Adoption patterns of on-farm nutrient management practices and nitrogen application rates in California’s Central Valley

氮肥农学效应与环境效应国际研究发展态势

Lowering carbon footprint of winter wheat by improving management practices in North China Plain

Pecan is an important nut crop in the United States. It is native to North America and dominantly produced in the southern states in the US. Nitrogen and zinc are two of the most critical nutrients for pecan production. This review provides a comprehensive overview of nitrogen and zinc fertilizer management in pecan orchards, covering key topics such as nitrogen sources, nitrogen application rates, the timing of nitrogen application, nitrogen application of damaged trees, the impact of zinc deficiency, and methods for zinc application. The deficiency of these nutrients causes severe loss in pecan production. However, the cost involving nutrient application and post the effect of excessive application on the soil and environment is of serious discussion. This review summarizes nitrogen and zinc management strategy and explores application methods that can reduce the cost of fertilizer with minimal adverse effect on the soil and environment. Also, this review sheds light on the areas that needs extensive research in nutrient management in pecan production.

<b><sc>Abstract.</sc></b> <b>Understanding the interactions between soil salt and nitrogen is of significant importance for promoting crop growth and nitrogen uptake. To evaluate the effects of irrigation water quality and nitrogen application rate on plant nitrogen uptake and cotton growth, a pot experiment was conducted in the arid region of southern Xinjiang in 2019. Treatments included three irrigation water qualities (groundwater (GW), 1.27 g l^-1; brackish water (BW), 3.03 g l^-1 and saline water (SW), 4.70 g l^-1) and three nitrogen application rates (255 kg ha^-1, 315 kg ha^-1 and 375 kg ha^-1). Results showed that a higher irrigation water salinity resulted in a higher soil salt accumulation and a lower nitrogen uptake. The highest nitrogen application rate tested can reduce soil salt accumulation by 65% and increase nitrogen uptake rate by 24%. The plant height, leaf area index (LAI) and aboveground biomass of cotton were significantly reduced with an increasing irrigation water salinity. And the increasing nitrogen application rate alleviated the adverse effects of salinity on cotton growth to some extent. When GW or SW was used, the highest nitrogen application rate always produced the highest plant height, LAI and aboveground biomass. When BW was used, no significant difference in aboveground biomass was found between nitrogen application rate of 315 kg ha^-1 and 375 kg ha^-1. Considering soil salt accumulation, nitrogen uptake rate and aboveground biomass, a moderate nitrogen application rate (315 kg ha^-1) under BW irrigation and a high nitrogen application rate (375 kg ha^-1) under GW and SW irrigation were recommended for cotton planting in arid region.</b>

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm−2, N1), medium nitrogen (225 kg·hm−2, N2), and high nitrogen (300 k kg·hm−2, N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p &lt; 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p &lt; 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p &lt; 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m3 hm−2 and a nitrogen application rate of 300 kg·hm−2 can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.

Crop establishment and nitrogen management affect greenhouse gas emission and biological activity in tropical rice production

The long-term nitrogen fertilizer management strategy based on straw return can improve the productivity of wheat-maize rotation system and reduce carbon emissions by increasing soil carbon and nitrogen sequestration

Finding the fertilization optimization to balance grain yield and soil greenhouse gas emissions under water-saving irrigation

To address the scientific challenges of low water-fertilizer use efficiency and the difficulty in achieving the synergistic improvement of the yield and quality in solar greenhouse cucumber production on the North China Plain, this study investigated the effects of varying water and nitrogen supplies on cucumber growth, yields, water-nitrogen use efficiency, and quality. The aim was to establish optimized water and nitrogen management strategies for high-yield, high-quality, and resource-efficient cultivation. A two-factor completely randomized design was implemented, with three irrigation levels (W1: 1.0 Ep-20, W2: 0.75 Ep-20, and W3: 0.5 Ep-20) based on cumulative pan evaporation and four nitrogen application amounts (N1: 432 kg·ha-1, N2: 360 kg·ha-1, N3: 288 kg·ha-1, N4: 216 kg·ha-1). Cucumber growth indicators were observed during the growing season, and the water and nitrogen application rates were scientifically optimized. The results showed that a full water and nitrogen supply enhanced the leaf area index, dry weight accumulation, and yield. Moderate water and nitrogen savings had a minimal impact on plant growth and production while significantly improving the water and fertilizer use efficiency. Using principal component analysis to comprehensively evaluate the cucumber quality, it was found that the irrigation amount had a significant impact on quality, with the quality improving as the irrigation amount decreased. By employing a regression formula and spatial analysis methods, this study optimized the water and nitrogen application rates with the goals of maximizing the cucumber yield, water-nitrogen efficiency, and quality. For spring cucumbers, the recommended combination is an irrigation amount of 225~240 mm and a nitrogen application amount of 350~380 kg·ha-1. For autumn cucumbers, the recommended combination is an irrigation amount of 105~120 mm and a nitrogen application amount of 375~400 kg·ha-1. This research provides theoretical and technical support for high-yield, high-quality, and efficient irrigation and nitrogen management in solar greenhouses in the North China Plain.

Nitrogen fertilizer plays an important role in corn cultivation in terms of both economic and environmental aspects. Nitrogen fertilizer positively affects corn yield and the soil organic carbon level, but it also has negative environmental effects through nitrogen-related emissions from soil (e.g., N20, NOx, NO3(-) leaching, etc.). Effects of nitrogen fertilizer on greenhouse gas emissions associated with corn grain are investigated via life cycle assessment. Ecoefficiency analysis is also used to determine an economically and environmentally optimal nitrogen application rate (NAR). The ecoefficiency index in this study is defined as the ratio of economic return due to nitrogen fertilizer to the greenhouse gas emissions of corn cultivation. Greenhouse gas emissions associated with corn grain decrease as NAR increases at a lower NAR until a minimum greenhouse gas emission level is reached because corn yield and soil organic carbon level increase with NAR. Further increasing NAR after a minimum greenhouse gas emission level raises greenhouse gas emissions associated with corn grain. Increased greenhouse gas emissions of corn grain due to nitrous oxide emissions from soil are much higher than reductions of greenhouse gas emissions of corn grain due to corn yield and changes in soil organic carbon levels at a higher NAR. Thus, there exists an environmentally optimal NAR in terms of greenhouse gas emissions. The trends of the ecoefficiency index are similar to those of economic return to nitrogen and greenhouse gas emissions associated with corn grain. Therefore, an appropriate NAR could enhance profitability as well as reduce greenhouse gas emissions associated with corn grain.

Effects of straw mulching and nitrogen application rates on crop yields, fertilizer use efficiency, and greenhouse gas emissions of summer maize

Agroforestry is an ecological agricultural model that promotes the coordinated development of agriculture and animal husbandry. Exploring appropriate water and nitrogen management strategies for forage grasses in agroforestry systems is of great significance for improving productivity. This study aims to investigate the effects of different water and nitrogen management practices on the growth, nitrogen uptake, and utilization efficiency of intercropped alfalfa in a goji berry-alfalfa system. It is assumed that moderate water deficiency combined with appropriate nitrogen fertilizer can optimize the growth of alfalfa in the intercropping of wolfberry and alfalfa. This study was based on a 2-year (2021 and 2022) field trial, focusing on alfalfa in a goji berry||alfalfa system. Four irrigation levels [full irrigation (W0, 75-85% θfc), mild water deficit (W1, 65-75% θfc), moderate water deficit (W2, 55-65% θfc), and severe water deficit (W3, 45-55% θfc)] and four nitrogen application levels [no nitrogen (N0, 0 kg·hm-2), low nitrogen (N1, 150 kg·hm-2), medium nitrogen (N2, 300 kg·hm-2), and high nitrogen (N3, 450 kg·hm-2)] were set up to systematically analyze the effects of water and nitrogen regulation on biomass allocation, nitrogen translocation, hay yield, and nitrogen use efficiency of alfalfa. The results showed that (1) irrigation and nitrogen application levels significantly affected the stem-to-leaf and root-to-shoot ratios of alfalfa (p < 0.01). The smallest stem-to-leaf ratio (0.758) was observed under W1N2, while the smallest root-to-shoot ratio (0.595) was observed under W0N2. (2) Irrigation and nitrogen application levels significantly affected nitrogen accumulation and nitrogen translocation in alfalfa (p < 0.05). The maximum nitrogen accumulation was observed under W0N2, which was 43.39% higher than that under W0N0. The maximum nitrogen translocation was observed under W1N2, which was 15.1% and 33.4% higher on average than that under W0N0 and W3N0, respectively. (3) Irrigation and nitrogen application had highly significant effects on alfalfa hay yield (p < 0.01). The highest hay yield (8325 kg·hm-2 and 12,872 kg·hm-2) was achieved under W0N2. The nitrogen productivity of alfalfa increased with increasing water deficit and initially increased, then decreased with increasing nitrogen application. The nitrogen use efficiency of alfalfa followed the order N2 > N1 > N3 and W1 > W0 > W2 > W3, with the highest value of 9.26 under W1N2. Based on the comprehensive evaluation of alfalfa in agroforestry systems under water and nitrogen regulation using the entropy weight-TOPSIS method, mild water deficit combined with medium nitrogen application (W1N2) can optimize the stem-to-leaf ratio, root-to-shoot ratio, and nitrogen use efficiency of alfalfa without significantly reducing yield and nitrogen production efficiency. This water-nitrogen combination is suitable for use in goji berry||alfalfa systems in the Yellow River irrigation area of Gansu Province and similar ecological zones.

Maximising herbage yield while reducing nitrogen (N) fertiliser input, particularly in spring, is essential to ensure environmental and economic sustainability on grassland farms. A plot experiment was conducted over 2 yr, comparing three different spring N application rates of 30 (30N), 60 (60N) and 90 (90N) kg N/ha using three different spring application strategies: 0:100 (S1), 50:50 (S2) or a 33:66 (S3) split across February and March, respectively. Half of the plots also received phosphorus (P) fertiliser with the first application of N at a rate of 13 kg P/ha. Nitrogen fertiliser application for the remainder of the year (April–September) was the same for all plots (23 kg N/ha/application). Both spring and cumulative herbage yields were significantly affected (P &lt; 0.05) by N application rate; 90N had the greatest spring and cumulative herbage yield compared to 30N and 60N (10,925, 9,834 and 10,499 kg DM/ha, respectively); however, N response reduced as N application rate increased. Nitrogen application strategy had a significant effect (P &lt; 0.05) on spring herbage yield, with S1 significantly lower than S2 and S3. Applying 13 kg P/ha in spring increased herbage yield at defoliations 2 (23 April) and 3 (15 May) (+133 and 56 kg DM/ha, respectively), relative to no application of P fertiliser, as well as increasing cumulative herbage yield (+241 kg DM/ha). The results of the current study indicate that N should be applied in early February and the strategic application of N and P during spring can increase spring and cumulative herbage yield.

To provide a scientific basis for rational nitrogen application under the rice–wheat rotation (R-W rotation) system, this study examined crop yield, NUE, and changes in soil nitrogen pools in response to different nitrogen application rates for rice (0–420 kg ha−1) and wheat (0–360 kg ha−1) from 2020 to 2022 in Jiangsu Province, China. Rice and wheat yields, along with their yield components, exhibited similar responses to nitrogen fertilization. In both cropping seasons, not only did current-season nitrogen application (CN) significantly affect yields but previous-season nitrogen application (PN) and the interaction between CN and PN also had notable effects. For both crops, the impact of CN on yield was greater than that of the CN × PN interaction, which in turn exceeded the effect of PN alone. These effects diminished with an increasing number of rice–wheat rotation cycles. The yields of rice and wheat initially increased and then declined with rising rates of both CN and PN. The maximum combined yield (14,459.9 kg ha−1) was achieved with nitrogen application rates of 265.7 kg ha−1 in the rice season and 257.1 kg ha−1 in the wheat season. Yield responses to CN were primarily driven by panicle number, spikelets per panicle, and crop-specific traits, grain filling efficiency for rice, and grain weight for wheat. PN effects were mediated through its interaction with CN, with panicle number serving as the main pathway. However, when nitrogen application rates fell below 300 kg ha−1 for rice and 240 kg ha−1 for wheat, a reduction in soil nitrogen content was observed. Therefore, to achieve high yields while maintaining soil nitrogen pool stability, recommended nitrogen application rates are 300 kg ha−1 for the rice season and 257.1 kg ha−1 for the wheat season.

Intensive irrigation and nutrient management practices in agriculture have given rise to serious issues in aquifer water depletion and groundwater quality. This review discusses the effects of irrigation and nitrogen management practices on potato growth, yield, and quality, and their impacts on water and nitrogen use efficiencies. This review also highlights the economics and consequences of applying deficit irrigation strategies in potato production. Many researchers have demonstrated that excessive irrigation and nitrogen application rates negatively impact potato tuber yield and quality while also increasing nitrate leaching, energy consumption, and the overall costs of production. An application of light-to-moderate deficit irrigation (10–30% of full irrigation) together with reduced nitrogen rates (60–170 kg/ha) has a great potential to improve water and nitrogen use efficiencies while obtaining optimum yield and quality in potato production, depending on the climate, variety, soil type, and water availability. There is an opportunity to reduce N application rates in potato production through deficit irrigation practices by minimizing nitrate leaching beyond the crop root zone. The best irrigation and nitrogen management techniques for potato production, as discussed in this review, include using sprinkle and drip irrigation techniques, irrigation scheduling based on local crop coefficients, soil moisture content, and crop modeling techniques, applying slow-release nitrogenous fertilizers, split nitrogen application, and applying water and nitrogenous fertilizers in accordance with crop growth stage requirements.