Optimized Fertilizer Application Research Articles

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.

Comparative analysis of spectroradiometric and chemical methods for nutrient detection in black gram leaves

This study evaluated the nutrient content in Vigna mungo leaves using a visible near-infrared spectroradiometer (VNIR 650–900 nm) and compared it with traditional chemical analysis. Nutrient deficiencies were induced in a controlled environment, focusing on Nitrogen (N), Phosphorus (P), and Potassium (K). The VNIR spectroradiometer measured the spectral reflectance of the leaves at different intervals. Peak reflectance for N, P, and K deficiencies occurred at 716 nm, 737 nm, and 720 nm, respectively. A 30 % deficiency in N, P, and K resulted in reflectance values of 45 %, 42 %, and 41 %, respectively, while a 40 % deficiency increased these values to 48 %, 46 %, and 43 %. Results showed a strong correlation between nutrient deficiency and spectral reflectance, providing a quicker, more economical method than traditional chemical analysis. The study concludes that VNIR spectroradiometry is an effective tool for non-destructive, real-time assessment of nutrient status in Vigna mungo, which could lead to optimized fertilizer application and improved crop management.

Temporal Synchronization of Nitrogen and Sulfur Fertilization: Impacts on Nutrient Uptake, Use Efficiency, Productivity, and Relationships with Other Micronutrients in Soybean

Nitrogen (N) and sulfur (S) are essential nutrient elements, and their deficiency affects crop growth, productivity, and nutrient uptake due to their multifaceted role in plant metabolism, which has been well documented. Therefore, agricultural management strategies that can overcome these deficiencies are the need of the hour. In this context, a study was undertaken with the objective to assess the impacts of N and S applications, either basally or through split application (12.5, 25 and 50 kg ha−1), on the nutrient uptake, productivity, use efficiency, and micronutrient content status in soybean seeds, and also the change in soil nutrient zinc (Zn) and iron (Fe) content at different critical stages of soybean crop growth. The field trial was conducted utilizing a randomized complete-block design, and comprised fourteen treatments with varying N and S quantities. N and S were applied through basal and split applications in different combinations. The salient findings indicated that the highest seed, straw yield, N, and S uptake were obtained with the application of N25+25, S25+25, and did not significantly vary with N25+25, S12.5+12.5, N50, and N25+S50. The highest N use efficiency was recorded with the application of N25+S50, and S use efficiency with the application of N25+25, S25+25. The split application of N and S as N25+25, S25+25 significantly increased soil Zn and Fe content at R2 and R5 stages of soybean crop growth, as well as seed Zn and Fe uptake. It can be concluded that the basal and split application of N and S at the rate of 25 kg ha−1 can improve soybean productivity through increased mobilization and assimilation by plants. The findings indicated that applying N and S separately, with 25 kg ha−1 each basally and at the R2 stage resulted in the highest nutrient uptake, and seed and straw yields. The nutrient use efficiencies, along with Zn and Fe uptake by seeds, exhibited noticeable improvements with this split application approach compared to the control. Furthermore, the soil Zn and Fe contents also experienced enhancements due to the split application of both Nand S fertilizers. These results underscore the potential benefits of temporally adopting optimized fertilizer application strategies to maximize agricultural productivity while ensuring efficient nutrient utilization and soil health maintenance. Further research and field trials could provide deeper insights into the long-term impacts and scalability of this approach across different crop varieties and environmental conditions.

Declines in nutrient losses from China’s rice paddies jointly driven by fertilizer application and extreme rainfall

Rice production consumes large amounts of fertilizer and irrigation water and contributes to the non-point source pollution (NPSP) by delivering nitrogen (N) and phosphorus (P) through surface and subsurface fluxes. However, due to the lack of spatially detailed datasets we barely understand the temporal variations of nutrient fluxes or what the key drivers are. Here, we developed a data-driven model and a rice-specific dataset of fertilizer and irrigation schemes to quantify N and P loss fluxes from China’s rice paddies across 2320 counties during 1979–2018. Both of the surface and subsurface fluxes decreased, ∼16 % for N and ∼28 % for P over the past four decades. Instead of a steady decrease, the N surface and subsurface fluxes slightly increase at first, until decrease since 1999 at rates of − 1.2 and − 4.7 kiloton N yr−2, respectively. Similarly, the P surface and subsurface fluxes decline rates jumped to − 0.4 and − 0.2 kiloton P yr−2, respectively. N loss via subsurface flux was slightly prevailing compared with surface runoff, their trends were mainly driven by fertilizer application and extreme rainfall, respectively. P was primarily exported via surface runoff, with its trends jointly driven by extreme rainfall and fertilizer application, while the trends of subsurface P fluxes were largely driven by the latter. Consequently, N and P require different mitigation strategies, with N focusing on optimized fertilizer application and P on optimized water scheme. The combination of mitigation strategies on 20 % of the national rice sowing area accounted for 48 % of N and 70 % of P mitigation potentials under future warming. These findings suggest that we should implement regional specific policy interventions for critical regions and pathways, to effectively alleviate the national NPSP.

Spatially Explicit Soil Acidification under Optimized Fertilizer Use in Sub-Saharan Africa

Acidic soils (pH < 5.5) cover roughly 30% of Sub-Saharan Africa. Low nitrogen fertilizer application (15 kg N ha−1 yr−1) has no effect on soil acidification in Sub-Saharan Africa (SSA). However, the effect of optimized fertilizer use on soil acidification (H+) in SSA crops remains unknown. This study intended to predict the spatial variation of H+ caused by optimized fertilizer use using data from 5782 field trials in SSA cropland. We used ensemble machine learning to predict spatial variation (H+) after measuring the inputs and outputs of major elements and their effect on H+ production. The results revealed that H+ ranged spatially from 0 to 16 keq H+ ha−1 yr−1. The most protons (H+) were produced by cassava, banana, and Irish potatoes systems with 12.0, 9.8, and 8.9 keq H+ ha−1 yr−1, respectively. The results of the 10-fold cross validation for the soil acidification model were a coefficient of determination (R2) of 0.6, a root mean square error (RMSE) of 2.1, and a mean absolute error (MAE) of 1.4. Net basic cation loss drives soil acidification under optimized fertilizer application and climate covariates had a higher relative importance than other covariates. Digital soil mapping can produce soil acidification maps for sustainable land use and management plans.

Effects of oyster shell powder on leaching characteristics of nutrients in low-fertility latosol in South China.

In this study, we analyzed the effect of oyster shell powder of different proportions on the nutrient leaching characteristics of latosol using an indoor soil column simulation test. Based on the optimized fertilizer application amount, we assessed five different amounts of oyster shell powder (0% (control, CK), 0.1% (T1), 0.2% (T2), 0.4% (T3), and 0.8% (T4)) and analyzed the intermittent and dynamic leaching characteristics of nutrients in the soil samples. The results indicated that the loss of nutrients in urea, superphosphate, and potassium chloride (due to leaching) increased linearly with the amount of fertilizer. By adding oyster shell powder, the leaching loss reduced by 23.90-57.25% for ammonium nitrogen, 6.31-10.07% for phosphorus, and 17.08-26.58% for potassium. However, the leaching loss for nitrate nitrogen increased by 2.5-5.8 times. In addition, the application of oyster shell powder to latosol provided acid adjustment and water retention enhancement, which increased the pH value of the soil by 3.77 (from pH 4.15 to 7.92) and reduced water loss by 2.52%. Thus, the application of oyster shell powder can reduce the acidity of the surface soil and retain water and fertilizer to a certain extent.

Optimal control of centrifugal spreader

Achieving an evenly distributed fertilization spread pattern is a complex technical task. A corresponding control algorithm must account for the tractor movement, the settings of the spreader, the prescribed dosage as well as machine constraints. It dictates, in particular, the fertilization process needs be estimated ahead to achieve an optimized spread pattern. The presented work is concerned with the development of a predictive control scheme for optimized fertilizer application using modeling of the tractor moving on the field and the spread pattern in form of a crescent behind the tractor. In particular, the form of the spread pattern is modeled via four normal distributions, two for each side of the pattern. The control goal is to achieve a desired fertilizer distribution on the field. The study presents three algorithms for comparison: a one-step optimization and two approaches using model-predictive control – one with a simplified model of the spread pattern in the prediction horizon, and one with a comprehensive one model, respectively. The best results are obtained with model-predictive control using the comprehensive model.

Effects of different fertilization regimes on nitrogen and phosphorus balance and eco-economic benefits in red paddy field.

The nitrogen (N) and phosphorus (P) balance was studied and the eco-economic benefits of N and P were evaluated for the paddy field in a red soil area, under the fertilization treatments of no fertilization (CK), chemical fertilizer (NPK), organic fertilizer (M), and chemical fertilizers combined with organic fertilizers (NPKM, NPM, NKM), based on the long-term experiment started in 1982, to optimize fertilizer application and reduce N and P losses. The results indicated that the slight N surplus (27.10 kg·hm-2) and P deficit (-6.85 kg·hm-2) were obtained in CK, while the N and P surplus respectively with 110.94-243.98 kg·hm-2 and 19.06-67.49 kg·hm-2 in other treatments were obtained. The treatments NPK and M had no effects on the N and P balance. Under the same fertilization rates, the N surplus in treatment NPKM was lower than that in treatments NPM and NKM by 6.3% and 12.9%, while the P surplus was lower by 3.7% and 13.8%, respectively. The total-N, total-P, alkali-hydrolyzable N, and available P contents in the 0-20 cm soil layer increased under the treatments of NPKM. Comparatively, the available P contents were relatively higher in the 20-40 cm soil layer under the treatments of high P application rates. Furthermore, the NPKM treatment had the highest eco-economic benefit value of 0.762, which indicated the optimized fertilizer application for the paddy fields in the red soil area. The treatment CK had the lowest eco-economic benefit values with 0.560. Based on the observations, the N and P (in P2O5) fertilization respectively at the rates of 157.71 kg·hm-2 and 112.18 kg·hm-2 could well maintain the N and P balance for the paddy field in the red soil area.

Soil testing at harvest to enhance productivity and reduce nitrate residues in dryland wheat production

The excessive application of fertilizer can inhibit the crop yield and decrease the nutrient use efficiency, as well as leading to nitrate-N residues in soils and other economic and environmental issues. In this study, an optimized method for fertilizer recommendation was developed based on soil testing at harvest of the previous crop. Multi-site and fixed location field experiments were conducted to assess this method from 2013 to 2016 in the typical dryland winter wheat (Triticum aestivum L.) production area of the Loess Plateau in China. Compared with the conventional fertilizer application (CFA), optimized fertilizer application (OFA) decreased the fertilizer application rates by 96kgNha−1 and 43kg P2O5 ha−1, and the nitrate-N residues by 120kgNha−1 in the 0–100cm soil layer, as well as increasing the winter wheat grain yield by 386kgha−1 and the economic returns by $ 230ha−1 averaged across sites and years. Furthermore, the OFA method caused no changes in nitrogen (N), phosphorus (P), and potassium (K) uptake in wheat compared with CFA, but increased the harvest index by 4%, 3%, and 7% for N, P, and K, respectively. Averaged across years and sites, compared with CFA, the internal efficiency rate of N, P, and K under OFA were increased by 9%, 4%, and 8%, respectively, and the corresponding partial factor productivity for these nutrients also increased by 85%, 61%, and 31%. Thus, soil testing at harvest and determining fertilizer recommendations according to the proposed OFA method can decrease the fertilizer rates, as well as achieving a balance among the conflicting aims of environmental protection, crop yield increases, nutrient use efficiency, and improved economic benefits in dryland farming areas where the over-application of fertilizers occurs.