No-till and strip-till soybean production with surface and subsurface phosphorus and potassium fertilization

Compared to no-till, strip-till can offer improved seedbed conditions and deep banding of fertilizer. The objective of this study was to quantify the effect of rate and placement of P and K in no-till and strip-till systems on soybean [Glycine max (L.) Merr.] seed yield. A 3-yr field experiment was conducted near Urbana, IL, on Flanagan silt loam (fine, smectitic, mesic Aquic Argiudolls) and Drummer silty clay loam (fine-silty, mixed, superactive, mesic Typic Endoaquolls) soils, with soybean planted following corn (Zea mays L.). Tillage/fertilizer placement was the main plot with no-till/broadcast (NTBC); no-till/deep band (NTDB); and strip-till/deep band (STDB); deep band placement was 15 cm beneath the planted row. Phosphorus-fertilizer rate (0, 12, 24, and 36 kg P ha ^-1 yr ^-1) was the subplot, and K-fertilizer rate (0, 42, 84, and 168 kg K ha ^-1 yr ^-1) was the sub-subplot. Soil water, soil and trifoliate P and K, and seed yield were measured. Overall, STDB produced 3.1 Mg seed ha ^-1, 10, and 7% more yield than NTBC and NTDB, respectively. Seed yield, number of pods plant ^-1, and trifoliate P concentration and accumulation increased with P fertilization uniformly across tillage/fertilizer placement indicating that fertilization cannot be reduced with deep band applications relative to broadcast applications without a reduction in seed yield, but deep banding increased subsurface soil test levels. Potassium fertilization decreased seed yield in both no-till systems but not in the STDB system. While P and K placement produced no differences, improved soybean yield and nutrient accumulation resulted from a tillage effect with STDB relative to the no-till systems.