[Effects of Early Rice Straw Returning with Reducing Potassium Fertilizer on Late Rice Yield and Soil Fertility].

Rice straw is an important organic fertilizer in the region for double-cropping rice in South China. To reveal the effects of early rice returning with reducing potassium fertilizer on the yield of late rice and soil fertility, field experiments were carried out in Baiyun and Huiyang district in Guangdong province. The biomass, K content, and yield of late rice and the soil fertility properties, such as soil available potassium, soil organic carbon, bacterial diversity, and bacterial community structure were analyzed under three treatments (CK, conventional fertilization; RS, straw returning with conventional fertilization; RS-K, straw returning with reducing 20% potassium fertilizer). The results showed no significant differences in the biomass and yield of late rice between the RS-K treatment and CK treatment. Compared with that in CK, the RS treatment significantly increased the K contents of rice by 3.97% (Baiyun) and 6.91% (Huiyang). The K contents of late rice under the RS-K treatment were significantly lower than that under the CK treatment during the early growth period in rice, but there was no significant difference between them during the late growth period. Compared with that in CK, the soil available K in the RS treatment increased by 13.90% (Baiyun) and 21.67% (Huiyang) (P<0.05), and the soil available K in the RS-K treatment also increased by 3.56% (Baiyun) and 4.23% (Huiyang). Compared with that in the CK treatment, the soil dissolved organic carbon increased significantly in the RS and RS-K treatments (P<0.05). Compared with that in CK, the straw returning treatments (RS and RS-K) significantly improved the Chao1 and Shannon indexes of soil bacteria (P<0.05). Straw returning treatments (RS and RS-K) increased the relative abundance of Proteobacteria, Actinobacteria, and Nitrospirae compared with that in CK, whereas they decreased the relative abundance of Acidobacteria, Bacteroidetes, and Firmicutes. Redundancy analysis showed that the soil bacterial community was mainly influenced by soil organic carbon, dissolved organic carbon, microbial biomass carbon, available P, and available K. In summary, early rice returning could increase soil available K and K content in late rice. Early rice straw returning with reducing potassium fertilizer had no negative impacts on the growth and yield of late rice and could also improve soil organic carbon and the diversity of soil bacteria. Therefore, early rice straw returning with reducing potassium fertilizer can guarantee the grain yield of late rice and improve soil fertility.

Recent Developments in Lead-Free Double Perovskites: Structure, Doping, and Applications.

Lead-free perovskite structures have been recently attracting considerable attention because of their eco-friendly nature and properties, such as their lead-based structure. In this work, we reviewed the lead-free double perovskite (LFDP) structure because of its unique electronic dimensions, chemical stability, and substitutional chemistry compared with other lead-free structures. We highlighted the recent progress on crystal structure prediction, synthesis methods, metal dopants, and ligand passivation on LFDPs. LFDPs are useful for several applications, such as solar cells, light-emitting diodes, degradation of photocatalytic dyes, sensors, and X-ray detectors. This report provides a summary of recent progress as a reference for further research on lead-free perovskite structures.

[Effects of selenium fertilization on selenium availability in rice soil.] / 施硒对水稻土壤硒有效性的影响.

Selenium (Se) is easy to be fixed in acidic rice soil of South China, and thus its availability is low. The aim of this study was to investigate the influence of Se fertilizer on Se availability in rice rhizosphere and non-rhizosphere soils. The results showed that Se application increased yield and rice Se concentration. The water soluble, exchangeable, Fe/Mn oxide-bound, organic matter/sulfide-bound, and residual Se contents of the rhizosphere soil were lower than those of the non-rhizosphere soil. There was no significant difference in the migration coefficient of Se between the rhizosphere and non-rhizosphere soils. Se application had no significant effect on the migration coefficient of Se between roots and leaves but improved its migration coefficient between leaves and grains. The secretion of organic acids was increased by the application of 0.5 mg·kg-1 and decreased by the application of 1.0 and 5.0 mg·kg-1 Se. The secretion of organic acids had no significant effect on the rhizosphere soil pH. The pH of rhizosphere soil was higher than that of the non-rhizosphere soil, while the application of Se decreased the pH of the rhizosphere soil. With the increases of Se application, the intensity of the infrared absorption of clay mineral (kaolinite) in the rhizosphere soil showed an increasing trend. In this study, most of the Se was transformed into forms that were difficult to be absorbed and utilized by rice and difficult to move to rhizosphere soil. The enhancement of soil Se availability following the secretion of organic acids was not due to its effects on soil pH.