Effects of Intercropping Groundnut and Green-Manure Legumes to Corn on the Yields of Corn and Productivity and Chemical Properties of Soil

Abstract

As an effort to find green-manure production methods that did not need complete devotion of land during the cropping season, a field experiment with three successive annual cropping was conducted in Thailand to examine effects of repetitive intercropping groundnut and green-manure legumes to corn for two successive years on the yields of the intercropped corn and soil productivity and chemical properties. Groundnut and green-manure legumes, which included creeping thornless mimosa, rice bean, sword bean, pigeon pea and lab lab, were intercropped to corn plants, which were grown with double-row spacing, and allowed to continue growing after harvesting and cutting down the stubble of the intercropped corn and were then chopped and plowed into the soil at about one month before the following annual cropping (9- 10 months after planting). Productivity of the soils were compared in the third cropping in which the plots for all of the treatments were planted to corn. Grain yields of corn intercropped with groundnut, lab lab, mimosa, pigeon pea, rice bean and sword bean in the first cropping were 102%, 92%, 86%, 79%, 76%, and 73% of that of the sole corn, respectively, whereas those obtained in the second cropping were 116%, 166%, 190%, 185%, 151%, and 123% of that of the sole corn, respectively. Grain yields of corn grown in plots previously cropped to corn-mimosa intercrops, corn-pigeon pea intercrops, corn-lab lab intercrops, corn-sword bean intercrops, corn-rice bean intercrops and corn-groundnut intercrops were 230%, 186%, 177%, 131%, 123%, and 112% of that of the plots previously treated with the sole corn. In general, the corn-mimosa intercropping system was the best and the corn-pigeon pea intercropping system and the corn-lab lab intercropping system were the second best in improving soil chemical properties. With the planting configuration used, intercropping corn with mimosa was most recommended and intercropping corn with pigeon pea or lab lab was the second most recommended for simultanous production of green-manure and corn.