Reducing whole farm and statewide phosphorus (P) balances

Date: 

2001

Summary: 

To evaluate and demonstrate the value of phosphorus (P) starter application on soils testing high for soil P, Cornell University researchers and staff, Pro-Dairy staff, and Cornell Cooperative Extension (CCE) educators initiated a large-scale, statewide, on-farm NY Starter P Project in 2001. Specifically targeted were soils testing (very) high in P. Since 2000, 65 on-farm trials were conducted, led by CCE field crops educators, across the state on a variety of soil types and across a range of climatic conditions. In addition, 13 trials were conducted at experimental stations. The results showed there is no advantage to adding starter P to very-high P testing sites in terms of yield or quality.

This message was delivered to New York producers through extension programs, popular press articles and other outreach mechanisms. The integrated network approach increased awareness for environmentally sound P management, and strengthened research/extension collaboration among producers, extension, universities, agribusiness, and agencies.

Now, seven years after the completion of the initial project, the true impact is visible in agricultural data and Agriculture Census data on fertilizer use on farms. Results show a greatly reduced statewide P balance for New York (published in the Journal of Soil and Water Conservation), and stabilization of the number of agricultural fields testing above the agronomic optimum for P. Assessment of P balances for individual farms are consistent with this trend with more farmers meeting the benchmarks over time.

Issue: 

Phosphorus use on farms is under increasing scrutiny due to water quality concerns. The Cornell Nutrient Analysis Laboratory rates soil test P (STP) levels of 9-39 and more than 40 lbs P/acre as "high" and "very high," respectively. For these fields, little or no additional P is needed. Producers and their advisers asked us about the risk involved in reducing P fertilizer use for fields that are high or very high in P for economic, agronomic, and environmental purposes.

Response: 

To evaluate and demonstrate the value of P starter application on soils testing high for soil P, Cornell University researchers and staff, Pro-Dairy staff, and CCE educators initiated the statewide, on-farm NY Starter P Project. Specifically targeted were soils testing (very) high in P. Since 2001, 65 on-farm trials were conducted, led by CCE field crops educators, across the state on a variety of soil types and across a range of climatic conditions. In addition, 13 trials were conducted at experimental stations. Producers were actively involved in establishment of the trials and field days that were held by extension educators. The last on-farm trials were concluded in 2003. The data were analyzed and the results are conclusive: the existing guidelines are sound. There is no advantage to adding starter P to very high-testing P sites in terms of yield or quality. Similarly, there is no advantage to adding more than 25 pounds of P2O5 in the starter on high-P testing sites in terms of yield or quality. This message was delivered to New York producers through extension programs, popular press articles, and other outreach mechanisms. The integrated network approach increased awareness for environmentally sound P management and strengthened research and extension collaboration among producers, extension, universities, agribusiness, and agencies. Now, eight years after the completion of the project, the true impact is quantified; a 24 percent reduction in P fertilizer sales, versus no trends in nationwide P fertilizer sales. See the project website for more information: http://nmsp.cals.cornell.edu/projects/starterp.html.

Impact: 

We have seen fertilizer P use statewide drop from annual sales of 85 million lbs P2O5 in the four years prior to 2000 to 53 million lbs of P2O5 in 2006, an overall savings of 165 million lbs of P2O5 since 2000! New York N sales did not go down and corn acreage was relatively stable, showing an actual change in fertilizer composition (more low-P or P-free fertilizers). Nationally, sales data do not show a decline either, showing the proactive approach of New York State farmers. The percentage of soils testing above the agronomic optimum did not continue the increase we have seen over the past 20 years; it stabilized to 45 percent testing high or very high in P. The statewide P balance was 7.2 lbs P/acre in 2002 and 1.5 lbs P/acre in 2006, considerably lower than in Mid-Atlantic states, due to reduction in P excretion and considerable decrease in P fertilizer use (24 percent decrease). These reductions show our intensive and integrated approach to research and extension contributed to New York State being in P balance. This work contributed to a successful delivery of a Watershed Implementation Plan justification by the New York State Department of Environmental Conservation and partners (to the Environmental Protection Agency) and invited talks at national meetings in the past several years.

Submitted by: 

  • Ketterings, Quirine M

Researchers involved: 

  • Czymmek, Karl J
  • Ketterings, Quirine M

Organizations involved: 

  • Greg Godwin
  • Sheryl Swink
  • CCE field crops educators
  • SWCD offices and consultants
  • Mike Davis
  • NY corn producers

International focus: 

  • United States of America

United States focus: 

  • New York