Farm-NUTMON is a research tool that integrates the assessment of stocks and flows of the macro-nutrients nitrogen, phosphorus and potassium on the one hand and economic farm analysis on the other. The tool is applicable at both the farm and the activity level. It includes a structured questionnaire, a database, and two simple static models (NUTCAL for calculation of nutrient flows and the ECCAL for calculation of economic parameters). Finally, a user interface facilitates data entry, data manipulation and extracts data from the database to produce input for both models. Farm-NUTMON allows (i) estimation of the extent to which farmers generate income from soil nutrient mining, (ii) assessment of the impact of changes in farm management techniques on nutrient balance and economic performance at activity level and farm level, and (iii) calculation of the economic impact of exogenous changes on the farm and activity level.