Fertilization is a regular management approach that can enhance soil fertility and stimulate the proliferation of beneficial microorganisms. However, the prolonged influence of fertilization practices on soil quality, microbial functional characteristics, and the underlying mechanisms still remain incompletely understood. In this study, we examined the impact of various fertilization strategies on the soil quality index (SQI) and community-level physiological profiles (CLPP) during two crop seasons (maize and soybean, respectively) in a 45-year field trial. Four treatments were implemented: unfertilized control (CK), inorganic nitrogen-phosphorus-potassium fertilizer (NPK), organic fertilizer (M), and organic-inorganic fertilization (MNPK). Results showed that across both seasons, NPK application reduced soil pH and the McIntosh index, whereas organic amendments (M and MNPK) notably enhanced total and available nutrients, SQI, microbial biomass, and enzyme activities. CLPP analysis revealed that organic fertilization significantly enhanced microbial metabolic activity and functional diversity, particularly boosting the utilization of carbohydrates (20-38%) and carboxylic acids (18-36%). Random forest modelling indicated available potassium (AK) as the primary driver of carbon metabolic activity in both seasons, revealing its critical role in regulating microbial functions. Functional metabolic diversity during the maize season was most strongly influenced by microbial entropy (qMB), whereas in the soybean season, it was available nitrogen (AN). Additionally, organic fertilization led to an indirect improvement in SQI during the maize and soybean seasons by increasing microbial biomass. In conclusion, the study underscored the importance of long-term organic fertilization for improving soil quality and provided empirical evidence to maintain the sustainable practices of agriculture in Northeast China.

Soil microbial community and function play a key role in root nutrient acquisition and growth. Yet, the combined effects of O3 stress and straw return on soil microbial composition and network complexity remain unclear. Here, a pot experiment was conducted in open-top chambers to monitor the responses of soil microbial diversity, composition, and network complexity at branching and podding stages of soybean (Glycine max; a species highly sensitive to O3 stress) to O3 stress (45 ± 5 ppb; 80 ± 10 ppb; and 110 ± 10 ppb) and straw treatment (no straw return and straw return). Under O3 stress at 110 ± 10 ppb, SOC and microbial biomass C and N significantly increased at the branching stage and decreased at the podding stage. Under O3 stress, the Chao1 and PD indices, along with the number of observed species, were significantly increased by straw return. The bacterial network complexity was negatively affected by O3 stress (80 ± 10 ppb) and positively affected by straw return. Microbial diversity (Chao1, Shannon, and PD indices) showed greater total standard effects than the factors of soil stoichiometry (C/N, C/P, and N/P ratios). Straw return had the lowest total standard effect on microbial network community and complexity than the other factors. Collectively, the slight alleviating effect of straw return on the reduced microbial topology induced by O3 stress was mainly associated with bacterial functions rather than soil physicochemical properties.

BACKGROUND:In rice production, nitrogen fertilizer plays a crucial role, influencing not only the growth and development process but also the quality and yield of rice. Therefore, studying rational nitrogen application strategies provides a theoretical basis for improving rice yield and quality. A 2-year field experiment was conducted using the rice varieties Tianlongyou 619 and Liaojing 419. The study examined the effects of two nitrogen levels (N1, 160 kg hm-2; N2, 240 kg hm-2) and three nitrogen application modes (T1, basal fertilizer:tiller fertilizer:panicle fertilizer = 5:4:1; T2, 4:3:3; T3, 3:2:5), along with a control treatment without nitrogen application (N0), on rice grain-filling characteristics and quality. RESULTS:Nitrogen application accelerated the grain-filling rate and intensity. The active grain-filling period of inferior grains for both varieties extended with increasing nitrogen application. Under different treatments, the grain weight during the rapid filling stage was consistently higher in N1 than in N2 for both varieties. The N1T3 treatment reduced the soluble starch synthase content in both varieties, while their starch branching enzyme and ADP-glucose pyrophosphorylase levels were highest under N1T3. Analysis of starch content during grain filling revealed that starch synthase activity peaked at 15 days, and the starch accumulation rate reached its maximum between 15-20 days after flowering. Delayed nitrogen application improved starch accumulation in superior grains to varying degrees. CONCLUSION:Overall, both varieties achieved superior quality under a nitrogen application rate of 160 kg hm-2 with a fertilizer management ratio of basal:tiller:panicle fertilizer = 3:2:5. In 2022, under N1T3 treatment, Tianlong You 619 and Liaojing 419 achieved taste values of 69.8 and 75.9, and balance degree of 6.6 and 7.57, respectively. © 2026 Society of Chemical Industry.

Northern japonica rice holds a significant position in China's food security. However, the traditional nitrogen fertilizer management model (nitrogen application rate > 225 kg/ha, base fertilizer proportion > 50%) has led to serious sustainability problems: the nitrogen utilization rate is only 25-30%, resulting in a large amount of fertilizer waste and economic losses. At the same time, it causes a decline in rice quality, manifested as a 15-20% increase in chalkiness and an 8-12% decrease in palatability value. It has also brought about environmental problems such as soil acidification and eutrophication of water bodies. As an important japonica rice production area, the Liaohe Plain has significant differences in the response of semi-upright and curved panicle varieties to nitrogen fertilizer. However, the agronomic physiological mechanism for the coordinated improvement of yield and quality of japonica rice with different panicle types is still unclear at present, which limits the sustainable development of rice production in this region. For this purpose, in this study, the typical semi-upright spike variety Shendao 47 and the curved spike variety Shendao 11 from the Liaohe Plain were used as materials, and five nitrogen fertilizer treatments were set up: N1, no nitrogen application; N2-N4, conventional nitrogen application rate of 165-225 kg/ha; and N5, and optimized nitrogen application rate of 195 kg/ha allocated in the proportion of 40% base fertilizer, 15% tillering fertilizer, 25% tillering fertilizer, 15% panicle fertilizer, and 5% grain fertilizer. The synergistic regulatory effect of nitrogen fertilizer management on yield and rice quality was systematically explored, and the key agronomic physiological mechanisms were analyzed. The research results show that: (1) The optimized nitrogen fertilizer treatment (N5) achieved a significant increase in yield while reducing the input of nitrogen fertilizer. The yields of Shendao 47 and Shendao 11 reached 10.71-11.82 t/ha and 9.50-10.62 t/ha, respectively, increasing by more than 35% compared with the treatment without nitrogen. (2) The N5 treatment simultaneously improved the processing quality (the whole polished rice rate increased by 4.11%) and the appearance quality (the chalkiness decreased by 63.8% to 77%). (3) The dry matter accumulation during the tillering stage (>= 3.2 t/ha) and the net assimilation rate during the scion development stage (>= 12 g/m(2)/d) were identified as key agronomic physiological indicators for regulating the yield-quality synergy. Optimizing nitrogen fertilizer management ensures an adequate supply of photosynthetic products through the high photosynthetic rate of flag-holding leaves and the extended lifespan of functional leaves. The phased nitrogen application strategy of "40% base fertilizer + 25% tillering fertilizer + 15% panicle fertilizer + 5% grain fertilizer" proposed in this study provides a theoretical and practical basis for the sustainable development of japonica rice production in the Liaohe Plain. This plan has achieved the coordinated realization of multiple goals including resource conservation (reducing nitrogen by 13%), environmental protection (lowering the risk of nitrogen loss), food security guarantee (stable increase in yield), and quality improvement (enhancement of rice quality), effectively promoting the development of the northern japonica rice industry towards a green, efficient and sustainable direction. Develop in the right direction.

The adaptability and microbial response mechanism of a sulfur autotrophic denitrification (SADN) biofilm under high nitrate (NO3--N) and sulfamethoxazole (SMX) stress through long-term operation of a fluidized bioreactor was evaluated. The SADN biofilm adapted to nitrate contents of up to 150 mg/L, and at 1 mg/L SMX, the nitrogen removal efficiency and SMX removal efficiency were as high as 85 % and 64 %, respectively. Microbial adaptation was driven by upregulated secretion of acyl-homoserine lactone (AHL) signal molecules, specifically 3OC6-HSL and 3OC8-HSL, which stabilized at concentrations of 575.7 ng/L and 579.9 ng/L, respectively. These molecules dynamically regulated the composition of extracellular polymeric substances, with total EPS content increasing from 113.37 mg/gVSS in the initial phase to 456.85 mg/gVSS under early SMX exposure, ensuring biofilm structural integrity. Under prolonged SMX stress, Simplicispira emerged as a key genus with a relative abundance of 21.20 %, utilizing apoptotic autotrophic denitrifiers and EPS metabolites as carbon sources for heterotrophic denitrification. This genus harbored critical nitrate reductase genes, including NarG, which accounted for 28.5 % of total functional gene abundance. In addition, SMX stress reduced the abundance of total anti-resistance genes (ARGs), with resistance mechanisms dominated by antibiotic efflux pumps, with the contribution increased from 63 % to 67 %. The relevance of this pump continuously increased, which hindered binding of SMX to cells and effectively reduced its toxicity. The results of this study provide scientific evidence for the application of SADN technology in a high-nitrate and antibiotically stressed environment. The results can further guide practical operations and provide technical support for increasing denitrification efficiency and antibiotic removal capacity in the SADN process.

Manure affects soil N content and composition, thereby influencing the nutritional quality of crop grains. This study aimed to assess the effects of long-term manure application on maize and soybean grain quality, as well as soil amino acids pools within a crop rotation system. Four treatments were selected from a maize-maize-soybean rotational fertilisation field experiment that has been ongoing since 1979: no fertiliser (CK), mineral fertiliser (NPK), low-rate manure (13.5 t ha−1) with NPK (M1NPK), high-rate manure (27 t ha−1) with NPK (M2NPK). Soil amino acids pools, as well as protein and amino acids content of grains was evaluated. The results indicate that soil organic nitrogen fraction increased with high-rate manure additions. Long-term high-rate manure application significantly increased the levels of free amino acids while reducing the proportion of soil alkaline hydrolysable amino acids. Maize grain protein content increased with higher manure addition rates; however, albumin and globulin content peaked at 0.76 and 0.45 g 100 g−1, respectively, under M1NPK. Manure addition had no significant effect on the protein content or its fractions in soybean grains. Soybean amino acids content peaked 348 mg kg−1 under M2NPK. A strong positive correlation was observed between the protein content of both maize and soybean grains and the soil's total N and amino acids pool. Long-term manure application in a crop rotation system increased soil amino acids pool and enhanced crop grain protein and amino acids content; however, lower manure rate (13.5 t ha⁻1) additions was more favourable for maize albumin and globulin.

Manure application affects soil chemical and biochemical properties and organic nitrogen (ON). In this study, we aimed to study the long-term application of manure on soil amino acid pools and the underlying mechanisms that remain unquantified. We studied the effects of 41-year manure application on soil ON fractions and amino acid pools during various crop seasons under maize-maize-soybean rotation. This study includes four treatments: no fertilization, inorganic nitrogen + phosphorus + potassium fertiliser (NPK), NPK + 13.5 t ha−1 manure, and NPK + 27 t ha−1 manure (M2NPK). The highest values for soil organic carbon (SOC), total nitrogen, pH, urease, and protease activity were observed in both the maize and soybean seasons under M2NPK. The contents of acidolysable ammonium nitrogen, acidolysable amino acid nitrogen (AAN), and ON in soil peaked under M2NPK in both seasons. Long-term high manure additions increased total soil amino acid content by 183

BACKGROUNDThe implementation of sterile insect technique (SIT) has proven effective in the area-wide suppression of several significant agricultural and sanitary pests by using traditional cobalt-60 (60Co-gamma) as a radiation source. Recently, X-ray has been validated as a feasible alternative to 60Co-gamma radiation sources. Nonetheless, higher doses of X-ray irradiation led to insect sterility but diminish mating competitiveness, thereby impacting the effectiveness of SIT applications.RESULTSIn this study, we assessed the impact of various X-ray irradiation doses (ranging from 0 to 366 Gy) on the fecundity, fertility, and mating competitiveness of Cydia pomonella, a globally invasive fruit pest. Results demonstrated that the sterility rate of irradiated males increased with dose up to 200 Gy, then stabilized. Exposure to 200 Gy reduced male mating competitiveness, with competitiveness index (CI) values of 0.17 in the laboratory and 0.096 in the orchard. This decline is likely linked to the decreased expression of genes associated with sex pheromones recognition, such as CpomOR3a, CpomOR3b, and CpomOR5, post-irradiation. Fumigation of linalool at varying concentrations (70, 83, and 96 mu L/m3) enhanced mating competitiveness of males, particularly at moderate levels, possibly by restoring pheromones recognition. Implementation of repeated releases of sterilized males on a pilot scale led to a notable reduction in the population of C. pomonella in the field.CONCLUSIONThese findings indicate that fumigation with plant volatiles has the potential to mitigate male sterility induced by X-ray irradiation, offering a promising approach to enhance the efficacy of SIT applications for the control of C. pomonella. (c) 2024 Society of Chemical Industry.

Maize (Zea mays L.), as a cornerstone crop, is integral to both livestock feed and human nutrition. However, the effects of long-term manure application on maize yield, micronutrient levels, and nutritional quality under a maize-soybean rotation system have not been fully elucidated. This study investigates the impact of long-term manure application on maize yield, the micronutrients content of grains, and grain nutritional quality in a maize-soybean rotation. Our results indicate that consistent manure application significantly enhances maize yield. Compared to the long-term chemical fertilizers only, the addition of manure increased the Fe, Mn, Cu, and Zn concentrations of the grains. In addition, the highest grain protein concentration was observed when treated with manure. Concentrations of protein fractions such as globulins, gliadins, and glutenins were found to be higher with a low manure application (13.5 t ha−1) compared to high manure application (27 t ha−1). The optimum increments in essential amino acids (EAA) and the ratios of essential to nonessential amino acids (EAA/NAA) was observed under low manure addition treatment. Collectively, incorporating manure into a long-term maize-soybean crop rotation not only escalates yields but also critically enhances the nutritional profile of maize grains through an increase in micronutrients and by promoting balance of proteins and amino acids within the grain. In the long run, low manure addition is more conducive to improving the nutritional quality of grains under crop rotation systems.

Transcription factors are key molecules involved in transcriptional and post-transcriptional regulation in plants and play an important regulatory role in resisting biological stress. In this study, we identified a regulatory factor, OsZF8, mediating rice response to Rhizoctonia solani (R. solani) AG1-IA infection. The expression of OsZF8 affects R. solani rice infection. OsZF8 knockout and overexpressed rice plants were constructed, and the phenotypes of mutant and wild-type (WT) plants showed that OsZF8 negatively regulated rice resistance to rice sheath blight. However, it was speculated that OsZF8 plays a regulatory role at the protein level. The interacting protein PRB1 of OsZF8 was screened using the yeast two-hybrid and bimolecular fluorescence complementation test. The results showed that OsZF8 effectively inhibited PRB1-induced cell death in tobacco cells, and molecular docking results showed that PRB1 had a strong binding effect with OsZF8. Further, the binding ability of OsZF8-PRB1 to ergosterol was significantly reduced when compared with the PRB1 protein. These findings provide new insights into elucidating the mechanism of rice resistance to rice sheath blight.

Global climate change presents a significant threat to food security. Analyzing the effects of elevated ozone (O3) concentration on photosynthetic fluorescence characteristics and yield addresses the damage of climate change on crops, which would serve food security. With open-top chambers (OTCs) and Tiefeng-29 soybeans, we investigated the responses of chlorophyll concentration, fluorescence characteristics, net photosynthetic rate (Pn) and yield components to different O3 concentrations, which included CK (ambient concentration approximately 45 nL·L−1, T1 (80 ± 10) nL·L−1 and T2 (120 ± 10) nL·L−1 O3. The parent soybeans (S1) were planted in the current year, and O3 fumigation commenced 20 days after seedling emergence. Aeration was stopped at maturity, and the offspring soybeans (S2) were retained after harvest for further experiments. In the following year, S1 and S2 soybeans were planted, and O3 fumigation began 20 days after seedling emergence. The results show that leaf chlorophyll a (chla) and chlorophyll b (chlb) significantly decreased with longer O3 fumigation time both in parents and offspring, causing damage to the light-trapping ability while the offspring suffered an earlier decrease. The elevated O3 damaged the electron transfer process by significantly reducing the original and actual photochemical efficiencies of PSII both in parents and offspring. The electron transfer rate (ETR) of the parents and offspring decreased, while the difference between them was not significant after O3 treatment. The non-photochemical quenching coefficient (NPQ) showed an increasing trend along time but showed no significant difference between parents and offspring. An elevated concentration of O3 significantly reduced Pn, while the differences in Pn between the parents and the offspring were not significant. Elevated O3 resulted in reduced yields in both parent and offspring soybeans. Although it was found that the offspring soybeans exhibited higher yields than the parents, their reduction in yield was more significant. Therefore, elevated O3 concentration reduced soybean yield through damaging photosynthetic process and electron transfer capacity by impairing energy conversion and material accumulation capacity. The offspring had relatively higher light energy conversion efficiency than the parents, resulting in a higher yield than the parents under all treatments.

Nitrogen fertilization can promote rice yield but decrease resistance to sheath blight (ShB). In this study, the nitrate transporter 1.1b (nrt1.1b) mutant that exhibited less susceptibility to ShB but without compromising yield under NH4+ fertilization was screened. NRT1.1B's regulation of ShB resistance was independent of the total nitrogen concentration in rice under NH4+ conditions. In nrt1.1b mutant plants, the NH4+ application modulated auxin signaling, chlorophyll content, and phosphate signaling to promote ShB resistance. Furthermore, the findings indicated that NRT1.1B negatively regulated ShB resistance by positively modulating the expression of H+-ATPase gene OSA3 and phosphate transport gene PT8. The mutation of OSA3 and PT8 promoted ShB resistance by increasing the apoplastic pH in rice. Our study identified the ShB resistance mutant nrt1.1b, which maintained normal nitrogen use efficiency without compromising yield.

Soil microorganisms play crucial roles in nutrient cycling and determining soil quality and fertility; thus, they are important for agricultural production. However, the impacts of long-term fertilization on soil microbial community remain ambiguous due to inconsistent results from different studies. The objective of this study was to characterize changes in bacterial and fungal diversity and community structures after 12 years of different fertilization in aeolian sandy soil by analyzing 16S rRNA and ITS rRNA gene sequences and the soil properties to discover the driving factors. Eight different fertilizer treatments have been set up since 2009: no fertilizer (CK), chemical N fertilizer (N), chemical N and P fertilizer (NP), chemical N, P and K fertilizer (NPK), pig manure only (M), pig manure plus chemical N fertilizer (MN), pig manure plus chemical N and P fertilizer (MNP), pig manure plus chemical N, P, and K fertilizer (MNPK). The results indicated that the long-term application of chemical fertilizer reduced soil pH, whereas the addition of pig manure alleviated a decrease in soil pH value. Chemical fertilizer plus pig manure significantly improved soil available nutrients and soil organic carbon. Long-term MNPK fertilization resulted in changes in bacterial diversity due to effects on specific bacterial species; by contrast, all fertilization treatments resulted in changes in fungal diversity due to changes in soil properties. Principal component analysis indicated that fertilization had a significant effect on soil microbial community structure, and the effect of chemical fertilizer combined with pig manure was greater than that of chemical fertilizer alone. Soil available phosphorus, total phosphorus, and pH were the most important factors that influenced bacterial taxa, whereas soil pH, total phosphorus, organic carbon, ammonium nitrogen and nitrate nitrogen were the most important factors influencing fungal taxa after 12 years of fertilization in aeolian sandy soil.

Carbon (C), nitrogen (N) and phosphorus (P) concentrations and stoichiometry play important roles in biogeochemical cycles of the ecosystems, yet it is still unclear how the allocations of C, N and P concentrations and stoichiometry among plant organs and soils related to O3 stress and straw return. Here, a pot experiment was conducted in open top chambers to monitor the response of C, N and P concentrations and stoichiometry of leaves, stems, roots and soils during a growing season (branching, flowering and podding stages) of soybean (Glycine max; a species highly sensitive to O3) to background O3 concentration (44.8 ± 5.6 ppb), O3 stress (79.7 ± 5.4 ppb) and straw treatment (no straw return and straw return). O3 stress significantly decreased root biomass. Straw return significantly increased root biomass under O3 stress at branching and flowering stages. Generally, O3 stress and straw return showed significant effects on the C, N and P concentrations of leaves and soils, and stoichiometric ratios of leaves, stems and microbial biomass. The C, N and P concentrations and stoichiometry of leaves, stems, roots and soils in response to O3 stress and straw return at the branching stage were inconsistent with the changes observed at the flowering and podding stages. The P conversion efficiency showed significant relationship with root P concentration under the combined effects of O3 stress and straw return. Altogether, the present study indicated that C, N and P concentrations of soybean might be more important than stoichiometric ratios as a driver of root defence against O3 stress in the case of straw return.

Lesion mimic mutants are an ideal model system for elucidating the molecular mechanisms of programmed cell death and defense responses in rice. In this study, we identified a lesion mimic mutant termed miner infection like 1-1 (mil1-1). The mil1-1 exhibited lesions on the leaves during development, and the chloroplasts of mil1-1 leaves were disrupted. Reactive oxygen species were found to accumulate in mil1-1 leaves. Cell death and DNA fragmentation were observed in mil1-1 leaves, indicating that the cells in the spots of mil1-1 leaves experienced programmed cell death. Most agronomic traits decreased in mil1-1, suggesting that the growth retardation in mil1-1 caused reduced per-plant grain yield. However, the mutation of MIL1 activated the expression of pathogen response genes and enhanced resistance to bacterial blight. The MIL1 gene was cloned using the positional cloning approach. A missense mutation 751 bp downstream of ATG was found in mil1-1. The defects of mil1-1 were able to be rescued by delivering a wild-type MIL1 gene into mil1-1. MIL1 encoded hydroperoxide lyase 3 (OsHPL3), and the expression of OsHPL3 was induced via hormone and abiotic stresses. Our findings provide insights into the roles of MIL1 in regulating programmed cell death, development, yield, and defense responses in rice.

Biological nitrogen fixation (BNF) is a vital approach to replenishing soil nitrogen (N) pools by converting atmospheric N-2. Agronomic practice of growing legumes frequently includes stover return, which generally induces the growth of N-2-fixers (i.e., diazotrophs) and stimulates BNF; however, there is uncertainty regarding the stover return effects along soil depth. Here, soil samples were collected from 0 to 10, 10-20 and 20-30 cm in the peanut (Arachis hypogaea) field experiment (established in 2013) comprising treatments with no fertilizer (CK), maize (Zea mays) stover (MS), and MS + chemical fertilizers (SNPK). The abundance of 16S rRNA and nifH genes was determined by real-time PCR, the rate of N-2 fixation in soil (R-Nfix) was measured by acetylene reduction assay, and diazotroph community structure was explored by high-throughput sequencing. Results showed that maize stover application alone increased nifH gene abundance in the 0-10 cm layer, and combined with chemical fertilizer application increased R-Nfix in the 0-20 cm layers, affecting diazotroph community structure succession in the 0-20 cm layers. This is consistent with the effects of stover on soil properties such as dissolved organic carbon and nitrogen, soil organic matter (SOM) and carbon-to-nitrogen ratio, with SOM playing a dominant role in governing the abundance, structure and activity of diazotroph communities in the soil. In addition, total nitrogen (TN) was the key factor in shaping the vertical stratification of diazotroph community structure, the abundance of diazotrophs and bacteria as well as the structure and R-Nfix of the diazotroph community were highly correlated. This study demonstrated that maize stover incorporation caused significant positive changes in the vertical stratification of soil diazotroph communities; although these effects decreased with soil depth and were minor when stover was combined with chemical fertilizers, they still highlighted the crucial role of stover return in enhancing BNF in soil where legumes were present.

为探究全球氮沉降持续增加对大豆干物质积累和氮代谢的影响,本研究以栽培大豆铁丰29号为材料,设置对照处理(不施氮)以及在种植前施氮50 kg-hm-2基肥(模拟实际农田施氮量)的基础上设氮沉降处理(0,50,100,150 kg·hm-2),探讨了氮沉降对大豆干物质积累、叶片氮代谢相关指标(硝酸还原酶、谷氨酰胺合成酶、谷氨酸脱氢酶、硝态氮、铵态氮和可溶性蛋白)、产量和品质的影响.结果表明:人为施氮肥结合少量氮沉降能够保证大豆有效氮供应,显著促进了大豆干物质积累,显著提高了叶片氮代谢产物含量及关键酶活性,进而增加了大豆产量和品质.在施基肥50 kg·hm-2条件下,氮沉降量超过50 kg·hm-2时,则对大豆干物质积累、硝酸还原酶活性、硝态氮和可溶性蛋白含量有明显的抑制作用.氮沉降量超过100 kg·hm-2时,会明显降低大豆谷氨酰胺合成酶和谷氨酸脱氢酶活性以及铵态氮含量.综合分析认为,氮沉降可以作为氮素资源促进大豆生长,氮沉降浓度持续升高条件下农田施肥可能抑制大豆干物质积累和氮代谢,导致减产.应在考虑各地区氮沉降量的基础上合理施用氮肥.

Elevated ozone threatens the sustainability of soil ecosystems by negatively affecting underground ecological processes. Crop residue, as an energy source with a low risk of environmental influence, can alleviate the negative impacts caused by climate change. However, little knowledge is comprehended about the influences of crop residue input on soil nematode metabolic activities and microfood-web under elevated ozone. Soil microfood-web consisting of microorganisms and nematodes plays a significant role in the underground processes such as energy flow and nutrient turnover. Thus, the objectives of this study were to explore the responses of soil nematode metabolic activities and microfood-web to different elevated ozone levels and crop residue application managements. The pot experiment was a split-plot design with elevated ozone system as main plot and residue addition treatment as subplot utilizing the open-top chambers. Elevated ozone systems included three levels (control, 45 +/- 5 ppb; lower elevated ozone level, 80 +/- 10 ppb and higher elevated ozone level, 110 +/- 10 ppb). Residue addition treatments were soil without residue addition and soil with residue addition. The results showed that elevated ozone generated negative influences on soil microorganisms and nematodes by decreasing their biomass carbon. Crop residue input practice increased the functional metabolic footprints of nematodes under elevated ozone. The carbon utilization of soil biological communities shifted from soil organic carbon to extractable organic carbon after crop residue incorporation. Soil nitrate-nitrogen was the main supplier to meet the nitrogen demand of soil biota. The analysis of structural equation modeling revealed that the system under elevated ozone without crop residue addition was predominated by a bacterial decomposition channel. While the application of crop residue into soils also made a contribution to the fungal decomposition pathway. Consequently, it can be concluded that organic input practice strengthens the cooperation of soil microfood-web channels, which plays an important role in alleviating the negative effects of elevated ozone on the stability of soil microfood-web. (c) 2021 Elsevier Ltd. All rights reserved.