Decomposition and nutrients release from crop residues placed on a Yellow Latosol in the savanna of the Maranhão State

Abstract

Resumo -No sistema plantio direto, o uso de plantas de cobertura é uma alternativa amplamente utilizada para aumentar a sustentabilidade do sistema agrícola. O objetivo deste trabalho foi avaliar a decomposição e liberação de nitrogênio (N), fósforo (P) e potássio (K) totais por resíduos culturais, provenientes do pousio e de culturas de cobertura (milheto e braquiária) solteiras e consorciadas, em Latossolo Amarelo no Cerrado Maranhense. O experimento foi conduzido em área sob plantio direto, após a colheita da cultura do milho, onde foram avaliadas a produção de fitomassa seca, decomposição dos resíduos em bolsas de polietileno (litterbags) e liberação de nutrientes (N, P e K), a cada 20 dias, até 100 dias após a dessecação. A braquiária e o milheto solteiros ou consorciados e a vegetação espontânea apresentaram decréscimos semelhantes na decomposição da matéria seca remanescente (MSR) nos primeiros 60 dias, com perdas de 10; 13; 16 e 12%, respectivamente. A maior e a menor taxa de liberação de N ocorreram no consórcio milheto + braquiária e no milheto, respectivamente. O K foi o nutriente liberado mais rapidamente do resíduo vegetal para o solo durante o processo de mineralização, em todos os tratamentos. A braquiária é a cobertura com maior resistência à decomposição, mantendo o resíduo sobre o solo por maior período de tempo em áreas do cerrado maranhense. Palavras-chave -Resíduos vegetais. Plantio direto. Capim-braquiária. Milheto.Abstract -In the no-tillage system the use of cover crops is a widely adopted alternative to increase the sustainability of the agricultural system. This study aimed to evaluate the decomposition rate and total nitrogen (N), phosphorus (P) and potassium (K) release from the biomass of natural bush fallow and cover crops (Brachiaria sp., millet and Brachiaria sp. + millet intercrop), cultivated on a Yellow Latosol in the savanna of the Maranhão State. The experiment was carried out under no-tillage system after maize harvesting. Dry matter production, decomposition rate and nutrient release (N, P and K) at twenty-day intervals, until one hundred days after biomass cutting were evaluated. Millet or Brachiaria sp. mono or intercropped and natural bush fallow showed similar decreases in their decomposition in the first sixty days, with losses of 10; 13; 16 e 12% respectively. The highest and lowest rate of N release was observed on millet and Brachiaria sp. + millet intercrop, respectively. Among the nutrients, K was the earliest released in all treatments. The Braquiaria sp. is the cover crop with greater resistance to decompose, keeping the residue on the soil for longer periods in the Cerrado of Maranhão State.

Decomposition and Nutrient Release of Cover Crops in Mango Cultivation in Brazilian Semi-Arid Region

“…Thus, virtually all the K contained in the phytomass of the plant mixtures (Table 3) was supplied to the soil after 315 days of evaluation. Leite et al (2010), evaluating K release in cover crops, observed that there were differences between treatments for the remaining values at almost all times of collection, except at the last one (100 days), when the treatments did not differ.…”

“…Studies evaluating phytomass decomposition describe a fast release of K in the initial phase of the process (Aita and Giacomini, 2003;Gama-Rodrigues et al, 2007;Leite, 2010 loss of K could be related to the fact that this element does not integrate into "stable" organic structures (Marschner, 1995;Gama-Rodrigues et al, 2007;Taiz and Zeiger, 2013;Gómez-Muñoz et al, 2014). One of the main mechanisms driving K release is leaching, so mineralization is not a pre-requisite for its transfer to the soil (Gama-Rodrigues et al, 2007).…”

Basic experimental unit and plot sizes with the method of maximum curvature of the coefficient of variation in sunn hemp

“…Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License raising to considerable levels of soil organic matter and nutrients (Leite et al, 2010). The crop rapid development enables the use of sunn hemp in cropping systems with rotation and crop succession.…”

“…The sunn hemp (Crotalaria juncea L.) is a cover crop option for soil protection due to its hardiness, high dry matter production and nitrogen fixation (Silva and Menezes, 2007), improving and maintaining soil quality, raising to considerable levels of soil organic matter and nutrients (Leite et al, 2010). The crop rapid development enables the use of sunn hemp in cropping systems with rotation and crop succession.…”

Sample Dimension for Estimation of Biomass and Yield of Sunn (Crotalaria juncea L.) and Showy rattlebox (C. spectabilis Roth.)

“…Among the various botanical families species that can be grown as green manures, stand out those of the Fabaceae family. The legumes in addition to providing similar benefits to other species, have the ability to accumulate N through biological fixation (Melo, 2012;Da Silva et al, 2009;Leite et al, 2010).…”