IRRIGATING FORAGE WITH RECYCLED WATER: PROBLEMS AND POSSIBILITIES

Irrigation with reclaimed municipal wastewater is a modern form of recycling that is practiced throughout the arid and semi-arid regions of the world. In California and the US Southwest, water recycling and conservation are the only significant new sources of water available to meet the increasing domestic, industrial, and environmental demands. With good agronomic management, the potential for damage to soils and human health due to this practice has been shown to be minimal. Risks sometimes associated with land application of sewage sludge (e.g., heavy metal accumulation in soil) are rarely at issue with treated effluent. Treated effluent usually contains significant fertilizer nitrogen, mostly in the organic form and in some instances in the ammonium form. In low-rainfall regions, farmers using treated municipal effluent must take care to monitor salinity, which is elevated compared to that in the municipal freshwater source. Wastewater storage capacity must be available for times when the crop water demand is low. Forage crops, including in the best cases alfalfa, are ideal for irrigation with treated municipal wastewater. For good results, the treatment entity and the farmer must be dedicated to development and implementation of a nutrient and water management plan that serves both parties