The fertilization of maize in Lavras

Abstract

The study of 38 trials on the fertilization of maize scattered in farms of the region of Lavras, State of Minas Gerais, Brasil, led to the following conclusions : 1. In experiments with control below 2000 kg./ha. there were significant responses for N, R, K and limestone. If we take the price of 100 kg. of maize as equivalent to that of 10 kg. of N, 12 of P2O5 or 30 of K2O, the recommended dressings are 38 kg./ha. of N, no phosphorus, and 88 kg./ha. of K2O. 2. In experiments with control not below 2000 kg./ha. only effects of N and R were significant, but it seems better to use a complete fertilizer. For the prices given above the recommended dressings are 44 kg./ha. of N, 75 of P2O5 and 51 of K2O. 3. In experiments carried out on cerrado soils significant responses were found for N, R, K and limestone. The recommended dressings, for the prices mentioned, are 51 kg./ha. of N, 40 of P2O5 and 99 of K2O. 4. For soils with known content of organic matter recommendations should take in account if it over 1.25% or not. When over 1.25%, the recommended dressing is 27 kg./ha. of N; if it is not over 1.25%, one should use 120 kg./ ha. of N. 5. For R and K soil analysis does not seem suitable to estimate responses to fertilization. 6. Responses to limestrone are higher in soils with Ca + Mg not above 3.40 meq./100 ml. of soil, or for pH not above 4,75, or else for exchangeable Al over 0.566 meq./100 ml. of soil.