Potential to assess nitrate leaching vulnerability of irrigated cropland

摘要: Irrigated cropland represents the largest source of groundwater nitrate (NO3) pollution in Central Valley (CV) California. Mitigation, through use best management practices that maximize crop nitrogen efficiency (NUE), will be most effective reducing if used where risk NO3 leaching loss is greatest. The University California9s Nitrate Groundwater Pollution Hazard Index (HI) tool was to map below rootzone irrigated fields a portion CV. HI an expert system calculates index value based on soil properties, characteristics, and type irrigation use. Depth groundwater, aquifer recharge rate, actual farm (e.g., rate [N] fertilizer applied) are not considered calculation. Application 1,318,000 ha (3,256,848 ac) four southernmost counties CV revealed 31% area at high managed carefully. Adoption drip or microsprinkler all orchards, vineyards, vegetable would decrease rated as vulnerable from 20% analyzed. Crop permeable soils and/or by surface gravity methods contributed risk. can help USDA, regulatory agencies, Cooperative Extension target regulatory, research, education efforts.