Effect of irrigation and maintenance fertilization in soybeans in recovered fertility soils

Abstract

Ten soybean (Glycine max (L.) Merrill) cultivars were evaluated in two fertility levels (with and without maintenance fertilization), and (with and without irrigation). The experiment was conducted at the Agronomic Experimental Station of the UFRGS, at Guaíba, RS, Brazil, during the 1982/83 growing season. Without irrigation, the maintenance fertilization decreased the apparent harvest index; with irrigation, the apparent biological yield increased. These changes did not affect grain yield. In both experiments pods per plant was the yield component most variable. Cobb and BR-4 were the top yielders with more than four tons per hectare. With irrigation and maintenance fertilization, 80% of the cultivars increased yield, while without irrigation, 90% showed yield reduction. Since the average grain yield of the irrigated experiment was similar in two consecutive years, this indicates the existence of residual effect of maintenance fertilization in the soil.