Management of acidity by combined application of lime and gypsum in a low activity clay soil of Kerala
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Date
1992
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Department of Soil Science and Agricultural Chemistry,College of Horticulture, Vellanikkara
Abstract
An investigation was conducted at the College of Horticulture, Vellanikkara in the period 1989-'91, with a view to identify the most appropriate and economic lime recommendation method and the most suitable combination of lime and gypsum for profitable management of upland latent e (LAC) soils. The first study was to characterise the low activity clay soils of Kerala m respect of acidity contribution factors. Another laboratory experiment was also conducted with PVC columns to study the mobility of Ca and Mg using different liming materials m combination with gypsum. A potculture experiment was also carried out using soybean to study the effect of liming in combination with gypsum on the growth, yield and uptake of various nutrients.
The characterisation study revealed that the soils in the Vellanikkara series come under the textural class ranging from silty loam to silty clay loam. The soils m general were acidic in reaction with fairly high content of exchangeable Al and low CaO and MgO contents. Sesquioxide, and Al2O3 contents were high. The soils were low m organic carbon and CEC.
The leaching experiment revealed that CaCO3 and MgCO3 can be used as an ameliorant for acid surface soils as it neutralised exchangeable Al and increased pH in the surface layer only. CaS0.2H20, however can be used as an ameliorant for acid subsoils as it neutralised exchangeable Al and supplied Ca throughout the length of the profile. The combination treatment with MgCO3 + 75 per cent CaSO4 2H2O can be suggested as an ameliorant for acid surface as well as subsoils as it resulted in uniform distribution of exchangeable Ca and Mg throughout the length of the column and neutralised exchangeable Al in the whole length of the profile.
Liming resulted m significant increase in plant height, nodule number, dry weight of pod, g r a m yield, haulm yield, total dry weight and N, P, K uptake. , Soil pH, effective CEC, total Ca, exchangeable Ca and available N were increased significantly due to liming. However significant reduction in total Mg, exchangeable Al, Al saturation and available P and K resulted due to liming.
Liming at the rate of 1.5 times exchangeable Al content of soil was found to be the most appropriate and economic lime recommendation method for the highly weathered and leached acid soils of Kerala.
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