Abstract

There is increasing global concern with environmental food production and sustainability to maintain high carbon stocks in soil biomass. The biomass produced in crop-livestock integration system increases soil organic matter, acts in nutrient cycling, improves the physical, chemical and biological characteristics of soil and increases grain production. Moreover, this soil management system mitigates greenhouse effect and preserves the environment. However, in the Savannah of Central Brazil region, an efficient mulching production of biomass is one of the factors limit sustainability of direct seeding of soybean, mainly due to accelerated decomposition of crop residues. Thus, this study aimed to evaluate biomass dynamics of pearl millet and Paiaguas palisadegrass in different forage systems and sowing periods on soybean yield. The experiment followed a randomized block design with a 5 x 2 factorial arrangement and three replications, under five forage systems (monocropped pearl millet, monocropped Paiaguas palisadegrass, pearl millet intercropped in rows with Paiaguas palisadegrass, pearl millet intercropped between rows of Paiaguas palisadegrass and pearl millet oversown and intercropped with Paiaguas palisadegrass) at two sowing periods (February and March). The results showed that Paiaguas palisadegrass in a monocropped system generated the highest biomass production and lowest carbon/nitrogen ratio. The highest carbon/nitrogen ratio and cumulative biomass loss occurred with millet in monocropped and intercropped with oversown Paiaguas palisadegrass in which biomass production was reduced by plant competition. Paiaguas forage systems in palisadegrass monocropped and intercropping on and between rows supported higher yield of soybean. The second sowing periods resulted in higher production of remaining biomass and grain yield, in all forage systems. Intercropping in crop-livestock integration systems showed a promising cultivation technique to maintain a sustainable stock of soil carbon.

Key words: Carbon/nitrogen ratio, half-lives, [Pennisetum glaucum (L.) R. Br.], Urochloa brizantha cv. BRS Paiaguas.