Fertilizer Utilization Efficiency Research Articles

Effects of Controlled-release Blended Fertilizer on Crop Yield and Greenhouse Gas Emissions in Wheat-maize Rotation System

The increasing use of nitrogen fertilizers exerts extreme pressure on the environment (e.g., greenhouse gas emissions, GHGs) for winter wheat-summer maize rotation systems in the North China Plain. The application of controlled-release fertilizers is considered as an effective measure to improve crop yield and nitrogen fertilizer utilization efficiency. To explore the impact of one-time fertilization of controlled-release blended fertilizer on crop yield and GHGs of a wheat-maize rotation system, field experiments were carried out in Dezhou Modern Agricultural Science and Technology Park from 2020 to 2022. Five treatments were established for both winter wheat and summer maize, including no nitrogen control (CK), farmers' conventional nitrogen application (FFP), optimized nitrogen application (OPT), CRU1 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 5:5 and 3:7, respectively), and CRU2 (the blending ratio of coated urea and traditional urea on winter wheat and summer maize was 7:3 and 5:5, respectively). The differences in yield, nitrogen fertilizer utilization efficiency, fertilization economic benefits, and GHGs among different treatments were compared and analyzed. The results showed that nitrogen application significantly increased the single season and annual crop yields of the wheat-maize rotation system (P < 0.05). Compared with those of FFP, the CRU1 and CRU2 treatments increased the yields of summer maize by 0.4% to 5.6%, winter wheat by -5.4% to 4.1%, and annual yields by -1.1% to 3.9% (P > 0.05). N recovery efficiency (NRE), N agronomic efficiency (NAE), and N partial factor productivity (NPFP) were increased by -8.6%-43.4%, 2.05-6.24 kg·kg-1, and 4.24-10.13 kg·kg-1, respectively. Annual net income increased by 0.2% to 6.3%. Nitrogen application significantly increased the annual emissions of soil N2O and CO2 in the rotation system (P < 0.05) but had no effect on the annual emissions of CH4 (except for in the FFP treatment in the first year). The annual total N2O emissions under the CRU1 and CRU2 treatments were significantly reduced by 23.4% to 30.2% compared to those under the FFP treatment (P < 0.05). Additionally, nitrogen application significantly increased the annual global warming potential (GWP) of the rotation system (P < 0.05), but the intensity of greenhouse gas emissions was reduced due to the increase in crop yields. Compared with that under FFP, the annual GWP under the CRU1 and CRU2 treatments decreased by 9.6% to 11.5% (P < 0.05), and the annual GHGs decreased by 11.2% to 13.8% (P > 0.05). In summary, the one-time application of controlled-release blended fertilizer had a positive role in improving crop yield and economic benefits, reducing nitrogen fertilizer input and labor costs, and GHGs, which is an effective nitrogen fertilizer management measure to promote cleaner production of food crops in the North China Plain.

Optimizing the Mulching Pattern and Nitrogen Application Rate to Improve Maize Photosynthetic Capacity, Yield, and Nitrogen Fertilizer Utilization Efficiency.

Residual film pollution and excessive nitrogen fertilizer have become limiting factors for agricultural development. To investigate the feasibility of replacing conventional plastic film with biodegradable plastic film in cold and arid environments under nitrogen application conditions, field experiments were conducted from 2021 to 2022 with plastic film covering (including degradable plastic film (D) and ordinary plastic film (P)) combined with nitrogen fertilizer 0 (N0), 160 (N1), 320 (N2), and 480 (N3) kg·ha-1. The results showed no significant difference (p > 0.05) in dry matter accumulation, photosynthetic gas exchange parameters, soil enzyme activity, or yield of spring maize under degradable plastic film cover compared to ordinary plastic film cover. Nitrogen fertilizer is the main factor limiting the growth of spring maize. The above-ground and root biomass showed a trend of increasing and then decreasing with the increase in nitrogen application level. Increasing nitrogen fertilizer can also improve the photosynthetic gas exchange parameters of leaves, maintain soil enzyme activity, and reduce soil pH. Under the nitrogen application level of N2, the yield of degradable plastic film and ordinary plastic film coverage increased by 3.74~42.50% and 2.05~40.02%, respectively. At the same time, it can also improve water use efficiency and irrigation water use efficiency, but it will reduce nitrogen fertilizer partial productivity and nitrogen fertilizer agronomic use efficiency. Using multiple indicators to evaluate the effect of plastic film mulching combined with nitrogen fertilizer on the comprehensive growth of spring maize, it was found that the DN2 treatment had the best complete growth of maize, which was the best model for achieving stable yield and income increase and green development of spring maize in cold and cool irrigation areas.

Hydrogel Nanocomposite Based Slow-Release Urea Fertilizer: Formulation, Structure, and Release Behavior

To enhance the nitrogen utilization efficiency of fertilizers, we developed a novel slow-release fertilizer hydrogel through free radical polymerization, incorporating lignin-containing cellulose nanofiber (LCNF), clinoptilolite (CL), urea, and acrylic acid (AA)-co-acrylamide (AAm) polymer. Various analytical techniques were utilized to examine the structure, swelling, and release behaviors of the fabricated hydrogels with varying LCNF concentrations. The results indicated that the addition of 10% LCNF led to a decrease in water absorption from 72.44 g g−1 to 24.04 g g−1. However, re-swelling was significantly enhanced, with a reduction in re-swelling capacity loss from 32.91% to 23.52%. Concurrently, water retention capacity notably increased from 18.03% to 39.20%. The hydrogel containing 10% LCNF exhibited a slower urea release over 30 days. The kinetic studies revealed that the swelling and urea release behaviors align well with the second-order kinetics model and the Peppas-Sahlin model, respectively. In summary, the developed LCNF/CL/(AA-co-AAm)/urea hydrogel nanocomposites present a novel strategy for the future production and utilization of slow-release fertilizers in agricultural and horticultural fields.

Substituting Partial Chemical Fertilizers with Bio-Organic Fertilizers to Reduce Greenhouse Gas Emissions in Water-Saving Irrigated Rice Fields

Conventional water and fertilizer management practices have led to elevated greenhouse gas emissions from rice fields and decreased the efficiency of water and fertilizer utilization in agricultural land. The implementation of water-saving irrigation and the substitution of chemical fertilizers with organic alternatives can influence CH4 and N2O emissions in rice fields. However, it remains unclear how the simultaneous application of both methods will affect the CH4 and N2O emissions in rice fields. Therefore, two irrigation methods (F: flooded irrigation; C: controlled irrigation) and three fertilization modes (A: full chemical fertilizer; B: bio-organic fertilizer replacing 15% chemical nitrogen fertilizer; C: bio-organic fertilizer replacing 30% chemical nitrogen fertilizer) were set up through field experiments to explore the effect of greenhouse gas emission reduction in rice fields by combining controlled irrigation and bio-organic fertilizers. Substituting some chemical fertilizers with bio-organic fertilizers can lower the peak CH4 and N2O fluxes in rice fields, leading to a decrease in the cumulative CH4 and N2O emissions by 11.9~29.7% and 10.8~57.3%, respectively. The reductions led to a considerable decrease in the global warming potential (GWP) and the greenhouse gas emission intensity (GHGI) by 16.1~48.1% and 16.3~48.1%, respectively. Controlled irrigation significantly reduced CH4 emissions by 55.2~69.4% compared with flooded irrigation in rice fields. However, it also increased N2O emissions by 47.5~207.9%, considerably reducing their GWPs by 11.8~45.5%. Neither bio-organic fertilizer substitution nor controlled irrigation significantly affected rice yield. Replacing 15% of chemical nitrogen fertilizers with bio-organic fertilizers in controlled irrigation rice fields can minimize rice GWP and GHGI. The study’s results are of significant importance for enhancing the regulation of greenhouse gases in farmland and achieving sustainable agriculture through cleaner production.

Nitrogen Utilization and Loss of the Tea Plantation System on Sloped Farmland: A Short-Term Response to Substitution with Organic Fertilizer

(1) Background: Excessive nitrogen (N) fertilizer application in tea plantations leads to challenges such as soil acidification and nitrogen loss, impending the sustainable development of the plantation system. Yet, there is a lack of research on blended fertilization strategies, and limited data regarding N loss when substituting with organic fertilizer. (2) Methods: A year-long field monitoring experiment was conducted to evaluate the effects of substituting compound fertilizer with organic fertilizer, specifically with respect to runoff N loss and uptake of chemical fertilizer N by tea trees. (3) Results: The annual runoff N loss ranged from 0.16 to 0.57 kg·hm−2 and accounted for a mere 0.22–0.48% of N from fertilizer applications. Substitution with organic fertilizer reduced runoff N loss by 21–53% and improved the tea tree utilization efficiency of chemical fertilizer N from 16% to 27%. A 50% organic fertilizer substitution (based on the amount of N) promoted a net soil N mineralization rate, creating an ammonium-rich environment favored by tea trees. (4) Conclusions: The positive effects of partially substituting N fertilizer with organic fertilizer in tea plantation systems on both N utilization efficiency and N loss were confirmed. If conditions permit, the study team would aim to expand the temporal scope of the study, and to investigate the impact of organic fertilizer substitution on N loss under various precipitation intensities.

Enhanced fertilizer utilization and heavy metals immobilization by ball-milling bentonite with NH4Cl: Experiments and DFT calculations

Over-application of nitrogen fertilizer induces soil acidification, which activates heavy metals availability and poses significant challenge to crop production and food safety. In this study, we prepared a clay-based material by ball-milling bentonite with NH4Cl (NH4Cl@bentonite) and assessed its synergistic performance in enhancing nitrogen fertilizer utilization efficiency, immobilizing heavy metals, and improving crop yield and safety. The results showed that the optimal performance of NH4Cl@bentonite was achieved by milling bentonite with NH4Cl at a 4:1 mass ratio for 9 h. NH4Cl@bentonite significantly improved soil water holding and retention capacity by 1.6 and 4.3 times, respectively. In comparison to NH4Cl alone, NH4Cl@bentonite led to a 22.3% increase in N-use efficiency and a 1.5 times enhancement in crop yield. The Pb and Cd content in water spinach shoots decreased by 55.3% and 57.5%, respectively, attributed to the transformation of heavy metals into lower bioavailability states by NH4Cl@bentonite. Experiments and Density Functional Theory (DFT) calculations indicated that NH4Cl@bentonite could immobilize Pb and Cd through processes such as cation exchange, surface adsorption, complexation, and enhancement of soil pH. This work proposes a simple and efficient method for improving cropland fertilizer utilization while ensuring healthy and sustainable development. Environmental implicationSoil acidification, caused using chemical fertilizers, especially nitrogen-based ones, threatens crop production and food safety by damaging soil structure, speeding up nutrient loss, and increasing the solubility of heavy metals. To tackle this problem, we made a clay material by mixing bentonite with NH4Cl (NH4Cl@bentonite) in a ball mill. NH4Cl@bentonite increased N-use efficiency by 22.3%, boosted crop yield by 1.5 times, and reduced the Pb and Cd levels in water spinach shoots by 55.3% and 57.5%, respectively. This work suggests a simple and effective way to enhance fertilizer use in croplands while ensuring healthy and sustainable development.

Can deep fertilization in spring maize fields improve soil properties and their distribution in soil profile?

Deep fertilization strategy has been proven to be an important fertilizer management method for improving fertilizer utilization efficiency and crop yield. However, the relationship between soil chemical and biochemical characteristics and crop productivity under different fertilization depth patterns still needs comprehensive evaluation. Field tests on spring maize were therefore carried out in the Loess Plateau of China for two successive growing seasons from 2019 to 2020. Four distinct fertilization depths of 5 cm, 15 cm, 25 cm, and 35 cm were used to systematically investigate the effects of fertilization depth on soil physicochemical parameters, enzyme activity, and biochemical properties. The findings demonstrated that although adjusting fertilization depths (D15, D25) did not significantly affect the soil organic carbon content, they did significantly improve the soil chemical and biochemical characteristics in the root zone (10–30 cm), with D25 having a greater influence than D15. Compared with D5, the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), Olsen-P, dissolved organic carbon, and nitrogen (DOC and DON) in the root zone of D25 significantly increased by 12.02%, 7.83%, 22.21%, 9.56%, 22.29%, and 26.26%, respectively. Similarly, the urease, invertase, phosphatase, and catalase in the root zone of D25 significantly increased by 9.56%, 13.20%, 11.52%, and 18.05%, while microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased by 18.91%, 32.01% and 26.50%, respectively, compared to D5. By optimizing the depth of fertilization, the distribution ratio of Ca2–P and Ca8–P in the inorganic phosphorus components of the root zone can also be increased. Therefore, optimizing fertilization depth helps to improve soil chemical and biochemical characteristics and increase crop yield. The results of this study will deepen our understanding of how fertilization depth influence soil properties and crop responses.

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=37.5mm, W2=45.5mm, W3=52.5mm) and three organic fertilizer application amounts (F1=3900-300kg 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: 52.5mm; 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.

Research on Underground Drip Irrigation and Soil Redistribution - Take Heshan District of Yiyang City as an Example

Abstract: The drip flow and the buried depth of drip irrigation zone are not only important parameters of subsurface irrigation design and operation management, but also important factors affecting the migration and redistribution of soil water and fertilizer. Crop growth is closely related to soil water and nitrogen leaching, water and fertilizer transport patterns and redistribution characteristics. It is of great significance to study the migration and redistribution of soil water and fertilizer under subsurface drip irrigation for improving the utilization efficiency of water and fertilizer and improving the system of subsurface drip irrigation. In this paper, the migration mode and redistribution characteristics of water and nitrogen in subsurface drip irrigation were studied and analyzed by means of laboratory soil box experiment, considering the two factors of drip flow and the buried depth of drip irrigation belt. The main research conclusions are as follows: Ⅰ. Different drip flows had effects on soil moisture front, soil moisture content and soil water redistribution. If other conditions remain unchanged, increasing the drip flow can increase the moist body area of soil and increase the moisture content of soil. The distance between vertical and horizontal directions increased with the large drip flow, and the soil water content decreased with the increase of distance. Large drip flow can promote the redistribution of soil water after drip irrigation. Ⅱ. Different drip depth had effects on soil moisture content and soil water redistribution. When the drip depth was 0cm, the surface shape of the wet body was a "horizontal" semi-ellipse after drip irrigation. When the drip depth was 10cm and 20cm, the surface of the wet body was an "upright" semi-ellipse after drip irrigation. The larger the buried depth of the drip can make the distribution of soil moisture more uniform, and the larger the buried depth of the drip can promote the migration of water in the soil. Ⅲ. Different drip discharge had an effect on soil nitrogen redistribution, and large drip discharge promoted soil nitrogen redistribution after drip irrigation. The Nitrate Nitrogen (NO3--N) content in the moist body is lower than that near the edge of the wetting front. The content of Ammonium Nitrogen (NH4+-N) near the edge of the wetting peak is higher than that inside the wetting body. Ⅳ. The redistribution of soil nitrogen was affected by different buried depth of drip head, and the greater buried depth of drip head could promote the redistribution of soil nitrogen. In terms of vertical and horizontal migration of ammonium nitrogen and nitrate nitrogen, on the day after drip irrigation, the cumulative effect of Nitrate Nitrogen (NO3--N) buried at a depth of 20cm was more significant near the wetting front edge at a larger vertical downward distance, and the cumulative effect of Nitrate Nitrogen (NO3--N) buried at a depth of 20cm was more significant inside the wetting body at a larger vertical downward distance. At the same time, the drip buried depth of 20cm can spread the cumulative effect inside the wet body and near the edge of the wet front to a longer horizontal distance.

Performance of a Drip Irrigation System under the Co-Application of Water, Fertilizer, and Air

The co-application of water, fertilizer, and air is a new water-saving irrigation method based on drip irrigation technology, which can effectively alleviate the phenomenon of soil rhizosphere hypoxia, improve water and fertilizer utilization efficiency, and inhibit the clogging of irrigation equipment in drip irrigation systems. The performance of drip irrigation systems is one of the important factors affecting the effectiveness of the co-application of water, fertilizer, and air. However, the impact of factors such as the aeration method, fertilization device, and working parameters on the performance of drip irrigation systems for the co-application of water, fertilizer, and air is still unclear. Therefore, based on two typical aeration methods, i.e., micro-nano and Venturi aeration, the performance of a drip irrigation system under the co-application of water, fertilizer, and air was studied by comparing and analyzing the effects of different aeration methods, working pressures of the drip irrigation system, and the pressure difference between the inlet and outlet of fertilizer irrigation on the spatial distribution uniformity of water, fertilizer, and air in the drip irrigation pipeline network. The results showed that the pressure difference between the inlet and outlet of fertilization irrigation had no significant impact on system performance, while the working pressure significantly affected system performance. Compared with the effective effect of Venturi aeration on system performance, micro-nano aeration can significantly affect drip irrigation system performance and effectively improve drip irrigation system performance. The micro-nano-aerated drip irrigation system with the co-application of water, fertilizer, and air under a working pressure of 0.1 MPa has better system performance. The research results are of great significance for revealing the mechanism underlying the impact of the co-application of water, fertilizer, and air on the performance of drip irrigation systems and constructing efficient drip irrigation technology for the co-application of water, fertilizer, and air.

PH-responsive chitosan nanoparticles for controlled-release nitrogen fertilizer: Template-tampering free radical graft copolymerization under energetic radiation study

Macromolecular template-tampering free radical graft copolymerization under energetic radiation is studied as a controlled process for fabricating and nanosizing chitosan-graft-polyacrylic acid interpolymer complex (CS-PAA IPC) nanoparticles. The CS-PAA IPC nanoparticles is proposed as a pH-responsive vehicle for water absorption and controlled release of nitrogen (N) fertilizer. Roles of chitosan macromolecular template and absorbed energy for controlling free radical graft copolymerization in an aqueous solution were studied. Controlling graft copolymerization, nanostructure, nanosize, and size distribution of the CS-PAA IPC nanoparticles were followed by varying different parameters, i.e., CS template chain length, AA concentrations (0.03–0.15 M), and absorbed energies (10–30 kJ/kg, kGy). The CS-PAA IPC nanoparticles have well-defined in spherical shape with the size in the range of 30–200 nm. The pre-irradiated CS template provides a crucial role for narrowing size distribution of the CS-PAA IPC nanoparticles. Kinetic swelling behavior, water absorption/diffusion mechanism, nitrogen (N) fertilizer (ammonium nitrate, NH4NO3) entrapment/controlled release based on pH-responsive characteristic were investigated in acidic to basic ranges (pH 5, 7 and 9). The diffusion mechanism of the CS-PAA IPC nanoparticles exhibited a non-Fickian diffusion. The N content was 23 g per 100 g of CS-PAA IPC nanoparticles fertilizer. Pot-testing was carried out through the baby corn growth in different soil conditions, i.e., sandy soil (SS), SS/ NH4NO3, SS/NH4NO3-entrapped CS-PAA, and cultivation soil/NH4NO3. The CS-PAA IPC nanoparticles is a promising water absorption and pH-responsive platform for N fertilizer entrapment and controlled-release for soil amending, enhancing fertilizer utilization efficiency, and reducing environmental impact due to N loss.

Controlled-Release Nitrogen Mixed with Common Nitrogen Fertilizer Can Maintain High Yield of Rapeseed and Improve Nitrogen Utilization Efficiency.

Field experiments were conducted to study the effects of different proportions of controlled-release nitrogen fertilizer mixed with quick-acting nitrogen fertilizer on the yield and nitrogen utilization efficiency of direct-seeding rapeseed. Using a conventional nitrogen application rate of 180 kg ha-1 as a control, a total of 5 types of available nitrogen fertilizers and different proportions of controlled-release nitrogen fertilizers were mixed for fertilizer treatment. The proportion of available nitrogen fertilizer used was 135 kg ha-1, and the addition ratios of the five types of controlled-release nitrogen fertilizers were 0%, 30%, 50%, 70%, and 100%, respectively (i.e., the proportion of controlled-release nitrogen to the total nitrogen application amount). These ratios were represented as N135R0, N135R1, N135R2, N135R3, and N135R4, respectively. The results showed that there was no significant difference in the number of pods per plant, the number of seeds per pod, or the grain yield under the treatment of controlled-release nitrogen fertilizer mixed with quick-acting nitrogen fertilizer for proportions of 30-50% (N135R1~R3) when compared with the control, and a stable yield was achieved. Mixing controlled-release nitrogen fertilizer under reduced nitrogen application can significantly improve the apparent utilization rate of rapeseed nitrogen fertilizer, but it first increases and then decreases with the increase of the controlled-release nitrogen mixing ratio, reaching its highest under the N135R2 treatment. The agronomic utilization efficiency and partial productivity of nitrogen fertilizer first increased and then decreased with the increased proportion of controlled-release nitrogen, and both reached their highest utilization with the N135R2 treatment. The mixed treatment of controlled-release nitrogen did not affect soil urease activity, but significantly increased soil sucrase activity. The mixed treatment of controlled-release nitrogen also increased soil microbial biomass nitrogen and carbon content. Especially in the flowering stage, the soil microbial biomass nitrogen and carbon content was significantly higher under a controlled-release nitrogen mixing ratio of 30-50%. At the same time, it had a similar effect on soil inorganic nitrogen content. Therefore, a controlled-release nitrogen mixing treatment provided sufficient nitrogen for the key growth period of rapeseed. Under the condition of reducing the amount of nitrogen fertilizer by 25% based on the amount of nitrogen fertilizer applied to conventional rapeseed, the application of controlled-release urea mixed with common nitrogen fertilizer mixed at a ratio of 30-50% can be an effective way to maintain grain yield levels and improve nitrogen utilization efficiency.

Mitigating growth-stress tradeoffs via elevated TOR signaling in rice

Rice production accounts for approximately half of the freshwater resources utilized in agriculture, resulting in greenhouse gas emissions such as methane (CH4) from flooded paddy fields. To address this challenge, environmentally friendly and cost-effective water-saving techniques have become widely adopted in rice cultivation. However, the implementation of water-saving treatments (WSTs) in paddy-field rice has been associated with a substantial yield loss of up to 50% as well as a reduction in nitrogen use efficiency (NUE). In this study, we discovered that the target of rapamycin (TOR) signaling pathway is compromised in rice under WST. Polysome profiling-coupled transcriptome sequencing (polysome-seq) analysis unveiled a substantial reduction in global translation in response to WST associated with the downregulation of TOR activity. Molecular, biochemical, and genetic analyses revealed new insights into the impact of the positive TOR-S6K-RPS6 and negative TOR-MAF1 modules on translation repression under WST. Intriguingly, ammonium exhibited a greater ability to alleviate growth constraints under WST by enhancing TOR signaling, which simultaneously promoted uptake and utilization of ammonium and nitrogen allocation. We further demonstrated that TOR modulates the ammonium transporter AMT1;1 as well as the amino acid permease APP1 and dipeptide transporter NPF7.3 at the translational level through the 5′ untranslated region. Collectively, these findings reveal that enhancing TOR signaling could mitigate rice yield penalty due to WST by regulating the processes involved in protein synthesis and NUE. Our study will contribute to the breeding of new rice varieties with increased water and fertilizer utilization efficiency.

Carbon footprint of major grain crops in the middle and lower reaches of the Yangtze River during 2011-2020

The middle and lower reaches of the Yangtze River is one of main grain production areas in China, which is of great significance to food security. Understanding the carbon footprint of major grain crop production is helpful to develop high-yield and low-carbon agriculture. Based on the data of yield, sown area and farmland production input of main grain crops (rice, wheat and maize) in six provinces (Jiangsu, Anhui, Jiangxi, Hubei, Hunan, and Zhejiang) in the middle and lower reaches of the Yangtze River from 2011 to 2020, we estimated carbon footprint in the production of the three grain crops. The results showed that from 2011 to 2020, yield per unit area, planting area, and total yield of rice, wheat and maize were the highest in Jiangsu Province. In terms of area-scaled carbon footprint, rice in the middle and lower reaches of the Yangtze River had the highest area-scaled carbon footprint, with an average of 2.0 t CE·hm-2, followed by wheat and maize. The area-scaled carbon footprint of the three staple crops was increasing. In terms of yield-scaled carbon footprint, rice was the highest, with an average of 0.8 kg CE·kg-1, followed by wheat and maize. In terms of carbon input structure, irrigation electricity, chemical fertilizers and pesticides accounted for a relatively high proportion. Irrigation electricity accounted for 35.0%, 36.3%, and 33.2% of the total carbon input of rice, wheat and maize, respectively. Chemical fertilizers accounted for 28.8%, 32.5%, and 32.5%, respectively, while pesticides accounted for 24.2%, 13.3% and 11.5%, respectively. In terms of carbon efficiency, maize had the highest (3.9 kg·kg-1 CE), followed by rice and wheat. With the green development of agriculture, carbon emission in the production of major grain crops in the middle and lower reaches of the Yangtze River could be reduced by improving irrigation efficiency, fertilizer utilization efficiency, pesticide utilization efficiency and mechanized operation efficiency, as well as diversification of straw returning, cultivation of new varieties and policy leverage.

Increasing iron use efficiency by controlling emitter clogging in drip irrigation systems

Iron is one of the essential elements for crop growth. Traditional iron fertilizer application method by injecting iron into soil results in low utilization efficiency of iron fertilizer and a considerable amount of iron residue in the soil. Applying iron fertilizer by drip irrigation system could effectively improve the utilization efficiency of iron fertilizer. However, emitter clogging seriously restrict this technology. Here, the effects of different types of iron fertilizers [Ferrous sulfate (FeSO4); Ferric citrate (FC-Fe); Sodium ferric ethylenediamine tetraacetate (EDTA-Fe); And no iron fertilizer (CK)] on emitters clogging were assessed. The components of emitter clogging substances were detected through X-ray Diffraction and Fourier Transform Infrared Spectrometer. The results showed that different types of iron fertilizers significantly affected emitter clogging. EDTA-Fe application significantly mitigated emitter clogging, reduced the total amount of clogging substances by 49.6% on average, and increased the emitter flow rate by 21.0%. This is due to EDTA-Fe chelated scaling cations (e.g., Ca2+) in water through its functional groups, thereby reducing the contents of calcite, monohydrate calcite and dolomite. However, FeSO4 and FC-Fe application aggravated emitter clogging, and increased the total clogging substances by 52.3% and 105.8%, respectively. Surprisingly, iron precipitation was not detected in the clogging substances. FeSO4 and FC-Fe aggravated clogging mainly by increasing the formation of particulate fouling (e.g., muscovite) and chemical precipitation (e.g., calcite). This study suggested choosing EDTA-Fe in drip irrigation systems to reduce emitter clogging. The research results are of significance for improving the utilization efficiency of iron fertilizer and promoting the application of iron fertilizer drip irrigation technology.

Metabolome and transcriptome analyses provide new insights into the mechanisms underlying the enhancement of medicinal component content in the roots of Acanthopanax senticosus (Rupr. et Maxim.) Harms through foliar application of zinc fertilizer.

Acanthopanax senticosus (Rupr. et Maxim.) Harms is a perennial shrub of the Acanthopanax genus in the Araliaceae family and has a high medicinal value. The application of zinc fertilizer can improve the yield and quality of medicinal materials. However, there are limited reports on approaches to increase the content of medicinal components in A. senticosus, hindering the improvement of its medicinal quality. In this study, A. senticosus was treated with 0.1% (LZn) and 0.4% (HZn) zinc sprayed on the leaf surface. The effects of zinc treatment on the medicinal components in the roots of A. senticosus were analyzed by comprehensive metabolomics and transcriptomics analyses. A total of 316 metabolites were detected, with a prevailing occurrence of terpenoids and phenylpropanoids. We identified metabolites related to the medicinal components that were upregulated after Zn treatment, including 43 terpenoids, 19 phenylpropanoids, eight phenols, and three flavonoids. Combining differential gene expression and K-means analysis, we found 95, 65, and 25 upregulated genes related to phenylpropanoid biosynthesis, terpenoid biosynthesis, and flavonoid biosynthesis, respectively. Under different concentrations of Zn treatment, the upregulated metabolite biosynthesis-related genes and differentially expressed transcription factors varied. Pearson correlation network analysis revealed significant correlations among terpenoids, phenylpropanoids, flavonoids biosynthetic genes, and several transcription factors (ERFs, WRKYs, bHLHs, NACs, and MYBs). This study lays the foundation for understanding the metabolic processes in response to varying levels of zinc foliar spray and provides a theoretical basis for enhancing the efficiency of zinc fertilizer utilization in A. senticosus.

Estimation of Agronomic Characters of Wheat Based on Variable Selection and Machine Learning Algorithms

Wheat is one of the most important food crops in the world, and its high and stable yield is of great significance for ensuring food security. Timely, non-destructive, and accurate monitoring of wheat growth information is of great significance for optimizing cultivation management, improving fertilizer utilization efficiency, and improving wheat yield and quality. Different color indices and vegetation indices were calculated based on the reflectance of the wheat canopy obtained by a UAV remote sensing platform equipped with a digital camera and a hyperspectral camera. Three variable-screening algorithms, namely competitive adaptive re-weighted sampling (CARS), iteratively retains informative variables (IRIVs), and the random forest (RF) algorithm, were used to screen the acquired indices, and then three regression algorithms, namely gradient boosting decision tree (GBDT), multiple linear regression (MLR), and random forest regression (RFR), were used to construct the monitoring models of wheat aboveground biomass (AGB) and leaf nitrogen content (LNC), respectively. The results showed that the three variable-screening algorithms demonstrated different performances for different growth indicators, with the optimal variable-screening algorithm for AGB being RF and the optimal variable-screening algorithm for LNC being CARS. In addition, using different variable-screening algorithms results in more vegetation indices being selected than color indices, and it can effectively avoid autocorrelation between variables input into the model. This study indicates that constructing a model through variable-screening algorithms can reduce redundant information input into the model and achieve a better estimation of growth parameters. A suitable combination of variable-screening algorithms and regression algorithms needs to be considered when constructing models for estimating crop growth parameters in the future.

Nitrogen (N) “supplementation, slow release, and retention” strategy improves N use efficiency via the synergistic effect of biochar, nitrogen-fixing bacteria, and dicyandiamide

Irrational nitrogen (N) fertilizer management and application practices have led to a range of ecological and environmental problems that seriously threaten food security. In this study, an effective N fertilizer management strategy was established for improving N fertilizer utilization efficiency (NUE). Biochar, N2-fixing bacteria (Enterobacter cloacae), and a nitrification inhibitor (dicyandiamide, DCD) were simultaneously added to the soil during maize cultivation. The goal was to increase soil ammonium nitrogen content and NUE by regulating the relative abundance, enzyme activity, and functional gene expression of N conversion-related soil microbes. Biochar combined with E. cloacae and DCD significantly increased soil N content, and the NUE reached 46.69 %. The relative abundance of Burkholderia and Bradyrhizobium and the activity of nitrogenase increased significantly during biological N2 fixation. Further, the abundance of the nifH gene was significantly up-regulated. The relative abundance of Sphingomonas, Pseudomonas, Nitrospira, and Castellaniella and the activities of ammonia monooxygenase and nitrate reductase decreased significantly during nitrification and denitrification. Moreover, the abundance of the genes amoA and narG was significantly down-regulated. Correlation analyses showed that the increase in soil N2 fixation and the suppression of nitrification and denitrification reactions were the key contributors to the increase in soil N content and NUE. Biochar combined with E. cloacae and DCD synergistically enabled the supplementation, slow release, and retention of N, thus providing adequate N for maize growth. Thus, the combination of biochar, E. cloacae, and DCD is effective for mitigating the irrational application of N fertilizers and reducing N pollution.

Water retention and sustained release of magnesium-based biochar modified hydrogel composite materials

In recent years, the low utilization efficiency of fertilizers and the scarcity of freshwater resources caused by globalization have received widespread attention. To address these issues, this study used an in-situ polymerization method to prepare a magnesium-based biochar modified hydrogel slow-release fertilizer (Mg-NBC/PAA) by combining magnesium-based biochar slow-release fertilizer (Mg-NBC) with polyacrylic acid hydrogel. The composition and properties of the material were characterized using various techniques, including FT-IR, SEM, XPS, and CA. The results show that the Mg-NBC successfully entered the network structure of the hydrogel material, and the hydrogel with added biochar exhibited higher water absorption performance than the pure hydrogel, with an improvement of 47.12%. Under the optimal synthesis conditions, the maximum water absorption capacity of the material was 1395.12 ± 35.45 g/g, which can increase soil water retention and holding capacity after being added to the soil. Moreover, the material also significantly promoted the growth of maize seedlings. Therefore, Mg-NBC/PAA has the potential to be widely used in sustainable agriculture, especially in dry and semi-arid areas, due to its ability to maintain soil moisture, reduce irrigation water use, and improve nutrient utilization efficiency.

Study on the effectiveness and mechanism of a sustainable dual slow-release model to improve N utilization efficiency and reduce N pollution in black soil

Long-term intensive cultivation has led to serious N loss and low N fertilizer utilization efficiency (NUE) in black soil areas. The lost N is not only a waste of resources but also a serious pollution threat to the environment, leading to the decline in water quality and food safety and the greenhouse effect. In the present study, a stable dual slow-release model, CPCS-Urea, was prepared by in situ polymerization using nitrapyrin, urea and melamine-formaldehyde resin as raw materials. The effect of the dual slow-release model was systematically evaluated using two consecutive years of field experiments. Five treatments were established in the field experiment: no N fertilizer (N0), urea (N180), 1 % CPEC-Urea, 0.5 % CPCS-Urea, and 1 % CPCS-Urea. The results showed that the new dual slow-release CPCS-Urea model outperformed both the use of urea and the traditional slow-release CPEC-Urea model in reducing N losses and improving NUE. The application of CPCS-Urea reduced nitrate (NO3−) leaching by 28.2 %–47.2 % and N2O emissions by 36.5 %–42.4 % and increased NUE by 20.7 %–28.5 % compared to urea application. The CPCS-Urea model modulated the activity of ammonia-oxidizing bacteria (AOB) and dissimilatory nitrate reduction to ammonium (DNRA) bacteria in soil, showing a significant decrease in AOB activity and an increase in DNRA activity. This results in a lower soil NO3−-N yield and a 53.1 %–72.0 % increase in NH4+-N content, providing sufficient N for the entire growth and development cycle of maize. In short, the dual slow-release CPCS-Urea model has great application prospects for promoting agricultural development in black soil areas.