The Impact of Potassium Management on Conservation Tillage Soybean Production, 2001
In the past 15 years, about half of Ontario’s soybean growers have adopted no-till practices. However, expansion of no-till seems to have stalled. Previous work on corn, supported by PPI/PPIC/FAR, showed increased importance of starter potassium (K) in no-till management. Field strip trials were conducted to measure the yield benefit of starter phosphorus (P) and K in no-till soybeans, with the goal of fostering the next wave of no-till expansion.
Ontario soybeans yielded about 50 percent below normal in 2001, owing to drought and aphid damage. The banded starter, which supplied 4-18-42 lb/A of nitrogen (N)-P2O5-K2O, boosted yield by about 5.9 percent averaged across 17 farms, each with two replications. However, because of the low yields, this amounted to only a 1.2 bu/A yield response, insufficient to justify the expense. Responses were largest on soils testing below 20 parts per million (ppm) in Olsen P. In the previous year, yield response averaged a modest 2 percent. Researchers concluded that large responses to starter P and K in soybean production, even in no-till, are rare, but since banded application can contribute to maintaining soil test levels, the practice may be worthwhile. ON-25