Agricultural Drainage Ditches: Soils and Implications for Phosphorus Transport and Retention

Abstract

Agricultural drainage ditches act as pathways for nutrients to local surface waters. Knowledge of ditch materials, the spatial variation and distribution of ditch soil phosphorus, is critical to effective ditch nutrient management strategies. Ditch materials from the University of Maryland Eastern Shore Research Farm in Princess Anne, Maryland were described and characterized using a pedological approach. The spatial variation of phosphorus was also investigated. The materials found within these ditches are natural soil bodies. Pedogenic processes operating in these soils include organic matter accumulation, structure formation, Fe oxidation and reduction, sulfuricization, sulfidization, and bioturbation. Soil phosphorus was well autocorrelated, and exhibited a high degree of spatial variation. Ditch soil phosphorus at depth ranged from 4 to 4882 mg kg-1 for total phosphorus, 4 to 4631 mg kg-1 for oxalate-extractable phosphorus, and 2 to 401 mg kg-1 for Mehlich-3 phosphorus. Future ditch management strategies should include a subsurface soils component.