Tillage and cover cropping influence phosphorus dynamics in soil and water pools

Abstract Winter cover crops (CCs) have the potential to reduce phosphorus (P) loss by temporarily fixing P into CC biomass. A field experiment with no‐tillage (NT) and conventional tillage (CT) was used to study the ability of different CC species planted after corn ( Zea mays L.) and soybean ( Glycine max L.) harvests to reduce the P availability in soil solution. The effect of three crop rotations (corn–no CC–soybean–no CC [C–S], corn–cereal rye ( Secale cereale )–soybean–hairy vetch ( Vicia villosa ) [C–R–S–HV], corn–cereal rye–soybean–oats ( Avena sativa )+ radish ( Raphanus sativus L.) [C–R–S–OR]) and two tillage (NT and CT) treatments was determined on soil available P and soil solution P content through pan (A horizon) and tension (100‐cm depth) cup lysimeters. The experiment was set up as a randomized complete block design with tillage as a split factor with three replicates. Over the study period, incorporating hairy vetch in C–R–S–HV rotation reduced the Mehlich‐3 P content in soil by 26%–29% compared to the C–S and C–R–S–OR rotation. Both CC rotations (C–R–S–HV and C–R–S–OR) were effective in reducing dissolved reactive P (DRP) concentration in pan and tension cup lysimeters compared to the C–S in both CT and NT systems. However, these results varied with CC species grown and seasonal variability in precipitation. A significantly lower DRP load with crop rotation and tillage treatments was observed mainly during the CC growing season. During the study period, crop rotations with reduced labile soil P content and DRP loss were ranked in an order of C–R–S–HV > C–R–S–OR > C–S. Overall, this study showed that CCs have the potential in both CT and NT systems to significantly reduce P in soil and soil solution, and these effects are resilient to a wide range of precipitation conditions.