Phosphorus research strategies to meet agricultural and environmental challenges of the 21st century

The accumulation, management, and transfer of P in intensive farming system s has increased P export from agricultural watersheds and accelerated eutro phication of surface waters. Even though much research on P has been done i n the last 20 years, there are still too few answers to the many questions now being asked regarding agricultural production;md environmental quality, To address these concerns, four areas of research are suggested: (i) Soil P testing for environmental risk assessment-What losses are acceptable and arm these losses be determined by plot-scale or watershed-scale studies? Th reshold P levers in soil and water should be established in combination wit h an assessment of site vulnerability to P loss. (ii) Pathways of P transpo rt-An analysis of the relative importance of different flow pathways is nee ded at a watershed scale, (iii) Best Management Practice (BMP) development and implementation-Overall, BMPs must attempt to bring P inputs rand output s into closer balance and should be targeted first to critical source areas within a watershed. Alternative management recommendations, uses, and mark et demand for manures must be developed. (iv) Strategic initiatives to mana ge P-To initiate lasting changes, research should focus on consumer-support ed programs that encourage farmer performance and stewardship to achieve ag reed-upon environmental goals.