Crop production impacts on soil phosphorus removal and soil test levels

ABSTRACT

An 8-year field study documented the impact of tillage, crop rotations, and crop residue management on agronomic and soil parameters at Brookings, South Dakota. The greatest annual proportion of above-ground biomass phosphorus (P) removed was from the grain (78–87% of total) although crop residue removed some P as well. Greater above-ground total biomass P (grain P + crop residue P) was removed from corn than from soybean and spring wheat crops mainly due to the greater corn grain biomass harvested. Cumulative above-ground biomass P removal was greatest for the corn-soybean rotation (214 kg P ha⁻¹), while it was lowest for the soybean-wheat rotation (157 kg P ha⁻¹). Tillage treatments within crop rotation or residue management treatments did not influence annual or cumulative P removal rates. Olsen extractable soil orthophosphate-P levels declined consistently through time from a mean of 40 µg g⁻¹ (2004) to 26 µg g⁻¹ (2011). Biomass P removal was calculated to be 15.7 ha⁻¹ yr⁻¹ to decrease Olsen extractable soil orthophosphate-P levels by 1 µg g⁻¹ yr⁻¹ over 8 years of the study.

Keywords:

• crop rotations
• P uptake
• P soil tests