models that were developed. The results showed that the moisture of the lysimeters made a significant contribution to the EC value prediction. It is worth mentioning that among ANN, ANFIS, and EANN, the EANN model yielded more precise results in EC estimation, with the average DC above 0.80 and 0.90 for individual and ensembled modeling in both the training and verification phases, respectively.
... Even though time clock scheduling is more reliable than other irrigation techniques, many times, results in a high percentage of drainage and suboptimal root conditions which negatively affect plant growth, as it not always in agreement with the crop transpiration rate values. Incrocci et al. (2014) concluded that there was considerably less water use and nutrient emission depleting into the environment when the irrigation scheduling was based either on the substrate water status or on calculated crop evapotranspiration, as opposed to time clock scheduling. Lizarraga et al. (2003) who evaluated time clock scheduling, with irrigation intervals of an hour, indicated that tomatoes growing in perlite during the afternoon hours were facing water stress conditions, even though the drainage amount was almost 46% of the daily irrigation water applied. ...
Chapter
Hydroponics is a technique of growing plants without soil, in water containing dissolved nutrients. Nowadays, the hydroponics has several applications, such as: (1) Aid in the acclimatization of micropropagated plants, (2) Treatment of wastewaters, (3) Method to produce foods in places of the earth or outside that cannot support crops in the soil, (4) Sustaining the growth of ministumps or microstumps to produce cuttings for plant propagation, (5) Allowing to collect roots without kill the plant to obtain active principles present in the roots in the case of medicinal plants and (6) allowing crop production in larger amount and quality. However, the practice of hydroponics is expensive and one alternative to reduce the production costs is to develop nutritive solutions from byproducts. Several wastewaters that can be used to develop these nutritive solutions are the vinasse, cassava wastewater, corn steep liquor and domestic effluent. Mineral nutrients must be determined to establish the chemical supplementation in some cases. Sometimes, decantation and filtration of wastewaters must be carried out to avoid toxicity to the crops. Adequate dilution of the wastewater is important to avoid salt stress (e.g., only 10% vinasse was used to develop a vinasse nutritive solution for lettuce, rocket and watercress). Crop productivity using wastewater solutions is similar to the commercial solutions used for hydroponics. The use of wastewaters to formulate nutritive solutions represents a rational alternative to wastewaters disposal and adds value to what is currently considered a waste product.
... In view of this great demand, a reduction in the availability of surface and groundwater is expected, as well as an increase in regulations regarding the flow of water and nutrients [6]. In this context, irrigation efficiency in forest nurseries needs to be substantially improved in order to allow them to maintain profitability and minimize environmental impact [7,8]. ...
Article
Full-text available
In forest nurseries, irrigation management becomes more complex as different seedlings of ropical species, with different architectures, are grown close to each other. In this context, there aregaps in knowledge about the physiological responses of species with different mean leaf angles whensubjected to different irrigation depths. Thus, this work aimed to analyze whether mean leaf anglesaffect irrigation efficiency and, consequently, physiological responses of tree seedlings. Six specieswith different mean leaf angles were submitted to three irrigation depths (6, 9, and 12 mm) applieddaily by micro-sprinklers in a completely randomized design in a split plot scheme. The followingvariables were evaluated: leaf water potential, stomatal conductance, relative water content in theleaf, daily transpiration, leaching fraction, and total dry mass. In tree species seedlings with positivemean leaf angles, smaller irrigation depths are already able to increase leaf water potential, stomatalconductance, leaf relative water content, and transpiration efficiency. In contrast, when the mean leafangles are negative, it is necessary to apply larger irrigation depths so that seedling physiologicalresponses do not reduce the production of total dry mass.
... For example, Thompson et al. (2007a) identified the poor management of drip irrigation in greenhouse crops as one of the main causes of nitrate leaching in the Almeria district (southeastern Spain), one of the most concentrated greenhouse areas in the world. Generally, the main cause of over-irrigation is the regulation of irrigation based on the grower's experience rather than on the real water crop needs (Incrocci et al., 2014). Since nutrient use and water are closely related, better water management generally results in improved nutrient use efficiency. ...
... Volumetric water content is believed to be a better method for determining irrigation rates in containergrown crops than ET due to the need to determine specific crop coefficients for numerous cultivars [27]. ET estimates also assume that the crop has access to unlimited water resources, which is often not the case in container-grown crops [28]. Midday leaf water potential has been studied for its use in scheduling deficit irrigation of vineyards, and it has been concluded that the method can increase the precision of irrigation with highly repeatable results [29]. ...
Article
Full-text available
The world's changing climate is placing great pressure on the resources for sustainable viticulture. With this, it has become necessary to investigate grape varieties that are well adapted to hot climates. This study investigated whether two Cypriot varieties (Xynisteri and Maratheftiko) responded differently to Shiraz and Sauvignon Blanc grown under different irrigation regimes (full, 50% and 25%). Irrigation trials were established in Cyprus in 2019 and in Australia in 2020/2021. Vine growth and physiology and fruit composition (field trial only) measurements were recorded. The trial in Cyprus in 2019 demonstrated that for all three irrigation regimes, Xynisteri had higher stem water potential, stomatal conductance, chlorophyll and greater biomass than Sauvignon Blanc under all irrigation regimes. In 2020/2021, Xynisteri had a greater biomass than Maratheftiko and Sauvignon Blanc, with Shiraz having the lowest. Under reduced irrigation, Xynisteri and Mara-theftiko had higher stem water potential, stomatal conductance and chlorophyll content than Shiraz and Sauvignon Blanc. These results indicate that Xynisteri in particular may possess better cultivar-specific growth traits than Shiraz and Sauvignon Blanc when grown under the same environmental conditions and in turn may be a more appropriate choice in areas where water is limited.
... Volumetric water content is believed to be a better method for determining irrigation rates in containergrown crops than ET due to the need to determine specific crop coefficients for numerous cultivars [27]. ET estimates also assume that the crop has access to unlimited water resources, which is often not the case in container-grown crops [28]. Midday leaf water potential has been studied for its use in scheduling deficit irrigation of vineyards, and it has been concluded that the method can increase the precision of irrigation with highly repeatable results [29]. ...
Preprint
The world’s changing climate is placing great pressure on the resources for sustainable viticulture. With this, it has become necessary to investigate grape varieties that are well adapted to hot climates. The aims of this study were to (1) assess the response of Xynisteri to different irrigation regimes, and (2) compare the performance of Xynisteri, Maratheftiko, Shiraz and Sauvignon Blanc grown in pots with different irrigation regimes. Trial one was established in a commercial Xynisteri vineyard in Cyprus under three different irrigation regimes - full, 50% and no irrigation in 2019. Trial two compared three irrigation regimes - full, 50% and 25% in a potted trial of Xynisteri and Sauvignon Blanc conducted in Cyprus in 2019. Trial three was a potted trial of Xynisteri, Sauvignon Blanc, Maratheftiko and Shiraz with the same three irrigation regimes conducted in Australia in 2020/21. Vine performance and physiology measurements were taken in both trials. Fruit composition analysis, yield (field trial only), shoot, trunk and root mass measurements were performed at the end of the season. Few differences between measures were found between irrigation regimes in the field trial. Fruit composition analysis revealed fructose to be lowest in the full irrigation group compared to deficit and no irrigation treatments. The potted trial in 2019 demonstrated that for all three irrigation regimes, Xynisteri had higher stem water potential, stomatal conductance and chlorophyll content than Sauvignon Blanc. Xynisteri produced greater end of season root, shoot and leaf mass than Sauvignon Blanc under all irrigation regimes. In 2020/21, Xynisteri had greater end of season root, shoot and leaf mass than Maratheftiko and Sauvignon Blanc with Shiraz the lowest. Few significant differences in stem water potential were observed in the early stages of the trial. However, toward the end of the trial and with reduced irrigation, Xynisteri and Maratheftiko had higher stem water potential than Shiraz and Sauvignon Blanc. Xynisteri had higher stomatal conductance and chlorophyll content than Maratheftiko and both were higher than Sauvignon Blanc and Shiraz. These results indicate that Xynisteri in particular may possess better cultivar specific growth traits than Shiraz and Sauvignon Blanc when grown under the same environmental conditions and in turn may be a more appropriate choice in areas where water is limited.
... Due to the scarcity of water resources, the correct evaluation of water losses by the crops as evapotranspiration is very important (Bhavsar and Patel, 2016).Plant water needs are estimated based on climatic parameters including air temperature, solar radiation, relative humidity and wind speed recorded by weather stations (Incrocci et al., 2014). These parameters help to determine the reference evapotranspiration (ET0) that can be calculated by many mathematical models. ...
Article
Full-text available
Accurate estimation of evapotranspiration of rapeseed is essentially required for irrigation scheduling and water management. The present study was undertaken during 2015-16 and 2017-18 in ICR Farm, Assam Agricultural University, Jorhat to determine the crop coefficients (Kc) and estimate evapotranspiration of rapeseed using lysimeter and eight reference evapotranspiration models viz. Penman-Monteith, Advection-Aridity (Bruitsaert-Strickler), Granger-Gray, Makkink, Blaney-Criddle, Turc (1961), Hargreaves-Somani and Priestly-Tailor models. During 2015-16, the crop coefficients were developed by these models. Actual evapotranspiration was determined by three weighing type lysimeters. During 2017-18, evapotranspiration was estimated by multiplying reference evapotranspiration with Kc derived by different models and compared with actual evapotranspiration estimated by lysimeter during similar growing periods. All the models except Turc (1961) showed less than 10% deviation between actual and estimated ET. The estimated evapotranspiration using Penman-Monteith and Priestly-Tailor reference evapotranspiration recorded the lowest MAE and RMSE. The study revealed that estimated evapotranspiration using Penman-Monteith reference evapotranspiration gave the best estimate of evapotranspiration of rapeseed followed by Priestly-Tailor. The crop coefficients for initial, mid and end stages were 0.83, 1.20 and 0.65, respectively for Penman-Monteith and 0.70, 1.05 and 0.55, respectively for Priestly-Tailor.These results can be used for efficient management of irrigation water for rapeseed.
... The majority of overhead applied irrigation fails to reach the containerized plant, with 74-87% landing in the inter-container spaces (Davies et al. 2016;Million and Yeager 2015;Pershey et al. 2015), with container spacing and crop canopy architecture further influencing application efficiency (Beeson and Yeager 2003). Microirrigation systems such as in-container spray stake irrigation are an alternative to overhead irrigation, and provide water directly to crop containers; however, this application method is often reserved for larger containers (typically over 19 L) since increased container spacing and canopy size for larger plants further reduces application efficiency and justifies the installation and maintenance investment required for microirrigation systems (Beeson and Knox 1991;Incrocci et al. 2014Incrocci et al. , 2019Majsztrik et al. 2017). ...
Article
Full-text available
The production of nursery crops demands substantial irrigation, with overhead irrigation the most common method of application ; however, this method is inefficient with respect to water used and the precision with which it is applied, resulting in the generation of irrigation return flow and concomitant agrochemical export. Microirrigation systems such as individual container spray stakes provide water directly to crops thus applying water more efficiently than overhead systems but may be more costly in terms of installation (smaller pipes and components; however, a greater quantity of pipes and components) and maintenance. The study was conducted at the Michigan State University Research Nursery, where four ornamental shrub taxa were produced in #3 (11.3 L) containers using a control with 19 mm overhead irrigation per day and a conventional phosphorus fertilizer (Conv) (19-2.16-6.64), compared with four treatments: a static, daily (2 L per container) spray stake irrigation (SS2Lpd) and conventional phosphorus fertilizer; a static daily (2 L per container) spray stake irrigation and low phosphorus fertilizer (LowP) (19-1.62-6.64); spray stake irrigation based on substrate volumetric water content (θ) (up to 2.4 L per container) (SSθ) and conventional fertilizer; and spray stake irrigation based on θ (up to 2.4 L per container) and low phosphorus fertilizer. Spray stakes reduced irrigation by 76-80% compared to the overhead control, and reduced the generation of both surface and subsurface irrigation return flow (IRF), mitigating the movement of both N and P (over 98% reduction in surface IRF). Plant growth index (GI) was measured on 12 June 2017 and 6 October 2017, followed by a destructive harvest to measure shoot dry weight, and shoot nutritional content. For all four taxa, microirrigation systems were capable of producing plants of equivalent GI and shoot nutritional concentration; however, plants receiving the low phosphorus fertilizer produced less shoot biomass. Microirrigation is effective in reducing water use, water lost to IRF (particularly surface IRF), and associated fertilizer movement, while maintaining crop size.
... Among different kinds of plant sensors used, monitoring of plant stem microvariation and leaf-air temperature differences, were found to be the most promising indicators for scheduling irrigation and to determine plant water stress (Fernández and Cuevas, 2010;Isoda, 2010;Naeeni et al., 2014;Nikolaou et al., 2017b). Irrespectively of monitoring the plant or not, the question arises whether it is necessary to shorten or lengthen the watering intervals (i.e., frequency of irrigation) with smaller or larger amount of water (i.e., dose of irrigation), as the irrigation scheduling proved to affect plant growth and production but also the percentage of nutrient amount outflow from the greenhouse to the environment in the case of soilless cultures (Savvas et al. 2007;Ta et al., 2012;Incrocci et al., 2014). Usually there are compromises with irrigation by slowing the submission of watering or watering with smaller sized irrigation norms. ...
Article
Full-text available
An experiment with a soilless cucumber crop (cv. Phenomeno) was conducted in order to evaluate the influence of two different cooling systems (i.e., whitewash as opposed to fan-wetted pad evaporative) on the greenhouse microclimate and on plant growth under high 0.32 mm and low 0.24 mm irrigation dose treatments. The results revealed that the transpiration rate was higher in the whitewash compartment, which resulted in less outflow of nutrient solution into the environment. In regards to the total greenhouse water use efficiency, no differences were obtained between the two different cooling systems, taking into account the amount of water used by the evaporative system per se. Irrigation doses tested did not significantly affect crop production. According to the results obtained, whitewash shading proved to maintain greenhouse cucumber growth and production throughout the spring cropping period in comparison with the use of an evaporative cooling system.
... Demand for ornamental plants has been significantly increasing during the past decade (Incrocci et al. 2014) for purposes of urban decoration and gardening and also for environmental restoration and bioremediation (Denys et al. 2006;Sun et al. 2011). This fact, in combination with the abovementioned aspects, implies a double challenge for the plant nursery industry, which will have to increase its production (Savé et al. 1999) and, at the ____________________________________________________________________________________________________________________ same time, reduce its water inputs through resource optimization. ...
Article
Full-text available
A detailed, species-specific comprehension of plant water behavior can be a central tool to improve water management in nursery production and irrigated landscapes. Potted plants of Nerium oleander, Pit-tosporum tobira, and Ligustrum japonicum 'Texanum' were exposed to controlled increasing drought conditions in greenhouse. Water use, gas exchange, and foliar thermoregulation were monitored along the trial. N. oleander showed the most efficient response to increasing water stress, maintaining high levels of gas exchange and evapotranspiration rate during the whole trial, whereas L. japonicum emerged as the most sensitive species, with a significant drop in physiological performances already from the second day. The more aggressive water behavior of N. oleander can be compared to the one of anisohydric plants, whereas L. japonicum displays an isohydric strategy. P. tobira showed intermediate characteristics between the two other species. This work comes to provide useful tools for the management of irrigation in plant nursery and for decision making in the use of ornamental shrubs for landscape applications. Abbreviations: ET-evapotranspiration (mm); ETEh-hourly evapotranspiration (mm·h-1); gs-leaf stomatal conductance (mol·m-2 ·s-1) (where gspor = measured values and gscal = calculated values); RG-incident radiation (MJ·m-2 ·h-1); VPD-vapor pressure deficit (kPa); C.C.-container capacity (%); ET/RG (g·MJ-1)
... Thus, lysimeter studies seem to be a promising alternative. These tests are used both to assess the size of irrigation requirements for cereals [32,39,46] to demonstrate the effect of compost [10,11,33] and to simulate the conditions prevailing in landfill [3,27,35]. The lysimeter experiment allows us to determine the value of contamination loads and the dynamics of their elution [1,35,41]. ...
Article
Full-text available
The size and chemical composition of leachates migrating into the aquifer are dependent on the parameters of the waste and the storage conditions. Lysimeter studies allow us to determine the size and chemical composition of leachates as well as the leachate water balance. Lysimeter studies were conducted on a 230-L municipal waste sample for 6 months. During the tests, the specific electrolyte conductivity, pH, Eh, and temperature, as well as the chemical composition, microbiological analysis, and profiling of physiological population level using EcoPlate™ microarrays were measured in collected leachate samples. During the entire experiment, the amounts of inflow and outflow from lysimeters were measured. To assess the existence of significant differences in the chemical component concentrations in leachates, use of Principal Component Analysis was taken into account. The maximum EC value from leachate from the lysimeter was 33 mS/cm. High concentrations of ammonium ion (up to approx. 1400 mg dm⁻³), chlorides (up to approx. 6800 mg dm⁻³), and iron (up to approx. 31 mg dm⁻³) were observed in the effluents. The number of enterococci in May reached 53,000 cells/100 ml. By contrast, the number of these microorganisms was about 15,000 and 16,000 CFU/100 ml in January and April, respectively. Community-level physiological profiling indicates that the activity and functional diversity of microorganisms were higher in the leachate samples obtained in winter compared to effluents collected from lysimeters in spring.
... Generally, chemical weed control is overall carried out by using oxadiazon during weed pre-emergence growth and localized glyphosate during their post-emergence weed elongation (Marble et al., 2015). Even when applied precisely, chemical herbicides can leach out with the irrigation water (Horowitz and Elmore, 1991;Zhigang, 2010) often supplied in excess to prevent salt accumulation that is harmful in containerized ornamental plants (Incrocci et al., 2014;Vox et al., 2010). Nonetheless, growers use to apply chemical herbicides at fixed rate without taking into account the different capability of competition that cultivated plants can naturally exert against weeds. ...
... Even though time clock scheduling is more reliable than other irrigation techniques, many times, results in a high percentage of drainage and suboptimal root conditions which negatively affect plant growth, as it not always in agreement with the crop transpiration rate values. Incrocci et al. (2014) concluded that there was considerably less water use and nutrient emission depleting into the environment when the irrigation scheduling was based either on the substrate water status or on calculated crop evapotranspiration, as opposed to time clock scheduling. Lizarraga et al. (2003) who evaluated time clock scheduling, with irrigation intervals of an hour, indicated that tomatoes growing in perlite during the afternoon hours were facing water stress conditions, even though the drainage amount was almost 46% of the daily irrigation water applied. ...
Chapter
This chapter describes the irrigation management techniques that are currently used for scheduling irrigation in a hydroponic culture. Precise irrigation should involve the determination of the timing and the quantity of each irrigation event which may be estimated based on the climate of the greenhouse, monitoring of the substrate, or evaluated different plant indicators of water stress. Depending on the crop growth stage, irrigation could also be used as a tool for stimulating vegetative or productive growth, or affecting the rate of drainage emissions and thus the quantity of water and nutrient outflow from the greenhouse to the environment. For many years, irrigation was applied to crops at fixed time intervals and quantities (i.e., time clock scheduling) and, more recently by estimating the quantity of solar energy corresponded to the irrigation dose consumed by the transpiration. However, it has been well documented that none of these two methods are sufficiently accurate to satisfy the crop irrigation needed when used as a solo criterion for irrigation. In principle, a time lag between water supply and transpiration often occurs in the case of time clock scheduling, while irrigation based on solar radiation is not taking into account other climatic factors which affects transpiration, such as the vapor pressure deficit.Therefore, irrigation scheduling should be based on more complex evapotranspiration models, which correlate to greenhouse climatic and plant data. As the climate equipment used in modern greenhouses allows for the computerized prediction of transpiration rates on a real time basis, the water used by the plant can be estimated accurately in a short interval rate. Under these circumstances a variety of evapotranspiration models which were originally developed by the Penman-Monteith equation which can be effectively used in soilless greenhouse production. However, the model equation coefficients must firstly be calibrated for the specific crop under the prevailing greenhouse environmental conditions. Other than direct measurement of plant transpiration, lysimeters may be the only way of calibrating evapotranspiration models, as it has been used to greatsuccess over the past few decades for the estimation of transpiration for field and greenhouse cultivations as well. Alternatively optimal approaches to irrigation control may include plant stress sensing as opposed to climate or substrate irrigation based approaches. Physiological real-time monitoring for assessing the dynamics of plant water status, seems to be of great value for tuning irrigation and developing crop water stress indices.
... Installation and management of injectors at small, site-specific zones would be simplified by using wireless sensing and control technology. Wireless networks and sensors have been tested in nursery environments and have been shown to be effective management tools (Balendonck et al., 2008;Pardossi et al., 2009;Coates et al., 2013;Incrocci et al., 2013;Lea-Cox et al., 2013). ...
Article
Site-specific fertigation can limit fertilizer waste and loss to the environment, but is not easily implemented when there are many small hydrozones, each demanding a unique rate of fertilizer application. With a simple and inexpensive fertilizer injection system, a separate injector could be installed at each zone to provide a unique fertilizer delivery rate, even when those zones are in simultaneous operation. Integration with a wireless control network would allow automated adjustment of the fertilizer delivery rate for each hydrozone and aid installation in existing facilities. A variable-rate injector was developed using a simple venturi injector, solenoid valve, electrical conductivity (EC) sensor, and small computer board (controller). EC was related to fertilizer concentration expressed as parts-per-million (ppm) nitrogen (N). Fertilizer injection rate was controlled by opening and closing a solenoid valve connected to the suction line of the venturi injector. The rate was adjusted by changing the valve duty cycle (percentage of time that the valve was open). For initial testing with a 2000 ppm N stock solution, the duty cycle was manually adjusted from 0 to 100% to deliver an applied fertilizer concentration of 0 to 200 ppm N at an injection ratio of about 1:10. For closed-loop control, the controller was programmed to monitor EC and automatically increase or decrease the valve duty cycle in order to achieve the target fertilizer concentration. The root mean square percentage error for the closed-loop control injection system was 4.8% in laboratory tests over a target range of 0 to 200 ppm N. A mobile injector station was assembled and integrated with a wireless sensor and control network in order to test adjustable-rate fertigation in container nurseries. Field trials to deliver specified nitrogen concentrations to several different nursery beds gave a root mean square percentage error of 2.2% over a target range of 50 to 150 ppm N. The fertilizer concentrations matched that specified by the user, indicating that the system did a good job of adjusting the duty cycle to meet the target rate, and the irrigation and fertilizer injection durations were correct. Furthermore, the wireless network performed well and exhibited acceptable range.
Conference Paper
Full-text available
In most parts of Sri Lanka, water is the critical factor for cultivation. Using the appropriate amount of water is the key factor and therefore efficient water management is very important to increase food production. Common practice of Irrigation water distribution is with the help of Irrigation Department Guidelines. Present work is a study of irrigation water issue practice in Rajangana Irrigation Scheme situated at Anuradhapura which is a district the North Central Province of Sri Lanka. The present study using field data from 2008-2013, computed the theoretical irrigation water requirements as recommended by the Guideline using 75% probable rainfall values and this was named as " Recommended Irrigation Plan", Then this plan was modified with the consideration of actual rainfall that had been experienced during operations. This modification represented the actual water issues that need to be anticipated during operation and hence was named as "Anticipated water use". At the Rajangana Irrigation scheme there is also the actual plan developed for each year along with the water issue at the sluice gate corresponding to the 2008-2013 period. The present research compared the case of Left Bank gravity fed irrigation area which covers an approximate 2500 Ha area with 39 Km tertiary canal network. This area is cultivated mainly with paddy for two main rainy seasons namely "Maha" and "Yala". Water issue model for the study was developed at a weekly time resolution. Comparison of actual water use with the quantities are computed by following Irrigation Department Guidelines disclosed a significant over issue in Maha and Yala seasons amounting to 63% and 52% respectively. In the case of making adjustment to the plan with the receipt of actual rainfall, then a further reduction of water issue by 35% and 8% in Maha and Yala respectively could have been possible. Evaluation revealed the need of gauge network, a spatially distributed performance monitoring system and a critical evaluation on the base of present Guideline in order to suitably manage the water utilization in the Rajangana Left bank irrigation scheme.
Article
The shortage of water in many parts of the world has led to the development of new irrigation strategies such as regulated deficit irrigation and sustained deficit irrigation. Water deficit induces different morphological and physiological responses in ornamental plants, but the application of irrigation strategies can obtain quality plants well adapted to the environment. Deficit irrigation controls plant growth, and can be considered a sustainable technique which avoids the use of plant growth regulators. In addition, root system morphology can be modified by water stress to improve the ability to extract water from the soil and strengthen a plant’s physical support. In addition, the application of deficit irrigation during nursery period is a technique frequently used to harden plants before transplanting. Water deficit affects morphological and physiological aspects that might provide a capacity to adapt to adverse conditions. All these features contribute to increasing water use efficiency and the root to shoot ratio and root density, promoting the more rapid establishment of ornamental plants in garden or landscape settings. In view of the results obtained, it is possible to apply and validate the most appropriate irrigation strategy for each species and to obtain the full benefits of applying deficit irrigation. Abbreviations: DI, Deficit irrigation; ETc, Crop evapotranspiration; gs, stomatal conductance; Pn, Net photosynthesis; RDI, Regulated deficit irrigation; SLA, Specific leaf area; WUE, Water use efficiency
Article
We evaluated mycorrhizal responses of two container-grown ornamental shrubs, Photinia x fraseri and Lantana camara cultivated in soilless substrate with two fertilization regimes and inoculated with two mycorrhizal inocula, a commercial one (Symb) and an experimental one (MicroLab). Fertilization rate, inoculum type and plant genotype differentially affected mycorrhizal colonization, plant growth and mineral nutrition. At high fertility levels a significant reduction of mycorrhizal colonization occurred in both shrubs inoculated with Symb, while MicroLab successfully colonized L. camara roots. In P. fraseri MicroLab increased shoot dry weight at low fertility by 44.3% and 78.6% compared with control and Symb, respectively. In L. camara Symb increased plant height and shoot fresh weight at both fertility levels, compared with MicroLab and Control. Our work shows that host plant/mycorrhizal symbionts compatibility and fertilization may modulate the establishment and performance of mycorrhizal symbioses in container-grown woody ornamentals.
Article
Full-text available
El intervalo hídrico óptimo, basado en umbrales de humedad volumétrica en el sustrato (θvs), permite un control preciso del volumen y la frecuencia de riego. Se determinaron los umbrales de θvs para el manejo del riego en los cultivos de tomate y chile dulce en fibra de coco en los invernaderos de la Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM), Alajuela, Costa Rica, en el 2015. En ambos cultivos se aplicó un tratamiento con riego (CR) y otro sin riego (SR), en un diseño completamente aleatorio. Se evaluó el contenido de θvs, el potencial hídrico (ψh) y la temperatura de la hoja (Th) y se estimó la evapotranspiración de ambos cultivos mediante un balance de agua en el sustrato. El umbral de θvs en la fibra de coco, para el manejo del riego en ambos cultivos, podría establecerse en el rango de agua fácilmente disponible de 56% a 38%, donde los valores de ψh fueron inferiores al umbral crítico de < -1 MPa reportado por diferentes autores y las Th fueron similares a la temperatura del aire. En los tratamientos CR, los promedios de θvs en tomate (44%) y chile dulce (50%) estuvieron dentro del rango de agua fácilmente disponible (38% a 56%) de la fibra de coco. En las pruebas SR de ambos cultivos, la θvs descendió a un valor promedio de 32%, próximo al punto de marchitez permanente. En ψh y Th las diferencias entre experimentos fueron de mayor magnitud al m.d. del día 2, donde los tratamientos CR fueron -0,84 MPa en tomate y -0,98 MPa en chile dulce; mientras que en las prácticas SR fueron -1,24 MPa en tomate y -1,3 MPa en chile dulce. Al m.d. del día 2, las Th de ambos cultivos en los diseños SR y CR fueron similares e inferiores, respectivamente, a la temperatura del aire (32,9°C).
Article
To design a suitable drip irrigation strategies for tomato production, an experiment was laid out in a randomized complete-block design, six treatments, which completely combined with three drip irrigation frequencies and two drip times were carried out in 2020 and 2021 with the variety “Heshengfeilong” tomatoes in the greenhouse. Four single comprehensive evaluation methods: PCA, TOPSIS, MFA, and GRA were used to comprehensively evaluate the fruit quality. Fuzzy Borda combined evaluation was performed on each comprehensive evaluation result that passed the pre-consistency test (Kendall-W). We found that MFA is the most suitable for evaluating the comprehensive fruit quality because its ranking results have the highest correlation coefficient with fuzzy Borda in 2020 and 2021, namely, 0.989 and 0.994, respectively. Total soluble solids (TSS) can be used as a single indicator representing the comprehensive fruit quality because it has a significant positive correlation with the comprehensive quality score in two years. The results of the TOPSIS evaluation of the TSS and the yield show that the optimal treatment in this experiment is for drip irrigation at 9:00, 11:00, 13:00, 15:00, and 17:00. The K-means clustering algorithm was used to determine the change in moisture content corresponding to different temperature ranges and further determine the irrigation strategy, which is the drip irrigation frequency of 5 times/day, and the drip irrigation volume was obtained according to the change in moisture content. During the day (9:00–19:00), the change in the substrate moisture content is divided into three temperature ranges, namely, 5.90–23.98 °C, 23.98–37.42 °C, and 37.42–53.58 °C, corresponding to 0.44%/2 h (40 ml/2 h), 1.34%/2 h (121 ml/2 h), 2.26%/2 h (203 ml/2 h), respectively. During the night (19:00–9:00 the next day), the change in the substrate moisture content is 0.19%/2 h (17 ml/2 h).
Article
Full-text available
The primary goal of this study was to determine the optimum number of substrate moisture sensors needed to accurately determine substrate water content for 10 tree species in a containerized nursery. We examined variation in volumetric water content (VWC, m(3).m(-3)) within containers, within species, among species, and over time. Across time, differences among species were not significant (P = 0.14). However, differences among time periods and the interaction effect between species and time periods were significant (P<0.001). Seasonal differences in within-species variation were also evident in nine of the 10 species. In an attempt to understand species-specific mechanistic factors that influence within-species variation in VWC, we accounted for physiological and morphological differences affecting transpiration with a spatially explicit mechanistic model, MAESTRA. Neither estimated transpiration rate per whole crown or m(2) of leaf area could explain variation in VWC. Based on our results, we recommend species-specific sensor deployment and report sensor quantities that estimate the mean substrate VWC of each species within a confidence interval of +/- 5% VWC. Given the economic value of water and its control on biomass production, we conclude that nursery managers can maintain optimal substrate moisture with minimal sensor deployment.
Article
Full-text available
The disposal of used growing media represents one of the weak points for the application of hydroponic technology to greenhouse and nursery production. In many cases, especially mineral wools, exhausted substrates are disposed to landfill. However, landfill costs are increasing and landfill sites are becoming ever more unavailable. Thus, substrate reutilization must be strongly encouraged along with the reduction of substrate volume applied per plant. The paper reports a literature survey on the biological, technological and environmental implications of the reuse of exhausted substrates in soilless culture.
Article
Full-text available
Visions of the future for container nursery irrigation were collected from twelve nursery irrigation scientists, growers and nursery organization leaders. The amount of water available for nursery irrigation unanimously is forecasted to decline over the next decade. Along with declining availability, the cost of water for irrigation is predicted to increase substantially for most nurseries. Limited availability, higher direct cost, and irrigation runoff issues are projected to compel the container nursery industry to adopt procedures and technology that will increase irrigation water use efficiency. Evidence in support of these prognoses, current solutions and suggested options are discussed.
Article
Full-text available
. In many sectors of agricul-ture, precision irrigation, applying only what water is needed for a given small area, has become a familiar term. Irrigation in most woody orna-mental nurseries, though, has changed little since the 1960s. In many areas of the U.S., irrigation volumes re-quired for nursery production have come under scrutiny due to projected, or real, competition for water with urban populations, or concerns over nursery runoff. Modeling of woody ornamental water use, and subse-quent irrigation requirements, has been limited and focused mostly on trees. Previous research for modeling of non-tree water use is reviewed as an introduction to current efforts to develop models for precision irriga-tion of woody ornamentals. Pitfalls and limitations in current model-ing efforts, along with suggestions for standardizing future research is emphasized. The latest model derived from recent research is presented.
Article
Full-text available
Crop coefficients, which define the relationship between estimated evapotranspiration from a standard reference crop and actual evapotranspiration of a specified crop, are generally not known for hardy ornamental nursery stock (HONS) crops. This severely limits the application of a sensor, known as the ‘Evaposensor’, which generates an electrical signal proportional to potential evapotranspiration, for irrigation scheduling of HONS. We therefore attempted to develop a method for the rapid estimation on the nursery of appropriate crop-specific calibration factors for use with the Evaposensor. Calibration factors were calculated for a range of HONS crops through the growing season, in a series of experiments under plastic tunnels or outdoors. Across all crops and over a growing season, 76% of the variation in calibration factors under a plastic tunnel could be explained by a combination of plant height, leaf area and stomatal conductance. For the same crops grown outdoors, 77% of the variation could be explained by these variables along with percentage cover. Plant height and percentage cover, which can both be easily and rapidly measured on commercial nurseries, alone explained 64 and 57% of the variation under plastic and outdoors, respectively.
Article
Full-text available
The primary goal of this study was to determine the optimum number of substrate moisture sensors needed to accurately determine substrate water content for 10 tree species in a containerized nursery. We examined variation in volumetric water content (VWC, m 3m 3) within containers, within species, among species, and over time. Across time, differences among species were not significant (P = 0.14). However, differences among time periods and the interaction effect between species and time periods were significant (P < 0.001). Seasonal differences in within-species variation were also evident in nine of the 10 species. In an attempt to understand species-specific mechanistic factors that influence within-species variation in VWC, we accounted for physiological and morphological differences affecting transpiration with a spatially explicit mechanistic model, MAESTRA. Neither estimated transpiration rate per whole crown or m 2 of leaf area could explain variation in VWC. Based on our results, we recommend species-specific sensor deployment and report sensor quantities that estimate the mean substrate VWC of each species within a confidence interval of ± 5% VWC. Given the economic value of water and its control on biomass production, we conclude that nursery managers can maintain optimal substrate moisture with minimal sensor deployment.
Article
Full-text available
Irrigation by help of freshwater resources in agricultural areas has a crucial importance. Because of highly increasing demand for freshwater, optimal usage of water resources has been provided with greater extent by automation technology and its apparatus such as solar power, drip irrigation, sensors and remote control. Traditional instrumentation based on discrete and wired solutions, presents many difficulties on measuring and control systems especially over the large geographical areas. This paper describes an application of a wireless sensor network for low-cost wireless controlled irrigation solution and real time monitoring of water content of soil. Data acquisition is performed by using solar powered wireless acquisition stations for the purpose of control of valves for irrigation. The designed system has 3 units namely: base station unit (BSU), valve unit (VU) and sensor unit (SU). The obtained irrigation system not only prevents the moisture stress of trees and salification, but also provides an efficient use of fresh water resource. In addition, the developed irrigation method removes the need for workmanship for flooding irrigation. The designed system was applied to an area of 8 decares in a venue located in central Anatolia for controlling drip irrigation of dwarf cherry trees.
Article
Full-text available
An autonomous weighing lysimeter system is explained in detail for quantifying water use for a wide range of species and plant sizes in greenhouse and outdoor environments. Complete computer programs for managing these systems are provided. The system is scalable and based on the direct measurement of mass using hermetically sealed and temperature compensated S-type load cells. It is designed for measurement of single plants growing in low bulk density substrates in containers suspended from above. With light substrates matched to load cell capacity, accuracies up to 0.25 g kg-1 measured (0.025%) can be achieved. An example of programming versatility for the study of long term deficit irrigation on shrub and tree growth is reviewed. A single value in the program regulates adjustable rates of controlled implementation of water stress that can be sustained once the desired level is achieved. Details and examples of mechanical components are provided along with solutions to issues that arose over time. A web page for complete programs written in EDLOG and CRBasic for 16 lysimeter systems is provided for reference for discussions of key programming components. The system is amendable to any crop that can be grown in low bulk density substrates where the emphasis is on transpiration and plant size, while root volume or extent is of minimum concern.
Article
Full-text available
Water use and plant growth and quality were compared across different nursery stock beds, different methods of applying irrigation, and different methods of scheduling irrigation. With overhead irrigation, scheduling of irrigation according to plant demand, along with an irrigation system designed to maximise irrigation uniformity, resulted in substantial water savings, without reducing plant quality. This was the case in both wet and dry years. In the dry year, plant quality was particularly good when grown on a sub-irrigated sand bed; this system also used less water than any of the overhead irrigation systems. Two different systems were effective in scheduling overhead irrigation, one based on the volumetric moisture in the growing substrate, and the other based on plant evapotranspiration. The latter was determined with a small sensor with wet and dry artificial “leaves”, the output of which correlated with that obtained following the Penman–Monteith method based on a full set of meteorological data.
Article
Full-text available
Crop irrigation uses more than 70% of the world's water, and thus, improving irrigation efficiency is decisive to sustain the food demand from a fast-growing world population. This objective may be accomplished by cultivating more water-efficient crop species and/or through the application of efficient irrigation systems, which includes the implementation of a suitable method for precise scheduling. At the farm level, irrigation is generally scheduled based on the grower's experience or on the determination of soil water balance (weather-based method). An alternative approach entails the measurement of soil water status. Expensive and sophisticated root zone sensors (RZS), such as neutron probes, are available for the use of soil and plant scientists, while cheap and practical devices are needed for irrigation management in commercial crops. The paper illustrates the main features of RZS' (for both soil moisture and salinity) marketed for the irrigation industry and discusses how such sensors may be integrated in a wireless network for computer-controlled irrigation and used for innovative irrigation strategies, such as deficit or dual-water irrigation. The paper also consider the main results of recent or current research works conducted by the authors in Tuscany (Italy) on the irrigation management of container-grown ornamental plants, which is an important agricultural sector in Italy.
Article
Full-text available
The theoretical background of modeling the gap fraction and the leaf inclination distribution is presented and the different techniques used to derive leaf area index (LAI) and leaf inclination angle from gap fraction measurements are reviewed. Their associated assumptions and limitations are discussed, i.e., the clumping effect and the distinction between green and non-green elements within the canopy. Based on LAI measurements in various canopies (various crops and forests), sampling strategy is also discussed.
Article
Full-text available
Sensor technology, which benefits from high temporal measuring resolution, real-time data transfer and high spatial resolution of sensor data that shows in-field variations, has the potential to provide added value for crop production. The present paper explores how sensors and sensor networks have been utilised in the crop production process and what their added-value and the main bottlenecks are from the perspective of users. The focus is on sensor based applications and on requirements that users pose for them. Literature and two use cases were reviewed and applications were classified according to the crop production process: sensing of growth conditions, fertilising, irrigation, plant protection, harvesting and fleet control. The potential of sensor technology was widely acknowledged along the crop production chain. Users of the sensors require easy-to-use and reliable applications that are actionable in crop production at reasonable costs. The challenges are to develop sensor technology, data interoperability and management tools as well as data and measurement services in a way that requirements can be met, and potential benefits and added value can be realized in the farms in terms of higher yields, improved quality of yields, decreased input costs and production risks, and less work time and load.
Article
Full-text available
A frequency domain dielectric sensor (WET®), which measures permittivity (ε), temperature (T, °C) and bulk electrical conductivity (σ, dS/m) simultaneously in the same soil volume, was calibrated for the volumetric water content (θ, m3 m-3) and the salinity of both pore water (σP) and water extract (σE) in different horticultural substrates: peat, pumice, perlite and mixtures (1:1, v:v) of peat and perlite or peat and pumice. The experiment was conducted under laboratory conditions over a T range between 22 and 28°C using plastic pots filled with each substrate, irrigated to fully container capacity with nutrient solutions of known concentrations and left to dry in air to θ ranging from approx. 0.20 and 0.50 m3 m-3. In order to avoid the development of significant gradients in substrate moisture and salinity, the pots did not host plants and the evaporation from the top surface was prevented by means of a plastic wrap. Pore water was collected by centrifugation, whereas water extract was obtained by means of 1 substrate: 2 water suspension method. A significant linear relationship was found between σE and σP, with the slope dependent on the type of substrate. θ calibration was faintly dependent on the nature of substrate and it was not affected by the salinity of irrigation water, at least in the peat-pumice mixture. In this substrate, the linear regression of σP against σ was markedly affected by θ and hence ε.
Article
Full-text available
Results of an experiment aimed at assessing the possibility of reusing reclaimed wastewater for nursery ornamental plants are presented. Tests were carried out in Pistoia (Italy). A pilot plant for tertiary treatment (filtration and peracetic acid + UV disinfection) of the local wastewater treatment plant (WWTP) effluent was set up. An experimental plot with six containerized ornamental species was irrigated with the tertiary effluent and growth and physiological parameters were monitored. A control plot irrigated with fertigated water (nutrient-enriched groundwater) was also set up in order to compare the plants response to different kinds of irrigation water. The refinery treatment by filtration and disinfection with Peracetic Acid (PAA) and UV together was very effective in bacteria removal. The value of 2 MPN of Total Coliforms in 100 ml set by Italian law (until June 2003) for unrestricted irrigation was constantly satisfied. Agronomic results indicate no major limitations to the use of a tertiary effluent as an irrigation source in an ornamental plant nursery. The nutrient content of the tertiary effluent was able to maintain good plant growth as well as fertigated water for most of the tested species.
Article
Measurements of crop transpiration have been carried out by the Applied Plant Research station in Naaldwijk for many years with increasingly better weighing equipment. Ultimately a weighing gutter system has been developed that operates well under practical conditions and is a useful tool in crop management. The APRNaaldwijk weighable gutter system monitors the water management of greenhouse crops and offers information for checking and automatically regulating the water supply. The collected data offer additional information on climate control and fresh weight growth of the crop. The system and results from testing are presented in this paper.
Article
An improvement to an iterative method for the simultaneous determination of soil hydraulic properties from One-Step data has been developed, inserting in the optimization algorithm some parameter among which 'θr' (residual water content) improved the procedure. Soil hydraulic properties were characterized by the Brooks and Corey equation for water retention, and by the Kozeny power equation for hydraulic conductivity. The iterative procedure was examined for a particular class of soil such as substrates for container cultivation represented by three mixes of peat and pumice. Estimated hydraulic conductivity was compared with the estimation obtained from the Van Genuchten-Mualem equation. The comparison showed a very high similarity between the two curves. Applying One-Step procedure, the duration of experiments can be decreased to one week, compared with the standard duration quantifiable in three or more weeks.
Article
Plant growth and water use of container-grown Photinia × fraseri (Dress) were studied under varying irrigation regimes. Treatments were based on management allowed deficit (MAD) irrigation (including 0, 5, 10, 25, 50, 75 and 95% MAD), which links evapotranspiration (ET) and plant available moisture in determining irrigation schedules. Plant growth was maximized under 25% MAD irrigation. Plant performance and water use were significantly reduced as moisture deficit levels in the growing medium exceeded 50% under MAD irrigation of 50%, 75% and 95%. Plant performance also tended to decrease, but plant water use increased with lower MAD treatments (i.e., 0%, 5%, 10%). The research reported provides a model for nursery managers and researchers to use MAD irrigation in determining optimum irrigation regimes to meet plant water needs and maintain maximum plant performance.
Article
Irrigation of container-grown ornamental crops can be very inefficient, using large quantities of water. Much research was conducted in the 1990s to increase water efficiency. This article examined water management, focusing on three areas: water application efficiency (WAE), irrigation scheduling, and substrate amendment. Increases in WAE can be made by focusing on time-averaged application rate and pre-irrigation substrate moisture deficit. Irrigation scheduling is defined as the process of determining how much to apply (irrigation volume) and timing (when to apply). Irrigation volume should be based on the amount of water lost since the last irrigation. Irrigation volume is often expressed in terms of leaching fraction (LF = water leached ÷ water applied). A zero leaching fraction may be possible when using recommended rates of controlled-release fertilizers. With container-grown plant material, irrigation timing refers to what time of day the water is applied, because most container-grown plants require daily irrigation once the root system exploits the substrate volume. Irrigating during the afternoon, in contrast to a predawn application, may increase growth by reducing heat load and minimizing water stress in the later part of the day. Data suggest that both irrigation volume and time of application should be considered when developing a water management plan for container-grown plants. Amending soilless substrates to increase water buffering and reduce irrigation volume has often been discussed. Recent evidence suggests that amending pine bark substrates with clay may reduce irrigation volume required for plant production. Continued research focus on production efficiency needs to be maintained in the 21st century.
Article
There is wide variety of soil moisture sensors available for use in greenhouse production and research applications. Such sensors can play a valuable role in improving uniformity of substrate water content in greenhouses, as well as in automating irrigation based on plant water use. Quantification of spatial variability can be used to improve the design of irrigation systems to better match plant water use. The use of soil moisture sensors for irrigation control is promising, because it can greatly reduce temporal variability in substrate water content by watering based on actual crop water use. This not only results in better temporal uniformity, but can also greatly reduce water use. Understanding the spatial distribution of substrate water content and root water uptake within a container is important in determining the optimal sensor location within a container. At the same time, the properties of different sensors need to be considered when choosing the optimal sensor for a particular application. In small containers, it may be possible to measure most of the substrate with a single sensor, while in larger containers sensors ideally would be placed in that part of the substrate where most of the water uptake occurs.
Article
Rooted cuttings of Rhaphiolepis indica, a low slow-growing evergreen shrub, were grown outdoors in weighing lysi meters to market size in 11.4-L containers. Actual evapo transpiration (ETA) and evaporation from containers shaded with plastic foliage was determined daily. The first 60 days after transplanting, substrate evaporation accounted for most of ETA and was the major component through the first 127 days. ETA generally followed variations in reference evapo transpiration (ETo). Mean cumulative ETA to produce 90% of measured plants to market size was 101 L or 1.99-m depth per plant based on container surface area. Water need indices, similar to crop coefficients, were highly correlated with percent canopy closure using an exponential decay equation (r2 = 0.898), but a more precise estimate at higher canopy closures was achieved using a third-order inverse polynomial equation (r2 = 0.907). When combined with similar previous data from Viburnum odoratissimum and Ligustrum japonicum, the inverse polynomial equation correlation was 0.802 for all three shrubs. This implies the %Closure model provides a good general base for ETA-based irrigation of woody evergreen shrub species based on canopy size and spacing with improved precision when individual equations are derived by species.
Article
Transpiration of woody shrubs appears to increase with decreases in plant density within production beds as plants are randomly removed for sale. To assess potential impact on irrigation management, this observation was tested with market-sized plants in suspension lysimeters at specific levels of canopy closure. Canopy closure was defined as the percentage of cumulative projected two-dimensional canopy area of individual plants per unit ground area on which they were placed. In 1997, evapotranspiration (ETA) of plants in 26.6-L containers was comparable from isolated plants up to 67% canopy closure. At full canopy closure (100%), ETA was 40% less than 67% closure or lower. When repeated in 2003, results were similar for similar-sized plants and for two sizes smaller (11.4and 3.8-L containers). ETA response to canopy closure was independent of height from 0.5 to 1.5 m tall. At full canopy closure, whole plant transpiration was equivalent to that measured from only the upper 40% (by height) of the canopy under full sun. This was independent of plant size. Implications for water conservation during production and plants' irrigation needs in landscapes are discussed.
Article
A model for automated precision irrigation of Ligustrum japonica developed from lysimeter data collected in 2001-2002 was used to produce market size plants in 11.4 L black polyethylene containers. The model calculated daily irrigation rates based on the previous day ET0 and a water needs index (WNI - a crop coefficient-like value derived from percent canopy closure). Percent canopy closure was calculated by squaring average canopy width and dividing by allocated plant area then multiplying by 100. Average canopy width was determined manually and input every 3 weeks during production. Plant allocated area was increased once. ET0 was calculated using instrumentation of a standard weather station connected to the irrigation controlling data logger. Plant growth and irrigation applications were compared to those of plants whose irrigation frequency and volume were adjusted manually to approximate 1800 mm of overhead irrigation annually. Each irrigation regime was replicated 4 times. ET0 controlled irrigation produced the same marketable size plants as the manual regime, but 3 weeks faster, with 400 mm less irrigation. The model functioned well without modification during the winter quiescent period and sequential spring growth flush.
Article
Improving plant quality and the uniformity of a crop are major objectives for growers of ornamental nursery stock. The potential to control excess vigour and to improve quality through regulated deficit irrigation (RDI) was investigated using a range of woody ornamental species. RDI regimes reduced vegetative growth consistently across different species and growing seasons. Plants adapted to reduced water supplies primarily via stomatal control, but also by osmotic adjustment when grown under the most severe RDI regimes. Only plants exposed to ≤ 25% of potential evapo-transpiration demonstrated any evidence of leaf injury, and the extent was slight. Growth inhibition increased as the severity of RDI increased. Improvements in quality were attained through a combination of shorter internodes and final shoot lengths, yet the number of 'formative' primary shoots remained unaffected. Compact, well-branched plants could be formed without a requirement for mid-season pruning. In addition to severity, the timing of RDI also influenced growth responses. Applying 50% ETp for 8 weeks during July-August resulted in the formation of good quality plants, which retained their shape until the following Spring. Re-positioning irrigation drippers within the pots of well-watered plants, in an attempt to induce a partial root drying (PRD) treatment, reduced growth, but not significantly. The adoption of irrigation scheduling, based on 50-100% ETp, has the potential to improve commercial crop quality across a range of ornamental species.
Article
The new crop coefficients are basal or minimal coefficients for conditions when soil evaporation is minimal but root-zone soil moisture is adequate. When combined with improved estimates of evaporation from wet soils, they should permit more accurate estimates of daily crop ET, more accurate irrigation scheduling, and more reliable estimates of crop water requirements. Curves were developed for alfalfa, potatoes, snap beans, sugarbeets, peas, sweet and field corn and winter and spring cereals. -from ASCE Publications Abstracts
Article
Twelve species of woody ornamentals were grown in containers in Riverside and Davis, Calif., to determine plant water use and compare crop coefficients (K(c)) calculated with reference evapotranspiration (ET) from local weather stations (ET(cim)) or atmometers (ET(atm)). Water use, Kc(atm), and Kc(cim) differed by species, location, and mouth of the year. Raphiolepis indica (L.) Lindl., Pittosporum tobira (Thunb.) Ait., Juniperus sabina L., and Photinia xfraseri Dress. were the highest water users in Riverside and Arctostaphylos densiflora M.S. Bak., Juniperus, Cercis occidentalis Torr., and Pittosporum used the highest amount of water in Davis, when averaged over the 20-month study period. Rhamnus californica Eschsch., Prunus ilicifolia (Nutt.) Walp., and Cercocarpus minutiflorus Abrams. were among the lowest water users in both locations. Although plant water use fluctuated considerably between individual sampling dates, the relative ranking of species water use in each location changed very little over the study period. During periods of high winds, ET(cim) may not provide an accurate reference for container crops. K(c) values fluctuated seasonally from as much as 1 to 4.7 for high water users, while values were stable for low water users and also for Buxus microphylla japonica Rehd. and E.H. Wils., an intermediate water user. During periods of low ET, especially in fall and winter, K(c) values were artificially high and failed to correspond to the plants' low water use. K(c) values for low water users seem to be useful to estimate water requirements over an extended period of time, whereas general K(c) values seem to have limited value for plants with high water demand and need to be modified for different growth stages and growing locations.
Article
Intensive vegetable cropping systems use large amounts of water and nutrients. Excess application of water and nutrients results in economic losses (higher fertilizers and pumping costs) and contributes to nutrient leaching and environmental degradation. Increasing nutrient use efficiency (NUE) and water use efficiency (WUE) should be a priority for sustainable horticulture. This increased NUE, WUE, or both depend on the utilization of efficient irrigation technology, including appropriate methods for irrigation scheduling (IS).Various methods are available for IS based on determination of crop water balance (weather-based method), soil/substrate moisture level, or plant water relations. Rather than discussing the physical and biological basis of irrigation management, this article focuses on currently available irrigation control devices for open-field and greenhouse production systems, with particular emphasis on soil moisture sensors (SMSs). SMS regulates the frequency of irrigation and, possibly, the water dose by continuously monitoring volumetric water content (q) or matrix potential (ym) of the growing media. A new generation of dielectric SMS has been developed to measure both q and the electrical conductivity (EC) of pore water in soil and artificial media. This provides the possibility of controlled fertigation based on measured EC. Despite the development in IS, in most regions worldwide, especially in less developed countries, many growers still rely on personal experience for determining crop water requirements and the timing of irrigation. Therefore, the main constraints to the improvement of irrigation efficiency are related to the overall cost of these technologies and to the policies adopted for their dissemination and transfer to professional growers.
Article
Before an aerial image can be used to support a site-specific application it is essential to perform the geometric corrections and geocoding. This research discusses the development of an automatic aerial image georeferencing method for an unmanned aerial vehicle (UAV) image data acquisition platform that does not require use of ground control points (GCP). An onboard navigation system is capable of providing continuous estimates of the position and attitude of the UAV. Based on a navigation data and a camera lens distortion model, the image collected by an onboard multispectral camera can be automatically georeferenced. When compared with 16 presurveyed ground reference points, image automatic georeferenced results indicated that position errors were less than 90 cm. A large field mosaic image can be generated according to the individual image georeferenced information. A 56.9 cm mosaic error was achieved. This accuracy is considered sufficient for most of the intended precision agriculture applications.
Article
tGerbera plants were grown in semi-closed rockwool culture under greenhouse conditions in differentseasons in a Mediterranean climate. The plants were irrigated using either fresh (FW; 1.0 mol m−3NaCl)or moderately saline (SW; 9.0 mol m−3NaCl) water. In autumn, NaCl concentration did not influencesignificantly plant growth, flower production and transpiration (E), which instead were reduced in springin the plants irrigated with SW. In both seasons, water salinity did not affect leaf stomatal resistance (rl),which was determined by the inversion of the Penman–Monteith (PM) equation or measured with adiffusion porometer. The PM formula and two regression equations were calibrated and validated forestimating the hourly rate of daytime transpiration (Ed); a regression model was also fit to nocturnaltranspiration (En). Regression models predicted Edas a function of vapour pressure deficit (VPD) and/orthe radiation intercepted by the canopy. Leaf area index (LAI), which is required by all the equations, wasmodelled as function of crop thermal time (i.e. growing degree days). The PM model predicted Edusinga constant value of rl. Model calibration and validation were performed using independent datasets. Theirrigation with FW or SW did not require a different calibration of transpiration models. Both PM formulaand regression equations provided accurate estimates of Ed; fitted equations explained between 80% and96% of the variance in measured Ed. A linear regression of Enagainst (LAI·VPD) accounted for 92% ofmeasured En.
Article
Hourly meteorological and soil water potential data collected during the summer season on a container crop of 2-year-old plants of Hypericum hidcote were used to develop a methodology that integrates climate-based (AET = ETo × Kc) and soil-based methods (soil water potential measurements by tensiometers) for the automatic control of the irrigation of plants growing in pots. Hourly ETo values were calculated by the CIMIS equation, derived from the Penman formula. Tensiometric data, by a soil-specific tensiometric curve, were transformed into pot water weight and used to estimate actual hourly evapotranspiration (AETt).AETt values were compared with AET data provided by precision balances (AETb). A good relationship was found between AETt and AETb (R2 = 0.7***), so AETt values were used to calculate hourly crop coefficient (Kc) by the AETt/ETo ratio. As the crop coefficients obtained by using AETb (Kcb = AETb/ETo) and by AETt (Kct = AETt/ETo) shows no significant statistical differences, hourly AET values were calculated as , where is a 7-day average. The relationships between AET, calculated by the integrated system (), and AETb shows an R2 = 0.685*** and slope = 0.77. The introduction of the actual Kc (AETt/ETo) in calculation determined an increase in the accuracy of AET estimation, with R2 and slope increasing to 0.896*** and 0.907, respectively.According to the above results, the integrated system allows the calculation of an operational Kc for ornamental crops that can be used to correctly manage the irrigation of plants growing in containers, also if tensiometer malfunctioning or lack of representativity occur.
Article
Low water use plantings may enhance water conservation in dry landscapes. However, appropriate plant selection is hindered by the dearth of information available on the water needs of different species. A direct method of classification was tested under the hypothesis that relative water use by woody landscape species growing in 3.8 l containers would be representative of the water use of the same species in the landscape. Four species of distinctly different ecological origin (Leucophyllum frutescens, Spiraea vanhouteii, Viburnum tinus, Arctostaphylos densiflora) were chosen in order to obtain a wide range of responses, and their water use was measured in plants growing in 3.8 l containers and compared to that of the same species growing in drainage lysimeters, representative of landscape conditions. Half of the plants were subjected to successive cycles of stress by withholding water after irrigation to container capacity in containers, or applying a fraction of the potential evapotranspiration in lysimeters. The good fit of the regression of average daily water use by lysimeter plants on average daily water use by container plants (R2=0.87,P<0.01) reflects the consistency of relative water use of the four species. Measurement of water use at the end of nursery production may be useful for predicting the relative water use of various species after establishment in the landscape.
Article
The capacity for evapotranspiration (ET)-based irrigation scheduling to reduce runoff volume and nutrient leaching was tested in Fall 2004 and Spring 2005. Runoff (container leachate plus unintercepted irrigation and precipitation) was collected continuously for 17 weeks during production of sweet viburnum [Viburnum odoratissimum (L.) Ker Gawl.] in 2.4-L (16-cm top diameter) containers fertilized with an 18N-2.6P-10K polymer-coated, controlled-release fertilizer. Treatments were a factorial arrangement of two irrigation rates (fixed rate of 1 cm·d-1 or a variable, ET-based rate) and two fertilizer rates (15 or 30 g/container in 2004 and 10 or 15 g/container in 2005). Averaged over the two experiments and compared with the 1-cm·d-1 rate, ET-based irrigation reduced the amount of irrigation water applied (L/container) by 39% and runoff volume (L/container) by 42% with greatest reductions observed during the second half of the 2004 experiment and the first half of the 2005 experiment. Compared with 1-cm·d-1 rate, ET-based irrigation reduced runoff nitrogen (N), phosphorus (P), and potassium (K) (mg/container) by 16%, 25%, and 22%, respectively, in 2004 and runoff K 15% in 2005 with irrigation effects varying on a weekly basis. Irrigation treatments did not affect the response of plants to fertilizer rate. Because shoot dry weight was unaffected by irrigation treatments, results indicate that compared with a fixed irrigation rate, ET-based irrigation can reduce irrigation and runoff volumes and to a lesser extent nutrient loss while providing adequate water for plant growth.
Article
In the spring-summer season of 2005 and 2006, we explored the influence of three fertigation strategies (A-C) on the water and nitrogen use efficiency of semi-closed rockwool culture of greenhouse tomato conducted using saline water (NaCl concentration of 9.5 mol m(-3)). The strategies under comparison were the following: (A) crop water uptake was compensated by refilling the mixing tank with nutrient solution at full strength (with the concentrations of macronutrients equal or close to the corresponding mean uptake concentrations as determined in previous studies) and the recirculating nutrient solution was flushed out whenever its electrical conductivity (EC) surpassed 4.5 dS m(-1) due to the accumulation of NaCl; (B) the refill nutrient solution had a variable EC in order to maintain a target value of 3.0 dS m(-1); due to the progressive accumulation of NaCl, the EC and macronutrient concentrations of the refill nutrient solution tended to decrease with time, thus resulting in a progressive nutrient depletion in the recycling water till N-NO(3)(-) content dropped below 1.0 mol m(-3), when the nutrient solution was replaced;
Article
A simple method was developed to estimate the fraction radiation intercepted by small eastern white cedar plants (Thuja occidentalis 'Brabant'). The method, which describes the crop canopy as rows of cuboids, was compared with methods used for estimating radiation interception by crops with homogeneous canopies and crops grown in rows. The extinction coefficient k was determined at different plant arrangements and an average k-value of 0.48 ± 0.03 (R2 = 0.89) was used in the calculations. Effects of changing plant characteristics and inter- and intra-row plant distances were explored. The fraction radiation intercepted that was estimated with the method for rows of cuboids was up to 20% and for row crops up to 8% lower than estimated with the method for homogeneous canopies at low plant densities and a LAI of 1. The fraction radiation intercepted by small plants of Thuja occidentals 'Brabant' was best estimated by the simple method described in this paper
Article
This paper reviews the various methods available for irrigation scheduling, contrasting traditional water-balance and soil moisture-based approaches with those based on sensing of the plant response to water deficits. The main plant-based methods for irrigation scheduling, including those based on direct or indirect measurement of plant water status and those based on plant physiological responses to drought, are outlined and evaluated. Specific plant-based methods include the use of dendrometry, fruit gauges, and other tissue water content sensors, while measurements of growth, sap flow, and stomatal conductance are also outlined. Recent advances, especially in the use of infrared thermometry and thermography for the study of stomatal conductance changes, are highlighted. The relative suitabilities of different approaches for specific crop and climatic situations are discussed, with the aim of indicating the strengths and weaknesses of different approaches, and highlighting their suitability over different spatial and temporal scales. The potential of soil- and plant-based systems for automated irrigation control using various scheduling techniques is also discussed.
Article
Hardy ornamental nursery stock (HONS) is container grown in systems employing frequent irrigation and considerable applications of nutrients and pesticides. These container systems are frequently isolated from the underlying soil by an impermeable membrane resulting in near-surface drainage from the beds. An experiment was established to examine the losses of nitrate, phosphorus and selected agrochemicals from a peat-based growing medium for HONS. Concentrations of nitrate-N in water draining from the beds exceeded 200 mg l−1 and phosphorus (P) exceeded 20 mg l−1, which are considerably in excess of the EC limit for drinking water and also represent a considerable eutrophication potential. Concentrations of pesticides in water draining from the beds were considerably in excess of the limit imposed by the EC Drinking Water Directive, of 0.1 μg l−1 for any one pesticide and 0.5 μg l−1 total, and could pose a threat to some aquatic environments. Peak concentrations observed were: oxadiazon 1500 μg l−1, fonofos 72 μg l−1, furalaxlyl 1500 μg l−1 and simazine 317 μg l−1. The use of sand beds irrigated by a sub-surface system did not noticeably reduce losses of either pesticides or nutrients, unless used in conjunction with a re-circulation system
Il vivaismo ornamentale tra competitività e sostenibilità ambientale
  • F P Nicese
  • F Ferrini
Nicese, F.P., Ferrini, F., 2009. Il vivaismo ornamentale tra competitività e sostenibilità ambientale (in Italian), Proceedings of Regional Congress on Lo sviluppo del vivaismo Toscano, Pistoia, 5 December 2008. Accademia dei Georgofili, Florence, pp. 79-89.
Nursery irrigation scheduling
  • Regan
Regan, R., 1999. Nursery irrigation scheduling. In: Proc. 2nd Annual Nursery Growers Short Course, Wilsonwille, Oregon, pp. 1-8.
  • L Incrocci
L. Incrocci et al. / Agricultural Water Management 131 (2014) 30– 40
Ambiente e vivaismo a Pistoia nel ARPAT News
  • Agenzia Regionale Protezione Ambiente
  • Toscana
ARPAT, Agenzia Regionale Protezione Ambiente Toscana, 2006. Ambiente e vivaismo a Pistoia nel. ARPAT News, 14 May, http://www.arpat.toscana.it/notizie/ arpatnews/2007/083-07-agroeco.pdf (accessed 08.08.13) (in Italian).
Managing Water in Plant Nurseries: A Guide to Irrigation, Drainage and Water Recycling in Containerized Plant Nurseries
  • C Rolfe
  • W Yiasoumi
  • E Keskula
Rolfe, C., Yiasoumi, W., Keskula, E., 2000. Managing Water in Plant Nurseries: A Guide to Irrigation, Drainage and Water Recycling in Containerized Plant Nurseries. New South Wales Agriculture, Orange, Australia. Scuch, U.K., Burger, D.G., 1997. Water use and crop coefficients of woody ornamentals in containers. J. Am. Soc. Hortic. Sci. 122, 727-734.
La gestione dell’irrigazione e della concimazione nelle colture florovivaistiche
  • Marzialetti
Marzialetti, P., Pardossi, A., 2003. La gestione dell'irrigazione e della concimazione nelle colture florovivaistiche. L'Informatore Agrario 21, 45-52 (in Italian).
Penman crop coefficients for container growth landscape ornamentals
  • Beeson
Beeson Jr., R.C., 1996. Penman crop coefficients for container growth landscape ornamentals. In: Camp, C.R., Sadler, E.J., Yoder, R.E. (Eds.), Proc. Intl. Conf. Evapotranspiration and Irrigation Scheduling. 3-6 November, San Antonio, TX, pp. 257-262.