Economic evaluation of puddling methods and weed control practices in a transplanted lowland rice-rice cropping system

摘要

A field experiment was conducted in the wetlands of Coimbatore, India, on 2 rice crops grown in sequence during the dry and wet seasons of 1996-97. The main weed species present were Echinochloa crus-galli, Leptochloa chinensis, Cyperus difformis, Marsilea quadrifolia and Monochoria vaginalis. Puddling with a tractor-drawn cage wheel restricted weed growth and resulted in higher grain yields of 5.23 and 4.80 t/ha in the dry and wet seasons, respectively, compared to conventional puddling with a bullock-drawn iron plough (4.97 and 4.65 t/ha). This increase in grain yield resulted in a higher benefit:cost (B:C) ratio, especially in the dry season (2.42). The traditional method of manual weeding twice (MW) controlled weeds effectively, but was not cost-effective. Although allelopathic weed suppression was expected from the planting of parthenium [Parthenium hysterophorus], the weed biomass was greater than in the other weed control methods. However, the grain yield was higher when parthenium was sown in both seasons: 5.77 and 5.33 t/ha for dry and wet seasons, respectively, compared to 5.53 and 5.12 t/ha with MW, and 5.43 and 5.19 t/ha with butachlor at 1.25 kg/ha + MW, in the respective seasons. The increase in grain yield with parthenium made itpossible to achieve better B:C ratios of 2.59 and 2.40 in the dry and wet seasons, respectively.