Efeito da adição de cinza e de pó de granito na compostagem de braquiária com gliricídia visando a produção de substrato e fertilizante orgânicos

Abstract

Composting is an important alternative for the processing of waste and by-products of organic composition aimed at the production of substrates and organic fertilizers, and the utilization of additives, such as ashes and rock powder, can improve the compost processes and the properties of the compost obtained. The objective of this work was to study the effects of the addition of ashes and granite powder on the mixture of straws of Brachiaria brizanta with Gliricidia sepium (Jacq.) Steud.): i) on the physicochemical characteristics observed over 120 days of composting; ii) on using of the compost as a substrate for the production of seedlings of lettuce (Lactuca sativa L.), beet (Beta vulgaris L.) and tomato (Lycopersicon esculentum Mill.); and iii) on the use of the compost as an organic fertilizer for the vegetable production of lettuce and beet. It has been observed that it is possible to produce organic composts from the mixture of brachiaria with gliricidia. The addition of ash or granite powder to the initial mixture reduces the C, N and K contents of the organic composts obtained, due to the lower content of C, N and K presented by these materials, especially in relation to gliricidia, but the addition of granite powder increases the humification of the organic matter and the addition of ash increases the contents of Ca, Mg and P. The organic composts obtained from the mixture of brachiaria with gliricidia can be used the substrates for the production of vegetable seedlings, and the addition of ash or granite powder in the mixture does not improve the performance of these substrates. The use of organic compost obtained from the mixture of brachiaria and gliricidia as fertilizers for the organic production of lettuce and beet did not provide significantly greater effects than those observed with the use of bovine manure and the control treatment without fertilization, but this result can be due to the high fertility found in the experimental area and to the fact that these crops have very short cycles, and there is insufficient time for the mineralization of most of the nutrients present in the organic fertilizers used