Nitrogen Application Rates Research Articles

Fresh maize yield in response to nitrogen application rates and characteristics of nitrogen-efficient varieties

Efficient nitrogen management is crucial in developing sustainable strategies aimed at enhancing yield while mitigating negative environmental impacts. However, limited research has focused on this aspect in the production of fresh maize. Therefore, this study analyzed nitrogen application rates and yield for 40 sweet and 44 waxy maize varieties in Zhejiang Province, China from 2015 to 2019 across five sites. Nitrogen application rates were categorized as relatively high (RHN: >300 kg ha-1 for sweet maize, >320 kg ha-1 for waxy maize) or relatively low (RLN). An increase in nitrogen application rates for both sweet and waxy maize significantly reduced nitrogen fertilizer partial productivity (R2=0.616, P<0.01; R2=0.643, P<0.01), indicating that the optimum nitrogen application rate in this study might be the lowest values (160 kg ha-1 for sweet maize and 180 kg ha-1 for waxy maize). The kernel number per ear of sweet maize had a potentially more significant impact on fresh grain yield compared to the 1,000-fresh kernel weight both under RLN and RHN. In waxy maize, 1,000-kernel weight contributed more to fresh grain yield under RLN, and kernel number ear-1 and 1,000-kernel weight cooperatively affected yield under RHN. In this study, it was observed that sweet maize required taller plant and ear height, along with an optimal ear-plant height ratio, to enhance dry matter accumulation and increase source size, particularly under RLN, to achieve a higher fresh grain yield. In contrast, a lower ear height and ear-plant height ratio of waxy maize probably contributed more to increased kernel number and weight under RLN, likely due to a lower ear height can reduce the distance between sink and source, enabling more efficient photoassimilate allocation to the ear.

Optimizing nitrogen application rates for winter canola in Mississippi

AbstractThe production of canola (Brassica napus L.) in the United States is low, whereas the demand is high. Most US canola research is centered in the Midwest, with minimal to no research in Southern states including Mississippi. Therefore, a study was conducted in Mississippi to assess the feasibility of canola as a double crop with soybean (Glycine max L.) rotation and determine its optimum nitrogen (N) requirement. After canola was harvested, soybean was planted within the same experimental plots. In total, six N treatments (0 [control], 34, 67, 101, 135, and 168 kg N ha−1) were applied to canola and replicated four times across all site‐years in a randomized complete block design. The application of N increased seed yield, aboveground biomass, and N content compared to the control in canola. Across all site‐years, the highest seed yield was 1726 kg ha−1 at 168 kg N ha−1. Moreover, N uptake, plant height, and test weight were highest at 135 kg N ha−1, which were 76%, 21%, and 44% greater than control, respectively. Oil content and seed weight were inversely related to N rates indicating dilution with increased N. Overall, 141 kg N ha−1 was found to be the agronomic optimum nitrogen rate, and no further supplementation was deemed necessary to maximize canola yield in Mississippi. Additionally, the following soybean crop benefitted from the N applied to canola and produced greater yields. This study establishes that canola has the potential for double cropping without adversely affecting subsequent soybean yield, provided optimum N rates are applied.

Interactive effects of number of plants and nitrogen fertilization on quality parameters of Salvia officinalis L. cultivated in semi-arid environments

This research aimed to elucidate the interplay between number of plants and nitrogen dose on the agronomic attributes, as well as the essential oil yield and composition of Salvia officinalis L. (sage) in the challenging ecological conditions of Mardin, situated in South Eastern Anatolia. A split-plot experimental design was employed during 2018-2019, manipulating the variables of number of plants and nitrogen application rates. The experiment identified camphor, 1,8-cineole, α-thujone, and β-thujone as the major components. The PCA analysis unveiled statistically significant inverse correlations between the concentration of camphor and 1,8-cineole, as well as α- and β-thujone. The results demonstrated that the combination of lower plant number with elevated nitrogen levels yielded higher fresh herb dry herb and dry leaf. While lower plant number and higher nitrogen application independently exerted positive influences on essential oil production and yield, the interactive impact of these treatments yielded inconclusive results. Specifically, nitrogen treatments led to an increase in camphor content while reducing α- and β-thujone contents in the essential oil. Conversely, lower plant numbers resulted in decreased camphor content and an increase in thujone content within the oil. In light of these findings, it is recommended that, under semi-arid conditions, optimal yields can be achieved by employing plant number of 50000 plants ha−1 and a nitrogen fertilizer rate of 120 kg ha−1. This research sheds light on the intricate relationship between agronomic factors and the quality of sage cultivation, offering valuable insights into sustainable agricultural practices in semi-arid regions.

Effect on greenhouse gas emissions (CH4 and N2O) of straw mulching or its incorporation in farmland ecosystems in China

Straw returning can enhance crop yield, promote soil organic carbon sequestration, and support sustainable crop production. However, straw management techniques, such as straw mulching (SR-M) and straw incorporation (SR-I), can significantly elevate greenhouse gas (GHG) emissions. This meta-analysis synthesizes data from 217 studies to explore the effects of different straw management approaches on mitigating GHG emissions in agricultural settings. The analysis reveals that SR-I (129.39 %) had a more pronounced impact on CH4 emissions than SR-M (14.86 %), but SR-M (18.47 %) had a more significant impact on N2O emissions than SR-I (7.76 %). Notably, SR-I had a greater impact on soil carbon content than SR-M. The effect of straw returning on CH4 and N2O emissions varied under different climatic conditions, management practices, and initial soil properties. Specifically, under conditions characterized by a mean annual temperature (MAT) ≤ 14 °C, mean annual precipitation (MAP) > 800 mm, initial soil organic carbon (SOCi) ≤ 14 g kg−1, initial soil total nitrogen (TNi) ≤ 1.2 g kg−1, and soil pH > 6, with straw returning amounts (SRA) ≤ 6000 kg ha−1, nitrogen application rate (NAR) > 200 kg ha−1, straw returning duration > 3 years, and maize, rice, wheat–maize, or wheat–rice as the cultivated crop, SR-M had a lesser impact on CH4 and N2O emissions than conditions under other environmental and management measures. Under conditions characterized by MAT ≤ 14 °C, MAP ≤ 800 mm, SOCi > 14 g kg−1, TNi > 1.2 g kg−1, and soil pH > 8, with SRA > 6000 kg ha−1, straw returning duration > 3 years, and wheat as the cultivated crop, SR-I had a lesser impact on CH4 and N2O emissions than conditions under other environmental and management measures. Furthermore, deep straw incorporation (SR-Ideep, straw mixed with 20–40 cm deep soil) did not significantly affect CH4 and N2O emissions, suggesting its potential for widespread adoption. These findings offer valuable insights for optimizing straw management practices and reducing GHG emissions in farmland ecosystems.

Optimizing Nitrogen Fertilization for Barley Crop at Full and Deficit Irrigation in the Arid Region

Background: Nitrogen and water are two major limiting factors that affects the growth and yield of barley. Optimization of nitrogen application is crucial in enhancing barley yield and nitrogen use efficiency while minimizing the negative effects of its intense application on human health and the environment. However, the crop yield response to nitrogen application rates differ under different irrigation conditions owing to the complementary relationship between nitrogen and water. Therefore, it is vital to study the impact of different nitrogen application rates on improving barley growth and yield under full as well as deficit irrigation to select the best field management option, thereby enhancing sustainable agriculture. Methods: The present study investigated the impact of three nitrogen application rates [0 (control), 50 and 100 kgN/ha)] at two irrigation rates corresponding to 100% and 75% crop evapotranspiration (ETc) on the growth, yield and nitrogen use efficiency of barley. Stable isotopic technique was used to determine the nitrogen use efficiency. Result: The nitrogen application rate enacted a significant impact on plant height, number of plants/m2, number of spikes/m2, biomass yield and nitrogen use efficiency; whereas irrigation rates significantly affected the plant height, number of plants/m2, spike length, number of spikes/m2, biomass yield, grain and straw yield. In addition, a significant interaction between irrigation and nitrogen was observed for all the studied parameters except plant height, spike length, straw yield and total nitrogen uptake. The deficit irrigation 75% ETc with 50 kgN/ha presented the highest nitrogen use efficiency (37.56%), but the total biomass yield was reduced by 37% in comparison to 100% ETc irrigation. Thus irrigation and fertilization combination of 100% ETc with 50 kgN/ha was identified as the best irrigation and fertilization practice producing highest biomass yield, grain yield and straw yield in barley with a nitrogen use efficiency of 20.48%.

Comprehensive Evaluation of Tomato Growth Status under Aerated Drip Irrigation Based on Critical Nitrogen Concentration and Nitrogen Nutrient Diagnosis.

In order to provide a theoretical basis for the rational application of nitrogen fertilizer for tomatoes under aerated drip irrigation, a model of the critical nitrogen dilution curve was established in this study, and the feasibility of the nitrogen nutrition index (NNI) for the real-time diagnosis and evaluation of the nitrogen nutrient status was explored. The tomato variety "FENOUYA" was used as the test crop, and aerated drip irrigation was adopted by setting three levels of aeration rates, namely, A1 (dissolved oxygen concentration of irrigation water is 5 mg L-1), A2 (dissolved oxygen concentration of irrigation water is 15 mg L-1), and A3 (dissolved oxygen concentration of irrigation water is 40 mg L-1), and three levels of nitrogen rates, namely, N1 (120 kg ha-1), N2 (180 kg ha-1) and N3 (240 kg ha-1). The model of the critical nitrogen concentration dilution of tomatoes under different aerated treatments was established. The results showed that (1) the dry matter accumulation of tomatoes increased with the increase in the nitrogen application rate in a certain range and it showed a trend of first increase and then decrease with the increase in aeration rate. (2) As the reproductive period progressed, the nitrogen concentration in tomato plants showed a decreasing trend. (3) There was a power exponential relationship between the critical nitrogen concentration of tomato plant growth and above-ground biomass under different levels of aeration and nitrogen application rate, but the power exponential curves were characterized by A1 (Nc = 15.674DM-0.658), A2 (Nc = 101.116DM-0.455), A3 (Nc = 119.527DM-0.535), N1 (Nc = 33.819DM-0.153), N2 (Nc = 127.759DM-0.555) and N3 (Nc = 209.696DM-0.683). The standardized root mean square error (n-RMSE) values were 0.08%, 3.68%, 3.79% 0.50%, 1.08%, and 0.55%, which were less than 10%, and the model has good stability. (4) The effect of an increased nitrogen application rate on the critical nitrogen concentration dilution curve was more significant than that of the increase in aeration rate. (5) A nitrogen nutrition index model was built based on the critical nitrogen concentration model to evaluate the nitrogen nutritional status of tomatoes, whereby 180 kg ha-1 was the optimal nitrogen application rate, and 15 mg L-1 dissolved oxygen of irrigation water was the optimal aeration rate for tomatoes.

Application of hyperspectral technology for leaf function monitoring and nitrogen nutrient diagnosis in soybean (Glycine max L.) production systems on the Loess Plateau of China

Farmland mulching and nitrogen application are the main agricultural management measures to improve soybean (Glycine max L.) production in dryland agriculture on the Loess Plateau. However, the interaction effects of various farmland mulching materials and nitrogen application rates on soybean leaf functionality and nitrogen nutrition status remains contradictory and inconclusive, and effective and rapid diagnostic of the leaf functionality and nitrogen status are still not well-understood. Therefore, the aim of this study is twofold: 1) to investigate the interactive effects of different mulching methods and nitrogen application levels on soybean leaf growth, physiological traits, and final grain yield throughout the entire growth period; 2) to establish a chlorophyll content monitoring model based on spectral parameters and a diagnostic model for soybean nitrogen status, and to assess the effectiveness of the latter in accurately diagnosing soybean nitrogen requirements. A two-year (2021 and 2022) field experiment, which consisted of four nitrogen levels (0, 60, 120 and 180 kg N ha−1) and four mulching strategies (NM: no mulching, SM: straw mulching, FM: film mulching, SFM: straw and film mulching), was conducted in the soybean growing seasons. Subsequently, nitrogen dilution curves were established based on chlorophyll content and the optimal spectral index to compute corresponding nitrogen nutrition index (NNI) values. The results indicated that: 1) FM, in comparison to SM and SFM, had the ability to delay leaf senescence, increase chlorophyll content, and improve physiological growth parameters, thereby increasing seed yield; 2) the application of 120 kg N ha−1 stood out, boosting soybean photosynthetic productivity and providing a solid foundation for high soybean yields; 3) the Random forest (RF) model had the highest accuracy in chlorophyll content estimation (R2 =0.854, RMSE=2.765 and MRE=5.758 % in validation set); and 4) both the nitrogen dilution curves constructed based on chlorophyll content and the optimal spectral index proved to be reasonably accurate in quantitatively diagnosing the nitrogen status of soybeans. Specifically, N0 and N180 indicated sustained nitrogen deficiency and excess, respectively, while N60 and N120 effectively met soybean's nitrogen requirements. In summary, the FMN120 effectively stabilized seed yield by regulating key functional traits in soybean leaves. This study provides a theoretical basis for the application of precision agriculture and remote sensing technology in monitoring and diagnosing plant nitrogen nutrition in soybean production.

Strategies for the management of water and nitrogen interaction in seed maize production; A case study from China Hexi Corridor Oasis Agricultural Area

The oasis agricultural area of the Hexi Corridor in China supports industrial-scale seed maize production which depends on significant inputs of water and fertilizer, however, the effects of water-nitrogen interaction on seed maize yield and its components, and on water and nitrogen use efficiency in seed maize are unknown, making optimization of inputs impossible. Here, we conducted a study to address these unknowns. Specifically, we established a two-factor split-plot experiment in the Zhangye area of the Hexi Corridor with three irrigation levels of low, medium, and sufficient water supply (50%, 75%, and 100% of the local typical irrigation quota), and three nitrogen application rates of low (160 kg ha−1), medium (280 kg ha−1), and high nitrogen (400 kg ha−1); three irrigation levels without nitrogen fertilizer were used as the control. We found that there was a significant interaction between water-nitrogen combinations, all of which had a significant effect on seed maize yield and its components, and water and nitrogen use efficiency. The yield of seed maize increased with the increase in irrigation quota, but when the irrigation quota reached 100% of the traditional, yield exhibited an increasing and then decreasing trend with the increase in nitrogen application. During the 4-year test period, the maximum yield of seed maize was observed in sufficient water and medium-nitrogen treatment, reaching an average of 9509.38 kg ha−1. Lower nitrogen lowered water productivity, while lower irrigation quotas limited nitrogen utilization. The relationship between irrigation quota, nitrogen application, and seed maize yield was binary quadratic, and the coefficient of determination, R2, reached 0.963–0.985 indicating that the model predicted the yield of seed maize well. The main factor analysis of yield increase showed that the effect of irrigation quota was greater than that of nitrogen application. The optimal combination of water-nitrogen for the highest target yield was obtained with an irrigation quota of 100% of the local typical and a nitrogen application rate of 292.0 kg ha−1-383.2 kg ha−1. This result can be used as a reasonable water and fertilizer management guideline and a technical reference for the seed maize industry in the oasis agricultural area of the Hexi Corridor with objectives of stable and high yields, and reductions in the risk of nitrogen non-point source pollution.

Global meta-analysis and three-year field experiment shows that deep placement of fertilizer can enhance crop productivity and decrease gaseous nitrogen losses

Context or problemThere is an urgent need to address the contradiction between food security and climate change, and achieve the highest crop productivity at the lowest environmental cost. Scientific fertilization is the key to solving this problem. Objective or research questionDeep placement of fertilizer (DPF) is an effective fertilization strategy for improving crop productivity and reducing gaseous N losses, but its effectiveness varies among agricultural systems and appropriate fertilization depths have not yet been determined. MethodsIn this study, we synthesized 99 global studies (120 locations) and conducted a three-year field experiment to evaluate the effects of DPF on the crop yield, nitrogen use efficiency (NUE), and nitrous oxide (N2O), and ammonia (NH3) emissions, and explored their responses to different climates, field management practices, and environmental factors. ResultsDPF could increase the grain yield by 13.5%, and NUE by 33.8%, and reduce N2O emission by 16.2%, and NH3 emissions by 86.6%, respectively. Random forest analysis showed that the fertilization depth and nitrogen application rate were the most important factors that determined the impacts of DPF on the crop yield, NUE, and N2O and NH3 emissions, but their effects also depended on the climate conditions, field management practices, and soil environmental factors. Meta-regression modeling showed that the effects of DPF on the crop yield and NUE increased but then decreased as the fertilizer application depth and nitrogen application rate increased, and the effects on N2O and NH3 emissions tended to increase gradually. The meta-analysis also demonstrated that under DPF, the emission factors for N2O and NH3 decreased by 35.8% and 84.5%, respectively. According to the meta-analysis, the global N2O and NH3 emissions under DPF can be reduced by 0.23 and 5.46 Tg N·year–1 respectively. ConclusionsThe results obtained based on global meta-analysis and a three-year experiment demonstrated that DPF obtained higher grain production with lower environmental costs, and the most suitable fertilization depth was identified as 15–25 cm. Implications or significanceThe results obtained in this study provide valuable insights into food security and environmental costs under effective fertilization management.

The Effect of Soil Microbial Residues-Mediated Nitrogen Conservation and Supply during the Growing Season on Nitrogen Uptake by Wheat

Microbial residue nitrogen can indicate soil quality and is crucial for soil nitrogen retention and supply. However, it is still unclear how the dynamic changes in soil microbial residue nitrogen affect crop nitrogen uptake in agricultural practice. Based on a long-term wheat-maize rotation experiment with different nitrogen application rates (150 kg N ha−1, 200 kg N ha−1, and 300 kg N ha−1), 15N-labeled nitrogen fertilizer was applied during the wheat season to track the dynamics of soil microbial residue nitrogen and its mediated fertilizer nitrogen. The results showed that nitrogen addition was beneficial to the accumulation of microbial residue nitrogen (mainly fungal microbial residue nitrogen). Its contribution rate to soil total nitrogen is 54.87–56.55%, and the fertilizer nitrogen allocated to it accounts for 27.10–47.50% of the remaining fertilizer nitrogen in the soil. Ultimately, 6.77–10.24% of the nitrogen fertilizer applied remained in the soil as microbial residue nitrogen. In addition, microbial residue nitrogen is mainly mineralized during the jointing and filling stages of wheat. In a word, the accumulation and mineralization of soil microbial residue nitrogen during the application of 200 kg N ha−1 better guaranteed the uptake of nitrogen by wheat, which provided a reliable basis for guiding farmland fertility improvement and nitrogen fertilizer reduction in the North China Plain.

Environmental Impact Assessment of Rice–Wheat Rotation Considering Annual Nitrogen Application Rate

Rice–wheat rotation is a widely adopted multiple-cropping system in the Yangtze River Basin, China. Nitrogen (N) fertilizer is a key factor in regulating crop yield; however, only a few studies have considered the impact of annual N application on the yield, environmental impacts, and economic profits of rice–wheat rotation systems. In this study, a field experiment was conducted in the Jiangsu Province from 2020 to 2022. The rice and wheat seasons included six and five N fertilizer application rates, respectively (Rice: 0, 180, 240, 300, 360, and 420 kg N ha−1; Wheat: 0, 180, 240, 300, and 360 kg N ha−1), combined to form a total of 30 treatments. Life-cycle assessment was used to evaluate the environmental impacts of rice–wheat rotation under different N application treatments, using area, yield, and economic profit as functional units. Ten environmental impact categories were selected, including global warming. The results showed that grain yield did not consistently increase with an increase in N application, and the annual yield was the highest when 300 and 240 kg N ha−1 (R300W240 treatment) was applied in the rice and wheat seasons, respectively. The area-based weighting index of the R300W240 treatment ranked 20th among the 30 treatments, while the yield- and profit-based weighting indices were the lowest among the 30 treatments, decreasing by 14.9% and 28.7%, respectively, compared to the other treatments. The R300W240 treatment was the optimal annual N application strategy for rice–wheat rotation. Among the 10 environmental impacts considered, urea production contributed significantly to over eight environmental impacts, whereas the pollutant losses caused by its application contributed significantly to six environmental impacts. These findings reveal the dependence of the rice–wheat rotation system on the unsustainable use of N fertilizer and indicate that N fertilizer management practices should be further optimized to improve the environmental sustainability of grain production in the future.

Cumulative transformation characteristics and application reduction potential of soil nitrogen in continuous cropping greenhouse

ABSTRACT Based on the continuous watermelon greenhouses in Daxing District, Beijing, this paper investigated the dynamic transformation characteristics and surplus risk of soil nitrogen in greenhouses of different cropping years and proposed a reasonable nitrogen fertilizer reduction potential for greenhouses of different continuous cropping years. Based on the results, (1) The total nitrogen inputs gradually decreased with the increase of cropping years. The soil nitrogen was accumulated mainly in the 0∼30 cm tillage layer. The nitrogen supply capacity of the soil gradually increased over 20 years (a) of continuous cropping and declined after >20a. (2) The environmental risk levels of soil nitrogen surpluses with different cropping years in the study area had all reached heavy levels and above. The nitrogen fertilizer reduction potential was large, in which the lowest recommended nitrogen application rate was for the greenhouses with 1∼5a of continuous cropping, and the highest was for the greenhouses with 11∼20a of continuous cropping. For watermelon greenhouses with different continuous cropping years, the range of the highest reasonable nitrogen fertilizer reduction potential to ensure the economic benefits of farmers was 74.18% to 87.28%, and the lowest environmentally safe nitrogen fertilizer reduction potential to safeguard environmentally safe conditions was 69.22 to 78.11%.

Optimizing the Total Spikelets Increased Grain Yield in Rice

Maximizing rice yield potential has always been the focus of high-yield rice cultivation research. For high-yield rice cultivation and breeding, more research into the link between yield and yield components is essential. In this experiment, 38 rice varieties with different yield types and 185 rice varieties as materials were chosen. The relationships between yield and yield components were studied. The regulation effects of total nitrogen application rate (TNAR) on yield and yield components were observed. The results showed that (1) the grain yield of high-yield varieties was 189.3−195.6%, 76.1−77.7%, and 27.0−28.7% higher than that of super-low-yield, low-yield, and medium-yield varieties, respectively. Compared with rice varieties with other yield types, rice varieties with high-yield type have a higher total number of spikelets. (2) The spikelet number per panicle and total number of spikelets were significantly positively linked with grain yield, but significantly negatively correlated with filled grains and grain weight. (3) With an increase in TNAR (0−340 kg ha−1), the panicles, spikelet number per panicle, and total spikelets of rice varieties with different yield types increased gradually, and the filled grains and grain weight decreased gradually. The higher the TNAR, the more obvious the decrease in filled grains and grain weight. The grain yield of rice varieties with different yield types was the highest under the TNAR at 250 kg ha−1. The main factor contributing to its high yield was the substantial increase in total spikelets. The above results showed that increasing the spikelet number per panicle and total spikelets played a material role in improving rice yield.

Response of the rhizosphere soil microbial diversity to different nitrogen and phosphorus application rates in a hulless barley and pea mixed-cropping system

The mixed-cropping mode of hulless barley (Hordeum vulgare L) and peas (Pisum sativum L) can optimize the planting system, effectively enhancing crop nitrogen and phosphorus utilization and increasing yield. This mode has been widely applied in Qinghai Province, China. In this study, a split-plot experimental design was employed to investigate the bacterial and fungal communities in the rhizosphere soil of monocropping and mixed-cropping treatments under different fertilization levels. The Illumina MiSeq sequencing technology was used for the research, and the physicochemical properties of the soil were measured. The results indicated that with the increase in the application of nitrogen and phosphorus, the bacterial α-diversity in the rhizosphere of the mixed-cropping system initially increased and then decreased after reaching a peak. The α-diversity index of soil bacteria was higher under the mixed-cropping mode than under the monocropping mode. For the rhizosphere soil fungi in the mixed-cropping system, the Shannon index initially increased and then decreased, while the Chao1 and ACE indices decreased initially and then increased. Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Sphingomonas, and Pseudomonas comprised the predominant bacterial genera in the rhizosphere soil of the hulless barley–pea intercropping treatment, whereas Fusarium, Metarhizium, and Cladosporium dominated among the fungal genera across the 12 treatments. Under the same fertilization levels, the relative abundances of Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium in the rhizosphere soil of the mixed-cropping treatment increased by 8.4 %, 7.1 %, 5.7 %, and 5.6 %, respectively, compared to the monoculture of hulless barley, with a decreasing trend as nitrogen and phosphorus levels increased. Compared to the monoculture of hulless barley, the relative abundance of Fusarium in the mixed-cropping treatment decreased by 37.3 %, 43.8 %, 56.8 %, and 40.3 %, respectively. Redundancy and correlation analyses suggested that the variation in bacterial and fungal diversity and community composition in the mixed-cropping zone due to the interaction between hulless barley and peas under different nitrogen and phosphorus fertilizer application levels was significantly correlated with changes in soil organic matter, available phosphorus, and alkaline hydrolyzable nitrogen.

Irrigation and Fertilization Scheduling for Peanut Cultivation under Mulched Drip Irrigation in a Desert-Oasis Area.

The aim of this study was to investigate the impact of water and nitrogen regulation on the characteristics of water and fertilizer demands and the yield, quality, and efficiencies of the water and nitrogen utilization of peanuts cultivated under mulched drip irrigation in a desert-oasis region. The experiment, conducted in Urumqi, Xinjiang, centered on elucidating the response mechanisms governing peanut growth, yield, quality, water consumption patterns, and fertilizer characteristics during the reproductive period under the influence of water and nitrogen regulation. In the field experiments, three irrigation levels were implemented, denoted as W1 (irrigation water quota of 22.5 mm), W2 (irrigation water quota of 30 mm), and W3 (irrigation water quota of 37.5 mm). Additionally, two nitrogen application levels, labeled N1 (nitrogen application rate of 77.5 kg·ha-1) and N2 (a nitrogen application rate of 110 kg·ha-1), were applied, resulting in seven treatments. A control treatment (CK), which involved no nitrogen application, was also included in the experimental design. The results indicate a direct correlation between the increment in the irrigation quota and increases in farmland water-related parameters, including water consumption, daily water consumption intensity, and water consumption percentage. The nitrogen harvest index (NHI) demonstrated a higher value in the absence of nitrogen application compared to the treatment with elevated nitrogen levels. The application of nitrogen resulted in an elevation in both nitrogen accumulation and nitrogen absorption efficiency within pods and plants. When subjected to identical nitrogen application conditions, irrigation proved to be advantageous in enhancing water-use efficiency (WUE), nitrogen partial factor productivity (NPFP), and the yield of peanut pods. The contribution rate of water to pod yield and WUE exceeded that of nitrogen, while the contribution rate of nitrogen to nitrogen-use efficiency (NUE) was higher. The total water consumption for achieving a high yield and enhanced water- and nitrogen-use efficiencies in peanuts cultivated under drip irrigation with film mulching was approximately 402.57 mm. Taking into account yield, quality, and water- and nitrogen-used efficiencies, the use of an irrigation quota of 37.5 mm, an irrigation cycle of 10-15 days, and a nitrogen application rate of 110 kg·ha-1 can be regarded as an appropriate water and nitrogen management approach for peanut cultivation under mulched drip irrigation in Xinjiang.

Improving maize carbon and nitrogen metabolic pathways and yield with nitrogen application rate and nitrogen forms.

Reduced fertilizer efficiency caused by excessive use of nitrogen (N) fertilizer is a major problem in agriculture and a hot topic of research. Most studies have focused on the effect of N application rate on N efficiency, whereas there are limited studies on changing the N form to improve N yield and efficiency. Here, the effects of different N application rates and nitrate-to-ammonium N ratios on post-anthesis carbon (C) and N metabolism and maize yield under shallow-buried drip irrigation were investigated. Two rates of N application (210 kg·ha-1 (NA1) and 300 kg·ha-1 (NA2)) and three nitrate-to-ammonium N ratios (2:1 (NF1), 3:1 (NF2), and 4:1 (NF3)) were utilized. Post-anthesis photosynthetic characteristics, activities of key enzymes in photosynthetic C and N metabolism, nonstructural carbohydrate content, post-anthesis N accumulation and transportation, yield, and N-use efficiency were determined. At both N application rates, NF2 treatment enhanced photosynthetic activity in the ear-leaf at silking stage and promoted key enzyme activities of C and N metabolic pathways, compared with NF1 and NF3. Furthermore, NF2 significantly increased nonstructural carbohydrate accumulation (4.00-64.71%), post-anthesis N accumulation and transportation (11.00-38.00%), and grain yield (2.60-13.08%). No significant differences between NA1 and NA2 were observed under NF2 in most of the measured variables; however, NA1 had higher N-use efficiency. Thus, the optimal treatment under shallow-buried drip irrigation was a N application rate of 210 kg ha-1 and a nitrate-to-ammonium N ratio of 3:1. These findings provide theoretical guidance on appropriate N applications for high-yield maize production.

Physiological Productivity of CABBAGE (Brassica oleracea var. capitata L.) in Response to Planting Distance and Rate of Nitrogen Application

Cabbage is one of the most important vegetables in the world, known for being a heavy nutrient feeder crop, especially nitrogen (N), and is influenced by planting distance, which plays a big role in production to attain a higher yield while producing the best quality cabbage suited to consumers’ preferences. A study aimed to determine the levels of nitrogen and planting distance that influence the growth parameters, yield attributes, and yield of cabbage, as well as the economic efficiency of the treatments. Results show that the yield of cabbage is significantly influenced by planting distances and rate of nitrogen application, wherein 30 cm x 30 cm spacing proved to be the most productive when applied with 150-200 kg N/ha, obtaining the same highest yield in tons per hectare. Moreover, the same treatment combinations influenced other key physiological parameters, e.g., polar and equatorial head sizes and cabbage head weight. Economic analysis revealed that planting cabbage at a closer distance (e.g., 30 cm x 30 cm) with 150 kg/ha N, which will eventually provide more plant population density per area, would lead to a highly profitable venture for cabbage production.

Impact of nitrogen fertilizer type and application rate on growth, nitrate accumulation, and postharvest quality of spinach.

A balanced supply of nitrogen is essential for spinach, supporting both optimal growth and appropriate nitrate (NO3 -) levels for improved storage quality. Thus, choosing the correct nitrogen fertilizer type and application rate is key for successful spinach cultivation. This study investigated the effects of different nitrogen (N) fertilizer type and application rates on the growth, nitrate content, and storage quality of spinach plants. Four fertilizer types were applied at five N doses (25, 50, 200, and 400 mg N kg-1) to plants grown in plastic pots at a greenhouse. The fertilizer types used in the experiment were ammonium sulphate (AS), slow-release ammonium sulphate (SRAS), calcium nitrate (CN), and yeast residue (YR). Spinach parameters like Soil Plant Analysis Development (SPAD) values (chlorophyll content), plant height, and fresh weight were measured. Nitrate content in leaves was analyzed after storage periods simulating post-harvest handling (0, 5, and 10 days). The application of nitrogen fertilizer significantly influenced spinach growth parameters and nitrate content. The YRx400 treatment yielded the largest leaves (10.3 ± 0.5 cm long, 5.3 ± 0.2 cm wide). SPAD values increased with higher N doses for AS, SRAS, and CN fertilizers, with AS×400 (58.1 ± 0.8) and SRAS×400 (62.0 ± 5.8) reaching the highest values. YR treatments showed a moderate SPAD increase. Fresh weight response depended on fertilizer type, N dose, and storage period. While fresh weight increased in all fertilizers till 200 mg kg-1 dose, a decrease was observed at the highest dose for AS and CN. SRAS exhibited a more gradual increase in fresh weight with increasing nitrogen dose, without the negative impact seen at the highest dose in AS and CN. Nitrate content in spinach leaves varied by fertilizer type, dose, and storage day. CNx400 resulted in the highest NO3 - content (4,395 mg kg-1) at harvest (Day 0), exceeding the European Union's safety limit. This level decreased over 10 days of storage but remained above the limit for CN on Days 0 and 5. SRAS and YR fertilizers generally had lower NO3 - concentrations throughout the experiment. Storage at +4 °C significantly affected NO3 - content. While levels remained relatively stable during the first 5 days, a substantial decrease was observed by Day 10 for all fertilizers and doses, providing insights into the spinach's nitrate content over a 10-day storage period. For rapid early growth and potentially higher yields, AS may be suitable at moderate doses (200 mg kg-1). SRAS offers a more balanced approach, promoting sustained growth while potentially reducing NO3 - accumulation compared to AS. Yeast residue, with its slow nitrogen release and consistently low NO3 - levels, could be a viable option for organic spinach production.

Chemical composition and quality of rapeseed meal as affected by genotype and nitrogen fertilization

Rapeseed meal (RSM) is known for its high nutritional quality as animal feed. However, there has been little studies on the effect of nitrogen fertilization on RSM chemical composition, mainly neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and ash content. Therefore, this study was carried out to evaluate the effect of nitrogen application rate on chemical composition of RSM in interaction with different spring rapeseed varieties (Brassica napus L). A field experiment was conducted during 2018/19 cropping season at the experimental station of the Ecole Nationale d’Agriculture de Meknès” according to a split-plot design with three replications, using six nitrogen application rates, as main plot, and six rapeseed varieties, as subplot. After seeds harvest and oil extraction, meals derived from the different treatments were used in this study. Results showed that increasing nitrogen rate from 0 to 120 kg N ha−1 led to a significant rise in meal yield up to 74.58%. A positive effect of nitrogen fertilization was observed on dry matter, protein content and ash content, recording the highest values at 120 kg N ha−1 treatment. However, cellulose and lignin content were affected negatively by nitrogen fertilization. The nitrogen supply of 150 kg N ha−1 resulted in a reduction of ADF and ADL contents by 23% and 28%, respectively, compared to the unfertilized control (N0). Variability within rapeseed varieties for all parameters except dry matter and ADL content was highlighted.

Optimizing planting density and nitrogen application to mitigate yield loss and improve grain quality of late-sown wheat under rice-wheat rotation

Late sowing is a critical factor that hinders achieving high-yield, good-quality wheat under rice-wheat rotation. Understanding the physiological basis and regulatory pathways that lead to late-sown wheat of high yield and good quality is crucial for developing effective cultivation strategies. A 2-year field experiment was conducted to investigate the effects of sowing date, nitrogen (N) application rate, and planting density on wheat yield, grain quality, population characteristics, and the underlying physiological factors. The results revealed significant interactions among the sowing date, planting density, and N application in regulating both yield and quality. Late sowing reduced grain yield primarily by reducing the number of spikes and kernels. However, the latter was improved by increasing N application and the planting density, thus mitigating the yield losses caused by late sowing. Moreover, the grain protein content (GPC) and wet gluten content (WGC) increased with delayed sowing dates and higher N rates, but decreased with increased planting densities. For wheat yields over 9,000 or 7,500 kg ha–1, the latest sowing date should not be later than Nov. 4 or 15, respectively. In addition, specific criteria should be met, including a maximum of 1.5 and 1.0 million stems and tillers ha–1, a maximum leaf area index of 6.7 and 5.5, and a dry matter accumulation (DMA) at anthesis of 14,000 and 12,000 kg ha–1, respectively. For high-yield, good-quality late-sown wheat, the optimal combination is a 25% increase in the N rate (300 kg N ha–1) and a planting density of 2.25 million (N300D225) or 3.75 million (N300D375) plants ha–1 for 10- or 20-day delays in sowing, respectively. These combinations result in higher leaf net photosynthetic rate; higher activities of leaf nitrate reductase, glutamine synthetase, and grain glutamic pyruvic transaminase; and a lower sugar-N ratio during post-anthesis.