Decades of intensive fertilization on small vegetable farms throughout the Hawaiian Islands has lead to the accumulation of high to excessively high soil phosphorus levels. Continuing such fertilizer practices has several negative effects including increased risk of polluting fragile surface and coastal waters, nutrient imbaslances in the soil, and decreased farmer profitability. In intensive vegetable farming systems in Hawaii, the problem is particularly acute due to year-round growing seasons. A survey of soil samples sent to the University soil testing lab found that 67% of the soil samples sent in 2002 showed excessively high soil P concentrations. We have initiated a farm-based study to monitor soil nutrient status on intensive vegetable farms, and encourage farmer adoption of soil and tissue testing as a tool for reducing nutrient inputs. We have begun working with five farms located on Oahu, Maui, and Hawaii Island. Results from baseline soil sampling at each farm show that P concentration in the soil is consistently in the excessive category. Soil K is also very high at all the locations. Through close collaboration with each farmer, five field trials were implemented to test the hypothesis that soil nutrient levels were sufficient for good crop growth, and that only N was required as a nutrient addition. Three treatments consisting of the farmer practice (blended NPK fertilizer), urea alone (at the farmer practice N rate), and urea with 90 kg ha-1 starter P. Head cabbage was the test crop in four of the five experiments. No significant differences were obtained in fresh weight yields in four of the five experiments supporting the hypothesis that N alone was sufficient for good crop growth. We discuss the economic and environmental implications of our findings and emphasize the importance of participatory methods and on-farm trials.