Effect of rubber plantations on soil properties with comparison to secondary forest of Kolasib district, Mizoram

A detailed soil survey was undertaken at Kolasib district of Mizoram, North-East India with the aim to examine the effects of slope gradient and land use changes from secondary forest to rubber plantation on soil properties and also to provide the basic information about its fertility status using nutrient index values. Soil samples were collected and analyzed for soil bulk density, pH, organic matter, primary nutrients (N, P, K) and secondary nutrients (Ca, Mg, S) using standard procedures. The pH values studied soils were found to be strongly acidic. The result further revealed that secondary forest had higher soil organic matter (OM) and macronutrients (N, P, K, Ca and Mg) contents than in rubber plantation soils except for sulphur. Based on the fertility ratings and nutrient indices, the studied soils had high N in secondary forest and low P in rubber plantation, while others attained medium values. However, the decline in quality of soil properties was observed from steep to gentle slopes. Therefore, there is a need to restore and sustain the nutrient balance along the different slope gradients. Proper management of rubber plantation like balanced intercropping, increased use of organic nutrients, mulching etc. could help minimize the land deterioration and maintained soil under good conditions.