Lime and gypsum effects on soil chemical characteristics and on yield and quality of tomato and melon

The influence of lime and gypsum on soil characteristics and on yield and quality of tomato and melon fruits was evaluated in two experiments, carried out in the same site in a sandy Red Yellow Argisol in the Submedio São Francisco River region. The experimental design was a randomized complete block with four replications and seven treatments: 1) control; 2) half of liming need (N.C.) as limestone (Cal.); 3) 1 x N.C. (Cal.); 4) 2 x N.C. (Cal.); 5) 0.5 x N.C. as 2/3 limestone and 1/3 gypsum (Cal.Ges.); 6) 1 x N.C. (Cal.Ges.); 7) 2 x N.C. (Cal.Ges.). Limestone and gypsum were applied in November 2000; the tomato crop was grown from May to August 2001 and the melon crop from September to November 2001. Liming and gypsum applications resulted in an improvement of pH and increased the levels of Ca2+and Mg2+ and reduced the amount of Al3+ in the soil, the effect being more evident on the increase of Ca2+ levels, up to 60%, and on the decrease of Al3+ levels, up to 68.7%. Limestone by itself was more efficient for neutralizing Al3+ at depth for melon crop than limestone associated with gypsum. The rate of 2.0 tons of limestone/ha (1 x N.C.) was enough to give a melon yield of 22.5 tons ha-1 and to reduce by 80.4% the incidence of the blossom end rot disease in tomatoes. Therefore, gypsum was not necessary for these crops.

Lycopersicon esculentum; Cucumis melo; liming; acidity; blossom end rot disease