Role of Nitrogen, Phosphorus and Potassium fertilizers in continuous corn culture on Nicollet and Webster soils
Iowa Agriculture and Home Economics Experiment Station Research Bulletin: Volume 35, Issue 522
The possibility of growing continuous corn is receiving increasing consideration with the changing agricultural patterns. Farmers are devoting more and more acres to intensive cropping sequences in which corn follows corn more often. The practice of continuous corn-growing consecutive corn crops on the same land-is on the increase. This is because corn is the most profitable crop generally grown in the Corn Belt, because limitations in production technology have been eased, and because farm product demands or values have altered.
Early research with crop rotations generally resulted in conclusions that continuous culture of inter tilled crops, especially of corn, was less profitable than other alternatives and resulted in decreasing soil fertility and continuously declining yields. The early experiments indicated that a crop rotation, including a nitrogen-fixing legume, was needed to increase or even maintain fertility levels. These experiments usually did not explore the use of N, and, if they did, the N usually was used in low amounts, probably because of the high cost. Forage-producing crops were also necessary for the livestock program, which then included draft horses, and the manure byproduct from the animals helped maintain fertility levels.