Increase In Nitrogen Use Efficiency Research Articles

Agricultural management practices in China enhance nitrogen sustainability and benefit human health.

The potential of enhanced agricultural management practices to drive sustainability is rarely quantified at grassroots level. Here we analyse nitrogen use and loss in Chinese cropland, drawing from data collected in 2,238,550 sites in two national agricultural pollution source censuses from 2007 to 2017. We find an upswing of 10% in crop yields and an 8% reduction in nitrogen pollution during this period, owing to the promotion and adoption of various management practices (including the combination of organic and chemical fertilizers, straw recycling and deep placement of fertilizer). These practices have collectively contributed to an 18% increase in nitrogen use efficiency in the country. By fully embracing them, we project that annual cropland pollution could be further reduced by up to 1.4 Mt of nitrogen without compromising crop yields. Environmental and human health benefits are projected to consistently outweigh implementation costs in the future, with total benefits reaching US$15 billion.

Shallow wet irrigation reduces nitrogen leaching loss rate in paddy fields by microbial regulation and lowers rate of downward migration of leaching water: a 15N-tracer study.

China consumes 35% of the world's fertilizer every year; however, most of the nitrogen fertilizers, which are essential for rice cultivation, are not used effectively. In this study, factors affecting the nitrogen leaching loss rate were studied in typical soil and rice varieties in South China. The effects of various irrigation measures on rice growth and nitrogen leaching loss were investigated by conducting experiments with eight groups. These groups included traditional irrigation (TI) and shallow wet irrigation (SWI). The TI is a common irrigation method for farmers in South China, maintaining a water layer of 5-8cm depth. For SWI, after establishing a shallow water layer usually maintaining at 1-2cm, paddy is irrigated when the field water level falls to a certain depth, then this process is then repeat as necessary. The nitrogen distribution characteristics were determined using 15N isotope tracing. In addition, the effects of nitrification, denitrification, and microbial composition on soil nitrogen transformation at different depths were studied by microbial functional gene quantification and high-throughput sequencing. The results revealed that in the SWI groups, the total nitrogen leaching loss rate reduced by 0.3-0.8% and the nitrogen use efficiency (NUE) increased by 2.18-4.43% compared with those in the TI groups. After the 15N-labeled nitrogen fertilizer was applied, the main pathways of nitrogen were found to be related to plant absorption and nitrogen residues. Furthermore, paddy soil ammonia-oxidizing archaea were more effective than ammonia-oxidizing bacteria for soil ammonia oxidation by SWI groups. The SWI measures increased the relative abundance of Firmicutes in paddy soil, enhancing the ability of rice to fix nitrogen to produce ammonium nitrogen, thus reducing the dependence of rice on chemical fertilizers. Moreover, SWI enhanced the relative abundance of nirS and nosZ genes within surface soil bacteria, thereby promoting denitrification in the surface soil of paddy fields. SWI also promoted ammonia oxidation and denitrification by increasing the abundance and activity of Proteobacteria, Nitrospirae, and Bacteroidetes. Collectively, SWI effectively reduced the nitrogen leaching loss rate and increase NUE.

Water and nitrogen footprint assessment of integrated agronomic practice management in a summer maize cropping system

The footprints of water and nitrogen (WF and NF) provide a comprehensive overview of the type and quantity of water consumption and reactive nitrogen (Nr) loss in crop production. In this study, a field experiment over two years (2019 and 2020) compared three integrated agronomic practice management (IAPM) systems: An improved management system (T2), a high-yield production system (T3), and an integrated soil-crop management system (ISCM) using a local smallholder farmer’s practice system (T1) as control, to investigate the responses of WF, Nr losses, water use efficiency (WUE), and nitrogen use efficiency (NUE) to IAPM. The results showed that IAPM optimized water distribution and promoted water use by summer maize. The evapotranspiration over the whole maize growth period of IAPM increased, but yield increased more, leading to a significant increase in WUE. The WUE of the T2, T3, and ISCM treatments was significantly greater than in the T1 treatment, in 2019 and 2020 respectively, by 19.8-21.5, 31.8-40.6, and 34.4-44.6%. The lowest WF was found in the ISCM treatment, which was 31.0% lower than that of the T1 treatment. In addition, the ISCM treatment optimized soil total nitrogen (TN) distribution and significantly increased TN in the cultivated layer. Excessive nitrogen fertilizer was applied in treatment T3, producing the highest maize yield, and resulting in the highest Nr losses. In contrast, the ISCM treatment used a reduced nitrogen fertilizer rate, sacrificing grain yield partly, which reduced Nr losses and eventually led to a significant increase in nitrogen use efficiency and nitrogen recovery. The Nr level in the ISCM treatment was 34.8% lower than in the T1 treatment while NUE was significantly higher than in the T1 treatment by 56.8-63.1% in 2019 and 2020, respectively. Considering yield, WUE, NUE, WF, and NF together, ISCM should be used as a more sustainable and clean system for sustainable production of summer maize.

The role of an Ascophyllum nodosum extract in lowering the environmental impact and improving nitrogen use efficiency in pasture systems under a reduced nitrogen regime

Nitrogen is a macronutrient that is applied in substantial amounts as a chemical fertiliser to conventional agricultural systems. However, loss of nitrogen from agricultural systems to the environment, in the form of gases (N2O) and leachate (NO3), is detrimental to the environment. As such, improving the nitrogen use efficiency (NUE) of crops is an essential component of sustainable agriculture. Biostimulants are a category of products that improve NUE when applied to crops and/or soil. Here, we examined the effects of PSI-362, an Ascophyllum nodosum biostimulant mixed with and applied on calcium ammonium nitrate (CAN) granules, on grass yield, quality traits, and environmental impacts in lysimeter trials under natural weather conditions. By using PSI-362, it was possible to reduce nitrogen application by 25% without a significant loss in yield compared to a conventional 100% N system. We also observed an increase in NUE under a 75% N with PSI-362 co-application fertilisation regime, and a significant increase in crude protein content compared to the 100% N fertilisation controls. Furthermore, this reduced nitrogen application also resulted in reduced nitrogen loss through leachate (NO3) and N2O to the atmosphere. The total NUE for PSI-362 + fertiliser granules ranged from 58.7% to 78.6% depending on the biostimulant dose, which was significantly better than the fertiliser alone. Our results showed that this biostimulant, which can easily be incorporated into conventional agronomic practices, allows for a more sustainable approach to pasture-based systems.

Enhancing wheat yield and nitrogen use efficiency in the Huang‐Huai‐Hai region of China: Insights from root biomass and nitrogen application responses

AbstractWheat yield and nitrogen use efficiency (NUE) have improved simultaneously with the genetic development of wheat varieties. However, wheat selection is carried out routinely in N‐rich field conditions, with breeding progress limited under low soil available nitrogen. Thus, we performed a 2‐year field investigation using eight milestone winter wheat varieties released between 1947 and 2017 in the Huang‐Huai‐Hai region of China with two N applications—normal (CK; 220 kg N ha−1) and reduced (RN; 110 kg N ha−1)—in Shaanxi, China, to examine changes in wheat yield, NUE, water use efficiency (WUE) and root biomass. Our findings revealed average annual yield increases of 49.615 kg ha−1 and 36.905 kg ha−1 under CK and RN, respectively. Notably, the NUE trend mirrored yield, increasing with the release year of wheat varieties, with average annual increases in NUE of 0.192 and 0.336 kg kg−1 under CK and RN, respectively. In the RN treatment, N uptake efficiency (UPE) increased with year of release, while N utilization efficiency (UTE) had no significant relationship. In the CK treatment, UTE increased with year of release, while UPE had no significant relationship. Across the 2‐year experiment, surface root biomass (0–20 cm layer) increased with year of release under CK but had no relationship under RN, while deep root biomass (20–200 cm layer) decreased with year of release under CK and increased under RN. The roots of modern wheat varieties responded better to soil nitrogen levels and produced higher yields, NUE and WUE than earlier varieties by adjusting root biomass distribution in soil.

Evaluation of nitrogen balances and nitrogen use efficiencies on farm level of the German agricultural sector

CONTEXTUse of Nitrogen (N), an essential macronutrient, must be optimised in order to ensure food security and food sovereignty, mitigate negative externalities of food production and achieve ambitious (inter-)national environmental, climate and sustainability goals. Nitrogen use efficiency (NUE) is an appropriate indicator for assessing N utilisation on farms. OBJECTIVEThe aim of the study was to evaluate N performance of the German agricultural sector, to generate knowledge gain regarding methodological design and estimating N indicators based on farm accounting data, to estimate the role and extent of externalities, and to increase understanding of interrelations between farm characteristics and N performance in order to support policymakers in finding targeted N mitigation measures. METHODSUsing data from the German Farm Accountancy Data Network (FADN) covering 5923 farms between the years 2016/17 and 2018/19, we calculated mean farm-level NUE and N balance values for six farm types, considering input and output parameters on farm level as well as externalities. We also developed two explanatory models to identify interrelations between N performance indicators investigated, and regional, socio-economic and farm structural characteristics. RESULTS AND CONCLUSIONSThe results indicated an increasing trend in NUE from dairy, to pig and poultry, and arable farms, but large variance within each farm type, indicating efficiency reserves in N use. Livestock farms undercut NUE and exceed N surpluses to such an extent that the sustainability goal for 2030 for the national N balance as defined in German Sustainable Development Strategy could be jeopardised. Different levels of externalisation, namely feed imports and manure exports, may deepen this gap. Multiple regression analysis revealed statistically significant interrelations between N performance and independent variables such as soil fertility, crop selection and diversity, production type, operating profit and consulting services received. Thereby, structural patterns and strategies in order to reduce N waste and increase NUE were identified. However, main source of uncertainty was due to the lack on imported manure amounts from FADN data. SIGNIFICANCEDetermination of N performance can improve understanding the complexity of agri-environmental interrelations and support policymakers in designing appropriate policies to improve N management.

Optimizing Garlic (Allium sativum) Yield through Irrigation Scheduling and Nitrogen Management

Background and Aim: Efficient utilization of natural resources, such as water and nutrients, plays a pivotal role in enhancing crop yield and overall productivity. This research aims to develop an efficient irrigation schedule and nitrogen and irrigation interaction effect to achieve higher productivity along with water use efficiency in garlic.
 Place and Duration of Study: To delve into the intricate interaction between water and nitrogen use efficiency in garlic cultivation, a two-year-long experiment was conducted.
 Methodology: The experiment consisted of twelve treatment combinations, encompassing four distinct irrigation schedules (I0 as the control, I1 with 4 cm irrigation at an IW/CPE ratio of 0.8, I2 at 1.0, and I3 at 1.2) and three nitrogen levels (N0 as the control, N1 at 75%, and N2 at 100% of the recommended nitrogen dose).
 Results: These treatments were replicated thrice using a factorial randomized block design. Notably, the irrigation schedule I3 exhibited a significant increase in nitrogen use efficiency, consequently resulting in higher garlic yields compared to the control irrigation (I0). Given the substantial difference in bulb yield observed in the I3 level (136.0 q/ha) compared to the control, it can be considered an efficient irrigation schedule for garlic cultivation. Among the tested nitrogen levels, N2 emerged as the most favorable, yielding significantly higher garlic production. The treatment combination of I3N2 recorded the highest bulb yield, boasting a remarkable increase of 64.5% over the control.
 Conclusion: In summary, this study underscores the effectiveness of the I3N2 treatment combination for achieving robust growth and increased garlic yields while optimizing the utilization of irrigation water and nitrogen resources.

Ammonia emission and nitrogen use efficiency with application of nitrification inhibitor and plant growth regulator in a calcareous soil (Karaj, Iran)

Ammonia volatilization (AV) is one of the main potential pathways of nitrogen (N) loss and re-deposited ammonia acts as an indirect source of N2O. The question arises how environmentally friendly inputs such as nitrification inhibitors (NI) and plant growth regulators (PGR) can affect AV in calcareous soils, while increasing nitrogen use efficiency (NUE) and crop yield. To answer this question, the effects of applying urea in combination with nitrapyrin (NP) as a NI and gibberellic acid (GA3) as a PGR on daily AV, winter wheat yield and NUE were evaluated. The treatments included a control treatment, urea and urea+NP + GA3 with five replications. Urea and urea coated with NP were applied in three equal split applications, and GA3 was foliar sprayed once. By using 15N-labeled urea and setting up three 15N microplots inside each plot, the nitrogen in the plant derived from fertilizer (Ndff) and the fate of N fertilizer were directly investigated. Ammonia emission factors and estimated values of indirect N2O-N produced from AV in urea and urea+NP + GA3 were 27% and 33%, and 0.38 and 0.45 kg N ha−1, respectively. The grain yield and 1000-grain weight in urea+NP + GA3 treatment were significantly increased by 15% and 13%, respectively, compared to urea. However, urea coated with NP increased AV and decreased Ndff by about 22% and 15%, respectively. The increase in AV caused by the addition of NP was relatively lower than amounts reported in previous studies. This could be due to the split application of N fertilizer on dry soil, the immediate incorporation and the ammonium fixation capacity of illite and vermiculite clay minerals presence in this soil and the reduction of readily available NH4+. The N difference method displayed 21% increase in NUE when urea was applied with NP and GA3 but tracking 15N showed that the combination of urea+NP + GA3 reduced NUE by about 8%. This suggests that NP may not be a viable option for increasing NUE in calcareous soils due to its ability to increase AV. Further research is needed to study the combination of other NIs with GA3 and investigate their effect on AV to simultaneously improve yield and NUE.

Layered-Strip Fertilization Improves Nitrogen Use Efficiency by Enhancing Absorption and Suppressing Loss of Urea Nitrogen

Appropriate deep application of fertilizer is the key basis for improving nitrogen use efficiency (NUE). However, the effects of different deep application methods and fertilizer types on nutrient migration, NUE and biomass in wheat season are unclear. Therefore, in this study, a barrel planting test with multilayer fertilization (15N labeled urea (U) and coated urea (CU)) was conducted in a long-term positioning trial of winter wheat in the North China Plain (NCP). We quantified the migration of fertilizer N (Ndff) in soil–plant–atmosphere and its effects on wheat biomass and NUE based on surface (Usur, CUsur), layered-strip (Ustr, CUstr) and layered-mix fertilization (Umix, CUmix) of U and CU. Compared with surface fertilization, the concentration of mineral N in root zone (0–40 cm) was increased by Ustr and Umix (8.6–50.3%), and the concentration of ammonium N was decreased by CUstr and CUmix (49.6–76.0%), but there was no change in the nitrate N. The biomass and total N absorption of wheat tissues (straw and root) were increased by 12.3–38.9% under Ustr and CUstr. Meanwhile, the distribution of Ndff in the 0–10 cm soil was decreased under Ustr and CUstr, but it was increased in the 10–30 cm soil, thereby promoting the absorption of Ndff in wheat tissues by 12.3–28.7%. The rates of absorption and loss of Ndff were the highest (57.6–58.5%) and the lowest (4.5%) under Ustr and CUstr, respectively, compared with other treatments. Consequently, layered-strip fertilization optimized the migration and utilization of Ndff within the soil–plant–atmosphere system. This approach equalized distribution, enhanced absorption and minimized losses of Ndff, resulting in an increase in NUE by 9.6–16.7%. Under the same treatment, CU was more suitable for crop nutrient requirements than U, which was more conducive to the improvement of NUE. Our findings will provide a scientific basis for the precise directional fertilization of winter wheat in the NCP.

Melatonin activates the OsbZIP79–OsABI5 module that orchestrates nitrogen and ROS homeostasis to alleviate nitrogen-limitation stress in rice

Melatonin (Mel) has previously been reported to effectively alleviate nitrogen-limitation (N-L) stress and thus increase nitrogen-use efficiency (NUE) in several plants, but the underlying mechanism remains obscure. Here, we revealed that OsbZIP79 (BASIC LEUCINE ZIPPER 79) is transcriptionally activated under N-L conditions, and its expression is further enhanced by exogenous Mel. By the combined use of omics, genetics, and biological techniques, we revealed that the OsbZIP79–OsABI5 (ABSCISIC ACID INSENSITIVE 5) module stimulated regulation of reactive oxygen species (ROS) homeostasis and the uptake and metabolism of nitrogen under conditions of indoor nitrogen limitation (1/16 normal level). OsbZIP79 activated the transcription of OsABI5, and OsABI5 then bound to the promoters of target genes, including genes involved in ROS homeostasis and nitrogen metabolism, activating their transcription. This module was also indispensable for upregulation of several other genes involved in abscisic acid catabolism, nitrogen uptake, and assimilation under N-L and Mel treatment, although these genes were not directly transactivated by OsABI5. Field experiments demonstrated that Mel significantly improved rice growth under low nitrogen (L-N, half the normal level) by the same mechanism revealed in the nitrogen-limitation study. Mel application produced a 28.6% yield increase under L-N and thus similar increases in NUE. Also, two OsbZIP79-overexpression lines grown in L-N field plots had significantly higher NUE (+13.7% and +21.2%) than their wild types. Together, our data show that an OsbZIP79–OsABI5 module regulates the rice response to N insufficiency (N limitation or low N), which is important for increasing NUE in rice production.

Halving mineral nitrogen use in European agriculture: Insights from multi‐scale land‐use models

AbstractThis paper explores the effects of a public policy that reduces by 50% the use of mineral nitrogen in European agriculture. Our results show that, for the European Union, halving mineral fertilizer use leads to: a decrease in agricultural production, a substantial increase in nitrogen use efficiency, lower use of organic fertilizer and a loss of agricultural competitiveness. At the global level, it leads to greater nitrogen consumption if no measure is taken on the demand side. Ultimately, our research highlights the critical importance of supply side adjustments, particularly in terms of cropland area expansion.

Early sowing increases nitrogen use efficiency of sunflower in wet clay soils

AbstractEarly sowing increases yield potential of sunflower on wet, saline clay soils but the effects on nitrogen (N) requirements have not been determined. In a 2‐year study on a drainable field with wet, saline clay soils in southwestern coastal Bangladesh, we investigated nitrogen use efficiency (NUE) and yield responses to N rates (0, 60, 90, 120, 150, 180 and 210 kg ha−1) for zero‐till sunflower cv. Hysun‐33 sown from November 30 (early) to December 30 (late). Early sowing produced highest seed yield (3.59 ton ha−1) and oil yield (1400 kg ha−1) at 150 kg N ha−1. Delayed sowing (December 15–December 30) reduced seed and oil yields by 4%–15% and 7%–18%, respectively. In late sowing, crops suffered from multiple stresses (soil–water deficit, salinity, and heat), which decreased yields. The N fertilizer requirement in late sowing was higher (180 kg ha−1) to achieve maximum yield, yet the yield was lower than from earlier sowing. Compared with nil N supply, the rates of 60–150 kg N ha−1 increased seed and oil yields of the early‐sown sunflower by 1.3–3.3 times and 1.2–2.9 times, respectively, whereas the rates of 180–210 kg N ha−1 decreased seed and oil yields by 2%–5% and 7%–14%, respectively. Higher net profit (US$764) was also achieved from earlier sowing with 150 kg N ha−1. We conclude that under wet and saline clay soils, higher sunflower yield in early sowing is attributable to lower stress that increased NUE and decreased N requirement.

Mechanisms underlying the responses of microbial carbon and nitrogen use efficiencies to nitrogen addition are mediated by topography in a subtropical forest

Microbial carbon use efficiency (CUE) and nitrogen use efficiency (NUE) are key parameters determining the fate of C and N in soils. Atmospheric N deposition has been found to heavily impact multiple soil C and N transformations, but we lack understanding of the responses of CUE and NUE to N deposition, and it remains uncertain whether responses may be mediated by topography. Here, a N addition experiment with three treatment levels (0, 50 and 100 kg N ha−1 yr−1) was conducted in the valley and on the slope of a subtropical karst forest. Nitrogen addition increased microbial CUE and NUE at both topographic positions, but the underlying mechanisms differed. In the valley, the increase in CUE was associated with an increase in soil fungal richness:biomass and lower litter C:N, whereas on the slope, the response was linked with a reduced ratio of dissolved soil organic C (DOC) to available phosphorus (AVP) which reduced respiration, and increased root N:P stoichiometry. In the valley, the increase in NUE was explained by stimulated microbial N growth relative to gross N mineralization, which was associated with increased ratios of soil total dissolved N:AVP and fungal richness:biomass. In contrast, on the slope, the increase in NUE was attributed to reduced gross N mineralization, linked to increased DOC:AVP. Overall, our results highlight how topography-driven soil substrate availability and microbial properties can regulate microbial CUE and NUE.

Functional characterization of the GhNRT2.1e gene reveals its significant role in improving nitrogen use efficiency in Gossypium hirsutum.

Nitrate is the primary type of nitrogen available to plants, which is absorbed and transported by nitrate transporter 2 (NRT2) at low nitrate conditions. Genome-wide identification of NRT2 genes in G. hirsutum was performed. Gene expression patterns were revealed using RNA-seq and qRT-PCR. Gene functions were characterized using overexpression in A. thaliana and silencing in G. hirsutum. Protein interactions were verified by yeast two-hybrid and luciferase complementation imaging (LCI) assays. We identified 14, 14, seven, and seven NRT2 proteins in G. hirsutum, G. barbadense, G. raimondii, and G. arboreum. Most NRT2 proteins were predicted in the plasma membrane. The NRT2 genes were classified into four distinct groups through evolutionary relationships, with members of the same group similar in conserved motifs and gene structure. The promoter regions of NRT2 genes included many elements related to growth regulation, phytohormones, and abiotic stresses. Tissue expression pattern results revealed that most GhNRT2 genes were specifically expressed in roots. Under low nitrate conditions, GhNRT2 genes exhibited different expression levels, with GhNRT2.1e being the most up-regulated. Arabidopsis plants overexpressing GhNRT2.1e exhibited increased biomass, nitrogen and nitrate accumulation, nitrogen uptake and utilization efficiency, nitrogen-metabolizing enzyme activity, and amino acid content under low nitrate conditions. In addition, GhNRT2.1e-silenced plants exhibited suppressed nitrate uptake and accumulation, hampered plant growth, affected nitrogen metabolism processes, and reduced tolerance to low nitrate. The results showed that GhNRT2.1e could promote nitrate uptake and transport under low nitrate conditions, thus effectively increasing nitrogen use efficiency (NUE). We found that GhNRT2.1e interacts with GhNAR2.1 by yeast two-hybrid and LCI assays. Our research lays the foundation to increase NUE and cultivate new cotton varieties with efficient nitrogen use.

Dietary protein oscillation: effects on digestibility, nutrient balance and estimated microbial protein synthesis in lactating dairy cows

Various studies with growing ruminants report increases in nitrogen use efficiency (NUE) when feeding oscillating (OS) dietary CP, whereas limited research with lactating dairy cows demonstrates a lack of improvement in NUE when feeding OS diets. We hypothesised that a total mixed ration (TMR) delivering OS CP (48-h phases of 134 and 171 g CP/kg DM, respectively) compared to a static CP TMR (ST; 152 g CP/kg DM) would result in similar or increased urinary purine derivative excretion (as a marker of microbial protein synthesis (MPS)) and greater urinary nitrogen excretion in lactating dairy cows. Responses in intake, production, apparent total tract digestibility (ATTD), nutrient balance, and estimated MPS were evaluated using faecal and urine collection in 12 multiparous cows (172 ± 39 d in milk) in a randomised complete block design, where total urinary output was estimated indirectly. All measurements were taken during d 8 (at 1700) to d 16 (at 1700) of the 16-d study that followed a 28-d period in which cows already received their respective treatments. Dry matter intake, yields of milk, protein, fat, lactose, and fat- and protein-corrected milk were similar for ST and OS. Milk composition, BW, and body condition score also did not differ between treatments, except for a tendency for increased milk urea concentration with OS (13.7 vs 12.4 mg/dL). Feed efficiency, NUE and ATTD of organic matter, NDF, CP and gross energy did not differ, but ATTD of crude fat (658 vs 627 g/kg) and starch (980 vs 975 g/kg) increased, and ATTD of DM (702 vs 691 g/kg) tended to increase with OS. Milk energy as a proportion of digested energy tended to decrease with OS (34.6 vs 37.1%), but other energy metabolism variables were not affected by treatment. Estimated urinary nitrogen excretion increased (165 vs 144 g/d), estimated urinary nitrogen as a proportion of nitrogen intake tended to increase (25.3 vs 22.7%), and milk nitrogen as a proportion of digested nitrogen decreased (47.3 vs 51.8%) in response to OS. Estimated urinary excretion of creatinine (184 vs 165 mmol/d), uric acid (29 vs 20 mmol/d) and urea (3.1 vs 2.5 mol/d) increased, but other nitrogen metabolism parameters were not affected by OS. Overall, oscillating dietary CP content did not affect lactational performance, milk NUE, or estimated MPS. However, ATTD of some nutrients increased, postabsorptive energy use for milk synthesis tended to decrease, and estimated urinary nitrogen losses increased with OS.

Nitrification inhibitor application at stem elongation stage increases soil nitrogen availability and wheat nitrogen use efficiency under drought stress

ABSTRACT One of the practices which could mitigate the negative effects of drought stress is ammonium nutrition. Nitrification inhibitor (DMPP) can keep ammonium concentrations high in the soil for several weeks. Although there are contradictory reports regarding the priority of NH4 + uptake and its toxicity effects on wheat, it is necessary to understand better how to apply DMPP to increase drought tolerance without any negative effects. The field experiment was conducted using 15N trace technology. The fertilizers treatment included (15NH4)2SO4 and (15NH4)2SO4 with DMPP at four drought stress levels. Available soil mineral nitrogen was measured, as well as yield components and 15N recovery. The results showed that DMPP application at full irrigation and moderate drought stress caused an increase in grain yield of 13% and 10%, respectively. DMPP application at full irrigation, moderate and severe drought stress caused a significant increase in nitrogen use efficiency of 19%, 11%, and 17%, respectively. It seems DMPP application at the stem elongation stage, promoted NH4 + assimilation and transfer to the shoots, which has created relative resistance to drought stress conditions. In conclusion, it is recommended that farmers use DMPP at stem elongation to avoid wheat yield reduction and nitrogen recovery under drought stress.

One-Time Nitrogen Fertilizer Application Using Controlled-Release Urea Ensured the Yield, Nitrogen Use Efficiencies, and Profits of Winter Wheat

One-time fertilization with controlled-released fertilizer (CRF) is a promising way for reducing labor cost, increasing nitrogen use efficiency (NUE) and alleviating environmental pollution in winter wheat (Triticum aestivum L.) cultivation. However, CRF release characteristics are related to various factors such as soil properties, temperature and precipitation, and further study is needed in developing suitable fertilizer formulas adapting to local conditions. In this study, five types of CRF were used for a one-time application in a two-year field experiment conducted at two sites with two wheat cultivars. Their effects on soil inorganic nitrogen (SIN) content, nitrogen uptake, wheat growth and grain yield were investigated. The results indicated that nitrogen supply in the CRF-60/80 treatments not only ensured the tiller differentiation at the early growth stage, but also provided adequate SIN after the jointing stage, thereby facilitating the dry matter accumulation and improving post-anthesis photosynthates accumulating in grains. When compared with conventional split fertilization, the CRF-60 and 80 treatments improved the NUE by 9.7–12.1%, and boosted farmers’ economic efficiency by 282.4–327.2 CNY ha−1. According to our research, a one-time application of CRF-60 and CRF-80 could meet the needs of the two-peak nitrogen demand of wheat in Jiangyan and Yanghzou respectively, therefore increasing NUE and having low labor costs for wheat fertilizer application.

Food Nitrogen Footprint of the Indian Subcontinent Toward 2050.

Substantial loss of nitrogen (N) in reactive forms (nitrogen species except for N2) induced by agro–food system is a cause of the environmental degradation and harms human health. The main factors influencing the food N footprint of the Indian Subcontinent (ISC) are the nitrogen use efficiency (NUE) of crop cultivation and religious dietary cultures. In this study, we assess the food N footprint of the ISC and establish reduction scenarios toward 2050. We used a religion-sensitive N-Calculator method and food consumption data from the Food and Agriculture Organization of the United Nations to estimate the food N footprint of the ISC of different religious communities. We developed four reduction scenarios as follows: The business-as-usual scenario; a 30% increase in the crop cultivation NUE; altered protein supplies to the healthy EAT–Lancet reference diet considering religious food taboos; and an integrated approach with a 30% increase in the NUE increase and the altered diet. We used the long short-term memory recurrent neural network approach to predict the future. The study revealed that the average food N footprint per-capita per-year increased from 7.94 kg-N in the 1960s to 8.43 kg-N in the early 2010s, and the crop cultivation NUE was reduced to less than 40%. Buddhists had the lowest footprint over the period. An increase in the NUE of the crop cultivation and an altered diet results in a 13% reduction in the N footprint compared to the business-as-usual scenario. We conclude that improved crop cultivation NUEs and an altered religion-specific healthy diet would reduce the N footprint.

Concurrent Improvement in Maize Grain Yield and Nitrogen Use Efficiency by Enhancing Inherent Soil Productivity.

Quantifying the relationships of maize yield and nitrogen use efficiency (NUE) to inherent soil productivity (ISP) could provide a theoretical basis for implementing strategies that concurrently narrow the yield gap, increase NUE, and improve soil quality. A field study under irrigation conditions was conducted at five locations with large differences in ISP (estimated by maize grain yield without using fertilizers) across various ecological regions in Inner Mongolia, China. Our results showed that the changes in maize yield and nitrogen partial factor productivity (PFPN) to ISP followed a linear-plateau model, with a common inflection point. When ISP was below 8.0 t ha–1, maize yield and PFPN were stagnating at a low level, due to a trade-off between the contribution of soil and chemical fertilizers to yield. When ISP exceeded 8.0 t ha–1, the contribution rate of soil to yield stabilized at 80%, resulting in a simultaneous increase in maize yield by 1.2 t ha–1 and PFPN by 4.6 kg kg–1, for increasing ISP at each t ha–1. Our results indicated that while keeping other management strategies unchanged, to increase maize yield and PFPN by 15% or further 30%, it is necessary to increase ISP to 9.3 and 10.4 t ha–1, respectively. In this scenario, N input will be reduced by 33.5 and 47.5%, and apparent N losses will be reduced by 11.7 and 21.5%, respectively. Therefore, enhancing ISP could lead to a simultaneous improvement in yield and NUE as well as strongly support the green development of maize production.

Genetic improvement analysis of nitrogen uptake, utilization, translocation, and distribution in Chinese wheat in Henan Province

Genetic improvement analysis of the nitrogen use efficiency (NUE) of wheat ( Tritium aestivum L.) was undertaken to determine the factors guiding NUE in order to develop new wheat cultivars with high yield, high NUE and high quality. To investigate the genetic improvement of wheat NUE and its components, 31 wheat cultivars that had been widely planted in Henan Province since 1941 were grown under high N treatment (HN) and low N treatment (LN). The results indicated that grain yield and NUE have increased significantly with cultivar development since 1941, with an annual genetic gain of 1.03% and 0.74%, respectively, under HN and LN. The significant increase in NUE mainly resulted from a significant increase in N uptake efficiency (NupE) and N utilization efficiency (NutE). NutE was the predominant component contributing to NUE under HN, while NupE was more important than NutE for NUE under LN. The improvement of NutE occurred at the expense of lower grain N content (GNC) as grain yield increased. Breeding was shown to increase N translocation (NTE) by an annual genetic gain of 1.33% and 0.33%, respectively, under HN and LN. N accumulation at the maturity stage was higher in the modern cultivars compared to the pre-modern cultivars, mainly as a result of increased N accumulation during the stem elongation phase. The N translocation capacity of the vegetative tissues increased, and the N translocation efficiency of the sheath and chaff were higher than that of the leaves. Important genetic improvement targets for high NUE include increasing pre-anthesis N assimilation ability and post-anthesis N translocation capacity. Furthermore improvements in wheat breeding should include increasing both N uptake and NHI to improve NUE and reverse the trend of declining GNC. • Higher genetic gain of grain yield and N use efficiency under better environment. • Modern cultivars had higher N accumulation, mainly raised during stem elongation phase. • N utilization efficiency increased at the expense of lower grain N content. • Enhanced N translocation and uptake was important for N use efficiency improvement.