The increase of rice cropping index supported by river dam irrigation in dry land

This study aimed to determine the increase of rice cropping index from 1 to 2 in several rice varieties supported by river dam irrigation on dry land during the second growing season. The research was conducted in dry land in Pacarejo, Semanu, Gunungkidul, Yogyakarta, Indonesia, in March-Juli 2019 during second growing season. The increasing of rice cropping index utilized supplementary irrigation from river dam to maintain soil moisture. Rice varieties used were Inpari 24, Inpari 30, Inpari 32, and Inpari 33, complete with a package of technological components. The result showed 139 mm of rainfall with 11 rainy days, so that the most of crop water requirements came from river dam irrigation. Inpari 24 gave the highest grain yield (442.8 kg/1,000 m2) which was not different from Inpari 30 but different from Inpari 32 and Inpari 33. Inpari 24 carbon absorption was 503.8 kg/1,000 m2, consisting of 207.4 kg/1,000m2 in grain, 218.6 kg/1,000 m2 in straw, and 77.9 kg/1,000 m2 in root which was different from Inpari 32 (p<0.05; n=3). B/C Inpari 24 was 1.18 and farmers profit was Rp. 1,006,600/1,000 m2. The profit of rice cultivation in all rice varieties were higher than groundnut with higher irrigation costs.