Weed seed bank in green-manure-cultivated fields

Abstract

In order to evaluate the composition of a weed seed bank in a soil cultivated with green manure, an experiment was carried out from December, 1999, to February, 2000, in a greenhouse of the Plant Production Department, ESALQ/University of Sāo Paulo, Piracicaba, Brazil. The experimental units were made of 30 × 20 × 5 cm trays, filled with 1.0 kg of soil. The soil was collected by a 4.3 cm core sampler from the experimental field where the green manure and weeds were grown. The experiment had a completely randomized block design with four replicates, green manure (Arachis pintoi Krapov. and W.C. Gregory, Crotalaria juncea L. and Cajanus cajan L. Millsp.) in the plots and weeds in the subplots. Weed emergence was evaluated at 30 and 60 days after experiment installation. Green manuring significantly reduced weed seed bank, showing to be a very important practice for integrated weed management.