INFLUENCE OF CROP-ROTATION ON SELECTED CHEMICAL AND PHYSICAL SOIL PROPERTIES IN POTATO CROPPING SYSTEMS

Crop yields are often increased through crop rotation. This study exam ined selected soil chemical and physical properties that may constitut e the N and non-N related effects of crop rotation in potato cropping systems. Potato (Solanum tuberosum L. Norwis) was grown continuously a nd in two-year rotations with annual alfalfa (Medicago sativa L. Nitro ), hairy vetch (Vicia villosa Roth), white lupin (Lupinus albus L. Ult ra), and oat (Avena sativa Astro). Hairy vetch contributed more residu e N than any other crop rotation, ranging from 110 to 119 kg N ha(-1). Inorganic N concentrations in potato soils were related to the previo us crop's residue N contents, and were highest following vetch and alf alfa and lowest following oat and potato. The highest mineralizable N concentration was found following vetch (46.6 mg N kg(-1)). Saturated soil hydraulic conductivity in potato following all rotations ranged f rom 9.88 to 11.28 cm h(-1) compared to 5.71 cm h(-1) for continuous po tato. Higher soil water contents were maintained in the 30 to 45 cm de pth for all rotations compared to continuous potato. Thus several para meters indicate substantial N effects associated with particular crop rotations. Soil hydraulic conductivity and soil water status may also represent significant components of the rotation effect not directly r elated to N for these cropping systems.