Reducing Phosphorus Fertilizer Inputs for Field Corn Production
Phosphorus (P) accumulation on farms has led to high soil test P levels and increased P runoff and leaching from agricultural fields in many Northeastern states. Dairy producers have been facing increasing pressure to reduce phosphorus (P) inputs in the form of feed and fertilizer. The aim of the NY Starter P Project is to reduce P fertilizer use for growing corn on fields that test high or very high in P. In addition, we aim to establish and strengthen research/extension collaboration among producers, extension, universities, agribusiness and agencies on issues of importance for the sustainability of agriculture. We proposed to achieve these goals through the establishment of on-farm trials, field days, extension meetings and documentation and by working with a collaborative network of producers, agribusiness, university faculty and staff, and regulatory agencies.
Our performance targets were: 1) 30 corn growers in 2002 and 2003 will conduct on-farm replicated trials, and they will show increased interest in on-farm experimentation following the termination of the project. Of the producers, 25 will reduce starter P use to <20 lbs P2O5/acre following the termination of the project; 2) 75% of New York corn silage and grain corn growers will be aware that starter P on high P soils and soils that receive manure is rarely needed. 3) 30% of the registered farmer participants in field days and extension meetings will re-evaluate starter P use for corn within the duration of the project and reduce starter P use by 50% or more; and 4) 20 extension field staff will be trained in on-farm experiment management, generate more reliable results with on-farm trials, and establish working relationships with producers that lead to continuation of on-farm experimentation following the termination of this project.
Together with our collaborators, we completed a total of 65 on-farm trials and 9 research station trials. Data were analyzed for effect of starter P use on yield and forage quality. Based on the results of the past three years, we conclude that on sites that test high in P and have no manure applications planned for the season, no yield penalty is expected when P starter levels are reduced below 25 lbs P2O5/acre. On sites that test very high in P or when manure is applied to high testing sites, there is a low probability of a starter P response and P could be eliminated from the starter without a yield penalty. Corn responds to N in the starter band more often than P and we continue to recommend 20-30 lbs of banded starter N, even where P is eliminated. Also for silage quality differences were not significant and well within laboratory analytical uncertainty, indicating that leaving P out of the starter fertilizer in high or very high P soils did not impact silage quality. The study showed that with the increased attention directed toward P non-point source pollution, it makes little sense to use more starter P than is necessary to support optimum yields, especially on fields where significant amounts of manure nutrients are regularly applied. Six research reports were generated in the form of “What’s Cropping Up?” articles. This includes three annual updates, an article on quality impacts and an article that evaluates potential P savings if P management is based on soil testing for 30 New York farms.
•Whole farm corn starter phosphorus fertilizer imports. Ketterings, Q.M., G. Albrecht, M. Hunter, P. Carey, S.N. Swink, and K.J. Czymmek (2004). What’s Cropping Up? 14(6): 3-5.
•New York Starter Phosphorus Project: Does starter P fertilizer impact silage quality? Ketterings, Q.M., S. Swink, G. Godwin, K.J. Czymmek, and G. Albrecht (2004). What’s Cropping Up? 14(5): 1-2.
•New York Starter Phosphorus Project – Results of the 2003 growing season. Ketterings, Q.M., S. Swink, G. Godwin, K.J. Czymmek, A. Durow, and G. Albrecht (2004). What’s Cropping Up? 14(1): 1-3.
•Phosphorus Starter Project – Results of the 2002 growing season. Ketterings, Q.M., T. Byron, G. Godwin and K.J. Czymmek (2003). What’s Cropping Up? 13(1): 4-6.
•Phosphorus starter demonstration project. Results of the 2001 growing season. Byron, T.M., Q.M. Ketterings, and K.J. Czymmek (2002). What’s Cropping Up? 12 (2): 4-5.
•Phosphorus starter demonstration project. Results of the 2000 Growing Season. Czymmek, K., J. Degni and Q.M. Ketterings (2001). What’s Cropping Up? 11(3): 4-6.
These articles can be downloaded at: http://nmsp.css.cornell.edu/projects/starterp.asp.Also downloadable are: Survey Results, Starter P postcard, Starter P poster, Starter P handout, and Starter P slides.
Impacts and Contributions/Outcomes
New York corn growers were surveyed between August 2003 and May 2004 to assess: 1) current phosphorus (P) starter fertilizer use for corn; 2) awareness of starter P research carried out over the past 3 years (the New York Starter Phosphorus Project funded by NESARE and others); and 3) the likelihood of growers reducing P application rates in the future. The survey showed that during the past few years, 71% of the producers surveyed had heard about the New York Starter P Project. Fifty percent of these producers reduced P starter use over the past five years as compared to 32% of those who had no knowledge of the project. Current application rates across all farms averaged from 36 lbs P2O5 per acre for those that attended extension events in the winter of 2004 to 42 lbs P2O5 for members of the New York Corn Grower Association. Among those surveyed, 77 to 86% indicated they were more likely to soil test on a regular basis and to change rates if needed, hence further changes in starter P use are expected in the future. The completed survey is downloabable from the NYS Starter P Project website: http://nmsp.css.cornell.edu/projects/starterP/survey.pdf.