Nitrogen Use Research Articles

Study on Optimal Nitrogen Application for Different Oat Varieties in Dryland Regions of the Loess Plateau.

The present study endeavored to tackle the challenges posed by limited diversity in oat varieties and suboptimal nitrogen fertilizer utilization in the arid landscapes of the Loess Plateau. We selected three oat varieties, including early-maturing oats (E), medium-maturing oats (M), and late-maturing oats (L). In 2022, four nitrogen applications were set up as CK (0 kg N ha-1), N1 (60 kg N ha-1), N2 (90 kg N ha-1), and N3 (120 kg N ha-1). We introduced two additional nitrogen applications, N4 (180 kg N ha-1) and N5 (240 kg N ha-1), in 2023. The two-year study results demonstrated a significant increase in oat yield due to nitrogen application (p < 0.05). The highest grain yield was observed for E oats at 2216.63 kg·ha-1 under the N3 treatment, while M and L oats had the highest grain yields at 2505.43 kg·ha-1 and 2946.30 kg·ha-1 under N4, respectively. The protein content of L oats reached a peak of 14.15% under N4, and the order of protein contents in oat protein components was globulin > gliadin> glutenin > albumin. The β-glucan content of L oats reached a peak of 4.92% under N3. The nitrogen fertilizer utilization efficiency (NFUE) of the three oats was highest under N2. L oats exhibited enhanced NFUE owing to an elevated pre-flowering nitrogen translocation amount (PrNTA), with a 42.94% and 29.51% increase relative to E and M oats, respectively. The pre-flowering nitrogen translocation contribution (PrNTC) in oats surpassed the post-flowering nitrogen accumulation contribution (PoNAC). Therefore, nitrogen application positively impacted oat growth, yet excessive application had an inhibitory effect. There is a significant positive correlation among oat yield, quality, nitrogen accumulation, and utilization efficiency. In summary, oat crops exhibited optimal performance in terms of yield, quality, and nitrogen use efficiency when nitrogen application rates ranged between 90 and 180 kg·ha-1. Late-maturing oats coincide with the rainy and hot season in the northern dryland regions, making them more suitable for planting in the dryland areas of the Loess Plateau.

Mechanisms of Irrigation Water Levels on Nitrogen Transformation and Microbial Activity in Paddy Fields

Nitrogen is a vital nutrient for rice growth; however, its inefficient use often results in nutrient loss, environmental degradation, and the emission of greenhouse gases. In this study, a rice paddy simulation was conducted under different water levels (1–4 cm), incorporating a comprehensive analysis of nitrogen dynamics, environmental factors, and microbial communities to evaluate the impact of water levels on nitrogen concentrations and microbial composition. The results indicated that the water level had a greater impact on nitrogen concentrations in surface water than in soil water. Compared to low water level conditions (1 cm), the average concentrations of ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen in surface water under 2–4 cm water levels decreased by approximately 53.8%, 36.7%, and 78.9%, respectively. Water levels also influenced the microbial composition and nitrogen cycling in paddy soil, with lower water levels promoting aerobic processes such as nitrification, while higher water levels facilitated anaerobic processes such as denitrification and dissimilatory nitrate reduction to ammonium. Correspondingly, microbial composition shifted, with aerobic bacteria predominating in shallow water conditions and anaerobic bacteria flourishing under deeper water. These findings suggest that optimized water management, particularly through shallow irrigation, may mitigate nitrogen loss and improve nitrogen use efficiency. Nevertheless, additional field studies are necessary to validate these results and explore their interaction with other agricultural practices.

Long-term effects of agronomic practices on winter wheat yield and NUE in dryland regions of USA and China: a long-term meta-analysis

Dryland agriculture is fundamental to global crop production and vital to food security. Conservation tillage is extensively practiced in USA wheat cultivation. Meanwhile, the adoption of conservation tillage by Chinese farmers is limited. This meta-analysis compared the yield and nitrogen use efficiency (NUE) between conservation tillage and conventional tillage (CT) with different types of cropping systems, mulching methods, levels of nitrogen fertilizer (NF), and addition of manure. The meta-analysis presented that conservation tillage at high-NF enhanced the yield and NUE, and reduced the yield and NUE at low-NF, compared to CT. The interaction of conservation tillage with leguminous cover crops (LCC) and manure application increased the yield and NUE at low-NF, compared to CT. Non-leguminous cover crops (NLCC) increased the yield and NUE under high-NF than low-NF. The interaction of conservation tillage with management practices showed that the no-tillage (NT) with leguminous cover crops (LCC) significantly increased wheat yield by 58% and NUE by 47% under low-NF compared to CT. However, increasing the rate of NF did not increase the yield under such interaction. Cropping systems, mulching types, and manure application mainly determined the effects of conservation tillage on wheat yield and NUE. The adverse impact of CT on yield and NUE could be alleviated with the application of LCC and manure under moderate NF. We demonstrate that adding LCC and manure have a generally substitutive relationship with N fertilizer, resulting in a significant increase in wheat yield and NUE at low-NF doses as at high N fertilizer dosages. Therefore, based on the obtained results, moderate NF with LCC and manure application is recommended for growing winter wheat in dryland regions of the USA and China.

Inoculation with Azospirillum brasilense as a Strategy to Reduce Nitrogen Fertilization in Cultivating Purple Maize (Zea mays L.) in the Inter-Andean Valleys of Peru.

Purple maize has gained global significance due to its numerous nutraceutical benefits. However, sustaining its production typically requires high doses of nitrogen fertilizers, which, when applied in excess, can contaminate vital resources such as soil and water. Inoculation with nitrogen-fixing microorganisms, such as those from the Azospirillum genus, has emerged as an alternative to partially or fully replace nitrogen fertilizers. This study aimed to evaluate the inoculation effect with A. brasilense and varying nitrogen fertilization levels on the yield and quality of purple maize. The experiment was carried out using a randomized complete block design (RCBD) with a 2 × 5 factorial arrangement and five replications. Treatments comprised two inoculation levels (control without inoculation and inoculation with A. brasilense) under five nitrogen doses (0, 30, 60, 90, and 120 kg∙ha-1, applied as urea). Inoculation with A. brasilense resulted in a 10.5% increase in plant height, a 16.7% increase in root length, a 21.3% increase in aboveground fresh biomass, a 30.1% increase in root fresh biomass, and a 27.7% increase in leaf nitrogen concentration compared to the non-inoculated control. Regarding yield, the inoculated plants surpassed the control in both purple maize yield (kg∙ha-1) and cob weight by 21.8% and 11.6%, respectively. Across all fertilization levels and parameters assessed, the inoculated treatments outperformed the control. Furthermore, for parameters, namely plant height, leaf nitrogen content, and cob dimensions (length, diameter, and weight), the A. brasilense inoculation treatment with 90 kg N∙ha-1 was statistically equivalent or superior to the non-inoculated control with 120 kg N∙ha-1. These results indicate that inoculation with A. brasilense positively impacted purple maize at all nitrogen levels tested and improved nitrogen use efficiency, enabling a reduction of 30 kg N∙ha-1 without compromising performance in key parameters.

Addition of Tannin-Containing Legumes to Native Grasslands: Effects on Enteric Methane Emissions, Nitrogen Losses and Animal Performance of Beef Cattle

Extensive cattle production on native grasslands is vital to the sustainability of the South American Pampas, and the inclusion of tannin-containing legumes can increase farm profitability, improve nitrogen (N) use and reduce greenhouse gas (GHG) emissions. This study quantified the effects of adding tannin-containing legumes to native grasslands on enteric methane (CH4) emissions, animal performance and N balance in cattle. A crossover design trial was conducted with 22 beef heifers under two treatments: native grassland (NG) and native grassland with the addition of Lotus uliginosus and L. angustissimus (NG+L). The results showed that forage mass disappearance was similar between treatments; however, 54% of the forage disappearance in the NG+L corresponded with legumes, indicating that the heifers in this treatment consumed a better-quality diet. While individual CH4 emissions were similar between treatments, heifers grazing the NG+L showed a higher average daily gain (ADG) and lower emissions intensity than heifers grazing NGs (0.25 vs. 0.58 g CH4/g ADG, p &lt; 0.05). Additionally, they also ingested 20% more N and were more efficient in its utilization. Incorporating tannin-containing legumes into native grasslands can improve animal productivity and N use efficiency while reducing the intensity of enteric CH4 emissions.

Contrasting Alleles of OsNRT1.1b Fostering Potential in Improving Nitrogen Use Efficiency in Rice.

Nitrogen use efficiency (NUE) is important for the growth and development of rice and is significant in reducing the costs of rice production. OsNRT1.1b is involved in nitrate assimilation, and the alleles at position 21,759,092 on chromosome 10 clearly separate indica (Pathum Thani 1 (PTT1) and Homcholasit (HCS)) and japonica (Azucena and Leum Pua (LP)) rice varieties. Rice morphological and physiological traits were collected at three nitrogen levels (N0 = 0 kg ha-1, N7 = 43.75 kg ha-1, and N14 = 87.5 kg ha-1). Leaf and tiller numbers in PTT1 and HCS at N7 and N14 were two to three times higher than those at N0. At harvest, the biomass yield in PTT1 was the highest, while the total grain number in HCS was the maximum. The leaf widths and total chlorophyll contents (SPAD units) of Azucena and LP increased with nitrogen application as well as photosynthetic pigment parameters; for example, plant senescence reflectance indices (PSRIs), structure-insensitive pigment indices (SIPIs), and modified chlorophyll absorption ratio indices (MCARIs) were highly related in the japonica varieties. PTT1 and HCS, both carrying the A allele at OsNRT1.1b, had better NUE than Azucena and LP with the G allele. HCS, overall, had better NUE than PTT1. The translation to grain yield of assimilates was remarkable in PTT1 and HCS compared with Azucena and LP. In addition, HCS converted biomass for a 75% higher yield than PTT1. The ability of HCS to produce high yields was achieved even at N7 nitrogen fertilization, manifesting efficient use of nitrogen.

Potato growth, nitrogen balance, quality, and productivity response to water-nitrogen regulation in a cold and arid environment.

The pervasively imprudent practices of irrigation and nitrogen (N) application within Oasis Cool Irrigation zones have led to significant soil nitrogen loss and a marked decrease in water and nitrogen use efficiency. To address this concern, a comprehensive field experiment was conducted from April to September in 2023 to investigate the impact of varying degrees of water and fertilization regulation strategies on pivotal parameters including potato yield, quality, nitrogen balance, and water-nitrogen use efficiency. The experimental design incorporated two water deficit degrees at potato seedling (W1, 55%-65% of Field Capacity (FC); W2, 45%-55% of FC), and four distinct nitrogen application gradients (N0, 0 kg ha-1 of N; N1, 130 kg ha-1 of N; N2, 185 kg ha-1 of N; N3, 240 kg ha-1 of N). A control was also included, comprising N0 nitrogen application and full irrigation (W0, 65%-75% of FC), totally eight treatments and one check. The results indicated that the tuber yield, plant dry matter accumulation, plant height, plant stem, and leaf area index increased with higher nitrogen fertilizer application and irrigation volume. However, tuber starch content, vitamin C, and protein content initially increased and then decreased, while reducing sugar content consistently decreased. Except for W1N2 treatment, the irrigation water use efficiency increased as the N application rate rose, while the nitrogen partial factor productivity, crop nitrogen use efficiency and soil nitrogen use efficiency decreased with an increase in N fertilizer application. The W1N2 treatment resulted in a higher yield (43.16 t ha-1), highest crop nitrogen use efficiency (0.95) and systematic nitrogen use efficiency (0.72),while maintaining moderate levels of soil nitrate and ammonium nitrogen. Therefore, through the construction of an integrated evaluation index (IEI), the W1N2 treatment of mild water deficit (55%-65% of FC) at potato seedling combined with the medium nitrogen application (185 kg ha-1 of N) has the highest IEI (0.978), it was recommended as the optimal water-nitrogen regulation and management strategies to facilitate high-yield, high-efficiency, and environmentally sustainable potato production in the cold and arid oasis areas of northwest China.

Harnessing Nitrogen Use Efficiency for Enhancing Productivity in Rice: A Review

Nitrogen fertilizers have significantly enhanced rice yields over the past decades, but they also have substantial negative impacts on the environment. Excessive application of nutrients, particularly nitrogen, beyond crop requirements is linked to environmental losses. High nitrogen fertilizer input leads to low nitrogen use efficiency (NUE) due to the rapid loss of nitrogen through ammonia volatilization, denitrification, surface runoff, and leaching in the soil-flood water system. Enhancing the yield potential of rice- based cropping systems in response to the global call for carbon neutrality is a crucial research target. New approaches are needed to boost yields while maintaining or ideally reducing nitrogen application to maximize crop NUE. Improving NUE is crucial for addressing the intertwined challenges of environmental degradation, climate change, and food security. This review provides an in-depth exploration of strategies for improving nitrogen use efficiency, including soil health management, optimized fertilizer application, crop management practices, physiological and morphological approaches, exploiting symbiotic relationships, and genetic approaches, all aimed at enhancing rice productivity while addressing agricultural and environmental challenges caused by nitrogen losses, such as ammonia volatilization and leaching and promoting more sustainable farming practices. It also reduces the input costs, leading to a more sustainable agricultural economy and improved living standards for farming communities.

Differences in Grain Yield and Nitrogen Uptake between Tetraploid and Diploid Rice: The Physiological Mechanisms under Field Conditions.

Research indicates that, owing to the enhanced grain-filling rate of tetraploid rice, its yield has notably improved compared to previous levels. Studies conducted on diploid rice have revealed that optimal planting density and fertilization rates play crucial roles in regulating rice yield. In this study, we investigated the effects of different nitrogen application and planting density treatments on the growth, development, yield, and nitrogen utilization in tetraploid (represented by T7, an indica-japonica conventional allotetraploid rice) and diploid rice (Fengliangyou-4, represented by FLY4, a two-line super hybrid rice used as a reference variety for the approval of super rice with a good grain yield performance). The results indicated that the highest grain-filling rate of T7 could reach 77.8% under field experimental conditions due to advancements in tetraploid rice breeding. This is a significant improvement compared with the rate seen in previous research. Under the same conditions, T7 exhibited a significantly lower grain yield than FLY4, which could be attributed to its lower grain-filling rate, spikelets per panicle, panicle number m-2, and harvest index score. Nitrogen application and planting density displayed little effect on the grain yield of both genotypes. A higher planting density significantly enhanced the leaf area index and biomass accumulation, but decreased the harvest index score. Compared with T7, FLY4 exhibited a significantly higher nitrogen use efficiency (NUEg), which was mainly due to the higher nitrogen content in the straw. Increasing nitrogen application significantly decreased NUEg due to its minimal effect on grain yield combined with its significant enhancement of nitrogen uptake. Our results suggest that the yield and grain-filling rate of T7 have been improved compared with those of previously tested polyploid rice, but are still lower than those of FLY4, and the yield of tetraploid rice can be further improved by enhancing the grain-filling rate, panicle number m-2, and spikelets per panicle via genotype improvement.

Improving sustainability of rice-canola rotation through water and nitrogen management in a humid region

Intensive cropping systems face significant environmental and economic challenges due to current water and nutrient management practices. This study addresses the limited research on optimizing these practices in rice-canola rotations, focusing on enhancing sustainability through improved water and nitrogen (N) management. Utilizing the DSSAT crop growth model, we evaluated three irrigation scenarios for rice- I1 (100 % irrigation requirement: IR), I2 (80 % IR), and I3 (60 % IR)-alongside three N application levels: N1 (30 % below RAN: regional average N), N2 (RAN), and N3 (30 % above RAN). Key sustainability indicators, including water productivity (WP), nitrogen use efficiency (NUE), and economic productivity, were analyzed. The DSSAT model demonstrated strong predictive accuracy, with yield differences of only 236 kg ha⁻¹ for rice and 121 kg ha⁻¹ for canola between observed and simulated values. A 40 % reduction in water use increased rice yield to a maximum of 5654 kg ha⁻¹ under I3N2 conditions. Additionally, this reduction in water consumption resulted in a 27 % decrease in production costs, significantly enhancing WP, net benefits, and gross benefits of rice by 46.7 %, 43.1 %, and 47.9 %, respectively. Conversely, a 30 % increase in N application for canola correlated with a 9 % yield increase, underscoring the importance of tailored N strategies. Furthermore, N3 raised WP, NUE, net benefits, and gross benefits of canola by 6.7 %, 1.4 %, 9.1 %, and 9.2 %, respectively, compared with current N application level. Overall, this study illustrates the potential for substantial water savings in rice cultivation while recommending stable or reduced N application levels. These management strategies enhance farm performance, lower production costs, and contribute to the sustainability of rice-canola cropping systems, promoting both agricultural productivity and environmental stewardship.

Comparison of Waste Reduction and NPK value between Black Soldier Fly and vermi

Vermicomposting and the employment of black soldier fly larvae (BSFL) for waste management can be compared to learn more about two different but related methods for recycling organic waste. Both approaches are green and support long-term waste management, but they differ in their features and intended uses. Here is a summary of the comparison between using black soldier flies can take longer to break down some materials, they can process organic matter more quickly, the potential of black soldier fly larvae (BSFL) and vermicomposting as organic fertilizer sources for agricultural and horticultural applications can be better understood by comparing nutritional composition of the two. Analyzing the availability, balance, and use of the vital plant nutrients nitrogen (N), phosphorus (P), and potassium (K) in each of these organic products is necessary to comprehend the extent of this comparison Key Words: black soldier fly larvae, vermicomposting, nitrogen (N), phosphorus (P), and potassium (K)

Urea loaded nanoclay biopolymer composites: synthesis, characterization and evaluation for enhancing nitrogen use efficiency

Urea loaded nanoclay biopolymer composites: synthesis, characterization and evaluation for enhancing nitrogen use efficiency

Application of straw-derived biochar: a sustainable approach to improve soil quality and crop yield and reduce N2O emissions in paddy soil.

The burning of agricultural straw is a pressing environmental issue, and identifying effective strategies for the rational utilization of straw resources is decisive for achieving sustainable development. Owing to its high carbon content and exceptional stability, straw biochar produced via pyrolysis has emerged as a key focus in multidisciplinary research. However, the efficacy of biochar in mitigating nitrous oxide (N2O) emissions from paddy soils is not consistent. A 2-year field experiment was conducted and investigated the impact of biochar derived from two feedstocks (rice straw and wheat straw, pyrolyzed at 450°C) on N2O emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), nitrogen use efficiency (NUE), crop yield, and soil quality. The static chamber technique was used for collecting N2O gas samples, and concentrations were analyzed through gas chromatography methods. The treatment combinations included BR0 (control), BR1 (NPK at the recommended dose, 120:60:40kgha-1), BR2 (wheat straw biochar, 5 t ha-1), and BR3 (rice straw biochar, 5 t ha-1). The results exhibited that cumulative N2O emissions from BR2 and BR3 treatments decreased by 10.55% and 13.75% respectively, compared to BR1. Lower GWP and GHGI were observed under both biochar treatments compared with BR1. The highest rice grain yield (3.48Mgha-1) and NUE (76.72%) were recorded from BR3, which also exhibitedthe lowest yield-scaled N2O emission. We observed positive correlations between soil nitrate, ammonia and water-filled pore spaces, while NUE showed negative correlations with N2O emissions. Significant (p < 0.05) improvements in soil quality were also detected in both the biochar treated plots, indicated by increased soil pH, water holding capacity, porosity, and nutrient contents. Overall, the results suggest that applying biochar at a rate of 5 t ha-1 in paddy soil is a viable nutrient management strategy with the potential to reduce reliance on inorganic fertilizers, mitigate N2O emissions, and contribute to sustainable food production.

The role of organic amendments combined with nitrogen fertilizers in enhancing nitrogen use efficiency for wheat in saline calcareous soil

This study investigates the effects of combining different nitrogen fertilizers with organic amendments and Azospirillum brasilense on wheat growth, yield, and nutrient uptake in saline calcareous soil, with a goal of enhancing crop productivity while reducing environmental impacts. The objective was to evaluate treatments involving ammonium sulfate (AS), urea, and sulfur-coated urea (SCU), mixed with organic amendments such as Moringa seed residues (MSR), biogas manure (BM), and vermicompost (Ver), along with Azospirillum brasilense (ASB). Among these treatments, SCU emerged as the most effective nitrogen source, especially when combined with Vermicompost and ASB. Key results include the following: the highest Chlorophyll a content of 1.96 mg/g f wt was observed in the SCU treatment with Ver and ASB; Likewise, the same treatment exhibited the highest values of Chlorophyll b, carotenoids, and proline; the tallest plant height (117.50 cm) was also achieved with this combination; and the highest straw and grain weights (2.63 g/plant and 2.22 g/plant, respectively) came from the same treatment. Additionally, this treatment yielded the highest protein content at 19.29%. In terms of nutrient uptake, SCU-based treatments consistently demonstrated the highest values. The SCU with Ver + ASB treatment recorded the highest nitrogen uptake in straw at 78.64 mg plant−1, phosphorus uptake at 12.86 mg plant−1, and potassium uptake at 61.66 mg plant−1. Similarly, this combination yielded the highest N, P, and K uptake in grains, with 68.05, 10.88, and 53.15 mg plant-1, respectively. e

Field Assessment of Biochar Interactions With Chemical and Biological N Fertilization in Pointed White Cabbage

ABSTRACTThe interaction of biochar with mineral fertilization has attracted attention as a strategy to reduce N losses and enhance nitrogen use efficiency. In this study, we investigated the coapplication of biochar with two optimized fertilization strategies based on split urea and a microbial inoculant (Azospirillum brasilense) in a commercial pointed white cabbage crop. Additionally, we evaluated a third optimized N fertilization alternative, a biochar‐based fertilizer (BBF) enriched in plant‐available N, which was developed from the same biochar. We assessed environmental impacts such as greenhouse gasses (GHG) and NH3 emissions, yield‐scaled N2O emissions, and global warming potential (GWP). Additionally, we evaluated agronomical outcomes such as crop yield, plant N, and chlorophyll concentration. Moreover, we examined the N‐fixing gene's total and relative abundance (nifH and nifH/16S). Biochar and BBF exhibited similar crop yield, GHG, and NH3 emissions compared to split applications of the synthetic fertilizer. The main difference was associated with the higher soil C sequestration in biochar and BBF treatments that reduced the associated GWP of these fertilization strategies. Finally, biochar favored the activity of the N‐fixing bacteria spread, compared to the sole application of bacteria and BBF demonstrated a promoting effect in the soil's total abundance of natural N‐fixing bacteria.

Co-application effects of rice husk biochar and different types of nitrogen fertilizers on rice yield, yield components, and nitrogen use efficiency

The Nitrogen (N) recovery index in rice paddy soils has never been exceeded by more than 30%, regardless of using proven fertilizer management strategies and amounting to significant N being out of rice plant use. Biochar application and the newly released N biofertilizers (singly or in combination) increase the N use efficiency by increasing the soil nutrient retention capacity. Therefore, a two-year pot experiment was conducted to explore the effects of the co-application of rice husk biochar and nitrogen fertilizers on rice yield, yield components, and nitrogen use efficiency indexes. The applied treatments were rice husk biochar at three levels (0, 20, and 40 tha−1) and N fertilizers at three levels (0, chemical (Urea), and N-biofertilizer). The most effective combination treatments (200 kg N ha−1 in source of urea plus 40 tha−1 rice husk biochar) significantly (p ≤ 0.01) increased the grain yield (2.38 times), straw and biological yield (2.83 and 2.62 times, respectively), N content of soil N (59%), nitrogen uptake efficiency (2.92 times), and nitrogen internal efficiency (59%), whereas, nitrogen recovery efficiency decreased by about 52%. Moreover, the maximum increase in N content of grain and harvest index was recorded at combination application of 20 tha−1 biochar plus urea by about 48 and 15%, respectively. It can be concluded that the co-application of rice husk biochar and N fertilizers has substantial advantages over their single applications in terms of N fertilizer recovery, N uptake. Thus, it might be an effective way to enhance rice yield.

On-farm experimentation of precision agriculture for differential seed and fertilizer management in semi-arid rainfed zones

Abstract Introduction This study explores the integration of precision agriculture technologies (PATs) in rainfed cereal production within semi-arid regions. Methods utilizing the Veris 3100 sensor for apparent soil electrical conductivity (ECa) mapping, differentiated management zones (MZs) were established in experimental plots in Valsalada, NE Spain. Site-specific variable dose technology was applied for seed and fertilizer applications, tailoring inputs to distinct fertility levels within each MZ. Emphasizing nitrogen (N) management, the study evaluated the impact of variable-rate applications on crop growth, yield, nitrogen use efficiency (NUE), and economic returns. For the 2021/2022 and 2022/2023 seasons, seeding rates ranged from 350 to 450 grains/m2, and basal fertilizer dosages varied between high and low levels. Additionally, the total nitrogen units were distributed differently between the two seasons, while maintaining a uniform topdressing fertilizer dose across all treatments. Results Results revealed a significant increase in yield in MZ 2 (higher fertility) compared to MZ 1 (lower fertility). NUE demonstrated notable improvement in MZ 2, emphasizing the effectiveness of variable-rate N applications. Economic returns, calculated as partial net income, showed a considerable advantage in MZ 2 over MZ 1, resulting in negative outcomes for low-fertility areas in several of the analyzed scenarios, and highlighting the financial benefits of tailored input management. Conclusion This research provides quantitative evidence supporting the viability and advantages of adopting PATs in rainfed cereal production. The study contributes valuable insights into optimizing input strategies, enhancing N management, and improving economic returns in semi-arid regions.

Nitrogen requirements of canola (Brassica napus L.) at sustained deficit irrigation levels in central Free State, South Africa

In South Africa canola (Brassica napus L.) is cultivated in rotation with wheat under winter rainfall in the Western Cape province. Expansion of the crop to the other eight provinces is propagated to reduce a shortage of locally produced plant oils. At the same time, canola may serve as a rotational crop for wheat in these summer rainfall provinces. In central Free State, agronomic information for canola production is lacking. An experiment with a line source sprinkler irrigation system was therefore conducted to establish the influence of water application levels (175, 233, 295, 351 and 420 mm) in combination with nitrogen (N) application rates (0, 70, 140, 210 and 280 kg ha−1) on the branches, pods and seeds per canola plant. The biomass and seed yields of canola were also measured, allowing calculation of harvest indices. All six variables were strongly influenced by the interaction of water and N applications. An optimal seed yield of 2.907 kg ha−1 was estimated with a 351 mm water application and a 280 kg ha−1 N application. This resulted in a water use efficiency of 8.28 kg seed ha−1 mm−1 water and a nitrogen use efficiency of 10.38 kg seed kg−1 N.

Correction to: Enhanced Nitrogen Use and Economic Benefits in Organic Vegetable Fields via Appropriate Manure Application in Northwestern China

Correction to: Enhanced Nitrogen Use and Economic Benefits in Organic Vegetable Fields via Appropriate Manure Application in Northwestern China

Isolation, Selection, and Biological Evaluation for Bacteria that Fix Nitrogen and Produce Indole-3-Acetic Acid from Paddy Soils in Vietnam

Introduction/Background Acidic soils are limiting the production of crops and indirectly harming the environment due to the use of nitrogen (N) chemical fertilizer. Therefore, the current study aims to isolate a promising N2-fixing candidate to solve this issue in some communes of Phu Luong District, Thai Nguyen Province, Vietnam. Materials and Methods The bacteria were isolated using the Ashby medium. The IAA generation and nitrogen fixation were assessed using spectroscopy. The selected bacteria were tested at temperatures ranging from 28°C to 42°C and pH levels of 4.0 to 9.0. As a result, the Box-Behnken model yielded a growth equation. The API kit test was used to measure the biochemical properties of the selected bacteria. Results The result demonstrated that there were ten nitrogen-fixing bacteria (NFB) isolates with capacities of N2 fixation and IAA production at 2.35–24.61 and 0.00–119.13 µg/ml. Among them, the NL3 strain was the best strain. The optimum condition to grow the NL3 strain was calculated as 5.44 days at pH 7.10 and temperature of 32.18°C to reach a bacterial density of 9.77929×108 CFU/ml. In addition, the NL3 strain was identified as an Azotobacter species. The genomic analysis revealed that the genome of Azotobacter sp. NL3 was nearly 5.4 Mb long and contained 45 N2 fixation-relating genes and 7 IAA production-relating genes. Conclusion Not only can this study provide insight into the features of Azotobacter spp., but it also introduces a potent candidate that can improve soil health and crop yield by fixing N2 and producing IAA in order to limit the use of N chemical fertilizer for a sustainable agriculture. Therefore, the selected bacterial strain should be further tested under the local field conditions and subsequently commercialized as a biofertilizer.