The characteristics of legumes and grasses used as cover crops are well known, but the release rate of nutrients associated with plant biomass becomes available to crops is still little studied. The objective of this work was to quantify the nutrient accumulation and release of sunnhemp and millet in monocrop and intercropping. The experimental design was a randomized complete block with four replicates. The treatments were sunnhemp, millet, sunnhemp + millet and weeds. The accumulation of P and Mg was strongly influenced by the dry matter yield, reaching high values in the presence of sunnhemp, while the accumulation of Ca was a result of both the high content and the high dry mater yield in the treatments with the leguminous. The rate of nutrient release showed similar dynamics, with two distinct phases: the first with higher release, in first the 15 days and the second, slowest, from this phase. The intercropping did not affect the release rates of K, Ca and Mg, while the presence of sunnhemp enhanced the release of N. Sunnhemp residues showed a P release higher than weeds, where the sunnhemp T 1/2 was of 11 days and the weeds of 17 days. Ca was released from de mass in a slower rate than the other nutrients, whereas the Mg was released more quickly. Weeds and millet show a high potential of K recycling and sunnhemp has a high potential of Ca and Mg recycling.
Green manure; nutrient recycling; Crotalaria juncea L.; Pennisetum americanum L
