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The significance of available nutrient fluxes in N and P budgets for maize cropping on a Rhodic Kandiustox: A study with compost, NP fertilizer and stubble removal
Abstract
Nutrient budgets may be useful tools for nutrient management of crops especially if they estimate the nutrient fluxes available
from a variety of sources including organic and inorganic fertilizer, crop residues and soil organic matter. The aim of the
present study was to develop a budget of available nutrients by determining the contribution of mineralized nutrient fluxes
and fertilizer input relative to nutrient losses and removal in harvested products in the overall N and P balances. N and
P inputs and outputs and available N and P fluxes in the soil were estimated for 3 consecutive maize crops where inputs and
outputs were altered by NP fertilizer, compost and stubble removal on a Rhodic Kandiustox. A sensitivity analysis of calculated
and measured nutrient budget items was conducted to identify the main factors affecting the accuracy of the nutrient balance
calculations. Mineral fertilizer rate was the major factor for maize nutrient budgets as shown by its contribution to N and
P balances. Without mineral fertilizer application, soil organic matter (SOM) mineralization was the most important within-season
nutrient input. In the case of N, shoot uptake was the main output followed by denitrification. Phosphorus adsorption by the
soil was the major P output from the available pools followed by shoot uptake. SOM mineralization maintained the pools of
available N and P if stubble of the previous crop was returned. Mineral fertilizer application, which produced surplus balances
of N and P, would however, be needed to attain high yield, even with stubble return. The available N and P from compost were
not significant inputs in the nutrient balances until year 3. Total N and resin extractable P in soil after five crops supported
the calculated nutrient balances indicating the importance of available nutrient fluxes in calculating N and P balances.
KeywordsCompost–Maize–Nutrient budget–NP fertilizer–Rhodic Kandiustox–Stubble removal
... JARQ 54 (1) 2020 N. Matsumoto et al. 2013). Nutrient input through the application of chemical fertilizer and manure shifts the nutrient balance from negative to positive, so as to maintain soil fertility for increased crop production (Pinitpaitoon et al. 2011, Wang et al. 2007a, Yanai et al. 2007). Few studies have been made on the nutrient balance in farmland in Laos. ...
... However, assuming that N removal continues for 15 years without replenishment through fertilization, N stock in the soil decreases from 2,980 to 2,205 kg N ha −1 , and total N content in the soil decreases from 1.35 to 1.00 g N kg −1 . In previous studies, total N content in soil was higher than 1 g N kg −1 and the maize seed yield was higher than 3 t ha −1 without any fertilizer input (Adamtey et al. 2016, Bedada et al. 2016, Hartmann et al. 2014, Liu et al. 2003, Pinitpaitoon et al. 2011, Qiao et al. 2014, Wang et al. 2007b, Yan et al. 2016). In our surveyed fields in Xayabury Province, when total N content in the soil was higher than 1 g N kg −1 , the maize seed yield exceeded 4 t ha −1 (Fig. 4). ...
... Changing the NPK balance from negative to positive increases NPK in the soil (Pinitpaitoon et al. 2011, Qiao et al. 2014, Wang et al. 2007b. Further studies on changes of the NPK amount in soil as related to the NPK balance will contribute to clarifying the nutrient dynamics in soil, especially in tropical areas. ...
The maize cultivation area in Lao PDR has increased since 2004, mostly without the use of fertilizer. For sustainable maize production, maintaining soil fertility is essential. This study aims to clarify nutrient removal by maize cultivation in fields located in the districts of Kenethao and Paklai in Xayabury Province—the main maize production area in Lao PDR. Field surveys were conducted at 27 plots in nine farmer fields in 2013 to measure maize production, collect plant samples for analyzing nutrient uptake and soil samples for analyzing nutrient stock in the soil, and interview farmers about cultivation practices and field history. N, P, and K removal by harvest from the fields totaled 51.7, 7.5, and 14.2 kg ha⁻¹, respectively. Nutrient stock in the soil surface layer at 0-20 cm deep was 2980 kg ha⁻¹ as total N, 10.1 kg ha⁻¹ as available P, and 233 kg ha⁻¹ as exchangeable K. N and K stocks in the soil were sufficient compared with N and K removal in maize at harvest, although available P in the soil was similar in amount compared to P removal by harvest. Most farmers did not apply any fertilizer for maize cultivation. The N, P, and K balances in the fields were estimated at −47.6, −7.4, and −14.3 kg ha⁻¹, respectively, without fertilizer input, and were improved to −25.6, +1.4, and +5.5 kg ha⁻¹, respectively, by applying chemical fertilizer.
... Four additional treatments involved maize stubble removal after harvest (S 0 ) in the following treatment combinations: C 0 F 0 S 0 , C 0 F 1 S 0 , C 0 F 2 S 0 and C 0 F 3 S 0 . Except where mentioned below all detailed methods for the experiment are reported in Pinitpaitoon et al. (2011). The single cross hybrid, Suwan 3851, was sown on August 28th, 2002;August 14th, 2003;August 13th, 2004;August 6th, 2005;and 24th August, 2006 for crops 1, 2 3, 4 and 5, respectively. ...
... Samples of the compost were also taken for moisture content determination, by oven drying, and other chemical properties. Properties of compost used in this study are reported in Pinitpaitoon et al. (2011). Briefly, organic carbon ranged between 3.5% and 7.3%, total N between 5.3 g kg −1 and 5.9 g kg −1 producing C/N ratios that ranged between 6.7 and 12.4. ...
... Stubble removal also decreased the profit. Stubble removal not only increased production cost but also, as reported by Pinitpaitoon et al. (2011), depleted soil N and P supply. ...
Application of organic manures and composts in crop production has been strongly encouraged in many places but often without due consideration to their quality and price. Since organic amendments can vary greatly in composition and mineralization rate, a framework is needed to make rational choices on their use as replacements of inorganic fertilizer, especially when considering poor quality organic materials. A field experiment was carried out with maize grown annually for 5 years on a Rhodic Kandiustox in Thailand to test response to mineral fertilizer (at 0–0 to 125–55 kg N-P ha−1 yr−1), compost (0.59% N, 0.31% P and 0.55% K at 0–7500 kg ha−1 yr−1) and stubble removal. The DSSAT model was calibrated to predict yields using the first year's trial data and then used to predict treatment yields for the following 4 years. The Seasonal Analysis module of DSSAT using Dominance Analysis showed that mineral fertilizer (125–55 kg N–P ha−1 yr−1) with stubble return gave the highest net profit whereas the highest rate of compost without mineral fertilizer gave the biggest loss. The yield response was attributed primarily to N supply rather than P. Effects of compost, mineral fertilizer, stubble management, and their interactions on yield and profit were not related to bulk density or soil available water capacity even though soil organic matter (SOM) levels increased. With stubble return, the highest rate of mineral fertilizer increased SOM whereas with compost application or stubble removal it did not. The DSSAT simulation of yield indicated that the low quality compost would only be as profitable as mineral fertilizer if the N concentrations are 3–4 times higher than the present compost (1.8–2.4% N) or if the compost price is greatly reduced. The DSSAT yield simulation and Seasonal Analysis provided a framework whereby the suitability of compost as a N fertilizer replacement for maize could be determined based on its composition, rate of application and price. Further validation of this approach is needed where the organic amendments have significant effects on soil physical properties and where other nutrients besides N are a significant factor in the crop yield response.Highlights► Organic amendment is widely encouraged as a replacement of mineral fertilizer. ► This is often done without due consideration on manure quality and profitability. ► Organic manures vary greatly in composition and price. ► DSSAT yield simulation provides choices to the use of compost as N fertilizer. ► The choices are based on composition, rate of application and price of compost.
... Soil TP content under different tillage management methods did not differ significantly from 2020 to 2022, but TP content decreased in 2020 (Table S1). This was because deep vertical rotary tillage can increase soil permeability and phosphorus leaching, but chemical fertilizer application and straw return to the field can provide carbon, nitrogen, and phosphorus to replenish the nutrients [30]. Different tillage management methods had less effect on TK content, probably because tillage in potassium-rich farmland is always in equilibrium with potassium replenishment and depletion. ...
A long-term high-saline soil environment will limit the improvement of soil quality and cotton yield. Modified tillage management measures can improve soil quality, and the establishment of a soil quality evaluation system will facilitate evaluation of the soil quality and land production potential in southern Xinjiang. The objective of this study was to determine the effects of different tillage management methods on soil quality in saline cotton fields in southern Xinjiang. A three-year experiment was conducted in Tumushuke, Xinjiang, with different deep vertical rotary tillage depths (DTM20, 20 cm; DTM40, 40 cm; DTM60, 60 cm) and conventional tillage (CTM, 20 cm). The soil quality index (SQI) under different tillage management methods was established by using the full dataset (TDS) with a scoring function for eight indicators, including physicochemical properties of the soil from 0 to 60 cm, to evaluate its impact on the soil quality of the saline farmland in southern Xinjiang. The results of the study showed that deep vertical rotary tillage management can effectively optimize soil structure; reduce soil bulk density (BD), soil solution conductivity (EC), and pH; and promote the accumulation of soil organic carbon (SOC) and total nitrogen (TN) in the soil. However, the average diameter of soil water-stable aggregates (MWD) in a 0–60 cm layer becomes smaller with an increasing depth of tillage. This does not reduce crop yields but does promote soil saline leaching. In addition, the significant linear relationship (p < 0.001) between seed cotton yield and soil quality indicated that improving soil quality was favorable for crop yield. The principal component analysis revealed BD, MWD, pH, and EC as limiting sensitive indicators for seed cotton yield, while SOC and TN were positive sensitive indicators. The soil quality index (SQI) values of DT40 and DTM60 were significantly higher than that of CTM by 11.02% and 15.27%, respectively. Overall, the results show that DTM60 is the most suitable tillage strategy to improve soil quality and seed cotton yield in this area, and this approach will provide a reliable theoretical basis for the improvement of saline farmland.
... Nitrogen balance was estimated for each treatment as the difference between inputs and outputs (Oenema et al. 2003;Pinitpaitoon et al. 2011;Zhang et al. 2013): N balance = Total N input -Total N output (5) where N balance is expressed in kg ha −1 , Total N input (kg ha −1 ) is N from mineral fertiliser (kg ha −1 ) + soil mineral N before sowing (kg ha −1 ), and Total N output (kg ha −1 ) is crop N uptake (kg ha −1 ) + N in drainage water (kg ha −1 ) + ΔN [soil mineral N before sowing (kg ha −1 )soil mineral N after harvesting (kg ha −1 )]. ...
Managing drainage intensity is important in controlling soil moisture and nutrient losses and improving crop yields. This thesis evaluated the effects of drainage intensity on nitrogen losses, salinity and rice grain yield in three cropping seasons, and on gaseous emissions of methane (CH4) and nitrous oxide (N2O) from rice flowering to ripening in one season, on a marshland in semiarid region of Rwanda. Three drainage treatments were compared in a randomised complete block design: drainage to 0.6 m depth, weir open four times per week (S4); drainage to 1.2 m depth, weir open four times per week (D4); and drainage to 1.2 m, weir open twice per week (D2). In seasons 1 and 3, treatment D4 had higher drainage outflow and higher salt loads than treatments D2 and S4, but in season 2 treatment D2 had higher drainage outflow and higher salt loads than D4 and S4. Drainage water salinity (ECwd) decreased by around 41-57% from season 1 to season 2, and by 29-37% from season 2 to season 3. Soil salinity decreased by one electrical conductivity (EC) unit (dS m-1) from season 1 to season 2, and by a similar amount from season 2 to season 3. Nitrogen uptake and rice grain yield were significantly greater in the deep drainage treatments (D4, D2) compared with shallow drainage (S4). Deep drainage (D4, D2) reduced CH4 emissions but had no marked effect on N2O emissions. These findings suggest that deep drainage performs better than shallow drainage in semi-arid paddy fields, as it enables a balance between maintaining water in the soil and having sufficient drain outflow to leach salts, reduce CH4 emissions and achieve high rice yield.
... The phosphorus geochemical cycle is unidirectional; it starts from land reach to sea owing to there is no emission of abovedescribed species of phosphorus, and it is almost not possible to transport phosphorus species from the ocean back to the soil ecology except through a slow process of movement of diminution at crustal plate environment (Elser and Bennett, 2011). Estimation of a main soil nutrient phosphorus for their fluxes, such as the dispersal of phosphorus fertilizer from agricultural soil, ranges from three to fivefold, and some other factors, such as the global return of phosphorus fertilizers from harvested produce, are unclear (Pinitpaitoon et al., 2011). ...
The biochar is a solid carbon-rich, porous material produced by the thermochemical conversion of a diverse range of biomass feedstocks under an inert atmosphere (i.e., in the absence of oxygen). We can produce the biochar at all likely scales, ranging from the industrial to the domestic level and even at individual farms, thus, the biochar industry is leading as a most appropriate at different socioeconomic settings. The possibility of sustainable biochar production practices and multi-functionality features make it a promising candidate to fulfill an increasing demand in the fields of soil amendment, agricultural sustainability, environmental protection, cutting-edge materials, and to achieve circular bioeconomy and mitigation of climate change. An available fraction of waste biomass (agroforestry waste, biomass crops, agricultural residues, mill residues, and animal manure, and many more) can be used efficiently in pyrolysis and converted into desired biochar materials, besides this alternative energy products, such as syngas, bio-oil, electricity generation, and process heat. This report emphasizes the fate of biomass composition, pyrolysis mechanisms, and applications of modern analytical and characterization techniques that are being adopted, applied, and standardized to improve understandings of molecular, structural, and surface properties characteristics of biochar. To achieve precisely designed biochar, there is a need to understand the latest advances in biochar materialization mechanisms and structure-application relationships to speed up their agronomic applications and to achieve a zero-waste dream. This report also summarizes a wide range of literature published on feedstocks, pyrolysis, and biochar and suggests several practical recommendations appropriate to implement and bring together specific details on the thermochemical conversion of biomass, desired biochar properties, organic and inorganic phases, and the significance to the agronomic applications.
... In addition, organic manure releases plant nutrients slowly to crops over time. Of the nutrients present in the manures, only 30% of the N and P may be released in the first year with a smaller proportion released in the following year [49,50]. The progressive mineralization and release of nutrients over time often results in better nutrient use efficiency than by the application of plant nutrients through inorganic fertilizers only [51]. ...
ncreasing productivity of maize while decreasing production costs and maintaining soil health are emerging challenges for the rice–maize system in South Asia. A range of integrated nutrient and weed management practices were tested in winter maize for their effects on yield, profitability, and soil health. The nutrient management treatments were a partial substitution of nitrogen with bulky (Farmyard manure; vermicompost) and concentrated organic manures (Brassicaceous seed meal, BSM; neem cake), whereas weed management practices compared chemical controls only versus an integrated approach. The N supplementation through BSM diminished the weed growth by reducing weed N uptake, and enhanced the maize crop uptake of nutrients. As compared to the sole chemical approach, atrazine-applied pre-emergence followed by hoeing reduced weed density by 58 and 67% in years 1 and 2, respectively. The N supplementation through BSM resulted in the maximum yield of maize grain (6.13 and 6.50 t ha−1 in year 1 and year 2, respectively) and this treatment increased yield in year 2 compared to N application through synthetic fertilizer. Hoeing in conjugation with herbicide enhanced the maize grain yield by 9% over herbicide alone. The maximum net return and economic efficiency were achieved with the application of BSM for N supplementation, together with the integrated weed management practice.
... In addition, organic manure releases plant nutrients slowly to crops over time. Of the nutrients present in the manures, only 30% of the N and P may be released in the first year with a smaller proportion released in the following year [49,50]. The progressive mineralization and release of nutrients over time often results in better nutrient use efficiency than by the application of plant nutrients through inorganic fertilizers only [51]. ...
Increasing productivity of maize while decreasing production costs and maintaining soil health are emerging challenges for the rice-maize system in South Asia. A range of integrated nutrient and weed management practices were tested in winter maize for their effects on yield, profitability, and soil health. The nutrient management treatments were a partial substitution of nitrogen with bulky (Farmyard manure; vermicompost) and concentrated organic manures (Brassicaceous seed meal, BSM; neem cake), whereas weed management practices compared chemical controls only versus an integrated approach. The N supplementation through BSM diminished the weed growth by reducing weed N uptake, and enhanced the maize crop uptake of nutrients. As compared to the sole chemical approach, atrazine-applied pre-emergence followed by hoeing reduced weed density by 58 and 67% in years 1 and 2, respectively. The N supplementation through BSM resulted in the maximum yield of maize grain (6.13 and 6.50 t ha −1 in year 1 and year 2, respectively) and this treatment increased yield in year 2 compared to N application through synthetic fertilizer. Hoeing in conjugation with herbicide enhanced the maize grain yield by 9% over herbicide alone. The maximum net return and
... Nitrogen balance was estimated for each treatment as the difference between inputs and outputs (Oenema et al. 2003;Pinitpaitoon et al. 2011;Zhang et al. 2013): ...
Drainage management is important in intensification of irrigated paddy rice production. This study assessed the effects of drainage intensity on water and nitrogen use efficiency and rice grain yield in a field experiment conducted during three seasons in Rwanda. The experiment comprised 12 plots with four blocks and three treatments: DS0.6 (0.6 m deep drain), DD11.2 (1.2 m deep drain, control structure open four times per week), and DD21.2 (1.2 m deep drain, control structure open two times per week). Outflow was calculated from water balance. Nitrogen (N) content in drainage water was determined weekly. Crop yield and N uptake were determined in grain and straw.
In all seasons, grain yield was 61–131% higher, crop N uptake was 24–90% higher, harvest index (HI) was 24–65% higher and water use efficiency (WUE) was 50–150% higher in treatments DD11.2 and DD21.2 than in DS0.6. There was a decrease in soil carbon/nitrogen ratio at the end of Seasons 2 and 3. Recirculating straw to fields is thus necessary to replenish SOC for long-term soil fertility. A practical implication of the study is that managed deep drainage systems could enhance water use efficiency and rice grain yield in poorly drained paddy fields.
... The yield of red pepper was highest in NPK+compost treatment followed by NPK (chemical fertilizer), compost, and control. Productive and sustainable production systems require mineral fertilizers in combination with management of crop residues and manure to maintain soil organic matter levels and nutrient supply (Pinitpaitoon et al., 2011). Substances determining acridity, containing capsaicin and dihydrocapsaicin, were low in NPK and NPK+compost treatments, while carotenoid was not significantly different between the treatments. ...
Nowadays, sustainable and environment-friendly agriculture has become an important issue all around the world, and repeated applications of mineral and/or organic fertilizer will probably affect mineral nutrient dynamics in soil in the long term but only a limited number of observations are available. This study was carried out to investigate whether there is any influence of different fertilizer management for red pepper (Capsicum annuum L.) cultivation on soil physicochemical properties, leaf mineral content, yield and fruit quality in the aspect of long-term practice in open field condition. NPK, NPK+compost, compost only, and unfertilized control plot were included in the treatments. The application of chemical fertilizer and/or compost repeated annually for 17 years from 1994 to 2011. Soil organic matter content was higher in compost treatments than in no-manure treatments. Available phosphate and the yield of red pepper were highest in NPK+compost treatment followed by NPK (chemical fertilizer), compost, and control. The results indicate that in the long term, nitrogen supply is still needed for increasing red pepper yield, but reduction in the use of chemical fertilizer could be also possible with the proper application of compost.
... A simple N budget was estimated for each plot from Jun. 2007 to Oct. 2009 as the difference between the inputs (N from fertilizer, initial inorganic N and miner- alized N) and outputs (crop uptake of N and residual soil N) (Oenema et al., 2003;Schröder et al., 2003;Pinitpaitoon et al., 2011). This difference, called the apparent N loss, represents N that is lost by leach- ing, ammonia volatilization, runoff, denitrification and other ways. ...
Nitrate-nitrogen (NO−3-N) dynamics and nitrogen (N) budgets in rice (Oryza sativa L.)-wheat (Triticum aestivum L.) rotations in the Taihu Lake region of China were studied to compare the effects of N fertilizer management over a two-year period. The experiment included four N rates for rice and wheat, respectively: N1 (125 and 94 kg N ha−1), N2 (225 and 169 kg N ha−1), N3 (325 and 244 kg N ha−1), and N0 (0 kg N ha−1). The results showed that an overlying water layer during the rice growing seasons contributed to moderate concentrations of NO−3-N in sampled waters and the concentrations of NO−3-N only showed a rising trend during the field drying stage. The NO−3 -N concentrations in leachates during the wheat seasons were much higher than those during the rice seasons, particularly in the wheat seedling stage. In the wheat seedling stage, the NO−3-N concentrations of leachates were significantly higher in N treatments than in N0 treatment and increased with increasing N rates. As the NO−3-N content (below 2 mg N L−1) at a depth of 80 cm during the rice-wheat rotations did not respond to the applied N rates, the high levels of NO−3-N in the groundwater of paddy fields might not be directly related to NO−3-N leaching. Crop growth trends were closely related to variations of NO−3-N in leachates. A reduction in N application rate, especially in the earlier stages of crop growth, and synchronization of the peak of N uptake by the crop with N fertilizer application are key measures to reduce N loss. Above-ground biomass for rice and wheat increased significantly with increasing N rate, but there was no significant difference between N2 and N3. Increasing N rates to the levels greater than N2 not only decreased N use efficiency, but also significantly increased N loss. After two cycles of rice-wheat rotations, the apparent N losses of N1, N2 and N3 amounted to 234, 366 and 579 kg N ha−1, respectively. With an increase of N rate from N0 to N3, the percentage of N uptake in total N inputs decreased from 63.9% to 46.9%. The apparent N losses during the rice seasons were higher than those during the wheat seasons and were related to precipitation; therefore, the application of fertilizer should take into account climate conditions and avoid application before heavy rainfall.
The study determined fertilizer use gaps between current farmers' practice and scientific recommendations; explored the agro-socio-economic factors affecting fertilizer use decision and nutrient use gaps at farm levels; and explored the major barriers to adoption of recommended fertilizer dose. The study revealed that farmers applied different types of fertilizers/ nutrients without considering scientific recommendations. They used much higher doses/over doses of all types of nutrients (NPKS) in high value crops like potato and watermelon, whereas used lower amounts in Kharif season crops like, T. Aman, maize etc. Except maize, respondent farmers applied much higher dose of P in different crops compared to recommended dose. However, the use of different nutrients were found close to the optimum dose only for T. Aus rice. In farm categories, women managed farm households and small & marginal farmers used much lower doses of nutrients compared to medium and large category farmers.
The estimated 12 beta regression models clearly revealed that the nutrient use gaps between current farmer’s practice and scientific recommendation were positively or negatively influenced by a number of agro-socio-economic factors. The major significant factors were gender, category of farmers, crop residue retention, crop rotation, fertilizer use in previous crop, distance of input/output market, fertilizer price, level of extension contact, number of cattle owned, and study region.
However, based on the findings of the study, the NUMAN project can undertake some initiatives to minimize the nutrient use gaps between current farmer’s practice and scientific recommendations. However, the following policy guidelines have been suggested for higher adoption of balanced fertilizer dose and minimizing the nutrient use gaps between current farmer’s practice and scientific recommendations.
Winter maize is an innovation in Indian cropping systems. It grows 50-60 days longer than rainy-season maize and is a heavy feeder cereal. It lacks proper management of nutrients, particularly nitrogen and phosphorous. N and P determine the photosynthetic and reproductive capacity of plants. The response of maize to these nutrients is season-dependent and location-specific, but has seldom been studied in winter maize areas in India. This study was designed to evaluate the impact of N and P independently and interactively on winter maize. Maize yield was highest at 240 kg N ha-1, but the yield obtained at 160 kg N ha-1 was comparable. Every kg N applied produced 44.34 kg grain, and the N-use efficiency was reduced with increased N dose (67.4, 38.4, and 27.2 kg grain kg-1 N for 80, 160, and 240 kg N ha-1, respectively). Phosphorus application increased yield up to 26.4 kg ha-1. A combination of 240 kg N ha-1 and 26.4 kg P ha-1, providing highest gross returns, net returns and net benefit: cost, was most profitable. The economic optimum dose for N and P was 196 kg N ha-1 and 23.4 kg P ha-1, respectively. This study shows that winter maize is responsive to higher levels of N up to 240 kg ha-1 compared to 120 kg N ha-1 recommended for rainy-season maize, but P application at 26.4 kg ha-1 remains same for both the seasons. The study provides recommendation of N and P for winter maize based on economics. The data would be useful for fitting models and simulating yields across the doses of N and P.
Taking two long-term local field trials at the south edge of the Loess Plateau, which were found in 1990 and 2003, respectively, as test subjects, the effects of different fertilization practices on the maize root biomass and nutrient content were investigated in this paper. Maize roots in the 0-20 cm top soil post-maize harvest from the different fertilization practices were collected by hand in October 2011. The results showed that compared with control without fertilization and N, NK, or PK treatments, the NP, NPK, fertilizers plus manure (M1NPK and M2NPK) or plus straw return (SNPK) treatments significantly increased the dry mass of maize root. The C, N, P and K contents in maize roots in the NP, NPK, M1 NPK, M2NPK and SNPK treatments were also significantly higher than those of control, especially in the NPK plus organic manure treatments (M1 NPK and M2NPK) in the trial. Compared with the N fertilizer free treatment (N0), root biomass in the 120 kg N · hm(-2) (N120) and 240 kg N · hm(-2) ( N240) fertilization treatments increased by 38% and 45%, respectively, but there was no significant difference between N120 and N240 treatments. Nitrogen fertilizer application (N120 and N240) also improved the C, N, P and K contents in maize root. The water soluble organic C and total soluble N contents of maize root in the NP, NPK, M1NPK, M2NPK, SNPK and the N120 and N240 treatments were greater than those of control and other treatments. Otherwise, the cellulose and lignin contents in maize roots declined in the NPK, M1NPK, M2NPK, and SNPK treatments compared with other treatments. So the root C/N and lignin/N ratios in the control, PK and N0 treatments were significantly higher than those in the NP, NPK, M1NPK, M2NPK and SNPK treatments. We concluded that the optimum fertilization (e. g., NP, NPK, MNPK and SNPK treatments) could increase maize root growth and nutrient content and improve soil fertility and carbon sequestration through root residue into soil.
Decomposition and nutrient release patterns of prunings of three woody agroforestry plant species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays) stover and rice (Oryza sativa) straw, were investigated under field conditions in the humid tropics, using litterbags of three mesh sizes (0.5, 2 and 7 mm) which allowed differential access of soil fauna. The decomposition rate constants ranged from 0.01 to 0.26 week−1, decreasing in the following order; Gliricidia prunings >Leucaena prunings > rice straw > maize stover >Acioa prunings. Negative correlations were observed between decomposition rate constants and C:N ratio (P < 0.004), percent lignin (P < 0.014) and polyphenol content (P < 0.053) of plant residues. A positive correlation was observed between decomposition rate constant and mesh-size of litterbag (P < 0.057). These results indicate that both the chemical composition of plant residues and nature of the decomposer played an important role in plant residue decomposition.Nutrient release differed with quality of plant residues and litterbag mesh-size. Total N, P, Ca and Mg contents of plant residues decreased with time for Gliricidia and Leucaena prunings, maize stover, and rice straw, and increased with time for Acioa prunings. There was some indication of N immobilization in maize stover and rice straw; P immobilization in Leucaena prunings and rice straw; and Ca immobilization in maize stover, rice straw and Gliricidia and Leucaena prunings. Acioa prunings immobilized N, P, Ca and Mg. All plant residues released K rapidly. Nutrient release increased with increasing mesh-size of litterbags, suggesting that soil faunal activities enhanced nutrient mobilization.
This edition updates a narrative that has been at the forefront of soil science for more than a century. The first edition, published in 1909, was largely a guide to good soil management for farmers in the glaciated regions of New York State in the northeastern U.S. Since then, it has evolved to provide a globally relevant framework for an integrated understanding of the diversity of soils, the soil system and its role in the ecology of planet Earth.
The 15th edition is the first to feature full-color illustrations and photographs throughout. These new and refined full color figures and illustrations help make the study of soils more efficient, engaging, and intellectually satisfying. Every chapter has been thoroughly updated with the latest advances, concepts, and applications. Hundreds of new key references have been added. The 15th edition, like preceding editions, has greatly benefited from innumerable suggestions, ideas, and corrections contributed by soil scientists, instructors, and students from around the world. Dr. Nyle Brady, although long in retirement and recently deceased, remains as co-author in recognition of the fact that his vision, wisdom and inspiration continue to permeate the entire book.
This edition,1082 pages in length, includes in-depth discussions on such topics of cutting edge soil science as the pedosphere concept, new insights into humus and soil carbon accumulation, subaqueous soils, soil effects on human health, principles and practice of organic farming, urban and human engineered soils, cycling and plant use of silicon, inner- and outer-sphere complexes, radioactive soil contamination, new understandings of the nitrogen cycle, cation saturation and ratios, acid sulfate soils, water-saving irrigation techniques, hydraulic redistribution, cover crop effects on soil health, soil food-web ecology, disease suppressive soils, soil microbial genomics, indicators of soil quality, soil ecosystem services, biochar, soil interactions with global climate change, digital soil maps, and many others. In response to their popularity in recent editions, I have also added many new boxes that present either fascinating examples and applications or technical details and calculations. These boxes both highlight material of special interest and allow the logical thread of the regular text to flow smoothly without digression or interruption.
For students: This book provides both an exciting, accessible introduction to the world of soils as well as a reliable, comprehensive reference that you will want to keep for your professional bookshelf. What you learn from its pages will be of enormous practical value in equipping you to meet the many natural-resource challenges of the 21st century. The book demonstrates how the soil system provides many opportunities to see practical applications for principles from such sciences as biology, chemistry, physics, and geology. Throughout, the text highlights the countless interactions between soils and other components of forest, range, agricultural, wetland, and constructed ecosystems.
As the global economy expands exponentially societies face new challenges with managing their natural resources. Soil as a fundamental natural resource is critical to sustained economic growth and the prosperity of people in all parts of the world. To achieve balanced growth with a sustainable economy while improving environmental quality, it will be necessary to have a deep understanding of soils, including their properties, functions, ecological roles and management. I have tried to write this textbook in a way designed to engage inquisitive minds and challenge them to understand soils and actively do their part as environmental and agricultural scientists, in the interest of ensuring a prosperous and healthy future for humanity on planet Earth. It is my sincere hope that this book, previous editions of which have served so many generations of soil students and scientists, will continue to help future generations of soil scientists to benefit from a global ecological view of soils.
Thoroughly updated and now in full color, the 15th edition of this market leading text brings the exciting field of soils to life. Explore this new edition to find:
A comprehensive approach to soils with a focus on six major ecological roles of soil including growth of plants, climate change, recycling function, biodiversity, water, and soil properties and behavior.
New full-color illustrations and the use of color throughout the text highlights the new and refined figures and illustrations to help make the study of soils more efficient, engaging, and relevant.
Updated with the latest advances, concepts, and applications including hundreds of key references.
New coverage of cutting edge soil science. Examples include coverage of the pedosphere concept, new insights into humus and soil carbon accumulation, subaqueous soils, soil effects on human health, principles and practice of organic farming, urban and human engineered soils, new understandings of the nitrogen cycle, water-saving irrigation techniques, hydraulic redistribution, soil food-web ecology, disease suppressive soils, soil microbial genomics, soil interactions with global climate change, digital soil maps, and many others
Applications boxes and case study vignettes bring important soils topics to life. Examples include “Subaqueous Soils—Underwater Pedogenesis,” “Practical Applications of Unsaturated Water Flow in Contrasting Layers,” “Soil Microbiology in the Molecular Age,” and "Where have All the Humics Gone?”
Calculations and practical numerical problems boxes help students explore and understand detailed calculations and practical numerical problems. Examples include “Calculating Lime Needs Based on pH Buffering,” “Leaching Requirement for Saline Soils,” "Toward a Global Soil Information System,” “Calculation of Nitrogen Mineralization,” and “Calculation of Percent Pore Space in Soils.”
Composting municipal solid waste and biosolids and applying it on arable land have become an alternative way to treat waste in large municipalities in North America. However, cost of compost transportation and application constrains the compost use on the land further away from where it is produced. A four-year experiment was conducted (1998-2001) in less productive soils in Alberta to determine the effect of once in four year application of cocompost on soil nutrient dynamics and crop N uptakes. There were three crop blocks: barley (Hordeum vulgare L.), wheat (Triticum aestivum L), and canola (Brassica rapa), and they were rotated annually. The compost was only applied in 1998 at a rate of 50, 100 and 200 t/ha. Soil samples were taken in spring of every year after initial compost application to determine extractable N, P, K, S, Cu, Zn, Soil pH and EC. Each year, crops were harvested and N uptake was determined. Total concentrations of an array of heavy metals in the first year and fourth year after compost application were determined as well. The results showed that the release of N from the compost was high in the first year after compost application and then declined in each subsequent year. Similar to that release pattern was sulphur. The release of phosphorus from compost was steady throughout the four-year experimental time. Crop N uptake from compost application varied with crops and sites. The over all N use efficiency for three crops and two sites was 11%, 3%, 1% and 2% for the first and subsequent three years. The total heavy metal concentrations in the compost amended soils in the first and fourth year after compost application were similar, and they were below the standard of Canadian Fertilizer Act. Our results showed that N released from compost occurred mostly in the first two years after application, suggesting that an application frequency of once in every second year may be better than the once in every four year application strategy, especially with 100 t/ha application rate.
One-season fallows with legumes such as Crotalaria grahamiana Wight & Am. and phosphorus (P) fertilization have been suggested to improve crop yields in sub-Saharan Africa. Assessing the sustainability of these measures requires a sound understanding of soil processes, especially transformations of P which is often the main limiting nutrient. We compared plant production, nitrogen (N) and P balances and selected soil properties during 5.5 years in a field experiment with three crop rotations (continuous maize, maize-crotalaria and maize-natural fallow rotation) at two levels of P fertilization (0 and 50 kg P ha(-1) yr(-1), applied as triple superphosphate) on a Kandiudalfic Eutrudox in western Kenya. The maize yield forgone during growth of the crotalaria fallow was compensated by higher post-fallow yields, but the cumulative total maize yield was not significantly different from continuous maize. In all crop rotations, P fertilization doubled total maize yields, increased N removal by maize and remained without effect on amounts of recycled biomass. Crotalaria growth decreased in the course of the experiment due to pest problems. The highest levels of soil organic and microbial C, N and P were found in the maize-crotalaria fallow rotation. The increase in organic P was not accompanied by a change in resin-extractable P, while H2SO4-extractable inorganic P was depleted by up to 38 kg P ha(-1) (1% of total P) in the 0-50 cm layer. Microbial P increased substantially when soil was supplied with C and N in a laboratory experiment, confirming field observations that the microbial biomass is limited by C and N rather than P availability. Maize-legume fallow rotations result in a shift towards organic and microbial nutrients and have to be complemented by balanced additions of inorganic fertilizers.
A major challenge in developing agroforestry approaches that utilize tree-leaf biomass for provision of N to crops is to ensure
synchrony between the N released from decomposing prunings and N demand by crops. A study was conducted in the subhumid highlands
of Kenya to assess the rate of decomposition and mineralization of soil-incorporated Calliandra calothyrsus Meissner (calliandra)
and Leucaena leucocephala (Lam.) de Wit (leucaena) tree biomass and maize roots (Zea mays L.) both in an alley cropping and
a sole cropping system. The amount of mineralized N peaked four weeks after planting (WAP) maize in all the treatments during
both seasons of 1995. Cumulative mineralized N at week 20 ranged from 114 to 364 kg N ha−1 season−1, the absolute control treatment giving the lowest and the prunings-incorporated treatments giving the highest amounts in
the two seasons. Total N uptake by maize, ranging from 42 to 157 kg ha−1 season−1, was lowest in the 'alley-cropped, prunings-removed' treatments, and highest in the 'non alley-cropped-prunings-incorporated'
treatments. The apparent N recovery rate by maize was highest in the fertilizer applied treatments in the two seasons. Decomposition
rate constants (kD) ranged from 0.07 to 0.21 week−1, and the rates among the different plant residues were as follows: leucaena < calliandra < maize roots. Nitrogen release
rate constants (kN), ranging from 0.04 to 0.25 week−1, followed a similar pattern as the rate of decomposition with leucaena releasing the highest amount of N followed by calliandra
and lastly by maize roots.
Nutrient input–output balances are often used as indicators for the sustainability of land use systems. In a case study on
plot scale in Central Sulawesi, Indonesia, we measured nutrient input–output balances of natural rainforest and two unfertilized
land use systems (maize, and coffee/cacao agroforestry). These are the two major land use systems on converted rainforest
sites in this part of Sulawesi. We wanted to test if (a) plant nutrient balances are negative, (b) which pathway is most important
for losses of plant nutrients, and (c) if partial plant nutrient balances are suitable to evaluate sustainability of the land
use systems. We measured nutrient inputs by precipitation and nutrient outputs by harvest export and leaching. We selected
two locations, the first was situated on a fertile Cambisol developed on alluvial sediment soil, and the second on a less
fertile Cambisol developed on weathered phyllite substrate. Nutrient losses through leaching were higher on sites with higher
soil fertility. Nutrient balances in natural forest on fertile soils were negative for N, Ca, K and Mg. Inputs of P by precipitation
and outputs by leaching were below detection limit. On less fertile soils, leaching of N and K in natural forest was lower
than inputs by precipitation. As net nutrient losses were highest in agroforestry, followed by maize and natural forest stands,
forest conversion into agricultural land will result in increased nutrient losses. Main output pathway of N, P and K was harvest,
whereas main output pathway for Ca and Mg was through leaching. The annual losses of nutrients we measured were higher than
in comparable studies on nutrient poor soils; however losses were only small fractions of available nutrient stocks. Our results
showed negative partial nutrient balances in both agricultural systems. Nutrient balances in this study were more influenced
by native soil fertility than by land use. Because we found indirect evidence that some nutrient pathways, which were not
measured, may have significantly changed the overall balance (biological N fixation, weathering), we conclude that partial
nutrient balances are no good indicators for sustainability of land use systems.
A simplified procedure for determining the amount of phosphate (P) extracted from soils by ion exchange resin membranes is reported. Strips of anion (HCO
3
-
form) and cation (Na+ form) exchange membrane were shaken with suspensions of soil in deionised water for 16–17 hours. After shaking, the strips were thoroughly rinsed in deionised water before the phosphate retained on the anion exchange resin strip was determined by shaking the strip directly with phosphate reagent. Compared to the common use of resin beads in nylon mesh bags, this resin membrane procedure is simpler, more convenient, and because an elution step is omitted, less time consuming.The mixed resin membrane method for soil phosphate extraction was compared to the use of resin bags on four New Zealand soils, contrasting in P sorbing capacity and exchangeable calcium. The soils were preincubated with and without 240 mg P kg–1 soil with three P sources of different solubilities. The resin strips extracted amounts of P which were closely correlated (R2 = 0.972) with that extracted by the resin bags. The amounts of P extracted by the mixed resin procedure were in proportion to the solubility of the P sources in each soil.
This is one of a series of seven in-depth country studies on maize production systems in Asia, funded by the International Maize and Wheat Improvement Center (CIMMYT) and the International Fund for Agricultural Development (IFAD). It is part of a project designed to promote sustainable intensification of maize production systems while ensuring equitable income growth and improved food security, especially for poor households that depend on maize. Maize is one of five major crops grown in the uplands of Thailand, along with rice, cassava, sugar cane, and rubber trees. Government-promoted crop diversification, increased population growth, improved transportation networks, inter national trade, expansion of upland farming areas, and increased demand for grains from the domestic livestock and poultry industry stimulated Thailands maize production beginning in the 1980s. However, Thailands domestic maize supply is currently not sufficient to meet the needs of its in-country demands, and small quantities have to be imported. Rapid economic growth and accelerated urbanization are expected to create an even higher demand for maize in Thailand. This trend will lead to the intensification of current maize production systems, with more land being shifted to maize production, particularly in marginal areas. Thailands challenge is to produce more maize for an expanding market, while preserving the natural resource base and the environment through careful agricultural planning. Effective policy design and implementation must be based on comprehensive, accurate data on the current state of maize-based farming systems. This study characterized the social and biophysical maize production environment of Thailand; examined its response to increasing maize demand; determined constraints to future productivity growth; indicated the potential envir onmental consequences, and examined the options available for promoting sustainable growth in maize production.
The effects of both barley and Lolium rigidum densities on weed growth and spike production and on crop yield were examined in five field experiments carried out in the Mediterranean drylands of Spain and Western Australia. The aim was to check the consistency of the competitiveness of the crop in different environmental and management conditions. L. rigidum reduced barley yields in most of the experiments ( between 0 and 85%), the number of ears per m(2) being the most affected. It was found that increasing the barley seeding rate did not reduce the crop losses but did limit weed biomass ( between 5 and 61%) and spike production ( between 24 and 85%). The variability observed in crop yield losses between sites and seasons was related to rainfall at the beginning of the season. The most sensitive component of yield to weed competition was the number of ears per plant.
Enhanced levels of nitrogen in the environment may have several adverse effects, including decreased plant species diversity in (semi) natural terrestrial ecosystems, eutrophication of surface waters, pollution of groundwater due to nitrate leaching and global warming due to nitrous and nitrogen oxide (N2O and NOx) emissions. To determine the effectiveness of policies aimed at the reduction of emission of ammonia (NH3), N2O and NOx, nitrate (NO3) leaching and nitrogen (N) runoff, it is essential to have information on the fate of nitrogen in both agricultural and non-agricultural soils on a regional and national scale and its inherent uncertainties. In this paper, we quantified the uncertainties in the emission, uptake, accumulation, denitrification, leaching and runoff of nitrogen at a national scale and for specific land use–soil type combinations. Furthermore, we identified which parameters contribute most to the overall uncertainty in the emission of ammonia to the atmosphere and the leaching/runoff to groundwater and surface water. To gain quantitative insight into the propagation of the uncertainty, a model was developed representing all crucial processes in the N chain by simple process descriptions. Uncertainties were quantified for the Netherlands as a whole, including terrestrial systems, both agricultural and non-agricultural land, and aquatic systems. For agricultural and non-agricultural land, plots were distinguished, consisting of a multiple of 500 × 500 m2 and of 250 × 250 m2 grid cells, respectively, with unique combinations of soil use, soil type and groundwater table class that were derived from existing digital maps. Model parameters were assigned by using relationships with soil type, groundwater level class and land use. The uncertainty was quantified by means of a Monte Carlo analysis, whereas statistical approaches were used to identify which parameters contribute most to the overall uncertainty of the fate of nitrogen. The 90% confidence interval for the fluxes of N compounds to air, groundwater and surface water (in Gg N.yr-1) ranged between 102 and 194 for ammonia emission, between 18 and 51 for N2O emissions, between 32 and 108 for NO3 inflow to groundwater and between 2 and 38 for N inflow to surface water. The uncertainty in NH3 emission was mainly caused by the uncertainty in the NH3 emission fractions for animal manure, whereas the uncertainty in N2O emission was mainly due to the uncertainty in the fractions relating total nitrification and denitrification to N2O emissions. The uncertainty in inflow to groundwater and runoff to surface water was mainly caused by the uncertainty in denitrification in the soil and in upper groundwater and in non-agricultural soils also by the N accumulation in the soil. In view of the need to monitor and evaluate the impact of N reduction policies and measures, it is essential to put more effort in activities yielding a reduction of these large uncertainties, such as additional data gathering and process research under field circumstances.
This chapter describes prevalent laboratory methods for determining salinity based on measurements of electrical conductivity (EC) or total dissolved solids after evaporation at 180°C. It discusses various methods for determining the concentrations of individual inorganic solutes in waters and soil extracts in common use in laboratories having modern instrumentation. The extraction ratios are easier to make than that of saturation, but they are less well related to field soil water composition and content. More importantly, salinity and compositional errors from dispersion, hydrolysis, cation exchange, and mineral dissolution increase as the water/soil ratio increases. Soil salinity may be estimated from measurement of the EC of the saturated soil-paste and estimates of saturation percentage. The amount of total dissolved solids in a sample is determined by weighing the residue obtained after evaporating a sample that has been filtered to remove particulate matter.
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.
On request of FAO a methodology was developed to assess the state of soil nutrient depletion under agriculture in Sub-Saharan Africa for 1983 and the year 2000. The nutrient balance is described with five input and five output factors, which result in a nutrient loss rate. Production figures and data on fertilizer consumption for 1983 and projections for the year 2000 were provided by FAO. Data on nutrient balances as well as additional country information were collected from literature. Nutrient depletion rates for Sub-Saharan Africa are approximately 20 kg N, 10 kg P2O5 and 20 kg K2O per ha on average up to a maximum of 40 kg N, 20 kg P2O5 and 40 kg K2O per ha in East Africa.
Total carbon (C) in soils is the sum of both organic and inorganic C. Organic C is present in the soil organic matter fraction, whereas inorganic C is largely found in carbonate minerals. The wet combustion analysis of soils by chromic acid digestion has long been a standard method for determining total C, giving results in good agreement with dry combustion. Methods for total C are basic for many of the procedures used to determine organic C in soils. In contrast to noncalcareous soils, inorganic C must be removed from calcareous or limed soils before the analysis if wet or dry combustion techniques are used to directly measure the organic C present. The organic matter content of soil may be indirectly estimated through multiplication of the organic C concentration by the ratio of organic matter to organic C commonly found in soils.
Assessment of net primary productivity of maize (Zea mays L.)- based agroecosystems is dependent on both above and belowground dry matter production that is ultimately returned to the soil as residue and decaying roots. Root to shoot ratio (R/S) is a parameter often used to estimate root biomass (RB) when shoot biomass is measured or estimated. The labor intensive nature of root sampling and wide vari- ety of sampling techniques has lead to a paucity of maize RB data in the literature, and few researchers have endeavored to characterize R/S throughout an entire growing season. In this paper, the results of 45 maize root studies published in 41 journal articles are summarized and the data used to generate estimates of maize RB and R/S versus days after emergence (DAE). The data from these studies indicate that on average, RB was maximized just after anthesis at approxi- mately 31 g plant21 (13.6 g C plant21) and that average R/S varied from a high of 0.68 at emergence to a low of 0.16 at physiological maturity. Net rhizodeposited C as a percentage of total net root- derived belowground C at time of sampling (%NRC) was reported for 12 maize studies and varied between 5 and 62%. The wide variation in the %NRC was shown to be highly correlated with an index combining irradiance level, photoperiod, and ambient temperature, suggesting a strong dependence of net rhizodeposited C on rate of photosynthesis and soil respiration. The net belowground C deposition at maize physiological maturity is estimated as 29 6 13% of shoot biomass C for maize that has not experienced stress.
Animal manures are an important source of N for crop production. Efficient use of manure is necessary to increase N recycling, eliminate excessive purchase of fertilizer N, and reduce N loss to the environment. An estimate of the annual rate of organic N mineralization in manure is a necessary prerequisite to efficient manure N management. A mineralization or decay series for the organic N in dairy manure was estimated for corn ( Zea mays L.) production from several field experiments over a 5‐ to 8‐yr period. Four rates of sidedressed fertilizer N (0, 56, 112, and 224 kg N ha ⁻¹ ) were superimposed over several springapplied manure treatments ranging from 0 to 168 Mg ha ⁻¹ yr ⁻¹ . Ammonia volatilization from manure was encouraged, to allow for an assessment of the fertilizer N equivalence of the more stable organic N fraction. Based on silage dry matter yield and N uptake, a decay series of 0.16, 0.10, 0.03, 0.03 and 0.02, and 0.21, 0.09, 0.03, 0.03 and 0.02, respectively, described the fertilizer N equivalence of organic N. The first number in the decay series estimates the fraction of organic N that is available for crop use during the year of application, and the second to fifth numbers are estimates of available N from residual N in Years 2 through 5. An independent set of field data was used to evaluate the accuracy of the decay series. The predicted decay series, based on dry matter yield ( R ² = 0.16) was more variable than the corresponding decay series based on N uptake ( R ² = 0.72). The non‐N effects of manure were insignificant, and therefore yield and N uptake were directly related to the N contribution.
Recycling of crop residues is essential to integrated and sustainable agricultural management system. Thus, it is of crucial importance to study the decomposition of these residues particularly in the humid-tropics. A litterbag experiment was carried out on an acid soil of the humid tropics of Malaysia. Haulm from groundnut and stover from were placed inside nylon 2 mm mesh bags (20 cm×20 cm) and placed on the soil surface in the field with a groundnut–maize rotation system. A total of 21 bags for maize and an equal number for groundnut residues were placed in a field plot. Three bags of each residue type were retrieved at 1, 3, 5, 7, 9, 11 and 13 weeks of decomposition. The decomposed tissue was analyzed for remaining dry matter weight (DMW), nitrogen (N), carbon (C), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) contents. Dry matter disappearance rate constant (0.158% week) from groundnut haulm was significantly (P=0.01) faster than that from maize stover (0.099% week). A 50% loss of residue N was found after 2 weeks for maize residues and only 1.5 weeks for groundnut residues. Generally, nutrient loss from both residues was in the order of K≥P=N=Mg≥Ca. The results indicated that sowing time of subsequent crop after residue application is crucial to synchronize nutrient release with plant uptake.
In the present investigation, organic and intensive cropping systems were compared on small autonomous drainage plots in limed Luvisoils and Cambisoils as well as non-acid Cambisoils during the period 1995-1998. In the intensive cropping system with balanced nutrient application, the yield of all crops was 38-77% higher than in the organic cropping system. Cropping intensity had no influence on mineral concentration in drainage water, which depended on geochemical soil media. The concentrations of Cl- and NO 3- in drainage water were, respectively, 8-22 and 24-80% higher than in the organic system. But at low N application, improvement of fertilisation efficiency increased crop yield and decreased nitrate leaching at the same time. The leached amount of solutes depended mainly upon drainage runoff, which was 6-57% lower in the intensive cropping system than in the organic one, and much less upon its concentration. From this study, organic agriculture has no essential advantage compared with intensive agriculture, considering the amount of leached elements and compounds, and secondarily, crop productivity.
Net mineralization of N in 39 widely differing soils was determined over a 30‐week period at 35C, using incubation intervals of 2, 2, 4, 4, 4, 6, and 8 weeks. Mineral N was leached from the soils before the first incubation and following each of seven incubations by means of 0.01 M CaCl 2 and a minus‐N nutrient solution. Soil water contents were adjusted by applying suction (60 cm Hg), and losses of water during incubation under aerobic conditions were negligible. With most soils, cumulative net N mineralized was linearly related to the square root of time, t ½ . The pH of soils changed very little in the course of 30 weeks' incubation. Because of the generally consistent results, the data were employed in calculating the N mineralization potential, N o , of each soil, based on the hypothesis that rate of N mineralization was proportional to the quantity of N comprising the mineralizable substrate. Values of N o ranged from about 20 to over 300 ppm of air‐dry soil. The fraction of total N comprising N o varied widely (5 to 40%) among soils. Mineralization rate constants did not differ significantly among most of the soils. The most reliable estimate of the rate constant, k was .054 ± .009 week ‐1 . The time required to mineralize one‐half of N o , t ½ , was estimated to be 12.8 ± 2.2 weeks. Results suggest that the forms of organic N contributing to N o were similar for most of the soils.
With the help of this guide, you can use obtained test results to evaluate the fertility status of soils and the nutrient element status of plants for crop production purposes. It serves as an instructional manual on the techniques used to perform chemical and physical characteristic tests on soils. Laboratory Guide for Conducting Soil Tests and Plant Analysis describes the basis and procedures for each test in detail, including analytical instrumentation procedures and laboratory quality assurance requirements.
The concept of a new continuous flow analyser system is described. Based on instant discrete sampling by injection into a carrier stream, the system allows continuous flow analysis to be performed in a fast, much simplified way. As the continuous flowing stream is characterized by a turbulent rather than a laminar flow, the discrete instant sampling creates geometrically well-defined segments of sample solution within the flowing stream. Because of the absence of lag phase, an unprecedented sampling rate for continuous flow analysis of well over 200 samples per hour can be achieved; and even manual injection of the samples allows a very high degree of accuracy and precision to be obtained ( ⩽ ± 1%). Uses of the system in various analytical procedures are described and discussed. A potentiometric sensor (the air-gap electrode used in a flow-through unit) and a spectrophotometric arrangement with a flow-through cell have been used as detector units.
Municipal solid waste compost (MSWC) can enhance soil organic matter and crop nutrient supply. High C:N ratio composts can temporarily deplete plant-available soil N reserves, requiring supplemental N fertilization to ensure optimum crop growth. The objective of our research was to measure seasonal soil NO3-N dynamics to serve as an indication of N mineralization, immobilization, and leaching as affected by MSWC and N fertilizer rates. The MSWC (C:N 40:1) was applied in one year only to a Galestown sand (sandy, siliceous, mesic Psammentic Hapludults) at rates of 0, 63, 126, and 189 Mg ha-1. Maize (Zea mays L.) was planted and N fertilizer rates of 0, 168, 336, 504, and 672 kg ha-1 were applied as split-plot treatments. First-year maize total dry matter production plateaued at the 250 kg ha-1 N rate, averaged across MSWC rates. Soil NO3-N decreased inversely proportional to MSWC rates, due to MSWC immobilization of soil and fertilizer N. Cereal rye (Secale cereale L.) winter cover crop total dry matter yield and total crop N increased linearly with increasing MSWC rates. Second-year maize total dry matter, total plant N, maize grain yield, and grain N increased linearly with increased MSWC rates applied the first year. During the second growing season, there was an increasing supply of plant-available N, due to mineralization of organic N in the MSWC with increasing MSWC rate; however, the supply of mineralized N was inadequate to meet crop growth requirements for maximum maize yield.
This study measured rates of mass loss and changes in N and P contents in Oi horizon needles decomposing in the laboratory, and in Oi, Oe1 and Oe2 horizon needles decomposing in situ in loblolly and slash pine plantations in Florida, (litterbag study). The quality was increased by both weed control and fertilizer treatments. Generally in the field, N was immobilized into Oi horizon needles but was released in modest amounts (<15% yr-1) from Oe1 and Oe2 horizon needles. In contrast, substantial release of P from Oi horizon needles (>35% yr-1) was followed by smaller release from Oe1 and Oe2 horizon needles (<15% yr-1). The rapid recycling of P in fertilized plots has the potential to enhance long-term productivity. -from Authors
An 18-yr field study was performed to compare organic and conventional cropping on a highly P and K depleted soil in southern Sweden that had not received any inorganic fertilizers (or pesticides) since the mid-1940s. The major management differences between the systems were (i) growth of legumes every second year and use of legumes as cover crops in the organic rotation; (ii) application of P in the organic system at higher rates than for the conventional system; (iii) exclusion of oilseed rape (Brassica napus L.) from the organic system but inclusion of potato (Solanum tuberosum L.); (iv) frequent mechanical weeding in the organic system; and (v) use of solid manure in the organic and liquid manure in the conventional system. Concentrations of soil-exchangeable P increased more after application of large amounts of basic slag and apatite in the organic system than after application of P fertilizers in the conventional system. Organic systems, which rely mainly on legumes for their N supply, will acidify soils faster than systems with fewer legumes in rotation. Crop yields were, on average, 50% less and weed biomass was greater (1-3 Mg dry matter ha(-1)) in the organic system than in the conventional system. Nitrogen was identified as the main yield-limiting nutrient for organically grown crops. Despite this, and even with use of cover crops, N leaching was not reduced by organic farming. Soil carbon (C) concentrations decreased in both systems, but less so in the organic system due to higher C inputs and lower soil pH values. Still, organic farming seems not be an option for sequestering C in soil in Sweden. After adjusting the two systems to the same boundary conditions for an unbiased modeling comparison, the C input is approximate to 60% higher in the conventional system than the organic system. The agronomic efficiency of N was 9 to 10 kg grain yield kg(-1) N in the organic system compared with 16-18 kg grain yield kg(-1) in the conventional system. The longterm use efficiency of P was lower in the organic system (7%) than in the conventional system (36%). These results show that yield and soil fertility are superior in conventional cropping systems under cold-temperate conditions.
In this study, three types of cropping systems with different nutrient management strategies were studied on a clay soil with the aim of comparing leaching of N, P and K and obtaining knowledge on nutrient budgets. A conventional cropping system with cereals and application of mineral fertilizers (CON) was compared with two organic cropping systems, one without animal manure in which green manure crops were used for N supply (OGM) and one where animal manure (cattle slurry) was applied (OAM). Leaching and crop uptake of N, P and K, and soil mineral N were measured in pipe-drained plots over a 6-year period.
The mean annual leaching loads of N were moderate and did not differ significantly (P > 0.05) between treatments; 13 kg N ha−1 in CON, 11 kg N ha−1 in OGM and 7.4 kg N ha−1 in OAM. Average annual P leaching showed greater variation than N leaching and was significantly greater in OGM (0.81 kg ha−1 year−1) than in CON (0.36 kg ha−1) and OAM (0.41 kg ha−1). For all cropping systems, removal in harvested crops was the most important export of nutrients from the field and constituted between 80 and 94% of total N outputs (harvested and leached N). Yields of cereals in the organic systems were considerably less (15–50%) than in the CON system, leading to a less efficient use of N than in the conventional system.
An analysis of properties of red Oxisols on calcareous sedimentary rocks under different climatic regimes in Thailand was carried out to ascertain their similarities and differences. These soils are Kandiustox in Northeast Plateau and Kandiudox in Peninsular Thailand and have characteristics typical of highly weathered soils. They are very deep (> 2 m depth), are generally acidic (pH 5–6), clayey, have low cation exchange capacity and negative ΔpH values. Their profile development illustrates some differences being Ap(A)–Bt–Bto for Kandiustox and Ap–Bto or Ap–Bto–Bo for the Kandiudox which can be due to differences in leaching conditions under different moisture regimes and a more favourable natural condition for iron oxide accumulation in the Kandiudox. These soils generally have low bulk densities (0.77–1.36 Mg m− 3) and low available water for plants (5.0–9.3 wt.%). The fabric of the soils indicates that there are more well rounded micropeds in Kandiudox than in Kandiustox and the sizes of microaggregates in these soils are somewhat different ranging from 10 to 1000 μm in Kandiustox and 50–1400 μm in Kandiudox. The iron oxide concentration in microaggregates is more variable in the Kandiudox possibly indicating a more complex pedogenesis in these soils as compared to the Kandiustox. Kaolin, quartz and hematite are the dominant minerals in all these Oxisols, gibbsite and goethite are major minerals only in the Kandiudox and boehmite occurred in only one Kandiudox in tropical rainforest environment. Differences in mineralogy also indicate the influence of parent material composition. Soil properties that relate to soil fertility status particularly organic matter concentration (2.1–34.5 g kg− 1), available phosphorus (0.3–47.5 mg kg− 1) and available potassium (5–233 mg kg− 1) are poor and similar for the Kandiustox and Kandiudox profiles. Both groups of Oxisols have low values of cation exchange capacity which is in consistent with the dominance of low activity clays (kaolin, sesquioxides) with the Kandiudox profiles having lower mean CEC (6.7–10.2 cmol kg− 1) than the Kandiustox (11.5–16.3 cmol kg− 1) profiles.
In a recent study on the NPK balance of land use systems in sub-Saharan Africa, it was found that scale-inherent simplifications were inevitable (Stoorvogel et al., 1993). This article reports on a similar exercise in a well-inventorized smaller area (Kisii District, Southwestern Kenya). Land use types and land/water classes (combinations of rainfall zones and soil units) were combined into geographically well-defined land use systems with NPK inputs by mineral fertilizers, manure, wet and dry deposition, and biological N fixation, and outputs by aboveground crop parts, leaching, denitrification, and erosion. Primary data were available on applied mineral fertilizers and manure, crop yields, nutrient contents, residue removal and erosion. Deposition, leaching and denitrification were estimated using rainfall, clay, N and K content, and fertilizer input. Erosion was estimated along the lines of the Universal Soil Loss Equation.The aggregated nutrient balance for the Kisii District was -112kgN, -3kgP, and-70kgKha–1yr–1. For all nutrients, removal of harvested product was the strongest negative contributor, followed by erosion. In terms of land use, nutrient depletion was highest under pyrethrum and lowest under tea. Sensitivity analysis revealed that changing mineralization rate and soil N content had an important impact on the N balance. Varying slope gradient and length, soil erodibility, land cover and the enrichment factor for eroded material affected all nutrients.Examples are given of possible ways to improve the NPK balance in the Kisii District by manipulating inputs and outputs. The methodology can prove valuable in any area where the farming community is receptive to integrated nutrient management systems.
Balances between nutrients applied or mineralized and nutrients removed in maize grain and stover were calculated in a hedgerow
intercropping experiment in which Leucaena leucocephala and L. pallida prunings and cattle manure were applied. Hedgerow intercropping (also called alley cropping) is an agroforestry system in
which trees are grown in dense hedges between alleys where short-cycle crops are grown. The hedges are pruned periodically
during the cropping period and the prunings are added to the soil as green manure. In control treatments, nutrient depletion
per season was in the order of 7–19 kg N ha–1, 4–12 kg P ha–1, 10–26 kg K ha–1, 0–2 kg Ca ha–1 and 3–6 kg Mg ha–1. N fertilizer reversed the depletion of N, but it accelerated the depletion of the other nutrients. Manure and at least two
applications of leucaena prunings resulted in net positive balances of N, K, and Ca between amounts applied or mineralized
and amounts removed by maize. The amounts of P and Mg applied with, or mineralized from, prunings or manure were insufficient
to offset the negative balances of these nutrients.
The present paper summarizes the results from a long-term experiment setup in 1980 in the Taihu Lake region, China, to address
the yield sustainability, the dynamic changes of soil organic carbon (SOC) storage, and soil fertility in the rice–wheat ecosystem.
Treatments in three replicates comprising manure-treated and chemical fertilizer-treated groups (two factors), each having
seven sub-treatments of different combinations of inorganic nitrogen (N), phosphorus (P), potassium (K), and rice straw, were
randomly distributed. Results showed that the treatments of manure (pig manure from 1980 to 1996 and oil rape cake thereafter)
+ N + P + K (MNPK) and chemical fertilizer + N + P + K (CNPK) produced the highest and the most stable yields for both rice
and wheat within the respective fertilizer treatment group. Potassium fertilization was necessary for yield sustainability
in the ecosystem. Treatments of straw (as rice straw) + N (CRN) and manure + straw + N (MRN) produced more stable yield of
rice but less stable of wheat. It was therefore recommended that straw should be only incorporated during the rice season.
SOC contents in all treatments showed increasing trends over the period, even in the control treatment. Predicted SOC in chemical
fertilizer-treated plots (mostly yet attainable) ranged from 16 to 18g C kg−1, indicating the high carbon (C) sequestration potential of the soil as compared to the initial SOC. SOC in manure- or straw-treated
plots ranged from 17 to 19g C kg−1, which had been attained roughly 10years after the experiment was initiated. Nutrient balance sheet showed that there was
P surplus in all P-treated plots and a steady increase in Olsen-P over a 24-year period in 0–15cm soil, which contributed
little to crop yield increases. It was therefore suggested that P fertilization rate should be decreased to 30–40kg P ha−1 year−1. Comparison of yields among the treatments showed that wheat was more responsive to P fertilizer than rice. Thus P fertilizer
should be preferably applied to wheat. Soil pH decrease was significant over the 24-year period and was not correlated with
fertilizer treatments. The overall recommendation is to incorporate straw at 4,500kg ha−1 year−1 during the rice season only, with additional 190kg N ha−1 year−1, 30–40kg P ha−1 year−1 mainly during the rice season, and 150–160kg K ha−1 year−1. Further research on the unusual P supply capacity of the soil is needed.
Biological nitrogen fixation (BNF), nitrogen (N), and phosphorus (P) imports-exports budgets were estimated at four locations,
each with 20 farmer-managed fields for two years in a semi-arid Tanzania and Malawi. The 15N isotope dilution method was used to quantify BNF by three pigeonpea (Cajanus cajan L. Millspp.) varieties intercropped with maize (Zea mays L.). The N and P accumulation in plant components of sole maize and intercrops of maize-pigeonpea systems were used to estimate
the mean exports and imports of N and P. The proportion of N derived from air (%Ndfa) by the pigeonpea varieties ranged from
93.8% to 99.9% in Malawi and 65.6% to 99.3% in Tanzania. The amount of fixed N (BNF; kgNha−1yr−1) varied from 37.5 to 117.2 in Malawi and 6.3 to 71.5 in Tanzania. The mean values for BNF during the two cropping seasons
were 64.3 for Nyambi, 85.3 for Ntonda, 34.1 for Gairo and −54.3 for Babati sites. The mean N budget (kg ha−1) was −26.1 in the sole maize plots and −40.3 for the intercrops at the two locations in Malawi, and −50.1 in the sole crop
plots and −51.1 in the intercrops at the locations in Tanzania. In a scenario where all the aboveground material except the
edible parts was returned to the soil, a positive value of 30.5kg N for the intercrops was recorded compared with −8.9kg
N for the sole maize in Malawi. For the same scenario in Tanzania, the budget was more negative (−35.4kg N) for sole maize
compared with intercrops (−5.9kg N). Including the roots in the calculations, did not change the differences between mono
and intercrops. The P budget was negative irrespective of whether the aboveground biomass of maize and pigeonpea was incorporated
or exported out of the fields, and the values were similar for intercrops and sole maize. The most negative N and P budgets
were recorded in the two study areas where the extractable soil P status of the soils and the maize yields were high. These
findings indicate that pigeonpea incorporated into maize-based cropping systems will maintain a very high %Ndfa (>90%) in
all plant parts and thereby contribute to improved N budgets but not increase the proportion of P mined of the soil.
Three approaches to nitrogen budgeting were developed and their ability to quantitatively describe nitrogen cycling in a fertilizer based and a grass–clover based beef system tested. Budgets ranged in complexity from the Economic Input:Output (EIO) budget, which accounted simply for purchases and sales of nitrogen over the farmgate, through the Biological Input:Output (BIO) budget, which included estimates of biological nitrogen fixation and attempted to partition losses into leaching and gaseous forms, to the Transfer:Recycle:Input:Output (TRIO) budget, which also accounted for key soil processes. Nitrogen unaccounted for in the fertilized system decreased with increasing budget complexity (285, 212 and 188 kg ha-1 yr-1 unaccounted for by the EIO, BIO and TRIO budgets, respectively). In the legume based grass–clover system, the EIO budget did not accurately describe total nitrogen inputs as it did not include 146 kg ha-1 yr-1 from symbiotic nitrogen fixation. In the grass–clover system, nitrogen unaccounted for was again greater using the BIO than the TRIO budget (103 and 79 kg ha-1 yr-1, respectively). In conclusion, the most complex budgeting approach (TRIO) was able to account for the fate of a greater proportion of nitrogen inputs than the simpler approaches. However, the perceived success of the different approaches was strongly dependent on the precise objective.
Legume crop residues serve as a source of nitrogen (N) for succeeding crops in low-input production systems, and characterizing Legume crop residues serve as a source of nitrogen (N) for succeeding crops in low-input production systems, and characterizing
the release of this N supports efforts to develop sound economic and environmental management practices. Nitrogen mineralization the release of this N supports efforts to develop sound economic and environmental management practices. Nitrogen mineralization
of 15N-labelled field crop residues was monitored in a Greenville sandy loam during a 140-day laboratory incubation at 25°C. Residue of 15N-labelled field crop residues was monitored in a Greenville sandy loam during a 140-day laboratory incubation at 25°C. Residue
type strongly influenced the rate of N mineralization; decomposition rate constants were 0.283, 0.083, 0.00047 and 0.0014 type strongly influenced the rate of N mineralization; decomposition rate constants were 0.283, 0.083, 0.00047 and 0.0014
day-1 for alfalfa (Medicago sativa L.) stover (above-ground plant parts), alfalfa roots, maize (Zea mays L.) stover (above-ground plant parts excluding cob and kernels) and maize roots, respectively. At the end of the incubation, day-1 for alfalfa (Medicago sativa L.) stover (above-ground plant parts), alfalfa roots, maize (Zea mays L.) stover (above-ground plant parts excluding cob and kernels) and maize roots, respectively. At the end of the incubation,
50% of alfalfa stover and 25% of alfalfa root residues N were mineralized, whereas these proportions were 8% for maize stover 50% of alfalfa stover and 25% of alfalfa root residues N were mineralized, whereas these proportions were 8% for maize stover
and 12% for root residues. Mineralization of 15N from alfalfa stover residues was also monitored in a greenhouse experiment to determine N availability during the growth12% for root residues. Mineralization of 15N from alfalfa stover residues was also monitored in a greenhouse experiment to determine N availability during the growth
of maize inoculated or not with vesicular-arbuscular mycorrhizal (VAM) fungi, and to evaluate the effects of the presence of maize inoculated or not with vesicular-arbuscular mycorrhizal (VAM) fungi, and to evaluate the effects of the presence
of plants on the decomposition of the residues. Stover and root dry matter yields were greatest for maize inoculated with of plants on the decomposition of the residues. Stover and root dry matter yields were greatest for maize inoculated with
VAM fungi and grown in residue-amended soil. At the final harvest, maize grown in residue-amended soils had accumulated 44% VAM fungi and grown in residue-amended soil. At the final harvest, maize grown in residue-amended soils had accumulated 44%
more dry matter and 40% more N than maize grown in unamended soils. Enhanced VAM colonization of roots inoculated with a mixture more dry matter and 40% more N than maize grown in unamended soils. Enhanced VAM colonization of roots inoculated with a mixture
of three Glomus spp. increased the residue N accumulation in maize roots at 5 weeks after silking and at the final harvest. Alfalfa stover of three Glomus spp. increased the residue N accumulation in maize roots at 5 weeks after silking and at the final harvest. Alfalfa stover
decomposed rapidly both in the presence and absence of maize plants, but the amount of 15N mineralized at the end of the experiment was influenced by the presence of living roots; 23% of the 15N in alfalfa stover residues was mineralized in soil without plants compared to about 38% when maize plants were present. decomposed rapidly both in the presence and absence of maize plants, but the amount of 15N mineralized at the end of the experiment was influenced by the presence of living roots; 23% of the 15N in alfalfa stover residues was mineralized in soil without plants compared to about 38% when maize plants were present.
These results suggest that N mineralization is enhanced by the presence of living roots. These results suggest that N mineralization is enhanced by the presence of living roots.
Diversity of arbuscular mycorrhizal fungi (AMF) in 27-year long-term NP-fertilization plots under a maize cropping system in Thailand was studied through spore morphological characterization. The plots received 0–0, 60–60, 120–120 and 180–180kg N-P2O5 ha–1 year–1 as ammonium sulfate and triple superphosphate. The plots were sampled monthly for one year, the AMF spores were counted and morphotyped, and taxa were identified after morphotyping and monospecific pot culture. Spore number g–1 soil, relative spore abundance and Shannon-Wiener indexes were calculated. Sixteen putative taxa were recorded from the field of which nine sporulated on maize roots in pot culture. The long-term fertilization caused decreases in AMF total spore numbers and variation in species diversity depended on sampling time. Effects of fertilization on spore number and also relative spore abundance varied with species and sampling time. Among the nine species sporulating under maize, only Acaulospora sp.1 showed no change (P > 0.003 after Bonferroni correction) in spore number with fertilization in the field; and was therefore classified as an AMF species insensitive to fertilization. Spores of Entrophospora schenckii, Glomus mosseae, Glomus sp.1, Glomus geosporum-like and Scutellospora fulgida, though they decreased in absolute numbers in response to fertilization, showed no change (P > 0.003 after Bonferroni correction) in relative abundance; these species were classified as AMF species slightly sensitive to fertilization. Three unidentified species of Glomus, though they decreased in absolute numbers in response to fertilization, showed decreases (P < 0.003="" after="" bonferroni="" correction)="" in="" relative="" abundance;="" these="" species="" were="" classified="" as="" amf="" species="" highly="" sensitive="" to="">
The impact of land use (unfertilized continuous maize cropping, unfertilized and fertilized alley cropping with maize, Gliricidia sepium tree fallow, natural fallow) on the soil organic matter (SOM) status and general soil fertility characteristics were investigated for a series of soils representative for the West African moist savanna zone. Three soils from the humid forest zone were also included. In an associated pot experiment, relationships between maize N and P uptake and SOM and general soil characteristics were developed. Soils under natural fallow contained the highest amount of organic C (1.72%), total N (0.158%), and had the highest effective cation exchange capacity (ECEC) [8.9 mEq 100 g–1 dry soil], while the Olsen P content was highest in the fertilized alley cropping plots (13.7 mg kg–1) and lowest under natural fallow (6.3 mg kg–1). The N concentration of the particulate organic matter (POM) was highest in the unfertilized alley cropping plots (2.4%), while the total POM N content was highest under natural fallow (370 mg N kg–1) and lowest in continuously cropped plots (107 mg N kg–1). After addition of all nutrients except N, a highly significant linear relationship (R
2=0.91) was observed between the total N uptake in the shoots and roots of 7-week-old maize and the POM N content for the savanna soils. POM in the humid forest soils was presumably protected from decomposition due to its higher silt and clay content. After addition of all nutrients except P, the total maize P uptake was linearly related to the Olsen P content. R
2 increased from 0.56 to 0.67 in a multiple linear regression analysis including the Olsen P content and clay content (which explained 11% of the variation in P uptake). Both the SOM status and N availability were shown to be improved in land-use systems with organic matter additions, while only the addition of P fertilizer could improve P availability.
Mining of nutrients from the soil, particularly in developing countries, is a major problem, causing soil degradation and threatening long-term food production. This paper develops a methodology for carrying out nutrient audits, which includes the calculation of nutrient balances and an evaluation of trends in nutrient depletion/enrichment. Nutrient balances for arable farming are constructed for 197 countries for 1996 and for the world and two specific countries – a developed/enriching country (Japan) and a developing/depleting country (Kenya) for the period 1961 – 1996.
The results indicate that nutrient efficiency is approximately 50% for N, 40% for P, and 75% for K. In some countries in Western Europe and in Japan and the Republic of Korea, with large, mixed farming systems, there is a surplus of N, P, and K. However, in almost all other countries, food production is currently dependent on depleting large quantities of nutrients from soil reserves and this is likely to continue. The world average soil depletion of nutrients in 1996 was estimated to be 12.1 kg N ha−1, 4.5 kg P ha−1, and 20.2 kg K ha−1. The depletion of K is particularly severe and could ultimately lead to a serious loss of crop productivity in several countries. There is an urgent need to investigate this issue further. Analytical tools, such as the nutrient audit model described, can play an important role in assessing the problem, and in developing sustainable nutrient management policies, strategies, and practices.
Nutrient budgets of agroecosystems are constructed either (i) to increase the understanding of nutrient cycling, (ii) as performance indicator and awareness raiser in nutrient management and environmental policy, or (iii) as regulating policy instrument to enforce a certain nutrient management policy in practice. This paper explores nutrient budgeting approaches and summarizes sources of uncertainty associated with these approaches. Possible implications of uncertainties associated with the different methodologies and approaches for nutrient management and environmental policy are discussed. Three types of nutrient budgets have been distinguished, i.e. farm-gate, soil surface and soil systems budgets. A farm-gate budget is the most integrative measure of environmental pressure, and seems most suitable as environmental performance indicator. A soil surface budget is appropriate for estimating the net loading of the soil with nutrients. Soil system budgets account for nutrient inputs and outputs, recycling of nutrients within the system, nutrient loss pathways and changes in soil nutrient pools; it is the most detailed budget and provides detailed information for nutrient management. Case studies for the dairy farm De Marke indicate that the three budgeting approaches supplement each other. The accuracy and precision of the nutrient budget depend on budgeting approach, data acquisition strategy and type of agroecosystem. There is often a considerable amount of uncertainty in the nutrient budget, due to various possible biases and errors, notably in the partitioning of nutrient losses. Possible sources of biases are personal bias, sampling bias, measurement bias, data manipulation bias and fraud. Sources of errors are sampling and measurement errors. Both biases and errors in nutrient budget estimates may lead to confusion and wrong conclusions. Yet, there is little published evidence that uncertainties are taken into account in decision making. Uncertainties are usually smaller for a farm-gate budget than for a soil surface budget. Therefore, farm-gate budgets are preferred over soil surface budgets as policy instrument. Quantifying uncertainties requires: (a) system identification and analysis, (b) classification of uncertainties, (c) specification of distributions of probabilities of the various sources using Monte Carlo simulation, and (d) monitoring of the nutrient pools, inputs and outputs over time. Analyses of uncertainties in nutrient budgets may provide information about the weakest chain in establishing agri-environmental cause–effect relationships and, therefore, may assist to better focus research efforts. Data for the nitrogen budget of The Netherlands indicate relatively large uncertainties for the items denitrification and leaching, with coefficients of variation >30%. In conclusion, there is a need for standard procedures and guidelines in nutrient budgeting and uncertainty analyses, to improve the confidence in and applicability of nutrient budgets.
Soil organic matter (SOM) produces positive effects on multiple soil properties. Increasing its level also provides an opportunity to reduce atmospheric concentration of carbon dioxide (CO2). Recycling animal manure and returning crop residue are among the main practices to enhance organic carbon (C) stock in arable croplands. This study analysed data of soil organic carbon (SOC) stocks from a medium-term field trial (established in 1992) through a Hénin–Dupuis-based equation to determine the proportion of different organic materials retained in the soil as SOM.
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.RésuméUne méthode spectrophotométrique est décrite pour le dosage du phosphate dans l'eau de mer, an moyen de molybdate d'ammonium, en présence d'acide ascorbique et d'antimoinc. Il se forme rapidement un composé violet bleu, renfermant antimoine et phosphore dans un rapport atomique de 1:1.ZusammenfassungBeschreibung einer Methode zur Bestimmung von Phosphat in Mecrwasser mit Hilfe von Ammoniummolybdat in Gegenwart von Ascorbinsäure und Antimon. Der gebildete blau-violette Komplex wird spektrophotometrisch gemessen.
The current increase in the organic agriculture segment has created a new market for fertilisers permitted for use in organic farming. Off-farm N sources for organic farming are scarce, considering the restriction on the use of chemical fertilisers. Thus, when some products are permitted in organic agriculture, commercial opportunities become available. In this study we compare the performances of Vegethumus (Veg) and Phenix (Phe), two manures that are permitted in organic farming, with several other manures, ammonium nitrate (AN) and control treatments. A 3-year field trial and a pot experiment were carried out in order to estimate dry matter yield, N uptake, and N nutritional status of the crops, as well as soil N availability, the latter was assessed by using anion exchange membranes inserted into the soil. Apparent N recovery (ANR) values in the field trial were 6.3% and 58.2% in Veg and AN plots, respectively, after the application of 380 kg N/ha in the previous five growing seasons. In the pot experiment, the ANR of Veg and Phe, the organic amendments permitted in organic farming, were 5.0% and 13.6%, while Beiraadubo (Bei) and Nutrisoil (Nut) had ANR of 27.2% and 42.0%. The poor results of the amendments permitted in organic farming, in light of their high prices suggest that their use must be carefully considered by farmer in their fertilization strategies.
