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Enhancing nitrogen use efficiency by combinations of nitrogen application amount and time in wheat

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Enhancing nitrogen use efficiency by combinations of nitrogen application amount and time in wheat

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Nitrogen (N) is one of the most important impact factors on development and growth of wheat. In this study the effects of nitrogen use efficiency on quantity and quality of grains were studied by agronomic management of N fertilizers on spring wheat (Triticum aestivum L.) grown under field conditions for two years. The experiments were performed at 16 combinations of N application amount and time, including four levels of N at 0, 60, 120 and 180 kg N ha−1 that were used as pre-plant fertilizers, sub-treated with four levels of the same N amount used as top-dress fertilizers. As a result, with an increase in total N fertilizers, grain yield increased in a cubic equitation, but partial factor productivity (PFPN, kg grain yield per kg N applied) decreased exponentially. With total fertilizers, N content and accumulation in vegetative tissues and grains increased linearly, but N uptake efficiency (UtEN, kg nutrient taken up per kg N applied) decreased exponentially. When N was over-applied (>360 kg N ha−1 in this study), grain yield clearly declined, due to decrease in productivity from per unit N. The high N level (240300 kg N ha−1), the reasonable distribution between pre-plant and top dress from the same amount N fertilizer not only increased grain yield but also enhanced N use efficiency.

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... Although, the most commonly used for implementing practice by N fertilization in sows, the use of high doses of N permitting expression of yield potential of existing varieties on the market today, requires careful and efficient management of bias the nutrient, this in order to minimize leaching losses during crop development and prevent contamination of groundwater and its harmful effect on human health and environmental sustainability (Campillo et al., 2007). The nitrogen to fractional complications have been widely studied in improving grain yield of crops such as wheat (Xinkai et al., 2011;Mohammed et al., 2013), maize (Amanullah and Paigham, 2010), barley (Cai et al., 2011) and rice (Sreekala et al., 2010). The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). ...
... The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). nitrógeno han sido ampliamente estudiadas en la mejora del rendimiento de grano de cultivos como trigo (Xinkai et al., 2011;Mohammed et al., 2013), maíz (Amanullah y Paigham, 2010), cebada (Cai et al., 2011) y arroz (Sreekala et al., 2010). La importancia del momento de aplicación, además de la dosis de fertilizante empleado, puede también inducir un mejoramiento en la eficiencia de absorción, según investigaciones relacionadas con el cultivo de trigo (Campillo et al., 2007) y cebada (Moreno et al., 2003). ...
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La fertilización nitrogenada es uno de los factores de impacto más importantes en el crecimiento y desarrollo de los cultivos de cereales. Esta investigación tuvo como objetivo, determinar el efecto de la aplicación fraccionada de nitrógeno en diferentes estados fenológicos de dos cultivares de triticale (X Triticosecale Wittmack), y su relación con el rendimiento del cultivo y sus componentes. El cultivo se estableció en el municipio de Lerma, Estado de México, durante los ciclos invierno-primavera (I-P) y verano-otoño (V-O) del periodo 2012-2013. Los cultivares evaluados fueron Siglo-TCL21 y Bicentenario, con dos dosis de N en I-P (0 y 150 kg ha-1), y tres dosis en V-O (0, 150 y 250 kg ha-1). El nitrógeno (N) fue fraccionado en tres momentos del desarrollo del cultivo: amacollamiento (AM), espiguilla terminal (ET) y hoja bandera (HB). La dosis de 150 fue fraccionada en: 1/3 AM,1/3ETy1/3 HB,1/2AMy1/2ETy,todoenAM;ladosis de 250 fue fraccionada en: 2/5 AM, 2/5 ET y 1/5 HB y, 2/5 AM y 3/5 ET. El diseño experimental consistió en un arreglo de bloques completos al azar. El cultivar Bicentenario presentó mayor número de granos y Siglo-TCL21 mayor peso de grano. Con la dosis de N de 250 kg ha-1 se incrementaron los valores de rendimiento y biomasa en ambos cultivares. Los máximos rendimientos para los cultivares Bicentenario y Siglo-TCL21, se obtuvieron con la dosis de 250 kg ha-1 cuando ésta se fraccionó en 2/5 AM y 3/5 ET.
... Different climatic conditions, soil physical and chemical properties, and field management practices are involved in the regulation of N use by crops (Habbib et al., 2017;Kubota et al., 2018;Hu et al., 2019;Xiao et al., 2019). Nitrogen partial factor productivity (NPFP) is decreased with the increased NAR and becomes stable within a certain amount of N input (Zhu et al., 2011). Excessive irrigation can lead to N loss though run-off and leaching, and insufficient irrigation can affect NUE and crop yield . ...
... We found that although N application significantly improved the N-induced NPFP (P < 0.05, Fig. 3j), a significantly negative relationship was observed between the effect size lnRs of Ninduced NPFP and NAR in the N application experiments (P < 0.05, Table 1). A study conducted by Zhu et al. (2011) reported the same trend that the NPFP of winter wheat decreased with the increase of N application. Results of the correlation analysis between yield and NAR showed that the yield of winter wheat increased with the increase in NAR, but tended to stabilize when the NAR was greater than 150 kg N ha À1 (Fig. 5a). ...
Article
Increasing nitrogen use efficiency by optimizing field management practices is necessary to promote intensive and sustainable development of winter wheat production. The objective of this study was to comprehensively assess the changes of nitrogen use efficiency induced by field management practices, and to identify the suitable combination of strategies for winter wheat management in the North China Plain. For this, a meta-analysis was conducted with 977 comparisons from 106 publications. The results showed that the nitrogen partial factor productivity of winter wheat is inconsistent in response to different agricultural practices. Nitrogen input and irrigation significantly increased the nitrogen partial factor productivity by 132.75% and 24.01% (P < 0.05), respectively. However, the change of the nitrogen partial factor productivity was not significant under different tillage practices or straw return. Nitrogen application rate, irrigation times, seasonal precipitation, and soil bulk density significantly affected the responses of the nitrogen partial factor productivity induced by management practices. In the nitrogen input or water irrigation treatments, the total water consumption of the winter wheat improved with the increase of the nitrogen partial factor productivity within a certain range. Theoretically, optimal nitrogen partial factor productivity could be obtained for winter wheat in the North China Plain under two different conditions: (1) optimum water with less nitrogen, experimental duration <3 years, nitrogen application <150 kg N ha⁻¹, irrigation amount plus precipitation >240 mm, one irrigation or (2) optimum nitrogen with less water, nitrogen application 150–180 kg N ha⁻¹, irrigation amount 80–160 mm, two irrigations. Both of these conditions could enhance the nitrogen use efficiency of winter wheat. According to our study, the pursuit of optimized field management practices must include a closer evaluation of the changes in nitrogen use efficiency, as well as other nutrients.
... Although, the most commonly used for implementing practice by N fertilization in sows, the use of high doses of N permitting expression of yield potential of existing varieties on the market today, requires careful and efficient management of bias the nutrient, this in order to minimize leaching losses during crop development and prevent contamination of groundwater and its harmful effect on human health and environmental sustainability (Campillo et al., 2007). The nitrogen to fractional complications have been widely studied in improving grain yield of crops such as wheat (Xinkai et al., 2011;Mohammed et al., 2013), maize (Amanullah and Paigham, 2010), barley (Cai et al., 2011) and rice (Sreekala et al., 2010). The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). ...
... The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). nitrógeno han sido ampliamente estudiadas en la mejora del rendimiento de grano de cultivos como trigo (Xinkai et al., 2011;Mohammed et al., 2013), maíz (Amanullah y Paigham, 2010), cebada (Cai et al., 2011) y arroz (Sreekala et al., 2010). La importancia del momento de aplicación, además de la dosis de fertilizante empleado, puede también inducir un mejoramiento en la eficiencia de absorción, según investigaciones relacionadas con el cultivo de trigo (Campillo et al., 2007) y cebada (Moreno et al., 2003). ...
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Nitrogen fertilization is one of the most important factors in the growth and development of cereal crops impact. This study aimed to determine the effect of split application of nitrogen in different growth stages of two cultivars of triticale (X Triticosecale Wittmack), and its relationship with crop yield and its components. The culture was established in the village of Lerma, State of Mexico, during the winter-spring cycles (W-S) and summer-autumn (S-A) for the period 2012-2013. The evaluated cultivars were Siglo-TCL21 and Bicentenario with two doses of N in W-S (0 and 150 kg ha-1) and three doses S-A (0, 150 and 250 kg ha-1). Nitrogen (N) was fractionated into three stages of crop development: tillering (TI), terminal spikelet (TS) and flag leaf (FL). The dose of 150 was divided into: ¹/3 TI, ¹/3 TS and ¹/3 FL, ¹/2 TI and ¹/2 TS and everything in TI; the dose of 250 was divided into: ²/5 TI, ²/5 TS and ¹/5 FL, ²/5 TI and ³/5 TS. The experimental design was a randomized complete array blocks. The cultivar Bicentenario showed higher number of grains and Siglo-TCL21 higher weight of grain. With the dose of 250 kg N ha-1 values and biomass yield in both cultivars increased. Maximum yields for cultivars Bicentenatio and Siglo-TCL21 were obtained with 250 kg ha-1 when it was fractionated into ²/5 TI and ³/5 TS.
... Although, the most commonly used for implementing practice by N fertilization in sows, the use of high doses of N permitting expression of yield potential of existing varieties on the market today, requires careful and efficient management of bias the nutrient, this in order to minimize leaching losses during crop development and prevent contamination of groundwater and its harmful effect on human health and environmental sustainability (Campillo et al., 2007). The nitrogen to fractional complications have been widely studied in improving grain yield of crops such as wheat (Xinkai et al., 2011;Mohammed et al., 2013), maize (Amanullah and Paigham, 2010), barley (Cai et al., 2011) and rice (Sreekala et al., 2010). The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). ...
... The importance of timing, plus the dose of fertilizer used, can also induce an improvement in the efficiency of absorption, according to investigations related to wheat (Campillo et al., 2007) and barley (Moreno et al., 2003). nitrógeno han sido ampliamente estudiadas en la mejora del rendimiento de grano de cultivos como trigo (Xinkai et al., 2011;Mohammed et al., 2013), maíz (Amanullah y Paigham, 2010), cebada (Cai et al., 2011) y arroz (Sreekala et al., 2010). La importancia del momento de aplicación, además de la dosis de fertilizante empleado, puede también inducir un mejoramiento en la eficiencia de absorción, según investigaciones relacionadas con el cultivo de trigo (Campillo et al., 2007) y cebada (Moreno et al., 2003). ...
... This is a common response for cereal yield, i.e. to increase with N-application until a maximum utilisation. At N-application levels higher than maximum utilisation, yield is maintained and then decreases (Hay and Walker 1989;Zhu 2011;Delin and Stenberg 2014). The seed yield we obtained from WR was below 3 t ha −1 (Figure 1), which is lower than the 3-4 t ha −1 that is normal for winter oilseed rape in Europe (Rathke et al. 2006). ...
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Irrigation is, on one hand, expected to increase the risk of nitrate leaching through increased rates of percolation, but, on the other hand, enhances plant nutrient uptake and growth, thereby limiting the risk of leaching. To investigate this dichotomy, we analysed the effects of irrigation at three nitrogen (N)-application rates in spring barley (Hordeum distichum L., two experiments with 50, 100, and 150 kg N ha −1) and winter oilseed rape (Brassica napus L., one experiment with 50, 150, and 250 kg N ha −1) on a coarse sandy soil in Denmark in a humid climate, which facilitates nitrate leaching. Analyses comprised grain/seed dry matter yield, N-uptake, nitrogen use efficiency (partial nitrogen budget, PNB, and partial-factor productivity, PFP) and nitrate leaching. For both crops, increasing N-application without consideration of the crops' drought-stress responses lead to a relatively lower N-uptake in grain, lower yield, lower PNB and PFP and higher nitrate leaching, although responses were not proportionally to increasing N-application. The effect of irrigation at the lowest N-rates was limited. The non-irrigated treatments with the highest N-rates had a grain/seed yield of 3.2, 2.3 and 0.7 t ha −1 and nitrate leaching rates of 64, 72 and 127 kg N ha −1 compared to a grain/seed yield of 5.3, 5.0 and 2.6 kg N ha −1 and nitrate leaching rates of 61, 42 and 85 kg N ha −1 (for spring barley, spring barley and winter oilseed rape, respectively). These results show that synchronised management of both irrigation and N-application are essential for reducing the risk of nitrate leaching and to promote efficient crop N-uptake in periods of droughts.
... Among the various methods of N application, deep placement, use of super granules and foliar spray of N fertilizer can enhance the recovery of applied N fertilizer [17]. Two to three split applications of N usually during the growing season, rather than a single, large application prior to planting, are known to be effective in increasing NUE and yield [104,105]. The amount of nitrogen fertilizer to be applied is varied depend on soil type, crop type, variety response, water availability and other sources of nutrients. ...
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... Among the various methods of N application, deep placement, use of super granules and foliar spray of N fertilizer can enhance the recovery of applied N fertilizer [17]. Two to three split applications of N usually during the growing season, rather than a single, large application prior to planting, are known to be effective in increasing NUE and yield [104,105]. The amount of nitrogen fertilizer to be applied is varied depend on soil type, crop type, variety response, water availability and other sources of nutrients. ...
... Miziniak and Praczyk [25] did not find the combined application of fenoxaprop-P-ethyl with chlormequat chloride and prohexadione calcium to adversely influence winter wheat yield, whereas in another study Miziniak and Praczyk [26] proved that the grain yield harvested from the plots treated with mixtures of sulfosulfuron and retardants was higher compared to the yield harvested from the treatments with the separate application of the above-mentioned chemicals. Most studies show mineral fertilization to have a positive effect on wheat productivity, with this effect being greatest in the case of nitrogen fertilization [21,[27][28]. Nevertheless, not all studies confirm this tendency. ...
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The aim of the present study was to evaluate yield, grain quality characteristics, and cost-effectiveness of different crop protection methods in the cultivation of spring wheat using two levels of mineral fertilization of crops. The study shows that the combined application of the herbicide Lintur 70 WG (dicamba and triasulfuron) with ethephon or chlormequat chloride did not adversely affect spring wheat productivity. The highest yield was obtained in the treatment with intensive fertilization (5.18 t ha⁻¹) and in the treatments with the application of herbicide in combination with ethephon (5.26 t ha⁻¹). The chemical crop protection methods caused significant differences in grain test weight. In turn, mineral fertilization modified all the studied grain quality characteristics. An analysis of the indicators used to evaluate the economic effects of the spring wheat production technologies investigated showed a clear advantage of the lower intensity technology over the more intensive technologies, which should be associated with the high costs of mineral fertilization that were not compensated by the yields obtained. In analyzing the production and economic effects, treatment with the application of the herbicide in combination with ethephon under basic mineral fertilization conditions proved to be most beneficial.
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Adopting suitable tillage and fertilization technologies for wheat (Triticum aestivum L.) can address poor soil conditions and high residual nitrogen following rice (Oryza sativa L.) harvest to improve the sustainability of rice‐wheat rotation systems. A field experiment was conducted in 2016–2018 to investigate the influence of tillage methods and nitrogen rates on wheat seedling growth (at the beginning of over‐wintering stage), tillering characteristics, and grain yield. The tillage methods included no‐tillage (NT), rotary tillage twice (RR), and plow tillage followed by rotary tillage (PR). The nitrogen rates were 270 (N270), 240 (N240), and 210 kg ha−1 (N210). In 2016–2017 (higher soil moisture during tillage), NT improved early growth (i.e., leaf area and biomass per stem), single spike yield, and grain yield compared with PR and RR. In 2017–2018 (lower soil moisture during tillage), PR and RR resulted in stronger seedlings (greater tiller number and leaf area and biomass per stem), more fertile tillers, and higher grain yield than NT. In both years, grain yield under RR was between that of PR and NT. With reduced nitrogen application, seedling growth, tiller number, single spike yield, and grain yield showed a declining tendency. We found that more tillers at seedling growth stage (the five‐leaf stage in both years) could boost fertile tiller number, and at this time greater leaf area and biomass per stem were correlated with higher single spike yield. This study demonstrates that suitable tillage and fertilizer applications can facilitate yield formation through improved number and vigor of the early‐produced tillers. This article is protected by copyright. All rights reserved
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Improvement of nitrogen use efficiency (NUE) via active optical sensors has gained attention in recent decades, with the focus of optimizing nitrogen (N) input while simultaneously sustaining crop yields. To the authors’ knowledge, a comprehensive review of the literature on how optical sensors have impacted winter wheat (Triticum aestivum L.) NUE and grain yield has not yet been performed. This work reviewed and documented the extent to which the use of optical sensors has impacted winter wheat NUE and yield. Two N management approaches were evaluated; optical sensor and conventional methods. The study included 26 peer-reviewed articles with data on NUE and grain yield. In articles without NUE values but in which grain N was included, the difference method was employed to compute NUE based on grain N uptake. Using optical sensors resulted in an average NUE of 42% (±2.8% standard error). This approach improved NUE by approximately 10.4% (±2.3%) when compared to the conventional method. Grain yield was similar for both approaches of N management. Optical sensors could save as much as 53 (±16) kg N ha−1. This gain alone may not be adequate for increased adoption, and further refinement of the optical sensor robustness, possibly by including weather variables alongside sound agronomic management practices, may be necessary.
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A two-year field study examined the effect of different sources of nitrogen (N) fertilization, soil tillage depths, and crop rotations on winter wheat yield, quality, and N utilization. Nitrogen fertilization treatments were: mineral N at 100 kg N ha (Nmin); municipal solid waste compost at 100 kg N ha of organic N (Ncomp); 50 kg N ha of both compost and mineral N fertilizer (Nmix); unfertilized control (control). Tillage treatments were conventional and minimum tillage applied on the rotations tomato—wheat, sugar beet—wheat, and sunflower—wheat. The Nmix treatment had the highest yield and N uptake (5.29 t ha and 157.9 kg ha, respectively). The partial substitution of mineral with organic N fertilizer increased yield by 8% and 33%, and N uptake by 2% and 31%, with respect to Nmin and control treatments, respectively. In comparison with Nmin, Nmix had a higher stability in these parameters throughout years and rotations, and no reduction in grain protein level and in N utilization. Conversely, the Ncomp performance was lower than Nmin and Nmix treatments, and the grain yield was only 12% higher than the control. Tillage affected yield and N uptake only in the year characterized by high rainfall during the vegetative stages, while no significant differences were found in protein content and N utilization in both years. Among the crop rotations, wheat after sugar beet had the highest grain yield (4.91 t ha) and a good protein content (11.9%), while sunflower and tomato rotations had a lower grain yield (4.35 t ha) and protein content (10.3%).
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To investigate the relationship between the timing of fertiliser N applications and the N use efficiency of wheat, three field experiments with 15N were set up on winter wheat, on three different soils in France. Different crop N demands on the day of fertiliser application were obtained by varying either crop densities or date of fertiliser application. Labelled 15NH4 15NO3 was applied at tillering and during stem elongation. The 15N recovered from plant and soil at different dates after 15N addition and at maturity of wheat was measured. The fate of fertiliser N was rapidly determined, most of the fertiliser N accumulated in the wheat at maturity having been taken up within a few days of application. 15N recovery by the crop at final harvest (%) varied greatly (19–55% N applied) according to crop density, soil type and date of application. It was linearly related to the instantaneous crop growth rate calculated at the day of 15N application. The amount of fertiliser N immobilised in the soil was constant at 20 kg N ha−1, for all soil types and crop densities. Because residual mineral 15N in the soil at harvest was negligible and immobilisation was constant, the level of total 15N measured in the different N pools (soil+plant) reflected the% 15N uptake by the plant. There was consequently a negative linear relationship between the percentage of 15N not recovered for measurement, and crop growth rate (i.e. crop N demand) at date of fertiliser application. These results suggest that crop N demand at the time of N application determines the ability of the crop to compete for N with other processes, and may be a major factor determining the division of N between soil and crop.
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The global challenge of meeting increased food demand and protecting environmental quality will be won or lost in cropping systems that produce maize, rice, and wheat. Achieving synchrony between N supply and crop demand without excess or deficiency is the key to optimizing trade-offs amongst yield, profit, and environmental protection in both large-scale systems in developed countries and small-scale systems in developing countries. Setting the research agenda and developing effective policies to meet this challenge requires quantitative understanding of current levels of N-use efficiency and losses in these systems, the biophysical controls on these factors, and the economic returns from adoption of improved management practices. Although advances in basic biology, ecology, and biogeochemistry can provide answers, the magnitude of the scientific challenge should not be underestimated because it becomes increasingly difficult to control the fate of N in cropping systems that must sustain yield increases on the world's limited supply of productive farm land.
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Transcriptome analysis, using Affymetrix ATH1 arrays and a real-time reverse transcription-PCR platform for >1,400 transcription factors, was performed to identify processes affected by long-term nitrogen-deprivation or short-term nitrate nutrition in Arabidopsis. Two days of nitrogen deprivation led to coordinate repression of the majority of the genes assigned to photosynthesis, chlorophyll synthesis, plastid protein synthesis, induction of many genes for secondary metabolism, and reprogramming of mitochondrial electron transport. Nitrate readdition led to rapid, widespread, and coordinated changes. Multiple genes for the uptake and reduction of nitrate, the generation of reducing equivalents, and organic acid skeletons were induced within 30 min, before primary metabolites changed significantly. By 3 h, most genes assigned to amino acid and nucleotide biosynthesis and scavenging were induced, while most genes assigned to amino acid and nucleotide breakdown were repressed. There was coordinate induction of many genes assigned to RNA synthesis and processing and most of the genes assigned to amino acid activation and protein synthesis. Although amino acids involved in central metabolism increased, minor amino acids decreased, providing independent evidence for the activation of protein synthesis. Specific genes encoding expansin and tonoplast intrinsic proteins were induced, indicating activation of cell expansion and growth in response to nitrate nutrition. There were rapid responses in the expression of many genes potentially involved in regulation, including genes for trehalose metabolism and hormone metabolism, protein kinases and phosphatases, receptor kinases, and transcription factors.
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In this review, recent developments and future prospects of obtaining a better understanding of the regulation of nitrogen use efficiency in the main crop species cultivated in the world are presented. In these crops, an increased knowledge of the regulatory mechanisms controlling plant nitrogen economy is vital for improving nitrogen use efficiency and for reducing excessive input of fertilizers, while maintaining an acceptable yield. Using plants grown under agronomic conditions at low and high nitrogen fertilization regimes, it is now possible to develop whole-plant physiological studies combined with gene, protein, and metabolite profiling to build up a comprehensive picture depicting the different steps of nitrogen uptake, assimilation, and recycling to the final deposition in the seed. A critical overview is provided on how understanding of the physiological and molecular controls of N assimilation under varying environmental conditions in crops has been improved through the use of combined approaches, mainly based on whole-plant physiology, quantitative genetics, and forward and reverse genetics approaches. Current knowledge and prospects for future agronomic development and application for breeding crops adapted to lower fertilizer input are explored, taking into account the world economic and environmental constraints in the next century.
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Recently emerged technologies permitting precision fanning provide opportunities to collect and evaluate vast amounts of data; yet, a formal method for incorporating additional yield-affecting information into fertilizer-yield response models is still largely unavailable to site-specific managers. This research develops an integrated yield model that combines laboratory-based fertilizer recommendations with data from multiple independent variables. Kansas wheat (Triticum aestivum L. sp. aestivum) was the target crop, and simulated soil test and yield data were characteristic of data from the literature and this geographic area. Independent variables in the plateau-type yield model included fertilizer N and P, soil test N (STN) and soil test P (STP), and Z (representing all other causal factors). Consideration of the potential benefits of managing STP is an explicit outcome of this research. To expand the modeling procedures to include actual farm information, data from a northwest Kansas farm were used to replace the simulated Z variable. Additionally, maximum entropy (ME) was examined as a statistical technique for using the farm's N and P data to modify the predicted N- and P-response of laboratory-based models. Based on out-of-sample yield prediction accuracy, the ME models were generally the most accurate, improving root mean squared prediction error by as much as 14% relative to a model estimated with only farm data. Because the ME models were the most accurate and provided fertilizer recommendations similar to those from soil testing laboratories, this approach should provide a reliable framework for developing site-specific fertilizer recommendations that depend on factors other than STN and STP.
Article
A field experiment with 3 cultivars each of wheat, rye, triticale and barley, grown at a density of about 320 plants/m, was conducted in 1986 on a fertile clay soil at East Flevoland, Netherlands. N at 120 kg/ha for wheat and triticale and 60 kg/ha for rye and barley was split-dressed in 2 applications. N yield was highest in wheat (196 kg/ha) and lowest in rye (123 kg/ha). The amounts taken up were influenced by the N rate. The triticale cv. Lasko and the barley cv. Marinka had a higher N-uptake than the other triticale and barley cultivars. N harvest index (i.e. the ratio of N in grains and N in above-ground DM at final harvest) was lowest in rye and highest in barley. N concentration in plant organs (grains, chaff, leaves, stems and roots) was higher in wheat and triticale than in rye and barley. This was probably caused by the difference in the level of N application. N use efficiency, expressed as grain DM production/kg N taken up, was 53 in wheat, 68 in rye, 50 in triticale and 61 in barley. In all species, the largest reserves of water-soluble carbohydrates (WSC) were found in the stems. Rye allocated more dry matter to stem growth before flowering than wheat, triticale and barley. Averaged over these cereals, 26% of WSC, produced before flowering, was used for redistribution and respiration during grain production.
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Worldwide, nitrogen use efficiency (NUE) for cereal production (wheat, Triticum aestivum L.; corn, Zea mays L.; rice, Oryza sativa L. and O. glaberrima Steud.; barley, Hordeum vulgate L.; sorghum, Sorghum bicolor (L.) Moench; millet, Pennisetum glaucum (L.) R. Br.; oat, Avena sativa L.; and rye, Secale cereale L.) is approximately 33%. The unaccounted 67% represents a $15.9 billion annual loss of N fertilizer (assuming fertilizer-soil equilibrium). Loss of fertilizer N results from gaseous plant emission, soil denitrification, surface runoff, volatilization, and leaching. Increased cereal NUE is unlikely, unless a systems approach is implemented that uses varieties with high harvest index, incorporated NH4-N fertilizer, application of prescribed rates consistent with in-field variability using sensor-based systems within production fields, low N rates applied at flowering, and forage production systems. Furthermore, increased cereal NUE must accompany increased yields needed to feed a growing world population that has yet to benefit from the promise of N2-fixing cereal crops. The Consultative Group on International Agricultural Research (CGIAR) linked with advanced research programs at universities and research institutes is uniquely positioned to refine fertilizer N use in the world via the extension of improved NUE hybrids and cultivars and management practices in both the developed and developing world.
Article
A recently developed system to predict the optimum N fertilizer rate for winter wheat (Triticum aestivum L. emend. Thell) at Zadoks growth stage (GS) 30 is based on the relationship between measured economic optimum N rate at GS 30 and wheat tissue N content measured at GS 30. However, winter wheat often needs an earlier application of spring N to achieve optimum yield. We therefore developed a test to determine which fields need this earlier (GS 25) application, and to predict the optimum N rate with split-application management using the tissue test or as a single spring application. The optimum N rate at GS 25 was measured over 5 yr, both with and without GS 30 N applications. These measured optimum N rates were regressed against a variety of possible predictor variables measured in the same fields. Tiller density at GS 25 was a good predictor of optimum N rate at GS 25 in a split spring application program. Using this relationship along with the GS 30 tissue test to make N recommendations for winter wheat increased estimated profit relative to using the tissue test alone. Soil NO3 measured to 0.9 m depth was the best predictor of optimum N rate at GS 25 when that is to be the only spring N application, and improved estimated profit relative to applying 90 kg N ha⁻¹ at all sites; however, the economic performance of split spring N applications was substantially better than for any single spring applications. The recommendation system developed by integrating these component relationships is powerful and flexible, and provides field-specific N rate recommendations for all spring N applications to winter wheat, regardless of management decisions about splitting spring N applications. Research supported in part by grants from the USDA-CSRS Water Quality Res. Program and the Virginia Div. of Soil and Water Conservation. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Article
Recently emerged technologies permitting precision farming provide opportunities to collect and evaluate vast amounts of data; yet, a formal method for incorporating additional yield-affecting information into fertilizer-yield response models is still largely unavailable to site-specific managers. This research develops an integrated yield model that combines laboratory-based fertilizer recommendations with data from multiple independent variables. Kansas wheat (Triticum aestivum L. sp. aestivum) was the target crop, and simulated soil test and yield data were characteristic of data from the literature and this geographic area. Independent variables in the plateau-type yield model included fertilizer N and P, soil test N (STN) and soil test P (STP), and Z (representing all other causal factors). Consideration of the potential benefits of managing STP is an explicit outcome of this research. To expand the modeling procedures to include actual farm information, data from a northwest Kansas farm were used to replace the simulated Z variable. Additionally, maximum entropy (ME) was examined as a statistical technique for using the farm's N and P data to modify the predicted N- and P-response of laboratory-based models. Based on out-of-sample yield prediction accuracy, the ME models were generally the most accurate, improving root mean squared prediction error by as much as 14% relative to a model estimated with only farm data. Because the ME models were the most accurate and provided fertilizer recommendations similar to those from soil testing laboratories, this approach should provide a reliable framework for developing site-specific fertilizer recommendations that depend on factors other than STN and STP.
Article
Nitrogen (N) fertilization in rice (Oryza sativa L.) is extensive throughout the world, but fertilizer N recovery is generally low. Split fertilizer applications that coincide with plant demand have been suggested as a method of improving fertilizer N efficiency. However, the effectiveness of split applications has not been established. Furthermore, there is little information available on plant N accumulation after a midseason application. The purpose of this study was to measure plant dry matter, root growth, and N accumulation after a midseason N application and to determine the length of time during which midseason N is accumulated by the plant. ‘Cypress’ rice was drill‐seeded in a Crowley silt loam soil (fine, montmorillonitic, thermic Typic Albaqualf) and urea‐N was broadcast at 101 kg N ha preflood. Microplots enclosed by retainers were established prior to panicle initiation (PI), and N‐labeled urea was topdressed at PI into the floodwater within each microplot at 67 kg N ha. Microplots were harvested at 1 day after topdress (DAT), 3 DAT.7DAT, 14 DAT, and at 90% heading (35 DAT). Dry matter production was not affected by the midseason N application and increased linearly from the time of midseason application until 90% heading. Root growth at the time of the midseason application was extensive and roots could be seen at the soil surface. Root length density was greatest in the top 7.5 cm of the soil profile and decreased with depth. Most accumulation of midseason N occurred within 7 DAT. Both midseason N and native N in the plant increased during this period. About half of the midseason N was accumulated by the crop, probably because of the extent of the root system. This approximates N recovery from preplant or preflood N applications. Nitrogen loss was probably due to ammonia (NH3) volatilization. Nitrogen accumulation by the plants continued throughout the duration of the experiment. This study shows that N broadcast into the floodwater at PI is quickly and efficiently utilized.
Article
Successful nitrogen (N) management requires better synchronization between crop N demand and N supply from all sources throughout crop growing season. An in-season N management strategy based on soil N min test had been developed under experimental conditions, and more than half-N fertilizer could be saved without grain yield losses, compared with farmer's N management practices. The objective of this study was to evaluate this in-season N management strategy for winter wheat (Triticum aestivum L.) in different farmers' fields of North China Plain (NCP). A total of 121 on-farm N-response experiments (check with no N fertilizer, in-season N management based on soil N min test, and farmer's practice) were conducted in seven key winter wheat production regions of NCP from 2003 to 2005. The average N rate determined with in-season N management strategy (128 kg N ha À1) was significantly lower than farmer's practice (325 kg N ha À1) without wheat grain yield losses. As a result, in-season N management strategy significantly increased economic gains by $144 ha À1 , reduced residual nitrate-N content in the top 90 cm soil layer and N losses by 81 and 118 kg N ha À1 , respectively (P < 0.05). Recovery N efficiency (REN), agronomic N use efficiency (AEN) and N partial factor productivity (PFPN) were significantly improved to 44%, 11 and 56 kg kg À1 , respectively, compared with farmer's N practice (REN, 18%; AEN, 3 kg kg À1 ; PFPN, 20 kg kg À1). Effective use of soil N supply and better synchronization between crop N demand and supply were main reasons for the increased N use efficiency. We conclude that the in-season N management strategy based on soil N min test can be applied for winter wheat production in NCP for improved N use efficiency and reduced environmental contamination. # 2007 Elsevier B.V. All rights reserved.
Article
A field experiment with the winter wheat cultivar Donata was carried out on a fine-textured river clay soil in 1978. The rates of nitrogen dressing ranged from 0 to 160 kg N per ha and were split over from one up to three application times: autumn, early spring and late spring. Total above-ground dry matter and grain dry-weight yields ranged from 9.1 to 13.7 tons per ha and from 4.17 to 6.35 tons per ha, respectively. Late top-dressings increased the harvest-index, whereas an autumn dressing had the opposite effect. Number of culms per m2, grain weight (mg) and grain number per m2 increased from 350 to 430, from 35.5 to 36.8 and from 11 680 to 16 980, respectively, as the nitrogen dosage was raised from 0 to 160 kg N per ha. The linear rate of grain growth ranged from 111 to 172 kg dry matter per ha per day with nitrogen doses from 0 to 160 kg N per ha. Differences in rate of grain growth per unit area were mainly related to number of grains per m2. The association between grain number and grain yield was reflected by a correlation coefficient of 0.97 (n = 32). A higher level of nitrogen dressing enhanced the leaf area index and leaf area duration. However, we could not derive an effect of nitrogen on the duration of grain growth. Total nitrogen yield ranged from 71 to 166 kg N per ha and grain nitrogen yield from 54 to 122 kg N per ha with nitrogen dosages of 0 and 160 kg N per ha, respectively. The nitrogen concentration of the grains varied between 1.3 and 2.0 N. An autumn dressing of 40 kg N per ha generally showed only minor effects on yield and yield components. Top dressings during spring resulted in a higher recovery and efficiency of the applied nitrogen. Therefore, it may be concluded from this experiment and literature that on fertile soils an autumn dressing of nitrogen will not be economical, but split-dressings in spring are very beneficial. In particular, a late nitrogen application during the boot stage increased grain number, harvest-index and grain yield as well as protein concentration of the grain.
Article
A 3-year field experiment in rainfed Vertisol was designed to study the effects of timing and splitting of N fertilizer on the efficiency of nitrogen in wheat (Triticum aestivum L.). A single rate of 150 kg N ha−1 was used, different fractions being applied at sowing, tillering and stem elongation. The experiment was designed as a randomized complete block with four blocks. At the same time, a 15N experiment was conducted within the main experiment area, with microplots, to quantify N uptake from fertilizer and soil. Mean wheat use of N fertilizer ranged from 14.1% when applied at sowing to 54.8% when applied as a top dressing at the beginning of stem elongation. The mean annual contribution of soil residual N and mineralization was 152 kg N ha−1, representing a considerable proportion of total wheat N uptake, ranging from 83.2% when N fertilizer was applied in the fall to 49.4% when it was applied at stem elongation. This would account for the poor and inconsistent response of grain yield and N efficiency indices, and for the importance of soil N in Vertisols for predicting wheat N fertilizer requirements, due to the carryover effect. Application of N fertilizer to wheat preferably as a top dressing, between tillering and stem elongation, is a strategy to be recommended from the standpoint both of the environment and of farmer returns.
Article
Nitrogen (N) uptake and utilization efficiency (NUtE) of the high-yielding cultivars `Gemini' of wheat and `Jaidor' of barley were tested with N rates of 0, 140 and 210 kg ha−1 and 0, 80 and 140 kg ha−1, respectively. The different grain yield response was linked to their difference in nitrogen uptake and utilization efficiency. The highest yield in barley was recorded with 80 kg N ha−1 and in wheat with 210 kg N ha−1. Nitrogen application affected the accumulation of biomass up to heading in wheat and barley. While N uptake during grain filling did not show any correlation to N applied in barley, it was markedly correlated in wheat. At N0 and N140 N applied, barley exhibited a 32 and 8% higher NUtE than wheat. N agronomic efficiency, a parameter representing the ability of the plant to increase yield in response to N applied, was similar in barley and wheat (8.7 and 9.2 kg kg−1 of N applied, respectively), suggesting that both species respond equally to nitrogen fertilization. Nevertheless, due to its lower NUtE, wheat requires high N fertilization to optimize yields; by contrast, in barley the lower N rate needed to achieve highest yields enables this crop to perform better in low-input conditions. As a results, the reduced N requirements for barley highest yield associated with a better RF value (apparent N fertilizer recovery of 63% in barley and 49% in wheat at N140) makes barley crop a better choice to reduce ground-water pollution due to nitrate leaching in winter and early spring.
Article
Experiments at two sites growing winter wheat show that in order to manage a wheat canopy more effectively, the use of specific remote sensing techniques both to monitor crop canopy expansion, and to determine variable nitrogen applications at key timings is required. Variations in seed rate were used to achieve a range of initial crop structures, and treatments were compared to standard farm practice. In the first year, the effect of varying seed rate (250, 350 and 450 seeds m−2) on crop structure, yield components and grain yield, was compared to the effects of underlying spatial variation. Plant populations increased up to the highest rate, but shoot and ear populations peaked at 350 seeds m−2. Compensation through an increased number of grains per ear and thousand grain weight resulted in the highest yield and gross margin at the lowest seed rate. In later experiments, the range of seed rates was extended to include 150 seeds m−2, each sown in 24 m wide strips split into 12 m wide halves. One half received a standard nitrogen dose of 200 kg [N] ha−1, the other a variable treatment based on near ‘real-time’ maps of crop growth. Both were split into three applications, targeted at mid-late tillering (early March), growth stages GS30-31 (mid April) and GS33 (mid May). At each timing, calibrated aerial digital photography was used to assess crop growth in terms of shoot population at tillering, and canopy green area index at GS30-31 and GS33. These were compared to current agronomic guidelines. Application rates were then varied below or above the planned amount where growth was above- or below-target, respectively. In the first field, total nitrogen doses in the variable treatments ranged from 188 to 243 kg [N] ha−1, which gave higher yields than the standards at all seed rates in the range 0·36–0·78 t ha−1 and gross margins of £17 to £60 ha−1. In the second field, variable treatments ranged from 135 to 197 kg [N] ha−1 that resulted in lower yields of −0·32 to +0·30 t ha−1. However, in three out of the four seed rates, variable treatments produced higher gross margins than the standard, which ranged from £2 to £20 ha−1. In both fields, the greatest benefits were obtained where the total amount of applied nitrogen was similar to the standard, but was applied variably rather than uniformly along the strips. Simple nitrogen balance calculations have shown that variable application of nitrogen can have an overall effect on reducing the nitrogen surplus by one-third.
Article
Nitrogen fertilization rates in cereal production systems are generally determined by subtracting soil test N from a specified N requirement based on the grain yield goal, which represents the best achievable grain yield in the last 4 to 5 yr. If grain yield could be predicted in season, topdress N rates could be adjusted based on projected N removal. Our study was conducted to determine if the potential grain yield of winter wheat (Triticum aestivum L.) could be predicted using in-season spectral measurements collected between January and March. The normalized difference vegetation index (NDVI) was determined from reflectance measurements under daytime lighting in the red and near-infrared (NIR) regions of the spectra. In-season estimated yield (EY) was computed using the sum of two postdormancy NDVI measurements (Jan. and Mar.) divided by the cumulative growing degree days (GDD) from the first to second reading. A significant relationship between grain yield and EY was observed (R2 = 0.50, P > 0.0001) when combining all nine locations across a 2-yr period. Our estimates of potential grain yield (made in early Mar.) differed from measured grain yield (mid-July) at three sites where yield-altering factors (e.g., late summer rains delayed harvest and increased grain yield loss due to lodging and shattering) were encountered after the final sensing. Evaluating data from six of the nine locations across a 2-yr period, EY values explained 83% of the variability in measured grain yield. Use of EY may assist in refining in-season application of fertilizer N based on predicted potential grain yield.
Article
Nitrogen is an essential element for plant growth and development and a key agricultural input-but in excess it can lead to a host of problems for human and ecological health. Across the globe, distribution of fertilizer nitrogen is very uneven, with some areas subject to nitrogen pollution and others suffering from reduced soil fertility, diminished crop production, and other consequences of inadequate supply. Agriculture and the Nitrogen Cycle provides a global assessment of the role of nitrogen fertilizer in the nitrogen cycle. The focus of the book is regional, emphasizing the need to maintain food and fiber production while minimizing environmental impacts where fertilizer is abundant, and the need to enhance fertilizer utilization in systems where nitrogen is limited. The book is derived from a workshop held by the Scientific Committee on Problems of the Environment (SCOPE) in Kampala, Uganda, that brought together the world's leading scientists to examine and discuss the nitrogen cycle and related problems. It contains an overview chapter that summarizes the group's findings, four chapters on cross-cutting issues, and thirteen background chapters. The book offers a unique synthesis and provides an up-to-date, broad perspective on the issues of nitrogen fertilizer in food production and the interaction of nitrogen and the environment.
Article
Over the next 50 years, considerable stress will be placed on worldwide crop production by a combination of factors, including an increased human population, an increase in the crops used per person, and a number of environmental issues. Given current trends, it will be necessary to approximately double yields worldwide during this time period, and meeting this challenge will require a considerable effort. This article explores the nature of the challenge and the requirements for meeting it. These include novel technical advances and fundamental discoveries as well as new multidisciplinary ways of organizing research to ensure that researchers and technologists target the advances and discoveries that are most needed and effectively use them to enhance important crop traits.
Article
Summary Nitrogen is quantitatively the most essential nutrient for plants and a major factor limiting crop productivity. One of the critical steps limiting the efficient use of nitrogen is the ability of plants to acquire it from applied fertilizer. Therefore, the development of crop plants that absorb and use nitrogen more efficiently has been a long-term goal of agricultural research. In an attempt to develop nitrogen-efficient plants, rice (Oryza sativa L.) was genetically engineered by introducing a barley AlaAT (alanine aminotransferase) cDNA driven by a rice tissue-specific promoter (OsAnt1). This modification increased the biomass and grain yield significantly in comparison with control plants when plants were well supplied with nitrogen. Compared with controls, transgenic rice plants also demonstrated significant changes in key metabolites and total nitrogen content, indicating increased nitrogen uptake efficiency. The development of crop plants that take up and assimilate nitrogen more efficiently would not only improve the use of nitrogen fertilizers, resulting in lower production costs, but would also have significant environmental benefits. These results are discussed in terms of their relevance to the development of strategies to engineer enhanced nitrogen use efficiency in crop plants.
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