Effect of land use on microbial biomass－C, －N and －P in red soils

Eleven red soils varying in land use and fertility status were used to examine the effect of land useon microbial biomass -C, -N and -P. Microbial biomass-C in the red soils ranged from about 68 rag C/kg to 225 mg C/kg, which is generally lower than that reported from other types of soil, probably because of low or-ganic matter and high acidity in the red soils. Land use had considerable effects on the amounts of soil Cmic.The Cmic was the lowest in eroded fallow land, followed by woodland, tea garden, citrus grove and fallow grassland, and the highest in vegetable and paddy fields. There was significant correlation between Cmic and organic matter content, suggesting that the influence of land use on Cmie is mainly related to the input and ac-cumulation of organic matter. Microbial biomass-N in the soils ranged from 12.1 Nmg/kg to 31.7 Nmg/kg andwas also affected by land use. The change of Nmic with land use was similar to that of Cmic. The microbial C/N ratio ranged from 5.2 to 9.9 and averaged 7.6. The Nmic was significantly correlated with soil total N and available N. Microbial biomass-P in the soils ranged from 4.5 mg P/kg to 52.3 rag P/kg. The microbial C/P ratio was in the range of 4-23. The Pmic was relatively less affected by land use due to differences in fertili-zation practices for various land use systems.

Effect of land use on microbial biomass-C, -N and -P in red soils

Eleven red soils varying in land use and fertility status were used to examine the effect of land use on microbial biomass -C, -N and -P. Microbial biomass-C in the red soils ranged from about 68 mg C/kg to 225 mg C/kg, which is generally lower than that reported from other types of soil, probably because of low organic matter and high acidity in the red soils. Land use had considerable effects on the amounts of soil C(mic). The C(mic) was the lowest in eroded fallow land, followed by woodland, tea garden, citrus grove and fallow grassland, and the highest in vegetable and paddy fields. There was significant correlation between C(mic) and organic matter content, suggesting that the influence of land use on C(mic) is mainly related to the input and accumulation of organic matter. Microbial biomass-N in the soils ranged from 12.1 Nmg/kg to 31.7 Nmg/kg and was also affected by land use. The change of N(mic) with land use was similar to that of C(mic). The microbial C/N ratio ranged from 5.2 to 9.9 and averaged 7.6. The N(mic) was significantly correlated with soil total N and available N. Microbial biomass-P in the soils ranged from 4.5 mg P/kg to 52.3 mg P/kg. The microbial C/P ratio was in the range of 4 - 23. The P(mic) was relatively less affected by land use due to differences in fertilization practices for various land use systems.