Water Productivity of Newly Developed Lowland Rice Field

. Newly developed wetland rice fields require more water because plough pan layer are not developed. Plough pan is established several years after the field development and its formation depends on the intensity of rice cultivation and the soil properties. Plot scale study was conducted on newly developed wetland rice field originated from upland in Pati village, North Kalimantan Province, Indonesia in 2013. The aim of this experiment was to study the water productivity of the newly developed wet land rice fields. Different water ponding treatments including water ponding layer of 5 cm as control (T0), ponding layer of 3 cm (T1) intermittent with two weeks wetting and one week drying (T2), and saturated condition with water layer of 0.5 cm (T3) were tested. Rice growth, rice grains yield and water productivity were evaluated. Water productivity was computed according to the ratio between rice grains yield and water input. Water input was predicted based on the difference between incoming and outgoing water. In this study water balance was not taken into account in calculating the water input. The results indicated that under saturated condition (T3), plant height and tiller number were significantly lower than the 5 cm ponding and also significantly lower than other treatments. Water productivity between 0.78 and 0.40 gram liter-1 were recorded under ponding water depth of 0.5 cm and intermittent ponding of 5 cm in the wet period

SOIL OF PAMETIKARATA, EAST SUMBA: ITS SUITABILITY AND CONSTRAINTS FOR FOOD CROP DEVELOPMENT

Pametikarata, Lewa subdistrict, is the priority area for food crop development in East Sumba. To evaluate its suitability and constraints, chemical properties, suitability and fertility capability classification for rice and secondary crops of some potential soils have been studied both in the field and in the laboratory. Seven soil profiles consisted of forty one soil samples were subjected to chemical and mineralogical analyses in the laboratory. The analyses consisted of clay fraction and organic-carbon contents, pH, potential P and K (25% HCI extraction), available P, phosphate retention. Exchangeable cations and cation exchange capacity (NH4OAc 1N, pH 7), and mineralogical composition of the clay fraction. The results indicate that soil acidity varies from acid to neutral Exchangeable cations are dominated by Ca cation and soil CEC ranges from low to very high. Clay mineral composition also varies, some are dominated by montmorillonite, others show mixed mineralogy between montmorillonite and kaolinite, and the rests are dominated by kaolinite with the exception of wet Vertisols, all soils are grouped as marginally suitable (S3) for rice and secondary crops. Nutrient availability and retention are the common limiting factors. Using fertility capability classification (FCC), all soils are grouped as clayey soils with low infiltration and high water holding capacity. The serious constraint for food crop development in this area is uncontrolled grazing that makes a conflict of interests between farming and cattle herding systems. Optimum success of food crop development in the area could be reached by controlling the herding system and improving the existing agricultural system