The symbiotic relationship between cover crops and soil microorganisms is closely linked to nutrient cycling and crop growth within agroecosystems. However, how cover crops with different root functional traits influence soil microbial communities, soil properties, and crop yields has remained understudied. This study assessed the root traits of hairy vetch (HV) and rapeseed (RP), along with soil properties, sweet potato yield, and microbial enzyme activity under red soil dryland conditions. High-throughput sequencing was also employed to characterize the diversity, composition, and network structure of soil bacterial and fungal communities. According to the plant economic spectrum theory and our research results on plant root traits, HV can be identified as a resource-acquisitive cover crop, and RP treatment can be identified as a resource-conservative cover crop. Although RP treatment did not significantly increase the sweet potato yield, the increase rate reached 8.49%. Resource-conservative cover crops were associated with increased pH, SOC, and TP, which enhanced bacterial species diversity and boosted the populations of Chloroflexi and Alphaproteobacteria. In contrast, resource-acquisitive cover crops promoted the proliferation of Gammaproteobacteria. Network analysis indicated that resource-conservative cover crops facilitated network complexity through intensified intra-community competition. Resource-acquisitive cover crops enhanced the stability of microbial communities. Collectively, these findings underscore the distinct advantages of cover crops with varying root functional traits in shaping soil microbial communities. Appropriate cover crop rotations can effectively regulate microbial communities and hold the potential to enhance crop yield.

Excessive water and fertiliser inputs, as well as long-term monocropping, not only cause resource waste and environmental pollution but also drive soil degradation and the occurrence of soil-borne diseases. Anaerobic soil disinfestation (ASD) is a widely used technique in greenhouse vegetable production to replace the use of agrochemicals in disinfestation and improve product quality. While the short-term effects of ASD on the soil microbial community have been well documented in the past 15 years, only a few studies have investigated the multiseason effects of ASD, particularly on the soil microbial community composition and stability, as well as on pathogens and antagonistic microorganisms. Field experiments were conducted in three adjacent greenhouses used for tomato production for at least 20 years. Three treatments were included: CK (control: no irrigation, no plastic film covering, incorporation of chicken manure), ASD (irrigation, plastic film covering, and incorporation of rice husks), and ASD+M (ASD plus incorporation of chicken manure). Results showed that (1) ASD significantly reduced the diversity of soil bacteria and fungi and improved the complexity and stability of the soil bacterial community at the end of the ASD, but the soil microbial diversity recovered to the level before the experiment after 1.5 years. (2) Compared with CK, ASD significantly increased the relative abundance of antagonistic bacteria Bacillus, Paenibacillus and Streptomyces, decreased the relative abundance of pathogens Fusarium and the quantity of nematodes and could still effectively eliminate soil pathogens after 1.5 years. (3) Chicken manure application did not increase the pathogenic microorganisms Fusarium and nematodes, but it significantly decreased the relative abundance of antagonistic bacteria. Our results highlight that ASD not only showed an inhibitory effect on soil-borne diseases after 1.5 years but also significantly increased the relative abundance of antagonistic bacteria. However, the additional incorporation of chicken manure for ASD should be avoided due to its negative effects on the abundance of antagonistic bacteria and its contribution to environmental pollution due to N leaching and increased emissions of GHG N₂O.

To investigate the effects of straw residues with reduced nitrogen (N) fertilizer on greenhouse gas (GHG) and N losses in paddy fields, we conducted a field experiment during two growing seasons in paddy rice systems in southern China to evaluate the impacts of the application of straw residues with reduced N fertilizer on rice yield, GHG emissions, and ammonia (NH₃) volatilization. The four treatments included N100 (conventional dose of N fertilizer), SN100 (conventional dose of N fertilizer + straw), N60 (60% of the conventional dose of N fertilizer), and SN60 (60% of the conventional dose of N fertilizer + straw). We found that the yield of the SN60 treatment was slightly reduced, but the partial factor productivity of applied N (PFP_N) was significantly increased by 63.9% compared to the N100 treatment. At the same N application rate, the application of straw increased soil organic C (SOC), methane (CH₄) emissions, carbon dioxide (CO₂) emissions, global warming potential (GWP), greenhouse gas intensity (GHGI), and net ecosystem carbon budget (NECB), but significantly decreased soil N₂O emissions and NH₃ volatilization. Compared with conventional fertilization (N100), straw residues with reduced N fertilization (SN60) reduced N₂O emissions and NH₃ volatilization by 42.1% and 23.9%, and increased GHGI and NECB by 11.1% and 18.3%, respectively. The results indicate that straw residues with reduced N fertilizer are a feasible strategy to reduce N losses in paddy fields while increasing carbon sequestration.

Conventional overfertilization combined with flooding irrigation is common practice in solar greenhouse vegetable production systems in Eastern China. However, how these practices may affect soil nutrient concentrations remains understudied. Here we report on a regional soil sampling study in Shouguang county, which is the major and pioneer area of greenhouse vegetable production in China. In our study, we measured soil nutrient concentrations (mineral N, Olsen-P, and available K) as well as soil physico-chemical parameters (e.g. pH, SOC) down to 3 m soil depth in 60 greenhouses differing in years since establishment (5, 10, and 20 years) and compared those to nutrient concentrations in 20 adjacent arable fields. We found that in greenhouse soils compared to soils of adjacent arable fields: (1) soil nutrients were significantly elevated in the topsoil (0-30 cm), while nutrient concentrations in the subsoil were much lower and differences between greenhouse and arable soils diminished; (2) N:P:K ratios were imbalanced towards P and K as these elements are not easily leached as N; (3) the soil pH is decreased. After about 20 years of continuous greenhouse vegetable production, the topsoil pH was lowered by 0.92 ± 0.07 units. Our study shows that overfertilization combined with flooding irrigation has serious impacts on soil chemistry and soil nutrient concentrations. The observed nutrient imbalances are dramatic and indicate that e.g. P and K fertilization may not be needed for years to come. Also the observed decline of the significant decrease in the soil pH of calcareous soil indicates, that the soil pH carbonate buffer system is at the edge to break down, with unknown consequences for soil fertility. These facts strongly suggest that unnecessary excessive fertilizer and irrigation water applications for producing vegetables in solar greenhouse systems should be stopped and replaced with more sustainable production methods, e.g. drip fertigation with reduced fertilizer application.