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

2012 Annual Report for LNE11-307

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

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


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. This year we evaluated the impact of K addition on forage quality, tissue K and S levels and stand composition for eight farms (total of 60 fields) and the research station trial at the Aurora Research Farm. Data are being summarized but preliminary results indicate that K addition, where not needed for yield, will negatively impact forage quality by increasing forage ash content. Soil test sulfur levels are typically sufficient where manure is applied while levels can decline over time without manure or S fertilizer addition. The project was presented at field days in Valatie and Aurora, NY. Two agronomy factsheets were developed to help farmers and farm advisors with on-farm research and this summer two students were trained in on-farm impact-oriented research through our undergraduate internship program (one agricultural science and one animal science major). We implemented K and S assessments for an additional nine locations (six fields in western NY, two fields in central NY, and one in eastern NY) as well. Due to the drought this summer, our statewide sampling was postponed until next year.

Objectives/Performance Targets

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 all alfalfa acres (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.


(1)Five farmers and one research station, working with farm advisors and campus staff, will host on-farm trials (plus K, no K) on six fields per farm, in 4 replications per farm, for 2 years (for a total of 72 trials).

We completed the forage quality and tissue sampling for the trials, and conducted a stand composition analysis for each site to evaluate the impact of K addition on grass versus alfalfa or in the stand. The final results are being summarized in reports early next year. Initial results suggest that K addition to stands with more than 50% grass, do not respond to K addition, while for alfalfa stands (>50% alfalfa) a K response can be expected for low K testing soils. Forage quality declined with K addition, reflecting an increase in ash content. Sulfur levels were high for fields in corn-alfalfa rotations with manure as the fertilizer source under the corn years. Assessments of K + S addition on yield, quality and soil test levels were completed for nine fields, to be continued next year.

(2)In addition, 25 farmers will evaluate two fields per farm (farmer selected) for K, S and micronutrient status (years 2 and 3) using an effective combination of tissue and soil testing.

Due to the drought, sampling this year was only done at the nine new fields with K and S trials and at one additional central NY farm. Additional samples will be collected next year, anticipating a better growing season than we had in 2012.

(3)In year 2-3, 60-80 farmers and farm advisors will be trained in on-farm research, through participation in four on-farm workshops, and have the tools to conduct on-farm testing.

We presented the project at the Aurora and Valatie Field Days (visited by about 130 people), and generated two agronomy factsheets to help farmers and farm advisors with implementation of an adaptive management process and conducting on-farm research as a component of the process (Factsheet #68: On-Farm Research (7/9/2012) and #69: Adaptive Nutrient Management Process (7/22/2012). A What’s Cropping Up? article was published on sulfur management of alfalfa (Ketterings, Q.M., G. Godwin, S. Gami, K. Dietzel, J. Cherney, and K.J. Czymmek (2012). Sulfur for alfalfa in New York State. What’s Cropping Up? 22(2): 12-16). We delivered presentations on conducting on-farm research and have expanded the approach used in this project for alfalfa to a new cover/double crop project (winter cereals) to be conducted next spring (impact beyond the project; expansion of our NY On-Farm Research Partnership).

(4)Of all alfalfa growers, 60% will become aware of the existence and results of the project by year 4 (through work with consultants, extension and farmers and extension and popular press articles). Of these farmers, 300 will be surveyed (postcard survey) for intent to use project results to evaluate K management at home, in year 4 of the project.

Many of our consultants and extension educators know about the project. Yield data for the research farm were shared with stakeholders. We are currently working on the summaries for the on-farm sites.

Impacts and Contributions/Outcomes

Fields were sampled and initial results of the research station trial were shared with our stakeholders through articles and presentations. We are working on data summaries and should be able to share the first summaries with our partners in the project and the larger stakeholder audience in the next 2-4 months. A growing number of people have become engaged in on-farm research (this project and others that are now following), illustrating a growing willingness among farm advisors and farmers to be a partner in the on-farm research. This is a great development as collaboration and networks of on-farm research can generate believable (and scientifically sound) guidance much quicker and also speeds up the implementation process. We initiated the NY ON-Farm Research Partnership, and continue to develop working relationships among the many collaborators while also trained them in on-farm research for impact beyond this project. Our student interns learned through interactions with consultants and extension educators as well as other members of our team.


Dr. Jerry Cherney

Cornell University
503 Bradfield Hall
Crop and Soil Sciences Department
Ithaca, NY 14853
Office Phone: 6072550945
Website: http://www.forages.org
Karl Czymmek

Senior Extension Associate
PRODAIRY, Cornell University
328 Morrison Hall
Animal Science Department
Ithaca, NY 14853
Office Phone: 6072554890
Website: http://nmsp.cals.cornell.edu