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

2011 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. 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. In this project we build upon an established project on K needs for alfalfa by adding (1) tissue testing for K and S (and micronutrients) to the on-farm field trials (30 sites); (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.

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 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.


Milestone 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).

A total of 30 on-farm trials were completed in collaboration with farmers and their advisors. Each trial consisted of a comparison of with and without K addition after 1st cutting. In total, 30 on-farm sites were harvested and sampled for tissue K and S at 3rd cutting in year 1 (samples were stored until funding was obtained), and again for 1st cutting and 3rd cutting in year 2 (current year). A number of sites rotated to corn or lost due to fertilizer or manure addition (7 locations), while new locations were added (2 locations) so our total number of fields that were sampled for tissue K and S during the 3rd cutting was 25 instead of 30. Due to a very challenging season (weather extremes), we were able to get a new stand established in the late summer but not in the spring. This new site will be sampled in 2012. A stand composition assessment was done for all 25 fields during the last cutting this season (4th cut for all locations). The stand composition consisted of determining the percentage of alfalfa, grass and broadleaf weeds for each of the fields in the study.

Milestone 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.

Next year. We talked with 15 extension educators (Agricultural Inservice) and about 30 participants in the on-farm research partnership session at the NRCCA training about the sampling of the fields next year for this project. Enthusiasm for participation next year is great.

Milestone 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 were able to conduct one initial session on on-farm research at the 2011 Northeast region Certified Crop Advisor Annual Training that was held in Syracuse on Nov 29-Dec 1. The training session was attended by approximately 30 crop advisors. The on-farm trials included 14 farm advisors (6 from extension, 7 from agricultural consultant firms, and 1 institute/research farm). All were trained in plot layout and sampling for yield, tissue testing, and soil sampling.

Milestone 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.

This summer, the project was featured at the Aurora Research Farm field day on July 14, 2011, attended by about 150 participants. We talked about both potassium and sulfur needs for alfalfa.

Impacts and Contributions/Outcomes

To date, 14 farm advisors were trained through hands-on experience in on-farm research, specifically this trial on effect of K addition to yield, tissue K and S, and soil sampling. In addition, approximately 30 farm advisors (Certified Crop Advisors) attended the on-farm research partnership presentation at the Northeast Region Certified Crop Advisor training on December 1, 2011. Data for the trials are currently being analyzed.


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