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Minnesota Long-Term Phosphorus Trial: Phase II, Testing Yield Response and Potential

Start Date: 2015
Principal Investigator: Albert Sims
Organization: University of Minnesota, Northwest Research and Outreach Center
Status: Ongoing

Background Info

Phosphorus management is critical to reduce environmental risk while sustaining field productivity. Phosphorus (P) is an essential nutrient and the second most commonly applied nutrient in Minnesota agriculture. Phosphorus fertilizer management is based on one of two philosophical approaches, Build & Maintain or Sufficiency. The primary goal of this project is to establish long-term trials at several locations across Minnesota to test P management strategies. These trials will be developed in phases each with its own set of objectives.

Objectives

Initiation of Phase II: Evaluate corn yield and P uptake response to P fertilizer within each STP category developed during Phase I

Determine if the maximum yield achieved within each STP treatment developed during Phase I differs regardless of the actual response to P fertilizer applied in Phase II.

Fractionation of soil phosphorus, determine the effects of previous P management, development of various STP categories in Phase I, on soil P fractions or pools.

Key Findings

Because the Slowly Available P pool is already relatively large at all the sites, detection of additional P into or substraction of P from this pool requires the movement of relatively large amounts of P. Therefore, the role of this pool to the crop in a P deficit or a P excess situation cannot be determined in this trial or at least in the current life span of the trial. Analysis of this data will continue in an attempt to understand the differences in soil characteristics among the sites and relate those differences to potential differences in crop response to building STP levels and to applied fertilizer P.

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