Project description:Returning straw to soil is an effective way to sustain or improve soil quality and crop yields. However, a robust understanding of the impact of straw return on the composition of the soil microbial communities under field conditions has remained elusive. In this study, we characterized the effects of wheat straw return on soil bacterial and fungal communities in a wheat-soybean rotation system over a 3-year period, using Illumina-based 16S rRNA, and internal transcribed region (ITS) amplicon sequencing. Wheat straw return significantly affected the α-diversity of the soil bacterial, but not fungal, community. It enhanced the relative abundance of the bacterial phylum Proteobacteria and the fungal phylum Zygomycota, but reduced that of the bacterial phylum Acidobacteria, and the fungal phylum Ascomycota. Notably, it enriched the relative abundance of nitrogen-cycling bacterial genera such as Bradyrhizobium and Rhizobium. Preliminary analysis of soil chemical properties indicated that straw return soils had significantly higher total nitrogen (TN) contents than no straw return soils. In addition, the relative abundance of fungal genera containing pathogens was significantly lower in straw return soils relative to control soils, such as Fusarium, Alternaria, and Myrothecium. These results suggested a selection effect from the 3-year continuous straw return treatment and the soil bacterial and fungal communities were moderately changed.
Project description:Straw return plays an important role in reducing the use of chemical fertilizer, promoting soil carbon sequestration, thus maintaining soil fertility and alleviating environmental pollution. To examine the effects of straw return on soil bacterial communities, quantitative PCR and high-throughput sequencing approaches were used to analyze the bacterial abundance and community structures at the depths of 5-25 cm and 25-45 cm in the soils under six-year continuous straw return and removal treatments in Langfang, Hebei, the North China Plain. As a result, straw return had no effects on soil chemical properties, bacterial abundance, richness or diversity at both soil depths. In contrast, vertical distributions of available nitrogen and available potassium were affected. Similarly, straw return also changed the vertical distributions of Proteobacteria and Chloroflexi. Principal coordinate analysis based on weighted UniFrac distance matrix indicated a moderate separation of the bacterial community in the soil treated with straw return from that with straw removal at 5-25 cm depth, but they were not distinctly distinguished at 25-45 cm depth. T-test identified increased abundance of Candidatus Latescibacteria in the soil under straw return treatment at 5-25 cm depth but no differentially abundant phyla at 25-45 cm depth was found. These results suggested a selection effect from the six-year continuous straw return treatment and the soil bacterial communities were moderately changed.
Project description:Roots hold complex microbial communities at the soil-root interface, which can affect plant nutrition, growth, and health. Although the composition of plant microbiomes has been extensively described for various plant species and environments, little is known about the effect of wheat straw return (WSR) on the soybean root microbiota. We used Illumina-based 16S rRNA and ITS amplicon sequencing to track changes in bacterial and fungal microbiota in bulk soil and soybean rhizosphere, rhizoplane, s1and endosphere during the third and fourth years after implementing WSR in a wheat-soybean rotation system. The results revealed that WSR had a greater impact on fungal communities than bacterial communities, particularly in bulk soil, rhizosphere, and rhizoplane. WSR enriched the relative abundance of cellulose-degrading fungi (e.g., Acremonium, Trichoderma, and Myrmecridium, among which Trichoderma also had antimicrobial activity), saprotroph (e.g., Exophiala), and nitrogen cycling bacteria (e.g., Chryseolinea). Furthermore, WSR depleted the relative abundance of pathogenic fungi (e.g., Fusarium and Alternaria). These data revealed for the first time that WSR had diverse effects on soybean root-associated microbial community composition, not only in soil but also in the rhizosphere, rhizoplane, and endosphere.
Project description:Nitrate leaching is one of the most important pathways of nitrogen (N) loss which leads to groundwater contamination or surface water eutrophication. Clarifying the rates, controlling factors and characteristics of nitrate leaching is the pre-requisite for proposing effective mitigation strategies. We investigated the effects of interactions among chemical N fertilizer, straw and manure applications on nitrogen leaching in an intensively managed calcareous Fluvo-aquic soil with winter wheat-summer maize cropping rotations on the North China Plain from October 2010 to September 2013 using ceramic suction cups and seepage water calculations based on a long-term field experiment. Annual nitrate leaching reached 38-60 kg N ha-1 from conventional N managements, but declined by 32-71% due to optimum N, compost manure or municipal waste treatments, respectively. Nitrate leaching concentrated in the summer maize season, and fewer leaching events with high amounts are the characteristics of nitrate leaching in this region. Overuse of chemical N fertilizers, high net mineralization and nitrification, together with predominance of rainfall in the summer season with light soil texture are the main controlling factors responsible for the high nitrate leaching loss in this soil-crop-climatic system.
Project description:Despite the integral role of the soil microbial community in straw decomposition, we still have a limited understanding of the complex response of microbial community to long-term of crop straw return in rotation system. Here we report on the structural and functional response of the soil bacterial and fungal community to more than 10 years of straw return in wheat-corn rotation system. Compared with single-season straw return, soil microbial phosphor lipid fatty acids (PLFAs) and catabolic activity were improved more greatly with double-season straw return. The relative abundance of bacteria and fungi decreased with double-season straw return, but increased with single-season straw return. The copiotrophic bacteria were more represented in the soils with corn straw return, while oligotrophic groups were more represented in soils with wheat straw return. Compared with wheat straw return, lower fungal community diversity and higher abundance of fungal pathogen (identified to be Leptosphaeria) were observed with corn straw return, especially at high return rates. Redundancy analysis showed that soil available potassium (P = 0.008) and ratio of C to N (P = 0.048) significantly affected the soil bacterial community, while soil electric conductivity (P = 0.04) was the significant factor impacting soil fungal community. It suggests that full corn straw return might have positive impact on soil mineral nutrient but negative impact on soil fungal community diversity and pathogenic risk, mainly due to the change in soil electric conductivity.
Project description:Rotational straw return technique is considered an effective measure for improving soil quality and maintaining soil microorganisms. However, there are few reports on the influence of wheat-maize crop rotation and straw-returning tillage on crop soil microbial communities in China. This study aimed to investigate how wheat or maize straw-incorporation practices affect bacterial and fungal communities under wheat-maize rotational farming practices. To clarify the effects of straw incorporation on microbial composition, microbial communities from soils subjected to different treatments were identified using high-throughput sequencing. Our results showed that, before corn planting, wheat and maize straw returning reduced bacterial density and increased their diversity but had no effect on fungal diversity. However, before wheat planting, returning wheat and corn stalks to the field increased the diversity of soil bacteria and fungi, whereas returning corn stalks to the field reduced the diversity of fungi and other microorganisms. Straw return significantly increased the relative abundance of Ascomycota in the first season and decreased it in the second season; however, in the second season, wheat straw return increased the relative abundance of Bradyrhizobium, which can promote the soil microbial nitrogen cycle and provide nitrogen to the soil. Wheat and maize straw return increased the relative abundance of Chaetomium, whereas, individually, they decreased the relative abundance. In addition, we detected two fungal pathogens (Fusarium and Trichoderma) under the two planting patterns and found that the relative abundance of pathogenic Fusarium increased with wheat straw return (FW and SW). Trichoderma increased after treatment with maize straw return before wheat planting (S group). These results suggest that wheat straw return (FW and SW) and maize straw return might have a negative impact on the pathogenic risk. Therefore, further studies are needed to determine how to manage straw returns in agricultural production.
Project description:This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-specific analysis to determine the uptake of 13C,15N-glycine by soil microorganisms. In the NF treatment, microbial 13C,15N-glycine uptake was lower compared with CK, suggesting that inorganic N was the preferred N source for soil microorganisms. However, The application of straw with N fertilizer (in NS treatment) increased microbial 13C,15N-glycine uptake even with the same amount of N fertilizer application. In this treatment, enzyme activities, soil microbial biomass C and microbial biomass N increased simultaneously because more C was available. Soil mineral N and plant N contents all decreased substantially. The increased uptake of intact 13C,15N-glycine in the NS treatment can be attributed to direct assimilation by soil microorganisms to satisfy the demand for N when inorganic N was consumed.
Project description:Inappropriate water and fertilizer management can lead to unstable crop yields. Excessive fertilization can potentially cause soil degradation and nitrogen (N) leaching. The aim of this study was to explore the optimal N application rate on two wheat varieties with different nitrogen responding under limited water irrigation at three experimental sites in the Piedmont plain of the Taihang Mountains, China. A two-year field experiment was conducted to explore the effects of five N application rates (N0, N120, N180, N240, and N300) on winter wheat growth, leaf area index, aboveground biomass, grain yield, grain N accumulation, and net return. The results showed that N application rate significantly affected leaf area index, aboveground biomass, grain yield, and harvest index. Variety and variety × N rate interactions had a significant effect on few indicators. Compared with N0, N180 improved leaf area index, aboveground biomass, grain yield, and grain N accumulation. Compared with N240 and N300, N180 increased the harvest index and N harvest index, without significantly reducing grain yield or grain N accumulation, while enhancing a higher N use efficiency. Fertilizers applied in the ranges of 144.7-212.9 and 150.3-247.0 kg ha-1 resulted in the highest net return for the KN199 and JM585 varieties, respectively. Our study provides a sound theoretical basis for high-efficiency fertilizer utilization in sustainable winter wheat production in the Piedmont plains of the Taihang Mountains of China.
Project description:Straw returning plays an essential role in crop yields and the sustainable development of agriculture. However, the effects and mechanisms of nitrogen (N) fertilizer management on grain yield, quality and aroma substance 2-acetyl-1-pyrroline (2-AP) content under wheat straw returning are still unclear. In this field experiment, two japonica rice cultivars were used as materials, wheat straw non-returning (NS) and wheat straw full returning (WS) were designed coupled with two N application ratios, namely basal fertilizer: tiller fertilizer: panicle fertilizer =5:1:4 (local farmers’ fertilizer practice, LFP) and 7:1:2 (increasing basal fertilizer rate, IBF) under the total N application rate of 270 kg ha-1. The effects of the four treatment combinations (NS-LFP, NS-IBF, WS-LFP, WS-IBF) on yield, cooking and eating quality, and 2-AP content in rice were investigated. The two-year (2020, 2021) results showed that: 1) WS-IBF significantly increased the number of panicles and grains per panicle, leading to the increase in grain yield by 6.67%–12.21%, when compared with NS-LFP, NS-IBF and WS-LFP. 2) WS-IBF enhanced the taste value, peak viscosity, breakdown value, the ratio of amylopectin to amylose, and the ratio of glutelin to prolamin while reducing the setback value and amylose content of rice flour. 3) Compared with NS, WS increased the activities of proline dehydrogenase and ornithine transaminase, the synthetic precursors of 2-AP, and finally increased 2-AP content in rice grains. WS-IBF slightly decreased 2-AP content, but there was no significant difference with WS-LFP. The above results indicated that adjusting the N regime and increasing basal N fertilizer rate under wheat straw returning is conducive to improving grain yield, cooking and eating quality, and 2-AP content in rice.
Project description:Soil sustainability is based on soil microbial communities' abundance and composition. Straw returning (SR) and nitrogen (N) fertilization influence soil fertility, enzyme activities, and the soil microbial community and structure. However, it remains unclear due to heterogeneous composition and varying decomposition rates of added straw. Therefore, the current study aimed to determine the effect of SR and N fertilizer application on soil organic carbon (SOC), total nitrogen (TN), urease (S-UE) activity, sucrase (S-SC) activity, cellulose (S-CL) activity, and bacterial, fungal, and nematode community composition from March to December 2020 at Guangxi University, China. Treatments included two planting patterns, that is, SR and traditional planting (TP) and six N fertilizer with 0, 100, 150, 200, 250, and 300 kg N ha-1. Straw returning significantly increased soil fertility, enzymatic activities, community diversity, and composition of bacterial and fungal communities compared to TP. Nitrogen fertilizer application increased soil fertility and enzymes and decreased the richness of bacterial and fungal communities. In SR added plots, the dominated bacterial phyla were Proteobacteria, Acidobacterioia, Nitrospirae, Chloroflexi, and Actinobacteriota; whereas fungal phyla were Ascomycota and Mortierellomycota and nematode genera were Pratylenchus and Acrobeloides. Co-occurrence network and redundancy analysis (RDA) showed that TN, SOC, and S-SC were closely correlated with bacterial community composition. It was concluded that the continuous SR and N fertilizer improved soil fertility and improved soil bacterial, fungal, and nematode community composition.