Implementation of Irrigation with Dairy Cattle Manure for Tropical Perennial Pastures in Costa Rica

Abstract

Animal manures allow nutrients recycling in cropping systems, while contributing to the fulfillment of environmental standards. Pasture irrigation with animal manures has been fostered for Costa Rican dairy farms over the last 15 yr. A lack of information and training regarding irrigation and management of animal manures has led to the implementation of diverse methods by producers, but those have not yet been characterized. This study aimed to describe the current management of Costa Rican dairy farms irrigating perennial pastures with slurries. The farms were mostly grass-based systems with supplements fed to cows during the time spent at the milking parlor and/or in feeding stalls through the day. Farms collect manure when facilities are washed with water, which is then stored in plastic tanks or cement structures for less than 1 day before irrigating pastures. The amount of water used by dairy producers was greater than the recommended water/manure ratio (13.4 vs. 4.0 L kg–1), with only one farm reporting values below this ratio. Slurries were sampled and analyzed for their nutrient and microbial content. Both nutrient and microbial content varied in this study due to factors specific to each farm, especially with respect to water management. The variability found in water use among farms and regions (2.4–36.7 L kg–1) may generate unintended consequences from an environmental standpoint. Sustainability of Costa Rican dairy farms can be enhanced if specific guidelines for manure irrigation are developed, which could have benefits for chemical fertilizer use and environmental effect.