Home / Programs / Research

Research and Practice of Ag-lime Application for Ameliorating Acid Soils in Yunnan

IPNI-1999-CHN-YN10

Overview Related Interpretive Summary
30 May 2001

1999 Annual Interpretive Summary


The research and practice of ag-lime application of ameliorating acid soils in Yunnan province, 1999

Yunnan province has about 8 M ha of acid soils with pHs ranging from 4.0 to 5.5. These soils usually have problems associated with low fertility and often suffer from aluminum (Al) and iron (Fe) toxicity if not properly managed. Correct application of lime can increase crop production on most of these low yielding soils. This eventually translates into higher use of P and K fertilizers. This project is studying the limiting factors in relation to low soil fertility and poor productivity, examines the relationship between soil acidity and lime requirement, and is determining the optimal rates, timing, and placement of aglime for Yunnan province. Preliminary results show that the lateritic red soil and yellow-red soil had average pH values of 5.2 and 4.3, respectively. The predominant fractions of soil P were fixed or specifically adsorbed by Fe and Al in both soils. The levels of available P, K, Ca, and Mg were 35, 14.9, 60 and 13.2 mg/kg for lateritic red soil and 13.8, 7, 134, and 14 mg/kg for the yellow-red soil, respectively. YUNNAN-10