Effects of crop succession and systems of soil preparation on yield of upland rice

The objective of this work was to study the effect of different crop successions (S1: rice-common bean; S2: soybean-wheat-soybean-common bean-rice-common bean; S3: rice associated with Calopogonium muconoides-common bean; and S4: corn-common bean-corn-common bean-rice-common bean) and systems of soil preparation (P1: moldboard plough/harrow disc; P2: moldboard plough; P3: harrow disc and P4: no-tillage) on grain yield and on component yield of upland rice (Oryza sativa L.). The work was conducted at Embrapa-Centro Nacional de Pesquisa de Arroz e Feijão (CNPAF), Goiânia, Goiás, Brazil, in a Dark Red Latosol, for three consecutive years. A complete randomized design was used. Rice was cultivated annually in sucessions S1 and S3 and every three years in S2 and S4 in the months of November and December. There was a reduction in grain yield of rice during the three successives cultivation, and Calopogonium muconoides was prejudicial for yield of rice crop. Higher yield of rice was obtained when it was cultivated in succession every three years. Leaf area index and nutrients absorption were lower in successions where rice was cultivated annually. The highest grain yield was obtained under no-tillage treatment.