Potassium and sulfur management of alfalfa; Farmer-driven testing of management methods

Project Overview

Project Type: Research and Education
Funds awarded in 2011: $119,984.00
Projected End Date: 12/31/2015
Region: Northeast
State: New York
Project Leader:
Dr. Quirine Ketterings
Cornell University

Annual Reports

Information Products


  • Agronomic: general silage crops, grass (misc. perennial), hay
  • Animal Products: dairy


  • Animal Production: feed/forage
  • Crop Production: nutrient cycling, tissue analysis
  • Education and Training: demonstration, extension, networking, on-farm/ranch research, participatory research
  • Farm Business Management: budgets/cost and returns
  • Natural Resources/Environment: indicators
  • Production Systems: agroecosystems
  • Soil Management: soil analysis, nutrient mineralization

    Proposal abstract:

    Soil can supply large amounts of potassium (K) but producers and agricultural advisors are reluctant to eliminate K use for large K consumers like alfalfa fearing reduced yield and/or winter kill. In addition, sulfur (S) deposition rates have drastically decreased over the past 10 years and recent on-farm trials show a yield response to S addition, possibly due to the role S plays in N fixation by alfalfa. Both K and S are macronutrients essential for crop growth. Producers want to know: (1) whether S and K applied with manure in corn years is sufficient to bridge alfalfa years in rotations; and (2) what tools to use to reliably identify if extra S or K are needed. For K management, three approaches are commonly used: (1) K removal, (2) soil test K, and (3) K saturation-based methods. For S management, recent NY farm trials resulted in the calibration of a new soil test for S; tissue testing was effective in identifying S and micronutrient deficient sites as well. Recommendations for K can vary from 0 to 350 lb K2O so side-by-side studies are needed to determine impact of K addition on crop yield, stand survivability, and forage quality. Recommendations for S are 20-30 lbs S/acre for S deficient sites. We propose to (1) conduct on-farm trials (72 field trials over two years) to determine the effectiveness of soil test K or K saturation in determining if K is limiting, and (2) to evaluate S and micronutrient status for alfalfa fields with varying fertility management histories. The NYFVI is funding a 2-year project (2010-2011) to evaluate crop response to K addition for 5 farms and one research station. We propose to build upon this project by adding (1) tissue testing for K and S (and micronutrients) to the on-farm field trials (72 trials); (2) evaluation of 50 alfalfa fields (across the state; two fields per farm) for nutrient status through both tissue testing and soil testing at 3rd cutting for two years, (3) stand composition assessment after the second year of K response trials; (4) impact evaluation in year 4 including farmer participants and statewide assessments, (5) four workshops on conducting on-farm research in year 2 of the project reaching 60-80 farmers/advisors; and (6) student training in on-farm impact-oriented research through our undergraduate internship program. At least 4 of 6 participating farms will adjust their K and S management resulting in an estimated savings of $100 per acre or more by the end of the project through (1) elimination of K where a crop response is unlikely based on soil test data, or (2) increased yield where K and/or S were limiting production. Of 300 farm surveys conducted at the end of the project 30% will indicate an interest in fine-tuning alfalfa K and S management on their own farm. Ten of 60-80 farms that attended on-farm field days and research workshops will use newly gained skills for on-farm testing of alternative management practices in year 4 of the project.

    Performance targets from proposal:

    Of the six participating farms, four will re-examine their K management and reduce production costs by $100/acre or more. Of the 25 farms that evaluate two alfalfa fields each in years 2 and 3, 15 will re-examine their fertility management, leading to K use reduction of 50 lbs K2O/acre (redistribution of manure, reduction of fertilizer use). Of 60-80 trainees in the on-farm workshops, a minimum of 10 will become actively involved in on-farm experimentation by year 4 of the project. And, of 300 farmers surveyed in year 4, 30% will express intentions to fine-tune K2O and S use in the next 1-3 years. This is expected to lead to a reduction of K use of 50 lbs K2O/acre on at least 25% of 680,000 alfalfa acres in NY (taking into account some acreage will need more K than is currently supplied), resulting in an estimated total statewide cost savings of $3.4 million or more.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.