Is soybean production affected by band and broadcast applications of P or K for corn?
Sustainable Production
DiseaseField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Jeff Vetsch, University of Minnesota
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:
The goal of this research project is to improve phosphorus (P) and potassium (K) fertilizer recommendations for soybean farmers in Minnesota. The primary objectives include measuring soybean yield effects following band and broadcast applications of P and K fertilizer to a previous corn crop; to correlate soybean yield response to soil tests for both P and K; to compare economic returns of band and broadcast application of P and K, and; lastly share the results to farmers and agricultural advisers through oral and written communications.
Key Beneficiaries:
#agronomists, #applicators, #extension specialists, #farmers
Unique Keywords:
#agronomy, #fertilizer, #nutrients, #phosphorus, #potassium
Information And Results
Project Summary

Previous research in the Midwest has shown mixed results for varying placement of P and K fertilizers. In a review paper, Boomsma et al. (2007) explained several factors and situations where band applications are likely to be superior to broadcast. These include low P and K soil test levels, soils with high fixation capacity, reduced tillage systems (resulting in cooler soils with smaller root systems), low subsoil P and K levels (partly due to nutrient stratification in reduced tillage systems), cultivar differences, using strip tillage, not using P and K starter fertilizers, and when using automatic guidance for multiple field operations (including controlled wheel traffic). Mallarino et al. (1999) found phosphorus (P) placement method seldom influenced corn or soybean yield regardless of tillage system; however, they also found deep banded potassium (K) increased corn and soybean yields compared to broadcast application mostly in ridge-till and no-till but also in chisel tillage. The yield differences between placements were similar for K rates ranging from 35 to 140 lb K2O/acre.
Minnesota fertilizer guidelines for corn (Kaiser et al., 2022) have substantial rate reductions, up to 50% for very low and low P and K testing soils, when banding compared to broadcasting. No fertilizer rate reductions for band placement are given for soybean as research has generally shown no yield response when banding P (Randall and Hoeft, 1988; Mallarino et al. 1999) and only small yield responses to banded K in soybean (Mallarino et al. 1999). The majority of Minnesota’s deep band placement research was conducted in the late 1980’s and 1990’s in ridge-till. Rehm and Lamb (2004) found deep banded K occasionally increased corn yields in ridge-till but responses were influenced by corn hybrid selection. The primary question is whether deep banding results in greater yields and/or profit as most states do not suggest rate reductions when banding P and K compared to broadcasting regardless of soil test level.
Except for in strip-till, band applications have lost favor for most farmers due to increased farm size, equipment size, equipment cost, and time savings. Broadcast P and K applications are easier, faster and cheaper on a cost per acre of application. Recent record high fertilizer prices have farmers looking for ways to reduce fertilizer costs and increase efficiency and profitability of these inputs while maintaining or increasing yields. Banding P and K at reduced rates may be a viable option for some. Additionally, subsurface banding of P fertilizer can reduce the risk of P runoff compared to broadcast application (Lewandowski et al., 2006), especially in minimal tillage systems.
From 2020 through 2022 a research study was conducted in Waseca and Rochester on clay loam and silt loam soils, respectively. This study compared deep band (6-inch depth) and broadcast placement of P or K for corn at various rates of application and at varied soil test levels in a conservation tillage system. The objectives of this research were to determine 1) whether band applications of P and K are more efficient and profitable than broadcast applications and 2) whether the rate reductions for band applications to corn in the University of Minnesota fertilizer guidelines are warranted. Preliminary results (Vetsch and Kaiser, data interpretation and reporting is on-going at this time) have showed no yield response to P placement. However, band placement of K increased corn yields slightly compared to broadcast in two site-years but reduced yield slightly in one site-year. Additionally, this research showed that reduced rates of P and K fertilizer, even on low P or K testing soils, often produced corn yields equal to or only slightly less than high rates of fertilizer or on higher testing soils. These findings have economic implications for farmers considering reducing P or K rates when fertilizer prices are high, as they currently are.
Often P and K fertilizer is applied for corn and the subsequent soybean crop relies on residual fertilizer. Or enough fertilizer for both crops is applied prior to corn. A recent multi-state project (Boring et al. 2018) found soybean production and yield was not negatively affected by P and K fertilizer application for corn in corn-soybean rotations. However, farmers are concerned that soybean yields may be limited in some conditions. Specifically, when soil tests for P or K are at low levels, when reduced rates of fertilizer P or K are band applied following Univ. of Minnesota fertilizer guidelines for corn and when equipment limitations or salt concerns limit high rates of fertilizer application in deep bands. Due to these concerns, additional research data are needed to determine how placement (deep band vs broadcast) of varying rates of P or K for corn affect subsequent soybean yields. Furthermore, the effects of rate and placement of P or K for corn on subsequent soybean production has not been recently studied in Minnesota.

Project Objectives

The goal of this proposed research is to improve P and K fertilizer recommendations for soybean farmers in Minnesota. The primary objectives are:
1) to measure the soybean yield effects following band and broadcast applications of P and K fertilizer to a previous corn crop,
2) correlate soybean yield response to soil test P (Bray P1) and K (exchangeable K, ammonium acetate extractant),
3) compare economic returns of band and broadcast application of P and K, and
4) disseminate these results to farmers and their agricultural advisors via oral and written communications and social media

Project Deliverables

The primary product of this research will be updated and improved fertilizer guidelines for soybean production in Minnesota. Specifically, the soybean yield data collected in this study will be used to 1) measure the residual effects of band and broadcast placement of P and K for corn on subsequent soybean production (objective 1); 2) correlate soybean yield response to soil test P or K (objective 2); and 3) calculate and compare economic return of band and broadcast applications for corn and soybean production. The results from this study may be extended via oral presentations at meetings, like Ag Professional update, SROC Winter Crops Day, and/or the CPM Short course. If requested, the PI will present these data at the Ag Expo in January of 2024.
In addition to the products outlined above, crop producers and other professionals benefit by having the latest research information in formats that are clear, concise, and actionable. Results from research outlined in this proposal can be communicated to crop producers and ag professionals quickly and effectively by dedicated University of Minnesota communication professionals. This streamlined, comprehensive communications effort will continue to take advantage of the broader Extension and University of Minnesota communications infrastructure. It will serve all nutrient management projects and ultimately lead to producers increasing on-farm use of research-based fertilizer management practices.

Progress Of Work


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November 2023 through January 2024 progress report is attached.

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Final Project Results

Benefit To Soybean Farmers

Often soybeans are the “red headed stepchild” of soil fertility programs. Fertilizers (P, K and S) are applied prior to planting corn and soybeans are left to feed on the residual. Generally, enough P and K is applied to corn to provide “leftovers” for soybean. With high fertilizer prices there is renewed interest in reducing P and K rates of application, which is justified when soil test P and K levels are high or very high as they are in many fields. When farmers apply reduced rates of P or K in a band for corn on low testing P or K soils, which is suggested in U of M fertilizer guidelines, there may not be enough left over to optimize soybean production. Additional research is needed to determine the optimum P or K rates at various soil test levels with both band and broadcast application.
The benefits of this proposed research for Minnesota soybean growers would be 1) greater confidence in University of Minnesota fertilizer guidelines, 2) greater soybean yields, and/or greater economic return from fertilizer inputs resulting from either greater yields or equal yields with significantly less fertilizer inputs.
This research project fits within the “Soybean Farmers need research and technology transfer on crop nutrition to maximize yield and quality potential including, but not limited to, calcium, sulfur, potassium, phosphorus, nitrogen and micronutrients. The project should be multi-location across the state from North to South and adapted to meet the needs of the diverse cropping systems across the state” priority area of the FW23 MSR&PC RFP.
Another benefit is both the PI (Vetsch) and Collaborator (Kaiser) have proven and well respected research, outreach and extension experience. We will be able to analyze these data, interpret them and effectively communicate the key points to farmers, ag professionals (advisors) and government agency staff via oral, written and social media methods of communication

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.