Dryland and Irrigated Corn Yield with Climate, Management, and Hybrid Changes from 1939 through 2009

Corn (Zea mays L.) yield has increased from about 1.5 Mg ha(-1) in the early 1900s to 8.5 Mg ha(-1) in the beginning of the 2000s in the United States. Information about yield and management changes in irrigated and dryland corn yields for the hybrid era is scarce. The objective of the present study was to determine the magnitude of yield and management changes in irrigated and dryland corn from 1939 through 2009. Data from selected irrigated and dryland corn performance trials conducted in Kansas from 1939 through 2009 were analyzed. On average, corn yields have increased at rate of 90 kg ha(-1) yr(-1) in dryland and 120 kg ha(-1) yr(-1) in irrigated trials. Corn yield changes from one decade to another were not similar for the seven decades considered. Both irrigated and dryland yields increased significantly at least every two decades until the last three, during which dryland yields stagnated. Changes in hybrid technology and changes in crop management factors, such as a decrease in planting and harvesting date by about a quarter of a day yr(-1), increased planting density at the rate of 597 plants ha(-1) yr(-1), and increased N and P fertilizer rates by 2.6 and 0.40 kg ha(-1) yr(-1), respectively, were found for the same time period in dryland corn. In addition, climate changes contributed to yield increases in the past through increased total rainfall, average monthly minimum and maximum temperature in March, and decreased maximum temperature from July through September.