Soil test crop response studies on groundnut in laterite soils of Kerala

Abstract

The investigation entitled “STCR studies on groundnut (Arachis hypogaea L.) in laterite soils of Kerala” was conducted during 2003-2004 in the farm attached to College of Horticulture, Vellanikkara.

Objectives of the study were to develop soil test based balanced fertilizer recommendation for specific yield targets to groundnut in laterite soils of Kerala, and to develop a basis for fertilizer recommendation for maximum and economic pod yield at varying STVs.

The experiment consisted of FGE and STCR experiment. The aim of FGE was to create desired gradient in soil fertility in one and the same field by applying graded doses of N, P and K fertilizers and raising an exhaustive crop, fodder maize Co-1. After development of fertility gradient, the STCR experiment was conducted in the same field with the test crop groundnut variety TAG-24. The soil nutrient status before and after the experiment were analysed for both FGE and STCR.

The nutrient requirements of groundnut variety TAG-24 were estimated as 49.46, 4.25 and 19.52 kg ha-1 N, P and K respectively to produce one tonne of pod. The soil efficiencies were worked out as 28.11, 7.70, 6.88 per cent for N, P and K respectively for groundnut in laterite soil. The contribution of nutrients from fertilizers were estimated as 45.61, 11.18 and 27.33 per cent for N, P and K respectively and the contribution from organic manure were 49.46, 4.25 and 19.52 per cent N, P and K respectively to produce one tonne of pod.

Fertilizer prescription equations for specific yield targets of groundnut variety TAG-24 were derived by using the above basic data and the equations were as follows:

Without FYM FN = 108.44 T - 0.616 SN FP = 38.01 T - 1.577 SP FK = 71.43 T - 0.305 SK

With FYM FN = 108.44 T - 0.616 SN - 1.59 OM FP = 38.01 T - 1.577 SP - 1.87 OP FK = 71.43 T - 0.305 SK - 1.85 OK

Multiple regression models were calibrated with yield as dependent variable and soil available and applied nutrients as independent variables. Among the three nutrients, P and K showed normal type (+, -, -) of response in both models with 15 and 17 variables. So equations were calibrated for these two nutrients. The equations were as follows: With 15 variables FP = 32.47 - 0.709 SP FK = 321.36 - 0.429 SK With 17 variables FP = 76.27 - 2.645 SP FK = 312.37 - 0.413 SK

Simple correlation coefficient was worked out for nutrient uptake with yield, nutrient uptake and yield with available and applied nutrients and major plant nutrient content with yield.

The study is useful to adjust fertilizer doses based on the specific objective and available resources of groundnut farmers of the state.