Soybean Seed Composition, Aboveground Growth, and Nutrient Accumulation with Phosphorus and Potassium Fertilization in No-Till and Strip-Till

Strip-till can improve soybean [Glycine max (L.) Merr.] yield and increase P and K availability relative to no-till. Our objectives were to evaluate the effect of P and K rate and placement in no-till and strip-till on soybean-seed oil and protein content, aboveground growth and P and K accumulation, and soil water. A 3-yr field experiment was conducted near Urbana, IL, with tillage/fertilizer placement treatment as the main plots: no-till/broadcast (NTBC), no-till/deep band (NTDB), and strip-till/deep band (STDB) with banded fertilizer at 15 cm beneath the planted row. Phosphorus (0, 12, 24, and 36 kg ha(-1) yr(-1)) was the subplot and K (0, 42, 84, and 168 kg ha(-1) yr(-1)) was the sub-subplot. Higher protein and oil yields were produced with STDB than the no-till treatments. Increase protein yield with P fertilization occurred only for the no-till treatments, but STDB maintained higher protein yield than the no-till treatments when no P was applied, indicating that STDB was more effective at making P available to the crop. Phosphorus and K placement made no difference in protein and oil concentration or yield. Leaf area index (LAI) was greater for STDB than NTBC and NTDB and greater for NTDB than NTBC. Phosphorus and K fertilization increased LAI relative to the check by V2 stage illustrating the importance of fertilization for early growth. The advantage for soybean production with STDB over the no-till treatments was the result of greater soil water content in STDB during the reproductive stages.