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Interpretive Summaries:
2007 - Maximizing Irrigated Crop Yields in the Great Plains
2006 - Maximizing Irrigated Crop Yields in the Great Plains
2005 - Maximizing Irrigated Crop Yields in the Great Plains
2004 - Maximizing irrigated crop yields in the Great Plains
2003 - Maximizing Irrigated Corn Yields in the Great Plains
2002 - Maximizing Irrigated Corn Yields in the Great Plains
2001 - Maximizing Irrigated Corn Yields in the Great Plains
2000 - Maximizing Irrigated Corn Yields in the Great Plains
Maximizing Irrigated Corn Yields in the Great Plains, 2002
Genetic improvements in corn continue to contribute to rising yields. Newer hybrids suffer less yield reduction under conditions of drought stress and insect infestations, and also have the ability to increase yields in response to higher plant populations. The objective of this study is to determine if soil test recommendations are adequate for new high yielding corn hybrids, and to evaluate the interactions among fertility treatments and plant population in a reduced-tillage production system.
Treatments included two plant populations (28,000 and 42,000 plants/A) and nine fertility treatments. Fertility treatments consisted of three nitrogen (N) rates (160, 230, and 300 lb/A). The N rates were applied with 1) current university soil test recommendations for phosphorus (P), potassium (K), and sulfur (S) (30 lb P2O5/A, and no K or S), 2) 100 lb P2O5 /A + 80 lb K2O + 40 lb S/A applied preplant, with N applied in two split applications (half preplant and half at V4), 3) 100 lb P2O5 + 80 lb K2O/A + 40 lb S/A applied preplant with N split in four applications (preplant, V4, V10, tassel). The experiment was fully irrigated.
Despite extremely low summer rainfall in 2002, corn yields were excellent since adequate irrigation water was available. Additional P, K, and S increased corn grain yield by an average of 75 bu/A over the university recommendations (30 lb P2O5/A). Applying N fertilizer in four applications was not superior to applying in two applications. There was no significant difference between plant populations when averaged over all fertility treatments. However, at the higher N rates and the higher rates of P, K, and S, the grain yield with the higher plant population was over 20 bu/A greater than with the lower population. Additional treatments were included in the experiment to determine which nutrients were providing the most yield increase. Addition of K and S, which were not included in the university recommendations, resulted in a 73 bu/A yield increase over the N and P treatment. This study continues to reveal the need for the reevaluation and update of conventional methods of fertility recommendation. Support for this study will continue in 2003. KS-33F
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