Phosphorus And Potassium Management For Corn And Soybeans In Conservation Tillage

This study evaluated the grain yield, P or K uptake, and early dry weight responses of no-tilled and ridge tilled soybeans [Glicine max (L.) Merr.] and ridge tilled corn (Zea mays L.) to broadcast, deep-band, and planter-band P and K fertilizer placements under Iowa soil and weather conditions. Long-term P and K trials were established in 1994 at five research centers and were evaluated for four years. Forty short-term P-K trials were established in farmers' fields from 1995 to 1997. Treatments were various P (O to 56 kg P ha−1) and K (O to 132 kg K ha−1) rates broadcast, banded with the planter 5 cm beside and below the seeds, and deep-banded at a 15-20 cm depth before planting. Plant samples were taken at V5 to V6 growth stages, dried, weighed, ground, and analyzed for total P and K content. Soil samples were taken from different depth and position relative to crop rows or fertilizer bands.