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

View the project final report

• 2011 annual report
• 2012 annual report
• 2013 annual report
• 2014 annual report

Commodities

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

Practices

• 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

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.

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.