No-till / strip-till
Tillage practices affect soil erosion, which is the primary transport process of P delivery in Iowa. Conservation tillage, where 30% or more of the soil surface is covered with crop residue after planting, or no-till, where 70% or more of the soil surface is covered with crop residue after planting, reduces soil erosion and surface runoff.
Tillage effects on P loss are site specific, but less P loss generally occurs with minimum or no tillage than with conventional tillage. The science assessment showed a 90% reduction in P load on no-till ground compared to chisel plowing, and a 33% reduction in P load on ground that had been chisel plowed, compared to moldboard plowed.