Effect of Ag-lime on Broadbean Production in Yunnan Province

The majority of soils in Yunnan province are acidic with a pH of 4.0 to 5.5. Acidity induced adverse soil conditions usually reduces availability of indigenous soil P, K and some other nutrients and those applied as fertilizers, considerably. However, there was no history in the province of lime application to farm land as an agronomic practice to improve soil fertility and productivity. For this reason, experiments were carried out in laboratory, greenhouse and fields to study : a) the limiting factors in relation to low soil fertility and poor productivity, b) to examine the relationship between soil acidity and lime requirement and c) to determine the optimal rates, timing and placement of ag-lime for Yunnan province.

It was found that among all the treatments (NPK, NPK+Mo, NPK+burned lime, NPK+slaked lime, NPK+ground calcite, NPK+ground dolomite, NPK+ground calcite+ground dolomite, NPK+slaked lime+straw and NPK+baked lime+straw) tested, ground limestone was the best treatment in improving yields of broadbean and corn in the laterite soil and ground dolomite was the best in the yellow earth in Yunnan province. Using a fertilizer application of 30-120-150 kg N-P2O5-K2O/ha for broadbean and 150-120-60 kg N-P2O5-K2O/ha for corn on both soils as farmers’ practice, addition of 4.5 t/ha of ground calcite to the laterite soil and 2.8 t/ha to the yellow earth could increase yield of broadbean by 1,572 kg/ha (49.7%) and 1,676 kg/ha (55.9%), respectively. Similarly, addition of 5.6 t/ha of ground dolomite to the laterite soil and 2.8 t/ha to the yellow earth increased yield of corn by 2,733 kg/ha (32.3%) and 2,806 kg/ha (27.4%), respectively. The different responses of the two soils to the calcite and dolomite were due to more severe deficiency in Ca in the laterite soil with Mg also being deficient in the yellow earth. In general, ag-lime treatments improved soil nutrient availability and crop uptake as well. Liming acid soil can be a very effective and economic practice to improve productivity and farmers’ income in China.


Figure 1. Effect of ag-lime materials and application rates on broadbean growth



Note: 1. The CK treatment in Table 1 received 30-120-150 kg N-P2O5-K2O/ha, and this was applied to all
other treatments. 2. Yield means with the same letter are not significantly different at P=0.05.