Análise do desempenho técnico e econômico de uso de adubos na produção de milho em sequeiro na zona sul de Moçambique

Abstract

Maize is an important food crop for most Mozambicans, contributing 25% of total calories and 61% of calories from all cereals. The poor availability of water and nutrients in the soil limits crop production in the southern part of the country. Matuba variety maize is largely cultivated in this area by small-scale farmers, in rainfed, due to its ability to tolerate certain periods of drought. In conditions of low soil fertility and in areas where rainfall is also low, fertilization in moderate amounts combined with the use of drought-tolerant varieties constitute some of the indispensable recommendations to improve crop performance. Information on the response of the matuba variety to dryland fertilization in the south is still scarce. The main objective of this work is to analyze the performance of maize under fertilization cultivated in areas of low agricultural suitability in relation to rainfall scarcity. In this study, two trials were conducted to test the response of corn to the application of n, p and k. In each trial, nek fertilizers were tested in a factorial scheme, with 4 levels of n (0, 100, 150 and 200 kg/ha) and 3 levels of k (0, 80 and 150 kg/ha), using blocks randomized completes with 3 repetitions. Phosphorus was tested at 2 levels (0.30 kg/ha of p), being level 1 (0 kg/ha of p) applied in test i and level 2 (30 kg/ha) applied in test ii. The tests were carried out in the experimental field of the faef of the emu in Maputo, in the agricultural season of 1993/94. The yield data from the two trials were submitted to an analysis of variance (ANOVA) separately and then, together. For the regression analysis, the means of the treatments were used to estimate the production functions for each of the two tests and the mathematical form assumed is the quadratic one. The prices and yield of corn in the "break-even" were determined by equating the value of the revenues with the costs of the n and k fertilizers. It was found that, given the irregularities of the rains that occurred during the period of conducting the tests, especially its distribution, the practice of fertilization was not able to solve the problem of yield in the maize crop produced in rainfed. And under the conditions in which these tests were conducted (with 2 additional waterings), it was possible to verify that the response of maize to the application of n and p fertilizers resulted in an increase in the yield of this crop. It also showed that the economic profitability of n, p and k fertilizers is strongly conditioned by their prices rather than by the price of corn grain, since the use of fertilizers was profitable for 1994 fertilizer prices (low) and not profitable for 2001 fertilizer prices (high)