The intensive use of chemical fertilizers in China to maintain high crop yields has led to significant environmental degradation and destabilized crop production. Returning straw to soil presents a potential alternative to reduce chemical fertilizer requirements and enhance soil fertility. This study investigates the effects of different nitrogen (N) input levels and straw additions on crop phosphorus (P) uptake and soil P availability based on a long-term N-fertilizer trial. The treatments included no fertilizer input (CK), conventional (NPK), reduced NPK (0.75NPK), and straw-amended (SNPK) treatments. Results indicate that SNPK significantly enhances shoot P uptake and crop yields by 43.7–61.9% and 29.3–39.6%, respectively. The SNPK treatment improved rhizosphere P availability and increased the phosphorus activation coefficient (PAC) by 1.72-fold compared to NPK alone. The enhanced soil P availability under SNPK was primarily attributed to an abundance of functional microbes, leading to higher P storage in the microbial biomass P pool and its turnover. Additionally, SNPK promoted root exudate and phosphate-mobilizing microbes, enhancing P mobilization and uptake. Nitrogen fertilization primarily influenced root functional traits related to P acquisition. These findings provide valuable insights for developing effective fertilizer management strategies in maize–oilseed rape rotation systems, emphasizing the benefits of integrating straw with chemical fertilizers.

The decoupling of cropland and livestock due to the industrialization of livestock production is a difficult problem for sustainable agricultural development in many global locations, including China. As population and urbanization increase, this decoupling is likely to become more serious. To date, the relationship between cropland and livestock has been mainly studied from a single perspective, and mostly at the regional and the local scales. Thus, the objective of our study is to systematically assess the coupling relationship between cropland and livestock from multiple aspects on a large scale. Here, we used a complex system covering cropland, livestock and environment subsystems to comprehensively analyze the spatio-temporal variation of the coupling coordination between cropland and livestock and its influencing factors in China over the past two decades. Elaborating on the data, we constructed a comprehensive system of evaluation indexes for cropland–livestock systems. We used a coupling coordination degree model to evaluate the coupling coordination relationship between cropland and livestock in 31 provinces of China during 2000–2020. The results show that the range of cropland–livestock and cropland–livestock–environment coupling coordination degree was 0.4–0.9. In most of the provinces, there was no risk of cropland and livestock decoupling; however, the coupling coordination degree needed to be increased. More attention should be paid to the coordinated development of cropland and livestock coupling in urbanized areas such as Beijing and Tianjin, where cropland and livestock decoupling was more likely to occur. Among the assessed 29 factors, 15 and 16 had an impact on the cropland–livestock and the cropland–livestock–environment coupling coordination degrees, respectively. Our study provides science-based evidence to support estimating the coupling relationship between cropland and livestock in the future.

Macroplastics are an emerging yet underexplored pollutant in agricultural soils, with the potential to disrupt nitrogen (N) cycling through physical interference and microbial community shifts. While extensive studies have focused on microplastics, the effects of larger plastic debris (>2 cm) on soil-plant systems in legume cropping systems remain poorly understood. We conducted a 71-d mesocosm study utilizing ¹⁵N isotopic tracing and metagenomic sequencing to demonstrate how macroplastics influence soybean growth and soil-soybean continuum N cycling. Soybean growth was not affected under macroplastics exposure (up to 200 kg ha⁻¹). However, macroplastics increased soil NO₃⁻ and NH₄⁺ concentrations, and elevated urease and ammonia monooxygenase activities, suggesting enhanced N availability. Paradoxically, macroplastics significantly disrupted the N-fixing microbial community, reducing the abundance of key bacteria such as Azorhizobium and Bradyrhizobium. Nitrogen fixation pathways (in log10-transformed TPM+1) were markedly suppressed in soils treated with 200 kg ha⁻¹ macroplastics compared to untreated soils (p < 0.001). Our findings highlight the potential risks of macroplastics posing to N cycling and microbial health in agricultural soils. This study addresses a critical knowledge gap by shifting the focus from micro- to macroplastic impacts on biogeochemical cycling.