Project ID: NH541

Title: Developing Phosphorus Management Guidelines for Agriculture in the Connecticut River Watershed

Focus Categories: Nutrients, Non Point Pollution

Keywords: Soil Test, Phosphorus Saturation, Phosphorus Management, Phosphorus, Water Quality

Start Date: 03/01/2001

End Date: 02/28/2002

Federal Funds: $12,407

Non-Federal Matching Funds: $24,832

Congressional District: 1

Principal Investigators:
Elizabeth A Rochette
Assistant Professor, University of New Hampshire

Tom Buob
Senior Extension Associate II, University of New Hampshire

Abstract

Agricultural management practices for phosphorus have traditionally been developed for crop production. However, water quality degradation from excess phosphorus in surface waters leads to eutrophication. Agricultural phosphorus can be a nonpoint source of pollution, and it has become clear that criteria and guidelines for P management that prevent environmental degradation are needed. Unpublished University of New Hampshire data suggest that greater than 50% of New Hampshire agricultural soils may have high or very high phosphorus. The data set currently available for New Hampshire is not adequate to assess the extent of high-phosphorus soils in New Hampshire. We intend to examine both chemical factors, such as the form of phosphorus and its association with soil minerals and organic matter, and physical environmental features controlling the fate of phosphorus, such as soil texture, erosion, runoff potential and proximity to water bodies. In this study we will focus on soil characteristics, group soils by the physical and chemical properties affecting their abilities to retain and/or release phosphorus, and determine the current phosphorus saturation levels for representative New Hampshire agricultural soils. Our specific objectives are to (1) chemically and physically characterize representative agricultural soils from the Connecticut River Watershed (CRW) in New Hampshire; (2) determine the relationships between soil test methods used in New England, using the CRW/New Hampshire soils; (3) determine the relationship between water-extractable P and soil test P for the CRW/NH soils; (4) produce P sorption and desorption curves for a subset of the soils; (5) determine the soil components most closely related to P sorption in the CRW/NH soils; (6) adopt reliable soil testing methods to evaluate the risk of P movement in CRW/NH soils; and (7) determine P sorption characteristics to be used as factors in creating and evaluating BMPs for phosphorus management in agricultural areas in the CRW. In order to achieve our objectives we will determine texture; pH; soil organic matter content; extractable metals; water-soluble P; P sorption/desorption isotherms; soil test P by Mehlich 3, Modified Morgan, and Mehlich 1; and soil P partitioning by selective extractions. Regression analyses will be performed using the results of our analyses to address objectives (2), (3), (5), and (7). Our ultimate goal is to incorporate soil retention and release (sorption - desorption) properties into a scheme to develop management practices (BMPs) to minimize the risk of off-site movement of phosphorus.

Progress/Completion Report PDF