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Evaluation of Fertilizer Placement and Timing in Continuous Corn in Three Long-Term Tillage Systems

Start Date: 2012
Principal Investigator: Daniel Kaiser
Organization: University of Minnesota, Department of Soil, Water, and Climate
Status: Complete

Background Info

A few years ago, economics favored a shift to more corn on corn acres for many growers in southern Minnesota. Increased residue levels in continuous corn, however, led to an increasing number of growers to shift back to more aggressive tillage practices, such as using the moldboard plow. Long-term tillage trials in continuous corn, conducted in southern Minnesota from 2008 to 2011, evaluated the effects of strip tillage (a conservation tillage system), a moderately aggressive tillage system (i.e., chisel plow or a disk rip/V-rip), and moldboard plow on corn yield and profitability. When yield differences were found among tillage systems in a given site and year, yields from using the moldboard plow system were consistently higher than in strip tillage. To help determine whether tillage effects on yield in continuous corn can be reduced or eliminated by changing fertilizer management practices, this study evaluated the effect of phosphorus (P) and potassium (K) application methods as well as nitrogen (N) application timing on corn yield and profitability when corn is planted in a continuous-corn rotation under three long-term tillage systems.

Objectives

Evaluate the influence of application method of P and K on corn population and yield in continuous corn under three long-term tillage systems (strip-tillage, in-line rip system, and moldboard plow)

Evaluate the effect of nitrogen application timing on corn population and yield in continuous corn under these three long-term tillage systems

Key Findings

Tillage had a significant effect on yield averaged across P and K treatments and N application timing, with strip tillage averaging a 26 and 35 bushels per reduction in corn grain yield than in-line rip system and moldboard plow, respectively.

Banding of P and K can result in greater yield than when the same rate of P and K are broadcast to the soil surface and incorporated regardless of tillage system.

A significant interaction between tillage and N application timing on yield showed that the difference observed between timings of N application was driven by differences observed in strip tillage, in which the preplant application of N yielded 16 bushels per acre more than the split application of N when averaged across P and K treatments. There was no difference observed between the timings of N application for the other tillage systems, when averaged across P and K treatments.

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