Soil acid and exchange properties of red soil in hilly regions under different cropping patterns

Abstract

Soil acid and exchange properties of red soil in hilly regions under continuous cropping of citrus,camellia and watermelon,under intercropping of citrus with camellia,grass,peanut or sweet potato,under intercropping of camellia with watermelon and under wasteland pattern in Yongzhou and Liuyang,Hunan Province were studied through field sampling and laboratory analysis.The results showed that soils under different cropping patterns were acidified seriously with pH value around 4.0 and showed low to middle fertility-preserving capacity with CEC being 8.7?10.96 cmol/kg,and soil with camellia intercropping showed comparatively stronger fertility-preserving capacity.Exchangeable acid and exchangeable Al3+ were both the lowest in citrus intercropping soil,thus the potential acid was the lowest;exchangeable base content and base saturation were both the highest in citrus intercropping soil,thus the fertility,fertility-preserving capacity and buffering capacity was the strongest.Exchangeable acid in the tested soils mainly existed in the form of exchangeable Al3+,accounting for 92.5%?95.1%,and the exchangeable base mainly existed in the form of exchangeable Ca2+ and Mg2+,accounting for 82.7%?91.8%.The difference of CEC content among soils under various cropping patterns was very significant,while there was no significant difference in soil pH,exchangeable acid,exchangeable Al3+,exchangeable K+,Na+,Ca2+ and Mg2+ contents under various cropping patterns.