Can Yield Goals Be Predicted?

Predicting required fertilizer N rates before planting a crop embodies the concept of establishing a pre-season yield goal and fertilizing for that expected yield. The study evaluates prediction of yield goals using data from long-term experiments. Winter wheat (Triticum aestivum L.) grain yield data from the Magruder plots (Stillwater, OK, 1930-present), Exp. 222 (Stillwater, OK, 1969-present), and Exp. 502 (Lahoma, OK, 1970-present) were used. Annual pre-plant N rates were applied for 87, 45, and 44 yr, respectively. Experiments 222 and 502 used randomized complete block experimental designs. This manuscript applied the theory that average yields over the last 3 to 5 yr can be used to predict the ensuing years' yield, or yield goal. For the Magruder plots, the NPK (67-15-29, N-P-K) and Check (0-0-0) Treatments were used. For Exp. 222, Treatments 1 and 4 (0-30-37 and 135-30-37) and in Exp. 502, Treatments 2 and 7 (0-20-55 and 112-20-55) were selected to test this concept. Wheat grain yield averages for the prior 3, 4, and/or 5 yr were not correlated with ensuing season yields in all three long-term experiments. Over sites and years, yield goal estimates were off by up to 3.69 Mg ha(-1). Failure of the yield goal concept to predict current-year yields is due to the unpredictable influence of environment. Mid-season prediction of yield potential using active sensors is a viable alternative for improved in-season cereal fertilizer N recommendations.