WATER AND ENERGY-CONSERVATION USING IRRIGATION SCHEDULING WITH CENTER-PIVOT IRRIGATION SYSTEMS

An extension project covering portions of two counties in north central Nebraska, USA, demonstrated that irrigation scheduling and pumping plant adjustment practices reduced energy costs for center-pivot irrigated com (Zea mays L.). Data were collected for 51 center-pivot systems; 19 employed irrigation scheduling techniques (Schedule Group), and 32 center-pivot systems managed water applications using other methods (Control Group). On average, the Schedule Group used 17% less energy, applied 29mm (11%) less water and harvested 322 kg/ha (3.5%) more grain than the Control Group. Harvested yields and annual water application depths were less variable for the Schedule Group. Results suggest that irrigation scheduling improved the irrigators ability to determine irrigation timing and application depths. Adjustment of pumping plants improved the operating performance by an average of 8.1% of the Nebraska Pumping Plant Performance Criteria. Energy use was reduced by 0 to 34%. Annual return averaged $4.70 per hectare compared to an estimated cost of $1.65 per hectare per year for pumping plant adjustment. Analysis of the operating costs indicated that compared to the Control Group, the Schedule Group realized a total increase in return which ranged from $1.54 per hectare in 1986 to $13.03 per hectare in 1984. Average annual return was increased by $5.40 per hectare.