%0 Journal Article
%T Nitrate-Nitrogen Leaching from Onion Bed under Furrow and Drip Irrigation Systems
%A Parmodh Sharma
%A Manoj K. Shukla
%A Theodore W. Sammis
%A Pradip Adhikari
%J Applied and Environmental Soil Science
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/650206
%X 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 (NO3-N) fronts, water and NO3-N balances, and irrigation efficiencies for two onion (Allium cepa L.) fields under furrow and drip irrigation systems. Monthly soil samples were analyzed for NO3-N and chloride concentration for two onion growing seasons starting September 2006 to August 2009. The average amount of NO3-N in the soil water estimated by chloride tracer technique varied from 97.4 to 105.2£¿mg£¿ for furrow and 65.2 to 66.8£¿mg£¿ for drip-irrigated fields for the 60- to 200-cm depth. The NO3-N loadings below the rooting zone ranged from 145 to 150£¿kg£¿h for furrow- and 76 to 79£¿kg£¿h 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. 1. Introduction Among all the elements needed for plant growth, nitrogen (N) is considered the most important fertilizer element applied to soils because crop requirements for N are high compared with requirements for phosphorous (P), potassium (K), and other essential plant nutrients [1]. However, solubility of nitrate (NO3) sources in water can cause rapid movement through soils, and among the various sources of N loss in agricultural fields, leaching is considered a major source of NO3-N loss under normal agricultural practices [1]. Crops differ in rooting depths, rooting densities, N and water requirements, and plant uptake efficiencies [2], and the percolation of NO3-N to deeper soil layers depends on the cropping systems. In addition to N fertilizers and water applied by irrigation or received through precipitation, type of irrigation system and soil physical properties also play important roles in NO3-N leaching to groundwater [3, 4]. In arid regions like New Mexico, excess irrigation is also applied to flush salts out of the rooting zone to control soil salinization [5], leading to high N leaching. Nitrate loading to groundwater ranged from 165£¿kg£¿ha£¿1 NO3-N for irrigated sweet corn (Zea mays) to 366£¿kg£¿ha£¿1 NO3-N for irrigated potato (Solanum tuberosum) on sandy soils in Wisconsin [6]. In the Santa Maria, California, region, where crops such as potatoes, beans
%U http://www.hindawi.com/journals/aess/2012/650206/