Agronomy and Horticulture, Department of
Document Type
Article
Date of this Version
2001
Abstract
During the past 35 years, average corn yields in the North Central Region (NCR) have increased at a rate of 1.7 bu/acre per year, mainly due to the adoption of improved crop management technologies and genetic improvement of corn hybrids. Fertilizer K rates used on corn are typically within a range of 0 to 110 lb K2O/acre, but average usage varies widely among states. Commercial fertilizer use rose sharply in the 1960s and 1970s, but corn yield increases since 1980 were achieved with stagnating fertilizer-N use and declining rates of P and K. Signs of emerging K deficiencies have become more common in recent years, particularly in no-till systems. This includes unusual visual symptoms such as K deficiency on younger leaves, but also an unknown range of less visible K deficiencies that are not easily detected based on leaf symptoms. A key question is whether present K management recommendations are adequate to meet future needs. Recent research suggests that (a) commonly used soil tests may not always reflect the actual crop response to K, (b) crop K requirements per unit yield are not constant, but vary with the absolute yield levels and crop management factors, (c) spatial variability of soil K affects K management strategies, (d) genotypic differences exist in the response to soil and fertilizer K, and (e) non-yield traits such as stalk strength or product quality must be taken into account in K management decisions. Therefore, future, fertilizer recommendation algorithms should be more robust and accommodate different crops, cropping systems, crop management technologies, soil conditions, and climate-driven yield potential. Such refinements can be made at different levels of complexity such that a general recommendation can be broken down into more specific recommendations. Agroecological zoning and crop simulation models should play a major role in making these refinements.
Comments
Supplemental paper for the Proceedings of the Thirty-First North Central Extension- Industry Soil Fertility Conference, Vol. 17, 2001