Fertilizer Utilization Efficiency Research Articles

Reduction of NH3 Emissions from Urea by Long-Term No-Tillage and Stover Mulching with Inhibitors: An Isotopic Field Study in Northeast China

Large nitrogen (N) losses during fertilization in agricultural production may result in energy wastage, soil and water contamination, and potentially influence crop development. Thus, with the help of a 15N-labeled tracer, we carried out a field monitoring analysis of NH3 emissions in a long-term (9-year) conservation tillage agroecosystem of Mollisols in northeast China, in order to determine whether a no-tillage regime and four levels of stover mulching (0%, 33%, 67%, and 100%), combined with urease and nitrification inhibitors, could improve fertilizer utilization efficiency in agricultural systems by reducing ammonia volatilization. Our results showed that in comparison with ridge tillage, no-tillage with stover mulching levels of 33%, 67%, and 100% significantly reduced NH3 emission rates and cumulative volatilization from 159.67 to 130.42 g N ha−1 and 15N-NH3 cumulative volatilization emission by 26% (on average). Furthermore, the application of urease and nitrification inhibitors significantly reduced 15N-NH3 volatilization levels from 1.19 to 0.98 g N ha−1. Our research results demonstrate that a long-term no-tillage regime and straw mulching can significantly reduce NH3 volatilization in fertilizers. Furthermore, when combined with the use of urease and nitrification inhibitors, these practices further enhance the reduction in NH3 volatilization. Although the volatilization of 15N-NH3 is minimally studied in Mollisols, these findings provide a solid foundation for improving fertilizer utilization efficiency, reducing crop production costs and mitigating subsequent environmental pollution.

Changes in the diversity of pecan (Carya illinoinensis) rhizosphere microbial community with different nitrogen fertilization, a case study in Oklahoma pecan orchard

Pecan (Carya illinoinensis) is primarily native to North America and is known as the leading nut produced in Oklahoma. Since the prices of fertilizers have increased and the activity of soil microbes may greatly affect fertilizer utilization, it is important to investigate the effect of fertilization on microbes. Samples were collected from pecan trees receiving full nitrogen (70 lbs/acre), half nitrogen (35 lbs/acre), and no nitrogen (0 lbs/acre) fertilization in an orchard. Microbes were characterized by using the next generation sequencing and annotated into functional groups (trophic mode and nitrogen related) by FUNGuild and FAPROTAX. Our results showed the core fungal genera in this orchard were Tuber and Hymenoscyphus, while the core bacterial families were Chitinophagaceae, Xanthobacteraceae, and Chthoniobacteraceae. Among them, the pecan truffle Tuber lyonii was the dominant fungus. In association with an increase of nitrogen fertilization, the Simpson Index (SI) of fungi in roots was decreased, and the presence of pathotroph (such as Monographella cucumerina and Lectera longa) was increased, implying that the risk of plant infection by pathogens was increased. The pecan with half rate of nitrogen fertilizer had the highest colonization of symbiotrophic fungi, the lowest presence of pathotrophic fungi, and the highest relative abundance of Tuber. The relative abundances of bacteria related to nitrate reduction, nitrogen respiration, and nitrate respiration were found to be the highest in pecan with half rate of nitrogen fertilizer, which might imply the highest efficiency of nitrogen fertilizer utilization in this treatment. It revealed that applying half the recommended nitrogen rate of fertilizer could improve beneficial microbe presence, perhaps increasing nitrogen uptake and decreasing nitrogen needed for optimum production.

Oxidation-Resistant Silicon Nanosystem for Intelligent Controlled Ferrous Foliar Delivery to Crops.

Since ferrous (Fe(II)) is the main form of plant absorption, traditional ferrous foliar fertilizers (TFFF) are widely used in modern agriculture. However, TFFF suffer from the shortcomings of weak antioxidant capacity (AC), low foliar adhesion efficiency (FAE), poor fertilizer utilization efficiency (FUE), and noncontrollable slow-release behavior. To overcome these limitations, an oxidation-resistant silicon nanosystem for intelligent controlled ferrous foliar delivery to crops was first developed by using environmentally friendly micro/nano structured hollow silicon as carrier, and combining with vitamin C (in situ antioxidant) to synthesize an oxidation-resistant ferrous foliar fertilizer (ORFFF) for ameliorating Fe-deficiency in crops and increasing crop yield. Compared with TFFF, the ORFFF has excellent ferrous AC (only 11.5% of Fe(II) was oxidized in ORFFF within 72 h), ultrahigh FAE (∼84% of adhesion percentage (%) after two-times simulated rain rinsing), nutrient slow-release ability (720 h gradually release 100.6 mg·g-1), pH-controlled release ability (pH 3-8), and verified high biological safety (100% survival rate for zebrafish and earthworm). The pot experiments showed that ORFFF can correct the Fe-deficiency symptoms of tomato seedlings promptly compared with TFFF, and the FUE of ORFFF is 4.2 times that of TFFF. The specific pH responsiveness of ORFFF can control the slow-release rate of Fe(II) to satisfy the needs of Fe in varying crops and different growing periods of crops. This work provides a feasible way to achieve green and safe Fe supplementation for crops, reduce Fe fertilizer waste, avoid soil pollution caused by Fe fertilizer abuse, and promote the sustainable development of modern nanoagriculture.

Novel biodegradable nanocomposite hydrogels based on biopolymers and various montmorillonite contents as high-strength coating membranes for efficient slow-release fertilizers

Slow-release fertilizers (SRF) have emerged as a sustainable remedy to the environmental problems caused by conventional water-soluble fertilizers. They have demonstrated their efficacy in reducing fertilizer dosage applications, enhancing fertilizer utilization efficiency, minimizing losses, and ultimately improving crop yield. This study developed biodegradable nanocomposite hydrogels (BHM) as a promising approach by combining cassava starch (Cst), polyacrylamide (PAM), natural rubber (NR), and various montmorillonite (MMT) contents (0–10 wt%) and fabricating via free-radical polymerization and semi-interpenetrating polymer network technology, crosslinked by glutaraldehyde. Notably, the addition of MMT played a crucial role and significantly improved the tensile strength, biodegradability, and N release efficiency of the BHM hydrogels. BHM3 (3 wt% MMT) demonstrated the highest swelling ratio of 7074% and improved N release efficiency, mechanical strength, and biodegradation rate by 39.1%, 260% and 58%, respectively, compared to BHM0. The FWBHM formulations (urea coated with BHM and wax layers) also exhibited good biosafety. Finally, FWBHM3 yielded acceptable growth rates, a greater yield, and a 4-fold lower price than commercial SRF. These findings provide a promising route for developing new nanocomposite hydrogels based on Cst, NR, and MMT components with high swelling and water-retention, high strengths, and excellent biodegradation with greater slow-release duration and sustained environments.

Drip fertilization improve water and nitrogen use efficiency by optimizing root and shoot traits of winter wheat.

Proper irrigation and fertilization measures can not only improve water and fertilizer utilization efficiency, but also have important significance in ensuring agricultural environment security and sustainable development. A field experiment was conducted to determine the optimal drip fertilization measure of winter wheat and explain its mechanism by analyzing the physiological and ecological characteristics and utilization efficiency of water and nitrogen under different irrigation and fertilization methods. The plants were treated with three irrigation and fertilization methods: the traditional irrigation and fertilization method (CK), surface drip fertilization (I1) and underground drip fertilization (I2). The results demonstrated that different irrigation methods had various effects on population and physiological characteristics of wheat. The plant height, leaf area and tiller number of I1 were significantly higher than those of CK during the whole growth period. I2 decreased plant height, leaf area and tiller number at jointing stage, but at flowering stage, the leaf area of I2 t was significantly higher than that of CK. Different irrigation methods also affected the root distribution of wheat. At flowering stage, I1 had lower root biomass than CK in all soil layers. The upper root system of I2 was smaller, but the deep root system was larger compared with the control. I1 and I2 had lower total root weight and higher shoot biomass compared to CK, so their root-shoot ratio decreased significantly. I1 and I2 increased and instantaneous water use efficiency (IWUE) by increasing the photosynthetic rate (Pn) and reducing transpiration rate (Tr) at the flowering stage, while I2 had a similar Pn to I1, but reduced Tr, resulting in a higher IWUE than I1. Both I1 and I2 also increased root efficiency, root activity, and Fv/Fm of wheat at the late growth stage, promoting accumulated dry matter after flowering (ADM) and pre-flowering dry matter remobilization (DMR), leading to a significant increase in grain yield. In addition, I1 and I2 had significantly higher water productivity (WP), irrigation water productivity (IWP), nitrogen partial productivity (NPP) and nitrogen agronomic efficiency (NAE) than CK, especially I2 had the highest IWP, WP, NPP and NAE. These findings highlight the potential benefits of drip fertilization in promoting sustainable wheat production and elucidate the mechanism by which it promotes efficient use of water and fertilizer.

Chemical Fertilizer Reduction Combined with Biochar Application Ameliorates the Biological Property and Fertilizer Utilization of Pod Pepper

Biochar is frequently utilized as a helpful amendment to sustain agricultural productivity. However, it remains uncertain whether biochar can effectively replace chemical fertilizers, especially in karst regions. To investigate the effects of co-applying biochar and chemical fertilizer on the biological characteristics and fertilizer uptake of pod peppers, as well as to determine the optimal ratio of biochar to chemical fertilizers, a two-year field experiment was conducted in southwest China. The results showed that, compared to the locally typical chemical fertilizer treatment (CF), the combined application of biochar and chemical fertilizer significantly increased the yield of both fresh and dry pod pepper. Chemical fertilizer reduction and biochar application also ameliorated fruit quality, increased nutrient accumulation, and improved fertilizer utilization efficiency. What is more, although the employment of biochar made production costs higher, the reduction in chemical fertilizers and the increase in yield improved economic efficiency, especially in the CF70B treatment (70%CF + biochar). In conclusion, moderate amounts of biochar instead of chemical fertilizers may be a valid nutrient management strategy for pod pepper in the karst mountain areas, which is beneficial for maintaining yield stability, improving quality, and increasing net income.

Ammoniacal and Nitrate Nitrogen Release Pattern from Biochar and Biochar Blended Urea Fertilizers in Sandy Soil

Biochar, an organic product of thermal decomposition of biomass in an oxygen limited environment can be used as a nutrient carrier to delay the release of nutrients into the soil, reduce nutrient leaching, and improve the nutrient utilization efficiency of fertilizers. Nutritional enhancement of biochar through fertilizer blending could be a low cost but high efficiency solution compared to non-blended fertilizers. However, the rate of nutrient release from the blended biochar fertilizer in different soils is ambiguous. Hence a 12 month incubation study was conducted in sandy soil (ultisol) of Thiruvananthapuram district of Kerala to elucidate the ammoniacal and nitrate nitrogen release rate and pattern from the produced paddy husk biochar, biochar and biochar bentonite (1:1) each blended with urea fertilizer in different ratios (1:0.5, 1:1, 1:2) including an absolute control. The individual effects of biochar, biochar-bentonite and urea were also studied. Paddy husk biochar was produced by the process of slow pyrolysis and biochar- blended urea fertilizers by the adsorbent process. To evaluate the influence of bentonite clay on the nutrient release pattern of biochar, it was blended with biochar and urea fertilizer. The highest total nitrogen content among the produced fertilizers was recorded in biochar: urea in 1:2 (33.04%) followed by biochar-bentonite: urea in a 1:2 ratio (31.13%). The incubation study revealed that the maximum release of ammoniacal nitrogen from soil+ urea fertilizer was at 30 days (115.73 mg kg-1) followed by a sharp decline, maintaining a low value till the end of incubation, whereas the release was sustained and gradually increased to reach a maximum at the 180th day (117.6 mg kg-1) for soil+ biochar: urea in 1:1 ratio. Nitrate nitrogen also followed the same trend with the maximum release observed for biochar: urea in 1:1 on the 150th day (151.2 mg kg-1). The release of nitrate nitrogen was more than that of ammoniacal nitrogen throughout the incubation period for all the treatments. Among the blended fertilizers, content of both ammoniacal and nitrate nitrogen were comparatively less for biochar –bentonite blended urea fertilizers. Thus, blending of urea with biochar/ biochar-bentonite prolonged the duration of maximum nutrient release.

Parametric optimization and experimental verification of multi-fertilizer mixing by air blowing and blade stirring based on discrete element simulations

In proportional variable-rate fertilization, improving the uniformity of multi-fertilizer mixing helps to improve the overall utilization efficiency of fertilizers. In this paper, a multi-fertilizer mixing by air blowing and blade stirring was presented. Using fertilizer granules mixing uniformity as an indicator, the method optimized the structures and working parameters of single-blade group stirring, double-blade group stirring and air blowing & double-blade stirring. EDEM and Fluent software were used for the simulation and the results were verified by experiments. The simulation results showed that the appropriate speed range of single-blade group stirring was 600 ∼ 900 r⋅min−1 and the highest mixing uniformity was achieved with the blade mounting angle α of 20°. The best structure of double-blade group stirring was achieved with an upper blade mounting angle β of 20°, a lower blade mounting angle θ of −20° and a spacing h of 89 mm. For the air blowing & double-blade stirring method, the best results were achieved when the input air velocity va was 8.4 m⋅s−1 and the blade speed of agitator nb was 740 r⋅min−1. The mixing uniformity of nitrogen (N), phosphate (P) and potash (K) fertilizer granules reached 98.41%, 98.12% and 98.31%, respectively. The bench test results showed that the mixing uniformity by air blowing & double-blade stirring was better than that by double-blade group, and the mixing uniformity by double-blade group was better than that by single-bladed group, which were consistent with the simulation results. Meanwhile the differences between experimental values and simulation values were within 2%, which showed that the simulation models were reliable. Results from this study can be used as reference for the design of mixing devices of variable-rate fertilization.

Multiple isotopes reveal the driving mechanism of high NO3– level and key processes of nitrogen cycling in the lower reaches of Yellow River

The continuous increase of nitrate (NO3–) level in rivers is a hot issue in the world. However, the driving mechanism of high NO3– level in large rivers is still lacking, which has limited the use of river water and increased the cost of water treatment. In this study, multiple isotopes and source resolution models are applied to identify the driving mechanism of high NO3– level and key processes of nitrogen cycling in the lower reaches of the Yellow River (LRYR). The major sources of NO3– were sewage and manure (SAM) in the low-flow season and soil nitrogen (SN) and chemical fertilizer (CF) in the high-flow season. Nitrification was the most key process of nitrogen cycling in the LRYR. However, in the biological removal processes, denitrification may not occur significantly. The temporal variation of contributions of NO3– sources were estimated by a source resolution model in the LRYR. The proportional contributions of SAM and CF to NO3– in the low-flow and high-flow season were 32.5%-52.3%, 44.2%-46.2% and 36.0%-40.8%, 54.9%-56.9%, respectively. The driving mechanisms of high NO3– level were unreasonable sewage discharge, intensity rainfall runoff, nitrification and lack of nitrate removal capacity. To control the NO3– concentration, targeted measures should be implemented to improve the capacity of sewage and wastewater treatment, increase the utilization efficiency of nitrogen fertilizer and construct ecological engineering. This study deepens the understanding of the driving mechanism of high nitrate level and provides a vital reference for nitrogen pollution control in rivers to other area of the world.

No-tillage with straw mulching promotes the utilization of soil nitrogen by rice under wheat-rice and oilseed rape-rice cropping systems.

To investigate the effects of no-tillage with straw mulching on the absorption and utilization of soil nitrogen (N), fertilizer N, and straw N by rice under paddy-upland rotations. A field experiment with three cropping systems: fallow-rice rotation without straw mulching (FRN), wheat-rice rotation with wheat mulching in rice season (WRS), and oilseed rape-rice rotation with oilseed rape straw mulching in rice season (ORS) was conducted from 2015 to 2017, along with a mini-plot experiment with 15N-labeled urea and straws, which was conducted in 2017. No-tillage with straw reduced rice N uptake up to 20 days after transplanting, the total amount of fertilizer N uptake of WRS and ORS rice plants was 46.33 and 61.67 kg/ha, respectively, which was 9.02 and 45.10% higher than that of FRN plants. Soil N was the main source for rice growth, followed by fertilizer N. Soil N uptake by WRS and ORS rice plants was 21.75 and 26.82% higher than that of FRN plants, accounting for 72.37 and 65.47%, respectively, of the total N accumulated in rice plants. Straw mulching increased the N utilization efficiency of tillering, panicle, and total fertilizer by 2.84-25.30%; however, base fertilizer was dependent on straw mulching. The total amount of N released from WRS and ORS straw mulching in the rice season was 34.97 and 24.82 kg/ha, respectively; however, only 3.04 and 4.82% of it was absorbed by the rice plants, accounting for only 0.62 and 0.66% of the total accumulated N. No-tillage with straw mulching under paddy-upland rotations increased the N utilization of rice, especially for the absorption of soil N. These results provide theoretical information for the effective utilization of straw and rational N application practices in rice-based cropping systems.

Biochar Can Partially Substitute Fertilizer for Rice Production in Acid Paddy Field in Southern China

Biochar application has been confirmed as an efficient way to increase the productivity of the agricultural system. However, the potential of biochar combined with reducing fertilization on the yield, and the fertilizer utilization efficiency of the rice (Oryza sativa) farming system on acidic soil remains to be further studied. Field micro-plot experiments with two factors were performed in 2018 and 2019 to evaluate the responses of the rice yield and nutrient utilization to the combined application of biochar (60, 80, and 100 t/ha) and fertilizer reduction (70%, 85%, and standard doses of N-P-K fertilizer). Taoyouxiangzhan and Taiyou 553 were used in the late growing season of 2018 and 2019, respectively. The results showed that compared with the control without adding biochar under standard fertilization, 70% doses of fertilizer application had no negative effects on the yield and the N, P, and K accumulation of rice after biochar application. K accumulation of rice increased with the increase of biochar application. The partial productivity of N, P, and K fertilizers increased as the fertilizer was decreased. The agronomic efficiency of N, P, and K fertilizers significantly increased after the combined applications of biochar and fertilizer. In both years, micro-plots with 70% doses of fertilizer had the highest N and P physiological efficiency, as well as K physiological efficiency in 2019. Compared with the control under standard fertilization, utilization efficiency of N, P, and K fertilizer under different biochar and fertilizer combinations significantly increased by 34.24~75.48%, 27.44~84.84%, and 78.52~166.70%, respectively. To sum up, biochar can partially substitute fertilizer for rice production in acid paddy fields in southern China. When the amount of biochar added is ≥60 t/ha, 70% doses of fertilizer application can still ensure the nutrient absorption of rice, improve the fertilizer utilization efficiency, and ensure the stable yield of rice.

Raspberry Pi-Embedded Intelligent Control System for Irrigation and Fertilization Based on deep learning

More than two-thirds of freshwater consumed worldwide are used for irrigation, and the existing control system for irrigation and fertilization is not intelligent and efficient enough. It is necessary to improve the utilization efficiency of irrigation water and fertilizer, and the intelligent level of irrigation and fertilization system. We have built tomato fertilizer deficiency and fertilization decision model based on leaf images and deep learning, this paper develops an Raspberry Pi-embedded intelligent control system for irrigation and fertilization based on previous deep learning models. The system included sensors, image acquisition, control part, control panel and remote control, the type of main hardware and sensors were selected, and the circuit of the system were designed. The C language is used to compile the source code of the deep learning framework, and the Python language is used to compress the deep learning model. The result shows that the compression rate of the deep learning model can reach 36.7% and the decision-making time can be shortened by 36% under the condition of ensuring the model accuracy. The Raspberry Pi-embedded intelligent control system can help farmers improve the utilization efficiency of irrigation and fertilizer.

The optimum economic nitrogen rate of blended controlled-release nitrogen fertilizer for rice in the Chanoyu watershed in the Yangtze River Delta, China.

The application of controlled-release nitrogen fertilizer (CRN) has become an important production method to achieve high crop yield and ecological safety. However, the rate of urea-blended CRN for rice is usually determined by conventional urea, and the actual rate is still unclear. A five-year field experiment was carried out in the Chaohu watershed in the Yangtze River Delta to study rice yield, N fertilizer utilization efficiency (NUE), ammonia (NH3) volatilization and economic benefit under the four urea-blended CRN treatments with a 4:3:3 ratio applied at one time (60, 120, 180, 240 kg/hm2, CRN60, CRN120, CRN180, CRN240), four conventional N fertilizer treatments (N60, N120, N180, N240) and a control without N fertilizer (N0). The results showed that the N released from the blended CRNs could well satisfy the N demand of rice growth. Similar to the conventional N fertilizer treatments, a quadratic equation was used to model the relationship between rice yield and N rate under the blended CRN treatments. The blended CRN treatments increased rice yield by 0.9-8.2% and NUE by 6.9-14.8%, respectively, compared with the conventional N fertilizer treatments at the same N application rate. The increase in NUE in response to applied blended CRN was related to the reduction in NH3 volatilization. Based on the quadratic equation, the five-year average NUE under the blended CRN treatment was 42.0% when rice yield reached the maximum, which was 28.9% higher than that under the conventional N fertilizer treatment. Among all treatments, CRN180 had the highest yield and net benefit in 2019. Considering the yield output, environmental loss, labor and fertilizer costs, the optimum economic N rate under the blended CRN treatment in the Chaohu watershed was 180-214 kg/hm2, compared with 212-278 kg/hm2 under the conventional N fertilizer treatment. The findings suggest that blended CRN improved rice yield, NUE and economic income while decreasing NH3 volatilization and negative environmental outcomes.

Polyphosphate Accelerates Transformation of Nonstructural Carbohydrates to Improve Growth of ppk-Expressing Transgenic Rice in Phosphorus Deficiency Culture

Crop yield and quality are often limited by the amount of phosphate fertilizer added to infertile soils, a key limiting factor for sustainable development in modern agriculture. The polyphosphate kinase (ppk) gene -expressing transgenic rice with a single-copy line (ETRS) is constructed to improve phosphate fertilizer utilization efficiency for phosphorus resource conservation. To investigate the potential mechanisms of the increased biomass in ETRS in low phosphate culture, ETRS was cultivated in a low inorganic phosphate (Pi) culture medium (15 μmol/L Pi, LP) and a normal Pi culture medium (300 μmol/L Pi, CP), respectively. After 89 d of cultivation in different concentrations of phosphate culture media, the total phosphorus, polyphosphate (polyP), biomass, photosynthetic rate, nonstructural carbohydrate (NSC) contents, related enzyme activities, and related gene expression levels were analyzed. The results showed that ETRS had a high polyP amount to promote the photosynthetic rate in LP, and its biomass was almost the same as the wild type (WT) in CP. The NSC content of ETRS in LP was higher than that of WT in LP, but slightly lower than that of WT in CP. PolyP notably promoted the sucrose phosphate synthase activities of ETRS and significantly down-regulated the expression levels of sucrose transporter genes (OsSUT3 and OsSUT4), resulting in inhibiting the transport of sucrose from shoot to root in ETRS. It was concluded that polyP can stimulate the synthesis of NSCs in LP, which improved the growth of ETRS and triggered the biological activities of ETRS to save phosphate fertilizer. Our study provides a new way to improve the utilization rate of phosphate fertilizer in rice production.

The nitrogen footprint and reactive nitrogen reduction potential of cotton production in China

Analyzing the nitrogen footprint (NF) and the potential reduction of reactive nitrogen in crop production and proposing higher N utilization efficiency strategies are important approaches to sustainable crop development. Cotton is an important cash crop in China. However, only a few studies have systematically quantified the NF of cotton production in China, analyzed its temporal and spatial varieties, clarified its main constituent factors and influential factors, and explored its nitrogen emission reduction potential. This study adopts the life cycle method and analyzes the temporal-spatial varieties in the NF of cotton production in China's main cotton planting areas from 2004 to 2018 based on statistical data, analyzes the main components of the nitrogen footprint of China's cotton production, studies the main driving factors of China's cotton nitrogen emissions based on principal component analysis, simulates the nitrogen emissions of China's cotton production combined with the STIRPAT model, and comprehensively analyzes the potential nitrogen emission reduction of China's cotton production. The results indicated that the average nitrogen footprint per unit area (NFa) of cotton planting districts in Northwest China (Nw.CPD), the Yellow River Basin (Yel.RCPD) and the Yangtze River Basin (Yan.RCPD) was 112 kg Neq·ha−1, 65 kg Neq·ha−1 and 155 kg Neq·ha−1, respectively, and the NFa of cotton production in Hunan was the highest. In terms of spatial distribution, the NFa, NFy and NFv of cotton production in Yan.RCPD were higher than those in Yel.RCPD and Nw.CPD, and the NF of cotton planted in Yel.RCPD was the lowest. The NFa of cotton planting in China increased continuously, and the NFa in Nw.CPD showed an increasing trend, while the NFa in Yel.RCPD and Yan.RCPD showed a decreasing trend. Principal component analysis (PCA) showed that fertilizer and the associated reactive nitrogen losses were the main components of the nitrogen footprint. The prediction results of the STIRPAT model showed that compared with 2018, China's cotton production can reduce nitrogen emissions by 54.43 kilotons in 2050 at most. Improved fertilizer utilization efficiency, optimized field management measures and effective policy intervention are effective strategies to reduce the nitrogen footprint of cotton production.

The win-win effects of nitrification inhibitors on soil-crop systems: Decreasing carbendazim residues but promoting soil bacterial community diversities and stabilities and crop yields

Applying nitrogen (N)-cycling inhibitors is an effective measure to improve N fertilizer utilization efficiency, but the effects of N-cycling inhibitors on fungicide residues in soil-crop systems are unclear. In this study, nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) were applied into agricultural soils with fungicide carbendazim applications. The soil abiotic properties, carrot yields, carbendazim residues, bacterial communities and their comprehensive relationships were also quantified. Compared to the control treatment, the DCD and DMPP significantly decreased soil carbendazim residues by 96.2% and 96.0%, and the DMPP and NBPT significantly reduced carrot carbendazim residues by 74.3% and 60.3%, respectively. The nitrification inhibitor applications also generated significant and positive effects on carrot yields and soil bacterial community diversities. The DCD application significantly stimulated soil Bacteroidota and endophytic Myxococcota and modified soil and endophytic bacterial communities. Meanwhile, the DCD and DMPP applications also positively stimulated the co-occurrence network edges of soil bacterial communities by 32.6% and 35.2%, respectively. The linear correlation coefficients between soil carbendazim residues and pH, ETSA and NH4+-N contents were − 0.84, − 0.57 and − 0.80, respectively. The nitrification inhibitor applications generated win-win effects on the soil-crop systems by decreasing carbendazim residues but promoting soil bacterial community diversities and stabilities and crop yields.

Remediating flooding paddy soils with schwertmannite greatly reduced arsenic accumulation in rice (Oryza sativa L.) but did not decrease the utilization efficiency of P fertilizer

Planting rice (Oryza sativa L.) in As-contaminated paddy soils can lead to accumulation of arsenic (As) in rice grains, while the application of phosphorus (P) fertilizers during rice growth may aggravate the accumulation effect. However, remediating flooding As-contaminated paddy soils with conventional Fe(III) oxides/hydroxides can hardly achieve the goals of effectively reducing grain As and maintaining the utilization efficiency of phosphate (Pi) fertilizers simultaneously. In the present study, schwertmannite was proposed to remediate flooding As-contaminated paddy soil because of its strong sorption capacity for soil As, and its effect on the utilization efficiency of Pi fertilizer was investigated. Results of a pot experiment showed that Pi fertilization along with schwertmannite amendment was effective to reduce the mobility of As in the contaminated paddy soil and meanwhile increase soil P availability. The schwertmannite amendment along with Pi fertilization reduced the content of P in Fe plaque on rice roots, compared with the corresponding amount of Pi fertilizer alone, which can be attributed to the change in mineral composition of Fe plaque mainly induced by schwertmannite amendment. Such reduction in P retention on Fe plaque was beneficial for improving the utilization efficiency of Pi fertilizer. In particular, amending flooding As-contaminated paddy soil with schwertmannite and Pi fertilizer together has reduced the content of As in rice grains from 1.06 to 1.47 mg/kg to only 0.38–0.63 mg/kg and significantly increased the shoot biomass of rice plants. Therefore, using schwertmannite to remediate flooding As-contaminated paddy soils can achieve the dual goals of effectively reducing grain As and maintaining the utilization efficiency of P fertilizers.

Attapulgite application improves maize yield, water, and fertilizer utilization efficiency in newly cultivated sandy farmland in northwestern China

We determined the effects of attapulgite clay additions to sandy soils on maize yield and water-fertilizer use efficiency to evaluate a new method for enhancing productivity in newly-reclaimed farmlands in the oasis. The 2-year field trial included six treatments: no fertilizer, single fertilizer application (N–P2O5–K2O at 320–240–200 kg·ha−1), and combined applications of different amounts of attapulgite clay and fertilizer (attapulgite powder at 1500, 3000, 6000 kg·ha−1), 20% fertilizer reduction (256–192–160 kg·ha−1) and attapulgite powder at 6000 kg·ha−1. The results showed that maize yield increased by 4.9–14.9% and above-ground biomass increased by 6.1–32.3% with the application of 1500, 3000, and 6000 kg·ha−1 of attapulgite powder compared with the single application of fertilizer. With a combined application of a 20% reduction in fertilizer and 6000 kg·ha−1 attapulgite powder, maize yield increased by another 6.6%. Maize irrigation-water productivity (MIWP) increased by 0.03–0.13 kg·m−3, and nitrogen use efficiency (NUE), agronomic efficiency (AEN) and partial productivity factor of nitrogen (PFPN) increased by 10.8–54.0, 15.5–49.5, and 4.6–14.8%, respectively, compared with no attapulgite application. The contribution rate of fertilizer to maize yield increment improved by 10.0–30.1% with attapulgite application. The attapulgite clay application increased the field water capacity of sandy soils, nutrient retention in the 0–40 cm soil layer, and reduced nutrient leaching losses to deeper soils, thus improving water-fertilizer use efficiency. In Linze County, the abundant reserves of attapulgite clay may be used as a regular application in sandy farmlands in newly-reclaimed oases for a new promising way to rapidly improve sandy soil structure, enhance water-fertilizer use efficiency, and increase crop yields.

Comprehensive evaluation of the optimal rates of irrigation and potassium application for strawberry

Accurate and effective management of irrigation and fertilization is essential for efficient greenhouse strawberry production. Here, the effects of the combined application of water and potassium on strawberry growth were evaluated by experimenting with 12 treatments, including four transpiration (ETC)-based irrigation levels (W1: 100% ETC, W2: 85% ETC, W3: 70% ETC, and W4: 55% ETC) and three potassium levels according to the target yield (K1: 369.5 kg/hm2, K2: 307.9 kg/hm2, and K3: 246.3 kg/hm2). Various indexes of strawberry yield, fruit quality, water and fertilizer utilization efficiency, and soil nutrient residues were measured. Irrigation and potassium application had significant effects on strawberry production. Higher irrigation levels increased yield (Y), and moderate water and potassium application increased single fruit weight (SFW), water utilization efficiency (WUE), total soluble sugar (TSSC), and the sugar-acid ratio (SAR). While low-application of potassium increased the soluble protein content (SP), partial factor productivity of potassium (PFPK), and reduce nutrient residues in soil effectively. A comprehensive system for evaluating strawberry growth and its benefits to the soil environment was developed. The FAHP and CRITIC methods were used to calculate the subjective weight and objective weight of each index, respectively. The largest subjective weight was observed for Y (0.200), and the largest objective weight was observed for soil-available potassium (0.101). The final weight was determined using Game theory; Y had the highest weight (0.185), and free amino acids (FAA) had the lowest weight (0.047). Grey relational analysis (GRA) was used to evaluate the optimal irrigation and potassium scheme for accomplishing multiple objectives. The response of the comprehensive score of strawberries to irrigation and potassium exhibited a negative parabolic relationship, and the effect of irrigation was greater than the effect of potassium application. There was a significant interaction between irrigation and potassium application, and an irrigation amount of 2053-2525 m3/hm2 with a potassium application rate of 288.1-334.2 kg/hm2 was optimal for promoting strawberry yield, fruit quality, and efficiency and reducing soil nutrient residues. The results of this study provide new insights that could aid the development of sustainable approaches for enhancing agricultural production. Keywords: strawberry, irrigation, potassium, FAHP, CRITIC, nutrient residues DOI: 10.25165/j.ijabe.20231602.7591 Citation: Yang X Q, Du R C, Zhang M C, Feng H W, Wang Z Q, Zhang Z. Comprehensive evaluation of the optimal rates of irrigation and potassium application for strawberry. Int J Agric & Biol Eng, 2023; 16(2): 65-72.

Effects of the configurations with different organic and inorganic fertilizers on grain yield and its related physiological traits of the main and its ratoon rice crops

The determination for properly combined application rate of organic and inorganic fertilizers is the key to coordinating soil nutrient supplies and rice growth demands, thereby obtaining improved economic and ecological returns in rice ratooning. A complete randomized block design (RCBD) trial with different configurations of organic and inorganic nitrogen fertilizers was conducted to determine the optimal substitution rate of organic nitrogen for inorganic nitrogen and its effect on the related physiological attributes and yield performance of the main and ratoon rice crops in 2018−2019. The results showed that 30% organic and 70% inorganic nitrogen in the mixture fertilizer (GM2) could produce the best effect on root activity, nitrogen nutrient uptake and its utilization, as well as the dry matter accumulation and its partitioning. This in turn resulted in improved productive panicles and harvest index, and hence increased grain yield by 10.36% and 15.48% in GM2 regime relative to that in CF treatment. Moreover, the uptake and utilization efficiency, agronomic utilization efficiency and partial productivity of nitrogen fertilizer were 44.37%, 23.82 kg/kg and 48.97 kg/kg, respectively under the optimal GM2 treatment, which were much higher than those in CF treatment by 12.66%, 5.05% and 13.4%, respectively. The results suggested that properly combined application of organic and chemical nitrogen fertilizer could improve soil nutrient supply to guarantee an efficient plant growth and rational dry matter allocation, thereby increasing the harvest index and grain yield in rice ratooning.