Fertility Restoration of Red Soils in Low—Hilly Region of Middle Subtropical China

摘要

There are about 1.27 million ha of upland red soils derived from Quaternary red clay facing the degradation in the low-hilly region of the middle subtropical China.From the aspects of chemistry,physics and microbiology,the processes of soil fertility restoration in the surface layer(0-20cm) under three types of land use patterns(i.e.citurs orchard,tea garden and upland)in two provinces were studied in this work.Results showed that the reclamation of eroded waste aldn improved most of soil properties.Soil organic matter,total N and P,available P and K,and exchangeable Ca and Mg increased,but soil total K and exchangeable Al decreased Soil pH decreased by 0.5 unit in the pure tea plantation for 20 years.Soil reclamation increased the percentage of soil micreased by 0.5 unit in the pure tea plantation for 20 years.Soil reclamation increased the percentage of soil microaggregates(<0.25mm),especially those with a diameter of 0.02-0.002mm.Soil total porosity increased in the cultivated lands with the increase of soil aeration and capillary porosity,The number of soil microorganisms increased with reclamation caused mainly by the huge increase of the total amout of bacteria,With the cultivation,the eativity of soil urease and acid phosphatase increased.but that of invertase dropped.