Nitrogen Agronomic Efficiency Research Articles

Influence of Different Sources and Levels of Phosphorus on Nutrient Use Efficiency (NUE) and Properties of Low Calcareous Soil

A field experiment was conducted during kharif season of 2023 at Post Graduate Instructional Farm, College of Agriculture, Pune to study the impact of different phosphorus sources and levels on soybean growth and nutrient uptake in low calcareous soil. The experiment was laid out in randomized block design having eight treatments with three replications. The treatments comprised T1 - Absolute control, T2 - RDF (50:75:45 kg ha-1 N: P2O5: K2O), T3 - 50% P2O5 through PROM, T4 - 75% P2O5 through PROM, T5 - 100% P2O5 through PROM, T6 - 100% P2O5 through DAP + FYM @12.5 t ha-1, T7 - 100% P2O5 through SSP + FYM @12.5 t ha-1 and T8 - 100% P2O5 through vermicompost. The soil of experimental site was clay loam in texture. The findings of the present investigation revealed that the higher nutrient use efficiency was registered in treatment 100% P2O5 through SSP + FYM @12.5 t ha-1 (16.25 kg kg-1). The application of 100% P2O5 through PROM recorded higher nutrient use efficiency (13.31 kg kg-1) over RDF (11.52 kg kg-1). In respect of agronomic nutrient use efficiency, 100% P2O5 through SSP + FYM @12.5 t ha-1 registered higher nitrogen (40 kg grain kg nutrient-1), phosphorus (26 kg grain kg nutrient-1) and potassium efficiency (44 kg grain kg nutrient-1) to soybean crop. The agronomic efficiency of nitrogen, phosphorus and potassium was observed higher in treatment 100% P2O5 through PROM over treatment RDF. After harvest of crop the soil pH was remained unaffected while the electrical conductivity of soil was significantly higher in 100 % P2O5 through vermicompost and PROM to soybean crop. The application of 100% P2O5 either through vermicompost or PROM recorded at par organic carbon content in soil (0.66% and 0.64% respectively). The application of 100% P2O5 through PROM significantly reduced calcium carbonate (6.29%) in soil. The 100% P2O5 through SSP + FYM @12.5 t ha-1 showed higher available nitrogen in soil (297.33 kg ha-1) while the application of 100% P2O5 through DAP + FYM @12.5 t ha-1 exhibited higher level of available phosphorus and potassium content in soil (41.33 and 745.33 kg ha-1, respectively). Further, the application of 100% P2O5 through vermicompost was also significantly superior in available micronutrients like iron (5.7 mg kg-1), manganese (9.9 mg kg-1), zinc (4.6 mg kg-1) and copper (10.4 mg kg-1). The application of 100% P2O5 through PROM registered significantly higher available nitrogen (287.33 kg ha-1), available phosphorus (37.33 kg ha-1), available potassium (737.67 kg ha-1), available micronutrients viz. iron (5.4 mg kg-1), manganese (9.2 mg kg-1), zinc (4.4 mg kg-1) and copper (10.4 mg kg-1) over recommended dose of fertilizers. In general, the integration of organic fertilizers, FYM, PROM and vermicompost, with chemical fertilizers can significantly enhance nutrient use efficiency, soil nutrient content, improve soil health and increase soybean yield in low calcareous soils.

Optimizing Irrigation and Nitrogen Application to Enhance Millet Yield, Improve Water and Nitrogen Use Efficiency and Reduce Inorganic Nitrogen Accumulation in Northeast China

Enhancing irrigation and nitrogen fertilizer application has become a vital strategy for ensuring food security in the face of population growth and resource scarcity. A 2-year experiment was conducted to determine to investigate the effects of different irrigation lower limits and nitrogen fertilizer application amounts on millet growth, yield, water use efficiency (WUE), N utilization, and inorganic nitrogen accumulation in the soil in 2021 and 2022. The experiment was designed with four irrigation lower limits, corresponding to 50%, 60%, 70%, and 80% of the field capacity (FC), referred to as I50, I60, I70, and I80. Four nitrogen fertilizer application were also included: 0, 50, 100, and 150 kg·hm−2 (designated as F00, F50, F100, and F150), resulting in a total of 16 treatments. Binary quadratic regression equations were established to optimize the irrigation and nitrogen application. The results demonstrated that the plant height, stem diameter, leaf area index, aboveground biomass, yield, spike diameter, spike length, spike weight, WUE, and nitrogen agronomic efficiency for millet initially increased before subsequently decreasing as the irrigation lower limit and nitrogen fertilizer application increased. Their maximum values were observed in the I70F100. However, the nitrogen partial factor productivity (PFPN) exhibited a gradual decline with increasing nitrogen application, reaching its peak at F50. Additionally, PFPN displayed a pattern of initial increase followed by a decrease with rising irrigation lower limits. The accumulation of NO3−-N and NH4+-N in the 0~60 cm soil layer increased with the increase of nitrogen fertilizer application in both years, while they tended to decrease as the irrigation lower limit increased. An optimal irrigation lower limit of 64% FC to 74% FC and nitrogen fertilizer application of 80 to 100 kg ha−1 was recommended for millet based on the regression equation. The findings of this study offer a theoretical foundation and technical guidance for developing a drip irrigation and fertilizer application for millet cultivation in Northeast China.

Substituting partial chemical nitrogen fertilizers with organic fertilizers maintains grain yield and increases nitrogen use efficiency in maize

IntroductionLong-term application of excessive nitrogen (N) not only leads to low N use efficiency (NUE) but also exacerbates the risk of environmental pollution due to N losses. Substituting partial chemical N with organic fertilizer (SP) is an environmentally friendly and sustainable fertilization practice. However, the appropriate rate of SP in rainfed maize cropping systems in semi-arid regions of China is unknown.MethodsTherefore, we conducted a field experiment between 2021 and 2022 in a semi-arid region of Northern China to investigate the effects of SP on maize growth, carbon and N metabolism (C/NM), and NUE. The following treatments were used in the experiment: no N application (CK), 100% chemical N (SP0, 210 kg N ha–1), and SP substituting 15% (SP1), 30% (SP2), 45% (SP3), and 60% (SP4) of the chemical N. The relationship between these indicators and grain yield (GY) was explored using the Mantel test and structural equation modeling (SEM).Results and discussionThe results found that the SP1 and SP2 treatments improved the assimilates production capacity of the canopy by increasing the leaf area index, total chlorophyll content, and net photosynthetic rate, improving dry matter accumulation (DMA) by 6.2%–10.6%, compared to the SP0 treatment. SP1 and SP2 treatments increased total soluble sugars, starch, free amino acids, and soluble protein contents in ear leaves via increasing the enzymatic reactions related to C/NM in ear leaves during the reproductive growth stage compared with SP0 treatment. The highest plant nitrogen uptake (PNU) and nitrogen recovery efficiency were obtained under the SP2 treatment, and the GY and nitrogen agronomic efficiency were higher than the SP0 treatment by 9.2% and 27.8%. However, SP3 and SP4 treatments reduced DMA and GY by inhibiting C/NM in ear leaves compared to SP0 treatment. Mantel test and SEM results revealed that SP treatments indirectly increased GY and PNU by directly positively regulating C/NM in maize ear leaves. Therefore, in the semi-arid regions, substituting 30% of the chemical N with SP could be considered. This fertilizer regime may avoid GY reduction and improve NUE. This study provides new insights into sustainable cultivation pathways for maize in semi-arid regions.

Organic substitution regime with optimized irrigation improves potato water and nitrogen use efficiency by regulating soil chemical properties rather than microflora structure

Context or problemImproving water and fertilizer use efficiency is an inevitable choice for sustainable potato production in North China. However, the regulation mechanism of potato water and nitrogen use efficiency under water-nitrogen coupling (W-N) regime is still unknown. Objective or research questionThe objectives from a 3-year field experiment were (1) to assess the impact of W-N regimes on potato yield and water and nitrogen use efficiency, (2) to elucidate the soil microflora structure under W-N regimes, and (3) to determine the relationship between soil chemical properties, microflora structure, and potato water and nitrogen use efficiency. MethodsA three-year two-factor split-zone potato field experiment was conducted in arid and semi-arid regions of the Inner Mongolian Plateau, with irrigation [(rainfed (W0), optimized (soil-based) irrigation (W1), conventional irrigation (W2)] as the primary treatment and N fertilizer [no N (N0), chemical N (N1), 25 % manure substitution (N2)] as the secondary treatment. ResultsPotato yield and water productivity followed N2 > N1 > N0, and partial nitrogen productivity and nitrogen agronomic efficiency followed N2 > N1 at the same irrigation level. Potato yield, nitrogen internal efficiency, partial nitrogen productivity and nitrogen agronomic efficiency first increased and then decreased, whereas water productivity gradually decreased with increasing irrigation levels under the same fertilization regime. Moreover, potato yield, soil total nitrogen, organic carbon, and microbial biomass carbon and nitrogen content peaked with the W1N2 regime. W-N regimes significantly influenced soil microbial community structure. Soil microbial α-diversity was less variable under W1 and N2 conditions. Soil bacterial network complexity and robustness were higher in W1 and W2 than in W0 regimes, whereas the opposite was true for fungi. The complexity and robustness of the soil bacterial and fungal network demonstrated for three fertilization regimes were higher in N1 and N2 than in N0 regimes. Neutral community model showed that soil microflora in W-N regime was mainly influenced by stochastic processes. PLSPM showed that organic substitution regime with optimized irrigation improves potato water and nitrogen use efficiency by regulating soil chemical properties rather than microflora structure. ConclusionsW1N2 regime synergizes well to improve potato water and N use efficiency and soil microflora stability, and organic substitution regime with optimized irrigation improves potato water and nitrogen use efficiency by regulating soil chemical properties. Implications or significanceOur findings initially clarified the regulatory mechanisms of potato water and nitrogen use efficiency in North China, offering theoretical guidance for further optimizing irrigation and fertilization management.

Optimizing Nitrogen Fertilization for Enhanced Rice Straw Degradation and Oilseed Rape Yield in Challenging Winter Conditions: Insights from Southwest China

The crop straw returning to the field is a widely accepted method to utilize and remediate huge agricultural waste in a short period. However, the low temperatures and dry conditions of the winter season in Southwest China can be challenging for the biodegradation of crop straw in the field. With a similar aim, we designed a short-term study where rice straw was applied to the field with different concentrations of nitrogen (N) fertilizer while keeping phosphorus (P) constant; CK, (N0P0); T1, (N0P90); T2, (N60P90); T3, (N120P90); and T4, (N180P90) were added to evaluate its impact on straw degradation during cold weather. We found that high fertilization (T4) significantly improved crop yield, organic matter, and lignocellulose degradation under cold temperatures (21.5–3.2 °C). It also significantly improved soil nitrogen agronomic efficiency, nitrogen use efficiency, and nitrogen physiological efficiency. The yield was highest in T4 (1690 and 1399 kg/ha), while T3 acted positively on soil lignocellulolytic enzyme activity, which in turn resulted in higher degradation of OM and lignocellulosic material. Pearson’s correlation analysis revealed that total nitrogen, total phosphorus, available nitrogen, and available phosphorus were important variables that had a significant impact on soil EC, bulk density, water holding capacity, and soil enzymes. We found that nitrogen application significantly changed the soil bacterial community by increasing the richness and evenness of lignocellulolytic bacteria, which aided the degradation of straw in a short duration. This study’s finding indicates that the decomposition of crop straw in the field under cold weather stress was dependent on nutrient input, and N, in an appropriate amount (N120-180), was suitable to achieve higher yield and higher decomposition of straw in such an environment.

Nitrogen application increased yield sensitivity of indica hybrid rice to climate resource

Rice yield variability can be attributed to the range of sowing dates across extensive cropping areas and varying nitrogen application rates. Nonetheless, the precise quantitative relationship between sowing dates, nitrogen application rates, and rice yield development remains elusive. In this study, we evaluated differences in dry matter and yield components of three indica hybrid varieties for five sowing dates at four ecological sites in the middle and lower reaches of the Yangtze River, China in 2019 and 2020, with three nitrogen application rates. Results indicated that yield initially increased and then decreased with delayed sowing dates. Photosynthetically active radiation accumulation after anthesis (PARAA) was identified as the key positive climate resource affecting rice yield, decreasing by an average of 19.7 MJ m−2 for every 15-day delay in sowing. Nitrogen agronomic efficiency decreased linearly with the delay in sowing dates. Early sowing of rice with high PARAA and effective accumulated temperature after anthesis (EATAA) showed yield increases due to nitrogen application, whereas late-sown rice with insufficient photothermal resources did not exhibit marked yield improvement and may experience yield reduction. Ensuring adequate dry matter accumulation after anthesis and high seed setting rate was the main way to increase yield, influenced by sowing dates and nitrogen application rates. Intriguingly, our study revealed that nitrogen application markedly enhanced yield sensitivity to PARAA and EATAA. This finding underscores the pivotal role of nitrogen in modulating crop responsiveness to climate resources, and contributes to a deeper understanding of agronomic practices for optimizing yield under varying climatic conditions.

Effects of Nitrogen Fertilizer and Planting Density on Growth, Nutrient Characteristics, and Chlorophyll Fluorescence in Silage Maize

The optimal combination of the nitrogen fertilizer application and planting density with reference to the silage maize yield and quality remains unclear. We hypothesized that increasing both would increase yields following the law of diminishing returns. Yayu26, a silage maize cultivar, was used in a split-plot experiment to investigate the effects of nitrogen fertilizer and planting density on growth, nutrient characteristics, and chlorophyll fluorescence. The main plots were assigned to three planting densities: 60,000 (A1), 75,000 (A2), and 90,000 (A3) plants hm−2, and the subplots were assigned to four nitrogen fertilizer rates: 0 (B1), 120 (B2), 240 (B3), and 360 (B4) kg hm−2. The results showed that increasing the nitrogen application rate and planting density both enhanced silage maize yield. Nitrogen accumulation and agronomic use efficiency peaked at a planting density of 75,000 hm−2. Structural equation modeling showed that the nitrogen application rate and planting density affected nitrogen accumulation and nutrient properties by influencing chlorophyll fluorescence parameters and nitrogen agronomic efficiency, ultimately resulting in a positive effect on the yield. The A3 × B2 treatments exhibited higher nitrogen accumulation, potentially compensating for any deficiencies in the dry-matter yield. Therefore, the A3 × B2 treatment was evaluated as the optimal treatment to achieve sustainable and economically feasible silage maize production.

Iron (Fe) and zinc (Zn) coated urea application enhances nitrogen (N) status and bulb yield of onion (A. cepa) through prolonged urea-N stay in alkaline calcareous soil

Onion (A. cepa) is an important horticulture crop which is sensitive to nutrient limitations worldwide. Urea hydrolysis to ammonia (NH3) and carbon dioxide (CO2), due to soil urease activity, causes urea-N loss. Comparative to several commercial products, the potential use of micronutrient coated urea to reduce urea hydrolysis based NH3-volatilization losses is novel to-date. In this study, boron (B), iron (Fe), zinc (Zn) and copper (Cu) were coated on urea at their full or half recommended rates as (B)-half, (Fe)-half, (Zn)-half, (Cu)-half, (B)-full, (Fe)-full, (Zn)-full, (Cu)-full, (B+Fe)-half, (B+Zn)-half, (B+Cu)-half, (Fe+Zn)-half, (Fe+Cu)-half, (Zn+Cu)-half, (B+Fe)-full, (B+Zn)-full, (B+Cu)-full, (Fe+Zn)-full, (Fe+Cu)-full and (Zn+Cu)-full having gum-only coated urea as an internal control. Parallel to these, p-Phenylenediamine (PPD-0.2 %, 0.4 %, 0.6 %, 0.8 % and 1.0 %) and hydroquinone (HQ-0.5 %, 1.0 % and 2 %) coated urea treatments were also used with acetone-only coated urea as an internal control. Whereas the uncoated urea treatment was taken as an overall control. In pot experiment, the soil residual urea concentrations were increased by 2, 0.5, 1.85, 2.69 and 3.15 folds at 8 days after incubation (DAI), by 5.6, 1.89, 5.97, 0.54 and 6.23 folds at 12 DAI and by 119, 123, 155, 84 and 87 folds at 16 DAI under (B)-full, (B+Zn)-full, (Fe+Zn)-full, PPD-0.8 % and PPD-1.0 % coated urea treatments, respectively, as compared to uncoated urea. Among these five coating combinations, 54.26 % and 44.82 % bulb yield increments were observed under (Fe+Zn)-full and PPD-1 % coated urea, respectively, in comparison to uncoated urea in field experiment. However, the 33.33 % increment in nitrogen agronomic efficiency (NAE) and subsequent economic gains proved (Fe+Zn)-full coated urea application as a solution to address N losses in alkaline calcareous soils.

Application of resource-environmental-economic perspective for optimal water and nitrogen rate under high-low seedbed cultivation in winter wheat

High-low seedbed cultivation (HLSC), a targeted agricultural method for increasing land utilization efficiency in North China Plain, has emerged as a key practice in enhancing sustainable agriculture, particularly in the context of the region’s unique ecological challenges and water scarcity. However, comprehensive analysis of resource-environment-economy for water and nitrogen strategy in HLSC-cultivated wheat was limited. A three-year field experiment with four nitrogen rates (360, 300, 240, and 180 kg ha−1, denoted as N1, N2, N3, and N4) and three irrigation quotas (120, 90, and 60 mm, referred to as W1, W2, and W3) was conducted to investigate effects of water and nitrogen rate on water productivity (WP), agronomic efficiency of nitrogen (AEN), energy use efficiency (EUE), carbon footprint (CF), water footprint (WF), nitrogen footprint (NF), and net benefits of HLSC-cultivated wheat. Results showed that the total energy output in moderate water and nitrogen input (i.e., N3W2) was 328.0×103 MJ ha−1, which was significantly increased by 31.8% compared with lower input (i.e., N4W3) but was decreased by 17.1% compared with higher input (i.e., N1W1). The total energy input, water consumption and grain yield in N3W2 was decreased by 22.3%, 14.4 and 4.1%, relative to N1W1, respectively, and increased by 18.2%, 20.8% and 42.2% relative to N4W3, respectively. This may lead to significant increase in EUE, WP, AEN and net income in N3W2. Furthermore, the CF, WF, and NF increased as the water and nitrogen input increased, whereas minimum CF, WF and NF per unit of yield was obtained N3/N4 or W1/W2 level. 240 kg N ha−1 coupled with 90–120 mm irrigation quota was recommended by TOPSIS for the HLSC-cultivated wheat to best trade-off resource use efficiencies, environmental footprints, and net benefits. Future studies are needed to further assess the scalability and adaptability of HLSC-cultivated wheat across different climatic zones and soil types.

Biochar Application Combined with Water-Saving Irrigation Enhances Rice Root Growth and Nitrogen Utilization in Paddy Fields

To improve nitrogen use efficiency (NUE) during rice cultivation, it is essential to comprehend the morphological and physiological traits of rice roots. However, in high-fertility black soil regions of Northeast China, the effects of combining biochar application with water-saving irrigation (WSI) conditions on rice root development and nitrogen utilization are still unknown. To address this knowledge gap, a combination of field experiments and 15N tracer micro-area investigations was conducted in this study. Four treatments were implemented: (i) controlled irrigation without biochar application (CB0); (ii) controlled irrigation with 2.5 t ha−1 biochar application (CB1); (iii) controlled irrigation with 12.5 t ha−1 biochar application (CB2); and (iv) controlled irrigation with 25 t ha–1 biochar application (CB3). Flooded irrigation conditions without biochar treatment (FB0) were used as the control. The primary objective of this research was to identify the mechanisms by which combined WSI conditions and biochar application affect rice root development and nitrogen utilization. Biochar application enhanced rice root morphological and physiological characteristics. Optimal biochar application increased the longest root length (RL), root volume (RV), root fresh weight (RFW), root active absorption area, root bleeding intensity, and root activity (RA) of rice while also optimizing the root–shoot ratio and facilitating nitrogen absorption by roots. These changes in root morphological and physiological characteristics facilitated the absorption of fertilizer-15N and soil nitrogen by rice roots, ultimately leading to improvements in rice yields and NUEs. Notably, the rice yields, NUE, nitrogen agronomic efficiency (NAE), and nitrogen partial factor productivity (NPFP) of CB2 plants were 16.45%, 39.42%, 24.48%, and 16.45% higher than those of FB0 plants, respectively. These results highlight the effectiveness of biochar application as a strategy to ensure food security and enhance NUE under WSI conditions. Furthermore, this study suggests that the recommended optimal application amount of biochar for the black soil area of Northeast China is 12.5 t ha−1.

Partial substitution of chemical fertilizer by organic fertilizer increases yield, quality and nitrogen utilization of Dioscorea polystachya.

This field experiment aimed to investigate the effects of different ratios of organic and inorganic fertilizers with maintaining equal nitrogen application rates on the yield, quality, and nitrogen uptake efficiency of Dioscorea polystachya (yam). Six treatments were set, including a control without fertilizer (CK), sole application of chemical fertilizer (CF), sole application of organic fertilizer (OM), 25% organic fertilizer + 75% chemical fertilizer (25%OM + 75%CF), 50% organic fertilizer + 50% chemical fertilizer (50%OM + 50%CF), and 75% organic fertilizer + 25% chemical fertilizer (75%OM + 25%CF). The experiment followed a randomized complete block design with three replications. Various yield parameters, morphology, quality indicators, and nitrogen utilization were analyzed to assess the differences among treatments. The results indicated that all fertilizer treatments significantly increased the yield, morphology, quality indicators, and nitrogen utilization efficiency compared to the control. Specifically, 25%OM + 75%CF achieved the highest yield of 31.96 t hm-2, which was not significantly different from CF (30.18 t hm-2). 25%OM + 75%CF exhibited the highest values at 69.23 cm in tuber length and 75.86% in commodity rate, 3.14% and 1.57% higher than CF respectively. Tuber thickness and fresh weight of 25%OM + 75%CF showed no significant differences from CF, while OM and 50%OM+50%CF exhibited varying degrees of reduction compared to CF. Applying fertilizer significantly enhanced total sugar, starch, crude protein, total amino acid, and ash contents of D. polystachya (except ash content between CK and OM). Applying organic fertilizer increased the total sugar, starch, crude protein, total amino acid, and ash contents in varying degrees when compared with CF. The treatment with 25%OM+75%CF exhibited the highest increases of 6.31%, 3.78%, 18.40%, 29.70%, and 10%, respectively. Nitrogen content in different plant parts followed the sequence of tuber > leaves > stems > aerial stem, with the highest nitrogen accumulation observed in 25%OM + 75%CF treatment. Nitrogen harvest index did not show significant differences among treatments, fluctuating between 0.69 and 0.74. The nitrogen apparent utilization efficiency was highest in 25%OM + 75%CF (9.89%), followed by CF (9.09%), both significantly higher than OM (5.32%) and 50%OM + 50%CF (6.69%). The nitrogen agronomic efficiency varied significantly among treatments, with 25%OM + 75%CF (33.93 kg kg-1) being the highest, followed by CF (29.68 kg kg-1), 50%OM + 50%CF (21.82 kg kg-1), and OM (11.85 kg kg-1). Nitrogen partial factor productivity was highest in 25%OM + 75%CF treatment (76.37 kg kg-1), followed by CF (72.11 kg kg-1), both significantly higher than 50%OM + 50%CF (64.25 kg kg-1) and OM (54.29 kg kg-1), with OM exhibiting significantly lower values compared to other treatments. In conclusion, the combined application of organic and inorganic fertilizers can effectively enhance the yield, quality, and nitrogen utilization efficiency of D. polystachya. Particularly, the treatment with 25% organic fertilizer and 75% chemical fertilizer showed the most promising results.

Improving Tuber Yield of Tiger Nut (Cyperus esculentus L.) through Nitrogen Fertilization in Sandy Farmland.

The cultivation of tiger nut (Cyperus esculentus L.) on marginal lands is a feasible and effective way to increase food production in Northern China. However, the specific influence of nitrogen fertilizer application on the growth dynamics, tuber expansion, overall yield, and nitrogen use efficiency (NUE) of tiger nuts cultivated on these sandy lands is yet to be fully elucidated. From 2021 to 2022, we conducted a study to determine the effect of N fertilizers on the leaf function morphology, canopy apparent photosynthesis (CAP), tuber yield, and NUE of tiger nut. The results indicate that the tuber yield and NUE are closely related to the specific leaf area (SLA), leaf area index (LAI), leaf nitrogen concentration per area (NA), CAP, and tuber expansion characteristics. Notably, significant enhancements in the SLA, LAI, NA, and CAP during the tuber expansion phase ranging from the 15th to the 45th day under the 300 kg N ha-1 treatment were observed, subsequently leading to increases in both the tuber yield and NUE. Moreover, a maximum average tuber filling rate was obtained under the N300 treatment. These improvements led to substantial increases in the tuber yield (32.1-35.5%), nitrogen agronomic efficiency (NAE, 2.1-5.3%), nitrogen partial factor productivity (NPP, 4.8-8.1%), and nitrogen recovery efficiency (NRE, 3.4-5.7%). Consequently, 300 kg N ha-1 of N fertilizers is the most effective dose for optimizing both the yield of tiger nut tubers and the NUE of tiger nut plants in marginal soils. Structural equation modeling reveals that N application affects the yield and NUE through its effects on leaf functional traits, the CAP, and the tuber filling characteristics. Modeling indicates that tuber expansion characteristics primarily impact the yield, while CAP predominantly governs the NUE. Above all, this study highlights the crucial role of N fertilizer in maximizing the tiger nut tuber yield potential on marginal lands, providing valuable insights into sustainable farming in dry areas.

Optimizing Nutrient and Energy Efficiency in a Direct-Seeded Rice Production System: A Northwestern Punjab Case Study

This study was carried out in Amritsar, Punjab, to find out how efficiently nutrients were used and how much energy was employed in direct-seeded rice (DSR) production. In this study, four levels of nitrogen (0, 40, 50, and 60 kg N ha−1) and three levels of phosphorus (0, 37.5, and 45 kg P2O5 ha−1) were tested. In a rice production system, the energy indices of various inputs and outputs were evaluated through the application of energy equivalency. The nutrient-use efficiencies in rice were assessed using different efficiency indices. The maximum grain yields of 38.9 q ha−1 and 36.9 q ha −1 were recorded at 50 kg N ha−1 and 45 kg P2O5 ha−1, respectively. On the other hand, application of nitrogen at 60 kg N ha−1 and phosphorus at 45 kg P2O5 ha−1 resulted in maximum straw yield of 57.1 q ha−1 and 51.1 q ha−1, respectively. In comparison with the control, application of 60 and 50 kg N ha−1 resulted in 161.9% and 151.0% higher grain yield, respectively. On the other hand, with applications of 45 kg P2O5 ha−1 and 37.5 kg P2O5 ha−1, an increase in the grain yield of 17.3 and 28.6%, respectively, over the control was recorded. Moving further towards nutrient-use efficiencies (NUEs), the highest values of partial factor productivity of nitrogen (PFPN), agronomic efficiency of nitrogen (AEN), partial nutrient balance of nitrogen (PNBN), and recovery efficiency of nitrogen (REN) were 89.1, 50.4, 1.78 and 0.72, respectively, which were obtained at 40 kg N ha−1, after which the values started decreasing steadily. In the case of phosphorus, the partial factor productivity (PFPP) of 88.6 was the maximum at 37.5 kg P2O5 ha−1, but partial nutrient balance (PNBP) of 0.36 and recovery efficiency (REP) of 0.08 were highest at 45 kg P2O5 ha−1. The main results revealed that the farmer field had an excessive amount of non-renewable energy inputs. The experimental field depicted greater energy-usage efficiency (EUE) of 4.5, energy productivity (EP) of 0.14, and energy profitability (EP1) of 3.5. These results were primarily ascribed to a significant drop in energy inputs under direct-seeded rice (DSR). In the case of non-renewable energy inputs, fertilizer made the maximum contribution to energy input (47.9%) in the farmer’s field. We conclude that nutrient-use efficiencies and energy-use efficiency were highest at 50 kg N and 45 kg P2O5 ha−1. This recommendation is beneficial for farmers because lower inputs and higher outputs are the main objective of every farmer.

Effects of irrigation and fertilization with biochar on the growth, yield, and water/nitrogen use of maize on the Guanzhong Plain, China

Excessive water and nitrogen inputs in agricultural production can result in resource wastage and environmental pollution. This makes it imperative to identify effective farmland management strategies to ensure sustainable agriculture development, and it remains to be explored whether biochar can be an effective solution. In this study, a 2-year (2021 and 2022) field experiment was conducted with two irrigation levels, W100 (ET) and W80 (0.8 ET), and three nitrogen fertilizer levels, NH (270 kg ha−1), NM (180 kg ha−1), and NL (90 kg ha−1), in full combination with biochar (30 t ha−1). The NM and N0 treatments without biochar at both irrigation levels were set as controls. The results of the study showed that there was no significant difference in maize yield between the high and medium N treatments. Further, maximum water productivity (WP), nitrogen agronomic efficiency (NAE), and nitrogen recovery efficiency (NRE) were obtained in NM treatments when water and nitrogen were kept consistent. Deficit irrigation was effective in reducing water consumption and increased WP by 15.54% and 11.06% in 2021 and 2022, respectively. Biochar application increased WP, nitrogen use efficiencies, and significantly increased the yield by 7.02% and 6.46% in 2021 and 2022, respectively. Therefore, the application of biochar can be an effective measure to promote crop growth and resource use. Based on the results of this experiment, an irrigation level of 0.8 ET in combination with NM and biochar application is recommended to ensure the sustainability of agricultural production.

Optimizing irrigation and nitrogen management improves soil soluble nitrogen pools and reduces nitrate residues in a drip-fertigated apple orchard on the Loess Plateau

Appropriate water and nitrogen fertilizer management is crucial for achieving sustainable development in the apple industry. However, the soil nitrogen supply capacity and residual nitrate characteristics under drip fertigation remain poorly understood. Therefore, this study aims to (1) investigate the coupling effects of irrigation and nitrogen levels on the concentrations and distribution characteristics of soil soluble nitrogen fractions and residual soil nitrate; (2) explore the relationships between Christiansen uniformity coefficient (CU) of soil nitrate and apple yield, water productivity (WPc) and nitrogen use efficiency (nitrogen agronomic efficiency, AEn). The field experiment was conducted in a drip-fertigated apple orchard starting in 2017, which included two irrigation levels, 85% (W1) and 100% (W2) of field capacity (FC), and four nitrogen rates, 0 (N1), 120 (N2), 240 (N3) and 360 (N4) kg ha–1. The results showed that nitrogen inputs significantly increased soil soluble inorganic nitrogen and soluble organic nitrogen (SON) contents. However, the SON content significantly decreased when 360 kg N ha–1 was applied, particularly at W1. The maximum nitrate accumulation in the 0–3 m soil layer at N4 reached 2540.97 kg ha–1 in 2021, but the maximum value decreased to 1251.62 kg ha–1 in 2022 due to extreme rainfall. The average CU of residual nitrate across irrigation levels in the 0–3 m soil layer was highest at N3, with values of 0.68 and 0.57 in 2021 and 2022, respectively. High irrigation level increased the diffusion distances of nitrate both vertically and horizontally, resulting in a significant effect on CU. Apple yield and WPc first increased and then decreased with increasing nitrogen rates, while AEn consistently decreased, but they were all greater with a higher CU. The recommended combination of irrigation and nitrogen application was 85% FC and 240 kg N ha–1, which can achieve the dual goals of enhancing soil nitrogen supply capacity and minimizing environmental risks while improving orchard productivity.

Effects of nitrogen topdressing fertilization on yield and quality in soybeans

<p>Soybean [<italic>Glycine max</italic> (L.)] has higher nitrogen requirements than other crops. We investigated the effects on soybean yield and quality of topdressing with nitrogen fertilizer. Nitrogen fertilizer was applied as a topdressing to soybeans at 0, 20, 30, and 40 kg ha<sup>−1</sup> (N0, N20, N30, and N40 treatments, respectively); half of the total topdressing treatment was applied at the pre-flowering (R 1) stage and the other half at the post-flowering (R 2) stage. Yield was highest in the N20 treatment and decreased with larger quantities of topdressing. The protein and total amino acid content were highest in the N20 treatment but tended to decrease with a greater quantity of topdressing. contents of most individual amino acids peaked in the N20 or N30 treatments and decreased as topdressing quantity increased, although proline and arginine contents increased with quantity of topdressing. Isoflavone content tended to be highest in either the N30 or N20 treatment. The agronomic efficiency of nitrogen (AE<sub>N</sub>) was highest in the N20 treatment. There was a positive correlation between AE<sub>N</sub> and yield, protein, isoflavone, and amino acid content. Topdressing with 20 kg ha<sup>−1</sup> N produced the highest yield, protein, and amino acid content. Topdressing with greater quantities of nitrogen fertilizer decreased the yield and quality of soybeans.</p>

Effect of nitrogen and boron treatments on harvest index and nitrogen use efficiency in sugar beet

The aim of this study is to examine the effect of different doses of nitrogen (N) and boron (B) treatment on sugar harvest index (SHI), nitrogen harvest index (NHI), and nitrogen use efficiency (NUE) parameters and to determine the economic optimum nitrogen rates (EONR) in sugar beet. The experiment was set up in a randomized block factorial design with three replications. Five doses of N (0, 90, 180, 270, and 360 kg N ha-1) and four doses of B (0, 2, 4, and 6 kg B ha-1) were applied in the study. According to the results of the research, the SHI decreased statistically significantly with the increase of dose of the N treatment, but the NHI was not affected by the N treatment. Physiological efficiency of nitrogen in taproot dry matter yield (NPETDMY) and physiological efficiency of nitrogen in sugar yield (NPESY) decreased statistically significantly (p<0.01) with the increase in the dose of N treatment. A similar case was observed in the parameters of nitrogen agronomic efficiency (NAgE) and nitrogen uptake efficiency (NUpE). The increase in boron treatment doses statistically significantly (p<0.01) increased the NAgE in the first year. The EONR, calculated using the quadratic model, was found to be 240 kg N ha-1 on average of two years. As a result, the nitrogen use potential decreased with the increase of N doses applied to sugar beet. The use of EONR can be recommended for optimum yield and quality in the region.

Optimizing One-Time Nitrogen Fertilization for Rice Production Using Controlled-Release Urea and Urease Inhibitors

One-time fertilization with controlled-release urea (CRU) is a research hotspot for its lower labor cost and stability of nitrogen (N) supply for rice growth. Yet the fertilizer formulation needs to be further improved to better adjust the N supplement to meet the demand of rice plants and obtain a higher grain yield. Therefore, the effects of novel fertilizer formulations composed of CRU, urease inhibitor (UI) and nitrification inhibitor (NI) on the rice growth and photosynthetic characteristics as well as high-yield formation were tested through a two-year field experiment. The result indicated that the combined use of CRU and UI treatment can achieve higher yields than with CRU at the same N application level. Meanwhile, with a 20% reduction of N use, one-time application of CRU + UI can obtain the same high yield as the conventional split application of urea. Compared with conventional fertilization and CRU treatment, the CRU + UI treatment had suitable leaf area and biomass accumulation at the vegetative growth stage and high effective stem tiller rate. More post-anthesis dry matter accumulation, higher net photosynthesis rate and low senescence rate were guaranteed for its high yield and nitrogen agronomic efficiency.

Organic substitution accumulates more nitrogen in soil while maintaining unchanged nitrogen use efficiency in rice‐fava bean rotation system

AbstractOrganic substitution management (OSM) is critical for soil conservation and nitrogen efficiency. However, integrated assessment of soil quality and crop productivity under paddy‐upland rotation systems after OSM introduction is still lacking. Here, soil nitrogen‐related properties and crop nitrogen use efficiency (NUE) were evaluated in 2018, 2019, and 2020, based on a long‐term rice‐fava bean rotation experiment started in 2015. In comparison to chemical fertilization, OSM increased total soil nitrogen (TN) and available nitrogen (AN) by 13.1% and 13.8%, respectively, during the rice season, and by 16.3% and 15.9% during the fava bean season. However, NUE, nitrogen recovery efficiency (NRE), and nitrogen agronomic efficiency (NAE) all showed season‐specific responses to OSM. OSM decreased NUE, NRE, and NAE by 18.2%, 37.5%, and 26.2% in the rice season but increased by 8.0%, 231.0%, and 184.1% in the fava bean season. From the rotation system scale, there were no significant differences in NUE and nitrogen surplus between the treatments. We suggest that the differences in soil conditions and crop requirements between seasons play significant roles in the response of nitrogen accumulation and nitrogen utilization to OSM. Based on these differences, OSM achieves inter‐seasonal synergy in soil N pools and crop uptake, and results in yield stabilization and soil nitrogen accumulation. Because of its high capacity for improving soil quality while ensuring no yield reduction, OSM has the potential to curb regional soil degradation in paddy‐upland rotation areas where there is increasing demand for food and chemical fertilizers are currently abused.

Trade-off strategy for the usage of thiencarbazone-methyl·isoxaflutole on maize fields: Nitrogen-associated microbial response and environmental implications

Due to the lack of knowledge on the mechanism of the effect of new herbicides on nitrogen-functioning microorganisms and nitrogen use efficiency, a balancing strategy for the application of new herbicides in maize fields is rarely proposed. By studying the effects of thiencarbazone-methyl·isoxaflutole (TMI) on nitrogen transformation in soil and nitrogen agronomic efficiency (NAE) of maize, the mechanism of nitrogen functional groups and genes involved was revealed, and controlling factors affecting soil nitrogen transformation were identified. Results showed that on day 18, the nitrate nitrogen (NO3−-N) content increased but ammonium nitrogen (NH4+-N) content decreased with the TMI application. This can be further verified by the positive correlations (p < 0.05) among isoxaflutole residues, “aerobic_ammonia_oxidation” and NO3−-N content. The NH4+-N content increased significantly with TMI application at 10 times the recommended dose (412.5 ml hm−2) on days 30 and 45, which explains the high value of NAE at the high-dose application of TMI. Random forest model and redundancy analysis confirmed the significant impacts of the nifH gene on NH4+-N content and TMI residues on NO3−-N content (p < 0.05). Comprehensively considering the disturbance of nitrogen-related microorganisms and the effects on the NAE of maize, this research proposed a trade-off strategy for the application of new pre-emergence herbicide in maize fields, involving background investigation, experimental design, analytical methods and trade-off indicators. This may be further popularised and achieve a balance between economic and environmental benefits.