Cement as a substitute for gypsum for improved pod-filling in groundnut

Abstract

Groundnut (Arachis hypogaea) cannot be grown economically on unamended acid soils because of poor pod-filling resulting from an inadequate supply of calcium. Gypsum improves pod-filling but in Mauritius it is now too expensive.

Field trials were conducted at two locations in 1994–95 and at four locations in 1995–96 to find out if cement could be used instead of gypsum. In three trials where the soil pH ranged from 5.4 to 6.3 and the soil calcium level from 2.4 to 6.9 cmol kg⁻¹, there were few empty pods and no response to gypsum or cement was observed. At the remaining three sites, the soil pH was 5.5, 4.9 and 4.3 and the soil calcium levels were 1.8, 0.39 and 0.92 cmol kg⁻¹, respectively. In the untreated plots at the three sites 17.4%, 27.5% and 50.6% of the pods were empty. Cement at rates of 525 and 700 kg ha⁻¹ and gypsum at 1000 kg ha⁻¹ applied to the foliage at flowering reduced the number of empty pods to less than 10% and significantly increased seed yield, shelling percentage and commercial-grade kernels. However, cement was not as effective when placed in the furrows at planting. At current prices, the use of cement was cost effective whereas that of gypsum was not. Cement may therefore be proposed as a replacement for gypsum for the improvement of pod-filling in groundnut.