SummaryIn order to study the reasons for poor peanut (Arachis hypogaea L.) performance on an Avalon medium sandy loam, a three year field study was undertaken to investigate the effects of lime and gypsum applications on growth, yield and quality. Rates of up to 2,400kg agricultural lime/ha/annum significantly increased soil pH (1 N KCI) and exch. Ca and decreased levels ofexch. A1 and AI saturation in the soil ((~150mm). The effect of the same rates of gypsum was much less marked, only exch. Ca increasing and A1 saturation decreasing to any substantial extent. In the absence of lime (i.e. even where gypsum was applied), nodulation was poor and the plants developed a general chlorosis c. 90 days after planting. Liming markedly improved nodulation whereas annual applications of gypsum had the opposite effect. Liming significantly increased the hay, pod and kernel yields by up to 73, 105 and 117%, respectively. On average, gypsum applications had no significant effects. Liming increased shelling percentage, the percentage mature pods, 100-kernel mass and protein concentration in the kernel, and decreased the incidence of pops and kernels with black plumule. Applications of gypsum had little effect on quality except for a decreased incidence of black plumule. It appeared that the improved crop performance with liming resulted from a reduction in A1 toxicity which improved nodulation. Calcium deficiency did not appear to be a major cause of poor peanut growth and quality in the unameliorated soil.