Hongyu Wang

Soil salinization in farmland is a critical factor limiting global soil health, food security, and ecosystem productivity. Biochar has recently shown great application potential in agricultural fields in many domains, such as soil structure improvement, carbon sequestration, and reductions in greenhouse gas emissions. Here, a meta-analysis of 113 published papers was carried out to quantify the effects of biochar on the remediation of saline-alkali soil and crop yield in terms of climatic conditions and agricultural management, with the aim of determining the optimal agricultural management strategy for biochar application to saline-alkali soils. The results show that adding biochar to saline-alkali farmland increases the TOC in soil (44.0%) and water utilization efficiency (8.7%), and decreases soil salinity (−9.6%), certain salt ion contents in particular (Na⁺, 12.5%; Cl⁻, 23.4%; HCO₃⁻, −17.7%), along with soil pH (−2.2%), resulting in a 20.8% higher crop yield. Applying shell biochar at a rate of 10–20 t·ha⁻¹ for monoculture is the most promising way to bolster the yield in severely saline-alkali irrigated farmland. However, adding biochar raises CO₂ and CH₄ emissions by 9.8% and 31.6%, respectively, but lowers the emission of N₂O by 29.4%. These findings provide scientific recommendations for the sustainable application of biochar in saline-alkali farmland areas worldwide.

Chemical products, such as seed dressings, are often used to regulate crop growth and development and improve yields. In this study, we investigated a seed dressing containing 0.136% gibberellic acid (GA), indole-3-acetic acid (IAA)-, and brassinolide (BL) as a wettable powder (WP), hereafter referred to as GA-IAA-BL WP. This product is a new plant growth regulator of plant origin that can improve crop stress resistance and yield. However, its effect on maize seed germination and seedling growth under low-temperature stress is unclear. In this study, GA-IAA-BL WP was applied to maize ‘Liukexing 99’ seeds at 50, 100, 150, or 200 mg mL⁻¹, and seeds were germinated in an artificial climatic chamber at 10, 15, or 25 °C for 14 d. Application at 100 mg mL⁻¹ significantly increased the germination rate as well as seedling shoot and root length and dry and fresh weight at all three temperatures. This application rate also increased the contents of proline, malondialdehyde, soluble sugars, and soluble proteins; the activities of catalase, superoxide dismutase, and peroxidase; and root vigor. Our results demonstrate that GA-IAA-BL WP can reduce the negative impacts of low-temperature stress on seed germination and seedling growth.

Soil acidification is a global environmental problem with significant impacts on agricultural production, environmental protection, and ecosystem health. Soil acidification is widespread in China, affecting crop yields, agricultural product quality, and biodiversity. Since the 1980s, much work has been done on acidic soils in China, but it is controversial whether excessive nitrogen fertilizer application can lead to soil acidification mechanisms. To address the above issues, we conducted a meta-analysis of 115 published papers to integrate and analyze the effects of N fertilizer application on soil acidification and biological properties from 1980 to 2024. We also quantified the effect of nitrogen fertilization on soil acidification and biological changes under different climatic conditions. The results showed that under long-term application of nitrogen fertilizers in China from 1980 to 2024, soil pH decreased by an average of 15.27%, and the activities of soil urease, nitrate reductase, nitrite reductase, catalase, glutamate dehydrogenase, and glutamate synthetase decreased by an average of 9.82–22.37%. The soil microbial community richness (Chao1 index) increased by 6.53%, but the community diversity (Shannon index) decreased by 15.42%. Among the dominant soil microorganisms, the relative abundance of bacteria decreased by an average of 9.67–29.38% and the abundance of gene expression of nifH, amoA-AOA, amoA-AOB, and qnorB decreased by 9.92–19.83%. In addition, we found that the mean annual temperature and rainfall impacted soil acidification via their effect on soil microbial diversity and community composition. This study provides a scientific basis for an in-depth understanding of the spatial and temporal variation of soil acidification and biological properties in China.

Soil-borne diseases are exacerbated by continuous cropping and negatively impact maize health and yields. We conducted a long-term (11-year) field experiment in the black soil region of Northeast China to analyze the effects of different cropping systems on maize yield and rhizosphere soil fungal community structure and function. The experiment included three cropping systems: continuous maize cropping (CMC), maize–soybean rotation (MSR), and maize–soybean intercropping (MSI). MSI and MSR resulted in a 3.30–16.26% lower ear height coefficient and a 7.43–12.37% higher maize yield compared to CMC. The richness and diversity of rhizosphere soil fungi were 7.75–20.26% lower in MSI and MSR than in CMC. The relative abundances of Tausonia and Mortierella were associated with increased maize yield, whereas the relative abundance of Solicoccozyma was associated with decreased maize yield. MSI and MSR had higher proportions of wood saprotrophs and lower proportions of plant pathogens than CMC. Furthermore, our findings indicate that crop rotation is more effective than intercropping for enhancing maize yield and mitigating soil-borne diseases in the black soil zone of Northeast China. This study offers valuable insights for the development of sustainable agroecosystems.

Crop rotation increases crop yield, improves soil health, and reduces plant disease. However, few studies were conducted on the use of intensive cropping patterns to improve the microenvironment of saline soils. The present study thoroughly evaluated the impact of a three-year maize–peanut–millet crop rotation pattern on the crop yield. The rhizosphere soil of the crop was collected at maturity to assess the effects of crop rotation on the composition and function of microbial communities in different tillage layers (0–20 cm and 20–40 cm) of sandy saline–alkaline soils. After three years of crop rotation, the maize yield and economic benefits rose by an average of 32.07% and 22.25%, respectively, while output/input grew by 10.26%. The pH of the 0–40 cm tillage layer of saline–alkaline soils decreased by 2.36%, organic matter rose by 13.44%–15.84%, and soil-available nutrients of the 0–20 cm tillage layer increased by 11.94%–69.14%. As compared to continuous cropping, crop rotation boosted soil nitrogen and phosphorus metabolism capacity by 8.61%–88.65%. Enrichment of Actinobacteria and Basidiomycota increased crop yield. Crop rotation increases microbial community richness while decreasing diversity. The increase in abundance can diminish competitive relationships between species, boost synergistic capabilities, alter bacterial and fungal community structure, and enhance microbial community function, all of which elevate crop yields. The obtained insights can contribute to achieving optimal management of intensive cultivation patterns and green sustainable development.

Currently, China’s soybean self-sufficiency rate is only 15%, highlighting the soybean crisis and the supply chain risks that pose a major threat to China’s food security. Thus, it has become imperative to step up efforts to boost soybean production capacity while promoting the green and sustainable development of regional farmland ecosystems. In this context, the present study comprehensively investigated the effects of intercropping and nitrogen application rate on soybean yield, as well as the changes in gradients generated by different levels of nitrogen application. Based on six consecutive years of maize–soybean intercropping planting patterns, the inter-root soils of soybeans were collected at the flowering stage and evaluated for soil nitrogen content, nitrogen-assimilating enzyme activities, and microbial community composition of soybean, which were correlated with yield, to clarify the main pathways and modes of intercropping effects. The N₂ level (80 kg·ha⁻¹) was favourable for higher yield. In comparison to monocropping, the intercropping reduced yield by 9.65–13.01%, photosynthetic characteristics by 1.33–7.31%, and plant nitrogen-assimilating enzyme activities by 8.08–32.01% at the same level of N application. Likewise, soil urease and catalase activities were reduced by 9.22 and 1.80%, while soil nitrogen content declined by an average of 6.38%. Gemmatimonas and Bradyrhizobium enrichment significantly increased soil nitrogen content, photosynthetic characteristics, and soybean yield, while it was reduced by Candidatus_Udaeobacter and Candidatus_Solibacte enrichment. The results of this study provide a theoretical basis for further optimising maize–soybean intercropping, which is crucial for enhancing the agricultural production structure and improving the overall soybean production capacity.