Enzymatic activity and mineralization of carbon and nitrogen in soil cultivated with coffee and green manures

There are great concerns about degradation of agricultural soils. It has been suggested that cultivating different plant species intercropped with coffee plants can increase microbial diversity and enhance soil sustainability. The objective of this study was to evaluate enzyme activity (urease, arylsulfatase and phosphatase) and alterations in C and N mineralization rates as related to different legume cover crops planted between rows of coffee plants. Soil samples were collected in a field experiment conducted for 10 years in a sandy soil in the North of Paraná State, Brazil. Samples were collected from the 0-10 cm layer, both from under the tree canopy and in-between rows in the following treatments: control, Leucaena leucocephala, Crotalaria spectabilis, Crotalaria breviflora, Mucuna pruriens, Mucuna deeringiana, Arachis hypogaea and Vigna unguiculata. The soil was sampled in four stages of legume cover crops: pre-planting (September), after planting (November), flowering stage (February) and after plant residue incorporation (April), from 1997 to 1999. The green manure species influenced soil enzyme activity (urease, arylsulfatase and phosphatase) and C and N mineralization rates, both under the tree canopy and in-between rows. Cultivation of Leucaena leucocephala increased acid phosphatase and arilsulfatase activity and C and N mineralization both under the tree canopy and in-between rows. Intercropped L. leucocephala increased urease activity under the tree canopy while C. breviflora increased urease activity in-between rows. Existe grande preocupação sobre a degradação dos solos agrícolas. Tem sido sugerido que o cultivo de plantas intercalares no cafeeiro aumenta a diversidade microbiana e a sustentabilidade do solo. No presente trabalho foi avaliada a alteração na atividade de enzimas do solo (urease, arilsulfatase e fosfatase) e na mineralização do C e N devido ao cultivo intercalar de diferentes leguminosas de verão na cultura do cafeeiro. Foram feitas amostragens em um experimento de campo de longa duração instalado em Latossolo Vermelho distrófico em Miraselva, PR, na profundidade de 0-10 cm, na projeção da copa e na entrelinha, nos seguintes tratamentos: testemunha, leucena (Leucaena leucocephala), Crotalaria spectabilis, Crotalaria breviflora, amendoim-cavalo (Arachis hypogaea tipo virginia), mucuna-cinza (Mucuna pruriens), mucuna-anã (Mucuna deeringiana) e caupi (Vigna unguiculata). As amostragens de solo foram feitas em quatros estádios de