Effects of Nitrogen Application at Different Levels by a Sprinkler Fertigation System on Crop Growth and Nitrogen-Use Efficiency of Winter Wheat in the North China Plain.

Nitrogen (N) is an essential macronutrient for crop growth; therefore, N deficit can greatly limit crop growth and production. In the North China Plain (NCP), winter wheat (Triticum aestivum L.) is one of the main food crops, and its yield has increased from approximately 4000 kg ha-1 to 6000 kg ha-1 in the last two decades. Determining the proper N application rates at different growth stages and in all seasons is very important for the sustainable and high production of wheat in the NCP. A field experiment with five N application rates (250, 200, 150, 100, and 40 kgN·ha-1, designated as N250, N200, N150, N100, and N40, respectively) was conducted during the 2017-2018 and 2018-2019 winter wheat seasons to investigate the effects of the N application rate on water- and fertilizer-utilization efficiency and on the crop growth and yield of winter wheat under sprinkler fertigation conditions. The results showed that in the N application range of 40-200 kg ha-1, crop yield and water- and fertilizer-use efficiencies increased as the N application rate increased; however, further increases in the N application rate (from N200 to N250) did not have additional benefits. The N uptake after regreening of winter wheat linearly increased with crop growth. Considering the wheat yield and N-use efficiency, the recommended optimal N application rate was 200 kg ha-1, and the best topdressing strategy was equal amounts of N applied at the regreening, jointing, and grain-filling stages. The results of this study will be useful for optimizing field N management to achieve high wheat yield production in the NCP and in regions with similar climatic and soil environment conditions.

[Optimized nutrients management improved citrus yield and fruit quality in China: A meta-analysis]. / å »åˆ†ä¼˜åŒ–ç®¡ç†æé«˜æˆ‘å›½æŸ‘æ©˜äº§é‡å’Œå“è´¨çš„æ•´åˆåˆ†æž.

Clarifying current situation of farmers' fertilization and yield in citrus producing areas and the effects of different fertilization measures can provide a scientific basis for improving the yield and quality of citrus in China. We retrieved 92 literatures on citrus fertilization from the CNKI and Web of Science to examine the impacts of nitrogen (N), phosphorus (P or P2O5), and potassium (K or K2O) fertilizer dosage and partial productivity under farmers' conventional fertilization and experts' optimized fertilization, as well as the effects of optimized fertilization measures on citrus yield and quality by using meta-analysis approach. The average conventional application rates of N, P2O5, and K2O were 507.3, 262.2, and 369.3 kg·hm-2 in citrus production in China. Compared with conventional fertilization, optimized fertilization resulted in a reduction of N and P2O5 by 14.7% and 8.3%, an increase in K2O application by 6.6%, which promoted partial productivity of N, P2O5, and K2O fertilizers by 7.8%, 18.4%, and 14.7%, correspondingly. The optimized fertilization resulted in 11.9% and 2.8% increase in fruit yield and single fruit weight, while improved vitamin C content (Vc, 3.1%), total soluble solids (TSS, 5.9%) and total sugar content (TSC, 8.6%). Additionally, it also led to a reduction in titratable acid (TA, -3.4%) and total acid content (TAC, -3.6%), and consequently elevated the TSS/TA (14.0%) and TSC/TAC (9.5%). Among different optimized fertilization methods, the effect of optimized NPK + medium and/or micro element fertilizer on citrus yield and fruit quality was the best, especially NPK decrement ≤25% between optimized NPK measures. The effect of conventional NPK + organic fertilizer was higher than conventional NPK + medium and/or micro element fertilizer. However, different citrus varieties, including mandarins, pomelos, and oranges, showed different responses to optimized fertilization. Optimized fertilization management could synergistically improve citrus yield, fertilizer use efficiency, and fruit quality. Therefore, the strategy of integrated nutrient management1 with reducing NPK fertilizer, balancing medium and/or micro nutrient fertilizer and improving soil fertility by organic fertilizer should be adopted according to local conditions in citrus producing areas of China.

Effect of Glycolipids Application Combined with Nitrogen Fertilizer Reduction on Maize Nitrogen Use Efficiency and Yield.

Microbial-driven N turnover is important in regulating N fertilizer use efficiency through the secretion of metabolites like glycolipids. Currently, our understanding of the potential of glycolipids to partially reduce N fertilizer use and the effects of glycolipids on crop yield and N use efficiency is still limited. Here, a three-year in situ field experiment was conducted with seven treatments: no fertilization (CK); chemical N, phosphorus and potassium (NPK); NPK plus glycolipids (N+PKT); and PK plus glycolipids with 10% (0.9 N+PKT), 20% (0.8 N+PKT), 30% (0.7 N+PKT), and 100% (PKT) N reduction. Compared with NPK, glycolipids with 0-20% N reduction did not significantly reduce maize yields, and also increased N uptake by 6.26-11.07%, but no significant changes in grain or straw N uptake. The N resorption efficiency under 0.9 N+PKT was significantly greater than that under NPK, while the apparent utilization rates of N fertilizer and partial factor productivity of N under 0.9 N+PKT were significantly greater than those under NPK. Although 0.9 N+PKT led to additional labor and input costs, compared with NPK, it had a greater net economic benefit. Our study demonstrates the potential for using glycolipids in agroecosystem management and provides theoretical support for optimizing fertilization strategies.

Comprehensive evaluation of the water-fertilizer coupling effects on pumpkin under different irrigation volumes.

Compared to conventional irrigation and fertilization, the Water-fertilizer coupling can significantly enhance the efficiency of water and fertilizer utilization, thereby promoting crop growth and increasing yield. Targeting the challenges of poor crop growth, low yield, and inefficient water and fertilizer utilization in the arid region of northwest China under conventional irrigation and fertilization practices. Therefore, a two-year on-farm experiment in 2022 and 2023 was conducted to study the effects of water-fertilizer coupling regulation on pumpkin growth, yield, water consumption (ET), and water and fertilizer use efficiency. Simultaneously the comprehensive evaluation of multiple objectives was carried out using principal component analysis (PCA) methods, so as to propose an suitable water-fertilizer coupling regulation scheme for the region. The experiment was set up as a two-factor trial using water-fertilizer integration technology under three irrigation volume (W1 = 37.5 mm, W2 = 45.5 mm, W3 = 52.5mm) and three organic fertilizer application amounts (F1 = 3900-300 kg ha-1, F2 = 4800-450 kg·ha-1, F3 = 5700-600 kg·ha-1), with the traditional irrigation and fertilization scheme from local farmers as control treatments (CK). The results indicated that irrigation volume and organic fertilizer application significantly affected pumpkin growth, yield, and water and fertilizer use efficiency (P<0.05). Pumpkin yield increased with increasing irrigation volume. Increasing organic fertilizer levels within a certain range benefited pumpkin plant growth, dry matter accumulation, and yield, however, excessive application beyond a certain level had inhibited effects on those. The increased fertilizer application under the same irrigation volume enhanced the efficiency of water and fertilizer utilization. However excessive irrigation only resulted in inefficient water consumption, reducing the water and fertilizer use efficiency. The Comprehensive evaluation by PCA revealed that the F2W3 treatment outperformed all the others, effectively addressing the triple objectives of increasing production, improving efficiency, and promoting green production. Therefore, F2W3 (Irrigation volume: 52.5 mm; Fertilizer application amounts: 4800-450 kg/ha-1) as a water and fertilizer management scheme for efficient pumpkin production in the arid region of northwest China.

Effects of Nutrient Solution Application Rates on Yield, Quality, and Water-Fertilizer Use Efficiency on Greenhouse Tomatoes Using Grown-in Coir.

The yield, quality, and water-fertilizer use efficiency of crops are important parameters for assessing rational water and fertilizer management. For an optimal water and fertilizer system with respect to the nutrient solution irrigation of greenhouse tomatoes using cultivation substrates, a two-year greenhouse cultivation experiment was conducted from 2022 to 2023. Three drip fertigation treatments (T1, T2, and T3) were implemented in the experiment, where nutrient solutions were supplied when the substrate's water content reached 60%, 70%, and 80%. The frequency of nutrient solution applications is based on weighing coconut coir strips in the morning and evening at 7:00 to determine the daily water consumption of plants. Nutrient solutions were supplied when the substrate's water content reached the lower limit, and the upper limit for nutrient supply was set at 100% of the substrate water content. The nutrient solution application was carried out multiple times throughout the day, avoiding the midday heat. The nutrient solution formula used was the soilless tomato cultivation formula from South China Agricultural University. The results show that plant height and the leaf area index rapidly increased in the early and middle stages, and later growth tended to stabilize; the daily transpiration of tomatoes increased with an increase in nutrient solution supply, and it was the greatest in the T3 treatment. Between the amount of nutrient solution application and the number of years, the yield increased with the increase of the amount of nutrient solution, showing T3 > T2 > T1. Although the average yield of the T2 treatment was slightly lower than that of the T3 treatment by 3.65%, the average irrigation water use efficiency, water use efficiency, and partial fertilizer productivity of the T2 treatment were significantly higher than those of the T3 treatment by 29.10%, 19.99%, and 28.89%, respectively (p < 0.05). Additionally, soluble solid, vitamin C, and soluble sugar contents and the sugar-acid ratio of tomatoes in the T2 treatment were greater than those in the other two treatments (p < 0.05). Using the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method, it was concluded that the nutrient solution application rate of 70% can significantly increase water and fertilizer use efficiency and markedly improve the nutritional and flavor quality of the fruit without a significant reduction in yield. This finding provides significant guidance for the high-yield, high-quality, and efficient production of coconut coir-based cultivated tomatoes in greenhouses.

An adaptive spacing of root-zone hole fertilization to improve production and fertilizer utilization of rapeseed.

BACKGROUND: Root-zone hole fertilization has a positive impact on enhancing crop production and fertilization efficiency. However, a suitable spacing for hole fertilization in rapeseed cultivation is unclear. To explore an adaptive hole spacing for improving rapeseed yield and fertilization efficiency, field experiments were conducted. Four spacings of hole fertilization were designed: 10 (FD10), 20 (FD20), 30 (FD30) and 40 cm (FD40), using no fertilization (F0) and deep-banded placement of fertilizer (DBP) as controls. The burial depth was 10 cm for FD and DBP treatments. RESULTS: Compared to DBP, hole fertilization impacted soil microenvironment, crop growth and yield components, resulting in a significant increase of 28.4% in seed yield and 25.6% in oil yield. Seed yield in FD20 (4345.43 kg ha-1) increased by 4.3%, 9.4% and 15.1% compared to FD10, FD30 and FD40, respectively. Fertilizer partial factor productivity under FD20 was 4.2%, 8.6% and 13.9% greater than FD10, FD30 and FD40, respectively; whereas the increase for agronomic efficiency was 6.0%, 12.7% and 21.0%, and the increase for N recovery efficiency was 39.5%, 52.5% and 62.9%, respectively. CONCLUSION: Fertilization with a hole spacing of 17 cm is a promising practice to maintain high production and fertilization efficiency when cultivating rapeseed. These results provide a theoretical foundation and scientific basis for improving rapeseed productivity and fertilizer utilization. © 2024 Society of Chemical Industry.

Impact of social networks on fertilizer use efficiency in China: Evidence from kiwifruit production in Shaanxi province.

Improving fertilizer use efficiency (FUE) is an effective way to reduce the fertilizer use and non-point source pollution in agriculture production in China. Existing research related to fertilizer use efficiency ignores the impact of famers' social networks, which can significantly affect the fertilizer use and its efficiency. This paper analyzed the impact of social networks on fertilizer use efficiency and the mediator effect of green fertilization technology adoption, based on the calculation of fertilizer use efficiency of 569 kiwifruit farmers in Shaanxi province of China surveyed in 2021 by using stochastic frontier method. The results show that the FUE of kiwifruit production ranged within 0.1027-0.9945, with an average value of 0.333, which showed great variability, and fertilizer input had an average 66.7% reduction potential without reducing output. Social networks and its four dimensions all had a significant positive impact on FUE, in which network trust and network learning had a greater impact on FUE. Farmers' adoption of green fertilization technology played a positive mediator effect in the process of social networks influencing their fertilizer use efficiency, which was mainly promoted by network trust and learning. Farmers' experience in agricultural production, joining the cooperative, the quantity of village agricultural supply points had a significant positive impact on fertilizer use efficiency, while age and gentle of the head of household had a significant negative impact of fertilizer use efficiency. Planting scale had a U-shape impact on FUE. Policies aimed at improving FUE and reducing non-point source pollution should, therefore, focus on improving the social networks of farmers, especially young farmers, strengthening network trust, promoting network learning, network reciprocity and network interaction, strengthening the research and development and extension of green fertilization technology, encouraging farmers to join agricultural cooperative, improving village production conditions, guiding sustainable agricultural production.

Inorganic fertilizer use and its association with rice yield gaps in sub-Saharan Africa.

Where and which countries should receive higher priority for improving inorganic fertilizer use in rice fields in sub-Saharan Africa (SSA)? This study addressed this question by assessing the spatial variation in fertilizer use and its association with rice yield and yield gap in 24 SSA countries through a systematic literature review of peer-reviewed papers, theses, and grey literature published between 1995 and 2021. The results showed a large variation in N, P, and K fertilizer application rates and rice yield and an opportunity for narrowing the yield gap by increasing N and P rates, especially in irrigated rice systems. We identified clusters of sites/countries based on nutrient input and yield and suggested research and development strategies for improving yields and optimizing nutrient use efficiencies. Further research is essential to identify the factors causing low fertilizer use and the poor association between its use and yield in rainfed systems.

[Effects of Mulching and Application of Organic and Chemical Fertilizer on Greenhouse Gas Emission and Water and Nitrogen Use in Summer Maize Farmland].

To explore the effects of mulching and the application of organic and chemical fertilizer on N2O, CO2, and CH4 emission; maize yield; water use efficiency (WUE); and nitrogen fertilizer use efficiency under the conditions of the same nitrogen fertilizer input in summer maize farmland, an experiment was conducted in the Guanzhong Plain of China. In this experiment, the two main experimental factors were mulching (M) and no-mulching, and the secondary experimental factors included no fertilizer application (CK), organic fertilizer substituting chemical fertilizer at 0% (T0, 0.00 kg·hm-2 organic fertilizer and 225.00 kg·hm-2 chemical fertilizer), 25% (T25, 56.25 kg·hm-2 organic fertilizer and 168.75 kg·hm-2 chemical fertilizer), 50% (T50, 112.50 kg·hm-2 organic fertilizer and 112.50 kg·hm-2 chemical fertilizer), 75% (T75, 168.75 kg·hm-2 organic fertilizer and 56.25 kg·hm-2 chemical fertilizer), and 100% (T100, 225.00 kg·hm-2 organic fertilizer and 0.00 kg·hm-2 chemical fertilizer), for a total of 12 treatments. The results showed as follows:1 both mulching and fertilizer application (with or without mulching) factors significantly increased soil N2O and CO2 emissions and reduced soil uptake of CH4(P<0.05). Compared to chemical fertilizer treatments, the organic fertilizer treatments reduced soil N2O emission by 11.8% to 52.6% and 14.1% to 68.0% and increased soil CO2 emission by 5.1% to 24.1% and 15.1% to 48.7% under mulching and no-mulching conditions, respectively (P<0.05). Compared to that under no-mulching, the global warming potential (GWP) under mulching increased by 140.7% to 206.6%. Compared to that in the CK treatment, the GWP of fertilized treatments increased by 36.6% to 67.6% and 31.2% to 89.1% under mulching and no-mulching conditions (P<0.05), respectively. Combined with the yield factor, the greenhouse gas intensity (GHGI) under the mulching condition increased by 103.4% to 166.2% compared to that under the no-mulching condition. Therefore, GHG emissions could be reduced by increasing yields. 2 The mulching treatments increased maize yield by 8.4% to 22.4% and WUE by 4.8% to 24.9% (P<0.05). Fertilizer application significantly increased maize yield and WUE. The organic fertilizer treatments increased yield by 2.6% to 8.5% and WUE 13.5% to 23.2% under the mulching condition compared to that in the MT0 treatment and increased yield by 3.9% to 14.3% and WUE 4.5% to 18.2% under the no-mulching condition compared to that in the T0 treatment. 3 In the 0-40 cm soil layer, the total nitrogen content of mulching treatments was increased by 2.4% to 24.7% compared with that of the no-mulching treatments. Fertilizer application treatments increased the total nitrogen content by 18.1% to 48.9% and 15.4% to 49.7% under the mulching and no-mulching conditions, respectively. Mulching and fertilizer application promoted nitrogen accumulation and nitrogen fertilizer use efficiency in maize plants (P<0.05). Compared to that in chemical fertilizer treatments, the organic fertilizer treatments increased nitrogen fertilizer use efficiency by 2.6% to 8.5% and 3.9% to 14.3% under mulching and no-mulching conditions, respectively. Combining ecological and economic benefits, the MT50 under mulching conditions and T75 under no-mulching conditions can be recommended as planting models to guarantee stable yield and achieve green and sustainable agricultural production.

Combined application of acidic biochar and fertilizer synergistically enhances Miscanthus productivity in coastal saline-alkaline soil.

Biochar amendment has been proven as an effective measure in the remediation of degraded soils, but few reports were focused on the interactive effects and mechanisms of biochar and fertilizer co-application in the amelioration of saline-alkaline soils. In this study, different biochar and fertilizer combinations were applied to investigate the interactive effect on fertilizer use efficiency, soil properties, and Miscanthus growth in a coastal saline-alkaline soil. Compared to the fertilizer or acidic biochar application alone, the combined application of acidic biochar and fertilizer significantly improved soil nutrient availability, ameliorated soil properties in rhizosphere soil. Meanwhile, the bacterial community structure and soil enzyme activities were considerably ameliorated. Additionally, the activities of anti-oxidant enzymes were substantially enhanced and the expression of abiotic stress-associated genes was significantly up-regulated in Miscanthus plants. Ultimately, the combined application of acidic biochar and fertilizer significantly enhanced Miscanthus growth and biomass accumulation in the saline-alkaline soil. Overall, our findings suggest that the combined application of acidic biochar and fertilizer represents a feasible and effective approach for improving plant productivity in saline-alkaline soils.

Nanobiochar Associated Ammonia Emission Mitigation and Toxicity to Soil Microbial Biomass and Corn Nutrient Uptake from Farmyard Manure.

The unique properties of NB, such as its nano-size effect and greater adsorption capacity, have the potential to mitigate ammonia (NH3) emission, but may also pose threats to soil life and their associated processes, which are not well understood. We studied the influence of different NB concentrations on NH3 emission, soil microbial biomass, nutrient mineralization, and corn nutrient uptake from farmyard manure (FM). Three different NB concentrations i.e., 12.5 (NB1), 25 (NB2), and 50% (NB3), alone and in a fertilizer mixture with FM, were applied to corn. NB1 alone increased microbial biomass in soil more than control, but other high NB concentrations did not influence these parameters. In fertilizer mixtures, NB2 and NB3 decreased NH3 emission by 25% and 38%, respectively, compared with FM alone. Additionally, NB3 significantly decreased microbial biomass carbon, N, and soil potassium by 34%, 36%, and 14%, respectively, compared with FM. This toxicity to soil parameters resulted in a 21% decrease in corn K uptake from FM. Hence, a high NB concentration causes toxicity to soil microbes, nutrient mineralization, and crop nutrient uptake from the FM. Therefore, this concentration-dependent toxicity of NB to soil microbes and their associated processes should be considered before endorsing NB use in agroecosystems.

Reduction in Nitrogen Rate and Improvement of Nitrogen Use Efficiency without Loss of Peanut Yield by Regional Mean Optimal Rate of Chemical Fertilizer Based on a Multi-Site Field Experiment in the North China Plain.

It is important to quantify nutrient requirements and optimize fertilization to improve peanut yield and fertilizer use efficiency. In this study, a multi-site field trial was conducted from 2020 to 2021 in the North China Plain to estimate nitrogen (N), phosphorus (P), and potassium (K) uptake and requirements of peanuts, and to evaluate the effects of fertilization recommendations from the regional mean optimal rate (RMOR) on dry matter, pod yield, nutrient uptake, and fertilizer use efficiency. Results show that compared with farmer practice fertilization (FP), optimal fertilization (OPT) based on the RMOR increased peanut dry matter by 6.6% and pod yield by 10.9%. The average uptake rates of N, P, and K were 214.3, 23.3, and 78.4 kg/ha, respectively, with 76.0% N harvest index, 59.8% P harvest index, and 41.4% K harvest index. The OPT treatment increased N, P, and K uptake by 19.3%, 7.3%, and 11.0% compared with FP, respectively. However, the average of yield, nutrition uptake, and harvest indexes of N, P, and K were not significantly affected by fertilization. The peanut required 42.0 kg N, 4.6 kg P, and 15.3 kg K to produce 1000 kg of pods. The OPT treatment significantly improved the N partial factor productivity and N uptake efficiency but decreased the K partial factor productivity and K uptake efficiency. The present study demonstrates that fertilizer recommendations from RMOR improve N use efficiency, and reduce N and P fertilizer application without yield loss in regions with smallholder farmers, and the corresponding estimation of nutrient requirements helps to make peanut fertilization recommendations.

Availability of Nitrogen in Soil for Irrigated Cotton Following Application of Urea and 3,4-Dimethylpyrazole Phosphate-Coated Urea in Concentrated Bands.

Low nitrogen (N) fertilizer use efficiency for irrigated cotton has been attributed to the limited ability of tap roots to access N from concentrated subsurface bands, or the preferential root uptake of microbially-mineralized dissolved organic N. This work investigated how applying high-rate banded urea affects the availability of N in soil and the capacity of cotton roots to take up N. Soil was analyzed for water-extractable total dissolved N and inorganic N species after urea or urea coated with 3,4-dimethylpyrazole phosphate (DMPP) was applied at concentrations of 261, 455, 461, and 597 mg N kg-1 of (air-dry) soil (mean bulk density: 1.01 g cm-3). A mass balance was used to compare N applied as fertilizer and in unfertilized soil (supplied N) with the N recovered from soil within the cylinders (recovered N) at five plant growth phases. Root uptake was estimated by comparing ammonium-N (NH4-N) and nitrate-N (NO3-N) in soil sampled from within cylinders with soil sampled from immediately outside. Recovered N was up to 100% above supplied N within 30 days of applying urea above 261 mg N kg-1 of soil. Significantly lower NO3-N in soil sampled from immediately outside the cylinders suggests urea application stimulates cotton root uptake. The use of DMPP-coated urea prolonged high NH4-N in soil and inhibited the mineralization of released organic N. These results imply the release of previously sequestered soil organic N within 30 days of applying concentrated urea enhances the availability of NO3-N in the rhizosphere, reducing N fertilizer use efficiency.

Fertilization depth effect on mechanized direct-seeded winter rapeseed yield and fertilizer use efficiency.

BACKGROUND: Deep fertilization is effective for improving crop yield and fertilizer use efficiency. However, its impact on mechanized direct-seeded rapeseed and the optimal fertilization depth are poorly understood. A field experiment was conducted to evaluate the fertilization depth effect on mechanized direct-seeded rapeseed growth. Five treatments were designed: surface broadcast fertilizer, no fertilization, and fertilizer banded placement at soil depths of 5 (D5), 10 (D10), and 15 cm (D15). RESULTS: Compared with surface broadcast fertilizer, deep fertilization generally increased seed yield and partial factor productivity by 11.0%, agronomic efficiency (AE) by 22.7%, and recovery efficiency (RE) by 79.2% due to the increase of root mass density (16.8%), plant height (8.6%), height of the first branch (10.6%), stem diameter (22.4%), shoot biomass (16.1%), and shoot nitrogen (35.7%), phosphorus (29.7%), and potassium (26.2%) uptake. D10 had the highest seed yield, oil yield, fertilizer use efficiency, and economic benefits at different fertilization depth treatments. Compared with D5 and D15 respectively, D10 increased seed yield by 5.4% and 46.0%, oil yield by 7.7% and 50.5%, partial factor productivity by 5.4% and 46.0%, AE by 9.0% and 99.5%, RE of nitrogen by 48.9% and 34.9%, RE of phosphorus by 83.1% and 38.0%, and RE of potassium by 57.5% and 32.5%. The economic benefits of D10 were CNY 867.31 ha-1 and CNY 4864.23 ha-1 higher than D5 and D15 respectively. CONCLUSION: Considering rapeseed growth and its economic benefits, this study shows that 10 cm is an appropriate placement depth with regard to mechanized direct-seeded winter rapeseed production. © 2022 Society of Chemical Industry.

Effects of Fertilization Approaches on Plant Development and Fertilizer Use of Citrus.

Fertilization is an important part of citrus crop management. However, limited details are available about the fertilization approach on citrus plant development. A pot experiment for the fertilization approaches and fertigation levels were conducted in this study. Four fertilization approaches, namely, drip fertigation (DF), broadcast fertilization (CK+), hole fertilization (HF) and pour fertilization (PF) were tested. The fertigation level treatment included 100% (DF-337.5), 80% (DF-270), 60% (DF-202.5) and 40% (DF-135) fertilizer supply with DF, and the 100% fertilizer supply with broadcast fertilization were served as control (CK). The results showed that DF not only increased the absorptions of nitrogen (N), phosphorus (P) and potassium (K) but also promoted citrus plant height, stem diameter and dry weight. In fruit quality, DF had the highest fruit total soluble solid (TSS) and titratable acidity (TA) contents. For fertilizer loss, DF had the lowest N and K leaching losses of 9.26% and 4.05%, respectively, and the lowest N and K runoff losses among the approaches. Isotopic tracing with 15N indicated that DF had the highest fertilizer use efficiency. Based on the analysis of fertigation levels, DF approach with 60% fertilizer reduction could improve citrus plant development. Therefore, DF promoted citrus plant growth and fruit quality by accelerating fertilizer utilization and impairing fertilizer loss. The fertilizer amount in citrus production could be reduced significantly using DF.

Evaluating China Food's Fertilizer Reduction and Efficiency Initiative Using a Double Stochastic Meta-Frontier Method.

Improving the efficiency of fertilizer usage is important to achieve sustainable agricultural production. As a major agricultural producer, China formally proposed a national fertilizer reduction and efficiency initiative in 2015. Using the double stochastic meta-frontier method to measure the fertilizer use efficiency of 31 provinces in mainland China from 2005 to 2019, this study evaluates the effectiveness of the said initiative on grain production. The results show that China's initiative has achieved some success, with the average value of fertilizer use efficiency in national grain production increasing by 2.53 percentage points. However, the changes in fertilizer use efficiency show regional heterogeneity. Specifically, the fertilizer use efficiency of the main grain-producing and marketing regions has increased significantly, while that of grain-producing-and-marketing-balanced regions has declined. Further investigation shows that this phenomenon may be related to the importance attached by local governments to the initiative and the uneven distribution of related resources.

Using highly stabilized digestate and digestate-derived ammonium sulphate to replace synthetic fertilizers: The effects on soil, environment, and crop production.

Recovered fertilizers (a highly stabilized digestate and ammonium sulphate) obtained from anaerobic digestion of sewage sludge, were used on plot trials with a maize crop, in a comparison with synthetic fertilizers. After three consecutive cropping seasons, the soils fertilized with the recovered fertilizers (RF), compared to those fertilized with synthetic fertilizers (SF), did not show significant differences either in their chemical characteristics or in the accumulation of inorganic and organic pollutants (POPs). The RF ensured an ammonia N availability in the soil equal to that of the soil fertilized with SF, during the whole period of the experiment. Furthermore, no risks of N leaching were detected, and the use of RF did not result in a greater emission of ammonia or greenhouse gases than the use of SF. The agronomic results obtained using RF were equivalent to those obtained with SF (fertilizer use efficiency of 85.3 ± 10 and 93.6 ± 4.4% for RF and SF respectively). The data show that utilising a very stable digestate can be a good strategy to produce a bio-based fertilizer with similar performance to that of a synthetic fertilizer, without environmental risks.

Combined effects of biochar and fertilizer applications on yield: A review and meta-analysis.

The use of biochar is changing, and the combined application of biochar with fertilizer is increasingly gaining acceptance. However, the yield gains results reported in the existing literature through the co-application of fertilizer with biochar are conflicting. To resolve this, we utilized a meta-analysis of 627 paired data points extracted from 57 published articles to assess the performance of the co-application of biochar and fertilizers on crop yield compared with the corresponding controls. We also studied the impact of biochar characteristics, experimental conditions, and soil properties on crop yield. Our analysis showed that individually, biochar and inorganic fertilizer increased crop yield by 25.3% ± 3.2 (Bootstrap CI 95%) and 21.9% ± 4.4, respectively. The co-application of biochar with both inorganic and organic fertilizers increased crop yield by 179.6% ± 18.7, however, this data needs to be treated with caution due to the limited dataset. The highest yield increase was observed with amendments to very acidic soils (pH ≤5), but the benefits of biochar were not affected by the rate and the time after the application. In addition, the effects of biochar are enhanced when it is produced at 401-500 °C with a C:N ratio of 31-100. Our results suggest that the co-application of biochar with either inorganic and/or organic fertilizers in acidic soils increase crop productivity compared to amendment with either fertilizer or biochar. Our meta-analysis supports the utilization of biochar to enhance the efficiency and profitability of fertilizers.

Fertilizer overuse in Chinese smallholders due to lack of fixed inputs.

Fertilizer overuse by smallholder farmers is widespread in China, leading to significant financial losses and threatening the environment. Understanding what mechanism behind this is critical for agricultural and environmental sustainability. By using a fixed effect panel model of over 20,000 rural households in China from 1995 to 2016, we found that the low ratio of fixed inputs such as machinery and knowledge to total inputs is the key factor leading to over-fertilization in smallholder farms. Low fixed input can result in or interact with nutrient-unbalanced fertilization, low agricultural income ratio and more cash crops that further aggravate fertilizer overuse. Smallholders lack fixed inputs, then compensate by over-applying fertilizer to attempt to achieve their yield goals. Thus, improving fixed input via increasing the average farm size to 3.8 ha or advanced service rental could save not only 45% fertilizers but also increase 16% agricultural net profit, benefiting agricultural and environmental sustainability.

Experimental approach to assess fertilizer nitrogen use, distribution, and loss in pear fruit trees.

Enhanced use efficiency of fertilizer nitrogen (N) is paramount for sustainable pear fruit production. Sufficient fruit N content is a major factor for pear fruit storage potential, but fertilizer N use efficiency in pear fruit trees is generally low. The objective of this work was to test a methodology to quantify N uptake, partitioning and leaching loss as influenced by different calcium nitrate (Ca(NO3)2) fertilizer timings. To this end, 10-year-old 'Conference' pear trees (Pyrus communis L.) were transplanted and grown in soil-filled pallet boxes subjected to different timing of fertilizer addition. A fraction of the calcium nitrate was labelled with 15N and applied one month before full bloom, during summer and post-harvest. By sampling newly formed biomass (i.e., leaves, fruit and flower buds), temporal dynamics in the N fraction derived from calcium nitrate fertilization were determined. Simultaneously NO3- leaching derived from calcium nitrate fertilization was quantified. Our data suggest that spring application of N was most efficiently partitioned to leaves, fruits and buds at the time of harvest with a mean percentage of calcium nitrate derived N (Ndff) of 9.2%, 20.4% and 18.6%, respectively. Summer application of calcium nitrate was far less efficient at the time of harvest with Ndff of 0.56%, 0.89% and 1.4%, respectively, and substantially higher NO3- leaching was observed compared to spring fertilization. Post-harvest application showed even higher levels of leaching. Applying a split fertilization scheme with 60 kg N ha-1 evenly spread over spring, summer, and post-harvest, about 9, 15 and 30%, respectively, of the fertilizer N had leached out as NO3- at the end of the growing season. This experimental approach may offer potential for detailed N budget studies for various fruit tree studies.