Abstract
Central Lombok Regency (Indonesia) is dominated by vertisol soil, where irrigated or rainy season rice crop is normally rotated with non-rice food crops during the dry season, and to minimize risks of failure, multiple-cropping systems are normally established. This research aimed to examine the effects of additive intercropping, by inserting 1-3 rows of mungbean or soybean between rows of waxy maize on the vertisol riceland. The experiment was designed with Split-Split Plot Design with three bocks and three treatment factors, i.e. types of legume crops (mungbean or soybean) as the main plots, additive intercropping (insertion of 0, 1, 2 or 3 rows of legume crops between maize rows) as the sub-plots, and doses of N fertilizer for waxy maize (full or half the recommended dose) as the sub-sub-plots. Results indicated that intercropping waxy maize with legume crops increased maize leaf N concentration and uptake, leaf P uptake, number of green leaves at 6 and 7 weeks after seeding, ear and shoot dry weight, plant height, and grain yield of the waxy maize. Reduction of maize N doses also reduced maize grain yield. However, there was a significant interaction between intercropping and N doses, in which reduction of maize N doses to 50% of the recommended doses did not reduce maize grain yield in the maize plants intercropped with 1 or 2 rows of legume crops but this treatment significantly reduced maize grain yield in the monocrop or in intercropping with 3 rows of legume crops. Therefore, insertion of 1-2 rows of legume crops between rows of waxy maize increases land productivity since the legume crops also produced seeds and biomass that can be used as cattle feed. Between the legume crops, intercropping with soybean was better than mungbean in increasing the waxy maize grain yield.