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The co-allocation of photovoltaic arrays with crops presents a promising strategy to mitigate the conflict between photovoltaics and agricultural land. However, there is a notable lack of quantitative research on the impact of agrivoltaic system on land quality in fragile areas. In this study, peanuts (Arachis hypogaea) and ryegrass (Lolium perenne) were cultivated in photovoltaic array in the dry–hot valley of southwest China, with an off-site native land serving as the control. Sixteen soil physicochemical and biochemical parameters were measured in the gap and under-panel and control area. Results demonstrated that the agrivoltaic system significantly enhanced soil moisture, organic carbon, nitrogen–phosphorus–potassium nutrients, microbial biomass, and urease activity. It also led to varying degrees of increase in soil pH and electrical conductivity, along with reduced soil sucrase and phosphatase activity. In comparison to the control, the agrivoltaic system notably improved soil quality and multifunctionality. Specially, gap cultivation had a more pronounced positive impact on soil quality than under-panel cultivation, and the cultivation of peanuts had a greater effect on soil quality and multifunctionality improvement than ryegrass. This study provides fundamental data to support the improvement of land quality in photovoltaic developed regions, and to alleviate the conflict between photovoltaics and agricultural land. [ABSTRACT FROM AUTHOR]

Cd is a heavy metal that contaminates soils. These kinds of heavy metals pose a serious threat to food security, ecosystems, and human health. To improve the phytoremediation efficiency of moderately Cd-contaminated cropland soils and achieve simultaneous production and remediation, intercropping ryegrass (Lolium perenne L.) with hollyhock (Althaea rosea) was investigated using pot experiments, and Bacillus thuringiensis (B. thuringiensis) inoculation was used as a booster to strengthen the absorption and accumulation of Cd in plants. The results showed that intercropping (Int treatment) decreased the Cd concentration in plants compared to hollyhock and ryegrass monocropping. However, the Cd accumulation in ryegrass and hollyhock was promoted by B. thuringiensis addition to intercropping (Int-B treatment), as the biomass of ryegrass and hollyhock was 2.33 and 1.13 times that of the Int treatment, respectively. Compared with the Int treatment, the total Cd concentration in soils of the Int-B treatment decreased by 8.1%, while diethylenetriaminepentaacetic acid solution extracted Cd (DTPA-Cd) increased by 18.2%, indicating that B. thuringiensis increases the available Cd concentration in soils to promote Cd adsorption by hollyhock enrichment plants. High-throughput sequencing results further revealed that the dominant microflora in the soils of the Int and Int-B treatments were consistent with the control, although their abundance and diversity decreased slightly. Overall, intercropping with B. thuringiensis addition effectively increased the hollyhock remediation efficiency in moderately Cd-contaminated soils, and the concentration of Cd in forage crops of ryegrass was lower than the limit value of "Hygienic standards for feeds' (GB 13078–2017) in China. [Display omitted] • Bacillus enhanced the remediation of Cd contaminated soil by plant intercropping. • Intercropping decreased Cd uptake by ryegrass. • Biomass and the Cd accumulation of ryegrass were promoted by Bacillus. [ABSTRACT FROM AUTHOR]

Abstract: Winter cover cropping is a common practice in paddy soils in southern China. This two year study (2008–2010) was undertaken to determine dry matter productivity and N uptake of two winter cover crops: ryegrass (Lolium multiflorum Lam.) and Chinese milkvetch (Astragalus sinicus L.) and their effects on soil properties as well as two subsequent rice (Oryza sativa L.) crops in Dongting Lake Plain in Hunan, China. Cover crops were broadcast sown in October, approximately 10d before the harvest of late rice. Ryegrass was first cut in March and finally harvested in April coincident with the plough of milkvetch. Two consecutive rice crops were grown following the cover crops without application of chemical N. Averaged over two years, ryegrass produced more aboveground dry matter and accumulated higher amounts of N than milkvetch (4.7Mgha−1 vs. 2.4Mgha−1, 128kgha−1 vs. 71kgha−1). Compared to CK (bare fallow without weed), both ryegrass (RG) and milkvetch (CMV) treated plots had lower soil bulk density at 0–15cm and 15–30cm depths. At the harvest of cover crops, CMV increased soil NH4 +-N concentration at 0–10cm, 10–20cm and 20–30cm depths. In contrast, RG decreased soil NH4 +-N and NO3 −-N concentrations in the three depths. Averaged over four sampling dates in the double rice seasons in 2010, soil microbial biomass C was slightly different between RG (257mgkg−1) and CMV (249mgkg−1), and these were significantly higher than CK (218mgkg−1). Soil microbial biomass N was highest for CMV (15.4mgkg−1), followed by RG (11.3mgkg−1) and CK (6.1mgkg−1). Grain yield and total N yield of early rice were 0.6Mgha−1 and 11kgha−1 higher for CMV, respectively, and 1.0Mgha−1 and 20kgha−1 lower for RG as compared with CK averaged over years. Grain yield and total N yield of late rice were not significantly affected by cover crops. [Copyright &y& Elsevier]