Site-specific nutrient management (SSNM) provides a field-specific approach for dynamically applying nutrients to rice. We evaluated economic benefits and estimated nitrous oxide emissions for SSNM, including use of a leaf color chart for fertilizer N management, in farmers' fields in southern India, the Philippines, and southern Vietnam for two cropping seasons. Based on focus group discussions, use of SSNM by farmers increased seasonal rice yield and added net annual benefit. The increased benefit with SSNM was attributed to increased yield rather than reduced costs of inputs. Use of on-farm data with the DNDC model revealed lower simulated N losses from fertilizers with SSNM. At the location in India where partial factor productivity for farmers' management of fertilizer N was high, the use of SSNM increased yield and use of fertilizer N with no simulated increase in nitrous oxide emission per unit of grain yield. At the locations in Vietnam and the Philippines where partial factor productivity for fertilizer N was lower, the use of SSNM increased yield with less use of fertilizer and a reduction in simulated nitrous oxide emission. SSNM increased profit and yield with the same or lower simulated emissions of nitrous oxide per unit of rice production.
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