Changes in soil microbial community composition and organic carbon fractions in an integrated rice-crayfish farming system in subtropical China.

Integrated rice-crayfish farming system is a highly efficient artificial ecosystem in which the rice (Oryza sativa) variety 'Jianzhen 2' is cultivated in waterlogged paddy fields along with crayfish (Procambarus clarkii). We investigated soil carbon fractions and microbial community structure by phospholipid fatty acids (PLFA) analysis in a 10-year field experiment using an integrated rice-crayfish (CR) model and a rice monoculture (MR) model at soil depths of 0-10 cm, 10-20 cm, 20-30 cm, and 30-40 cm. Compared with the MR model, the CR model had significantly more total organic carbon, particulate organic carbon, and dissolved organic carbon contents in all of the layers examined and microbial biomass carbon content in the 20-40 cm layer.

[Nutrient spatial variability of tobacco soil restoration area and fertility suitability level evaluation].

By using geographic information system technology (GIS) and geostatistics methods, this paper studied the spatial variability of soil properties and available nutrients in the new regulation area units located in Qingjiangyuan modern tobacco agriculture science and technology park (Enshi, Hubei), suburb of Enshi City and the Baiyang base of Lichuan City, and further evaluation of the soil fertility suitability index (SFI) was carried out by use fuzzy mathematics. The results indicated that the effects of land restoration on the soil available phosphorus content variability and spatial distribution were very obvious, possibly due to the landform characteristics and restoration extent. The effect of land restoration on soil pH was small, however, serious soil acidification was detected in the soil sampled from Baiyang (pH < 5.