Sodium Sealed Microwatersheds and Skip Rowing for Water Harvesting and Cropping on Limited Rainfall
A microwatershed system was established in an area with 250 mm of growing season (June-September) average rainfall. Two growing beds, each 1 m wide, received the runoff from 3 m of adjacent sodium (NaCl) treated watersheds. Six levels of salt from 1.67 to 10 m tons/ha were used on the sheds with grain sorghum grown on the beds. The six years involved two very dry years, two wet years, and two average years. Grain sorghum yields ranged from 1980 to 8650 on the beds with an average of 6200 kg/ha, indicating economic feasibility. Salt levels had no visible effect on the plants and the lowest rate was still effective, both in shedding water and in controlling weeds. A number of other crops were tried on the salt beds over the six years with cotton, sunflowers, soybeans, and sweet sorghum the most successful. A skip-row system (2 in, 1 out on 1 m beds) was compared to 1 m and 2 m rows over 1983-1985. The skiprow system was superior in the dry and near normal years while the 1 m spacing was better in the very wet years. It was concluded that the skiprow system was superior under the local 250 mm growing season rainfall while the salt bed system would be superior in drier areas (100 to 200 mm).