Estoques de carbono e nitrogênio e densidade do solo em sistemas de adubação orgânica de café conilon

Abstract

Production of Conilon coffee under organic management systems has increased in the State of Espirito Santo, Brazil. However, information is lacking in regard to the impact of these management practices on soil carbon and nitrogen stocks. The aim of this study was to evaluate the effect of organic fertilization on C and N stocks and soil bulk density (Bd) in a Conilon coffee agrosystem. A field experiment was carried out in Linhares, ES, in a randomized block design in a 2 × 2 × 5 factorial arrangement, with three replications. The factors were: two organic composts; presence and absence of the jackbean legume between the rows; and five different proportions of each organic compost (0, 25, 50, 75, and 100 %) to substitute the recommended mineral fertilization. Each replicate consisted of 30 coffee plants. Soil samples were collected under the canopy of each plant. The organic composts were compound 1, prepared from elephant grass and coffee straw in a 1:1 ratio (v:v); and compound 2, prepared from elephant grass, coffee straw, and chicken litter in a 2:1:1 ratio (v:v:v). Soil samples were taken 240 days after fertilization (240DAF) in the 1st crop year and 30 days after the 1st stage of fertilization (30DAF) in the 2nd crop year. The use of organic compounds to fertilize coffee led to a decrease in Bd of approximately 13 %. The increase in the proportion of organic compounds in fertilization increased the content and stock of C and N in the soil at 30 days after fertilization in the 2nd crop year. There were increases of 11 and 0.4 Mg ha-1 for the stock of C and N, respectively, for coffee plants fertilized with 100 % of compound 1, in relation to mineral fertilization. Fertilization with organic compounds is an alternative for increasing C and N stocks in agrosystems of conilon coffee.