Nitrate-Nitrogen Leaching from Onion Bed under Furrow and Drip Irrigation Systems

摘要

Water is a limited resource for crop production in arid areas of Southern New Mexico. The objectives of this study were to estimate the amount and depth of water and nitrate-nitrogen (NO_3-N) fronts, water and NO_3-N balances, and irrigation efficiencies for two onion (Allium cepa L.) fields under furrow and drip irrigation systems. Monthly soil samples were analyzed for NO_3-N and chloride concentration for two onion growing seasons starting September 2006 to August 2009. The average amount of NO_3-N in the soil water estimated by chloride tracer technique varied from 97.4 to 105.2 mg L~(-1) for furrow and 65.2 to 66.8 mg L~(-1) for drip-irrigated fields for the 60- to 200-cm depth. The NO_3 -N loadings below the rooting zone ranged from 145 to 150 kg ha~(-1) for furrow- and 76 to 79 kg ha~(-1) for drip-irrigated fields. The irrigation efficiencies varied from 78 to 80% for furrow- and 83% for drip- and N application efficiencies (NAEs) were 35 to 36% for furrow- and 38 to 39% for drip-irrigated fields. Small N fertilizer applications, delayed until onion bulbing starts, and water applications, preferably through drip irrigation, are recommended to reduce deep percolation and increase nitrogen and water efficiencies.