Initial Field Evaluation of the Agro-Economic Effects of Determining Nitrogen Fertilizer Rates with a Recently-Developed Soil Test Methodology

R. Daren Harmel, Richard L. Haney

Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service (ARS), Temple, Texas, USA..

DOI: 10.4236/ojss.2013.32010                

Abstract

Although agriculture is not the only contributor of excess nutrients to US waters, agriculture is an important contributor and should do its part to reduce nutrient loading. One important step in reducing agricultural contribution is to accurately account for all sources of plant available nutrients so that only needed nutrients are applied. In this study, three fertilizer rate treatments were evaluated: no fertilizer (control), traditional rate, and reduced rate based on a recently-developed enhanced soil test methodology. For each of nine sites in Texas, fertilizer data (formulation, rate, cost, and application date) and crop data (yield, price, and harvest date) were recorded, and economic throughput (profit) was determined. In this four year study, fertilizer rates were reduced 30%-50% (and fertilizer costs reduced 23%-39%) based on enhanced soil test methodology recommendations for wheat, corn, oats, and grain sorghum, but yields were not significantly reduced (0%-6%) and oat yields actually increased 5%. Profit decreased <1% for corn and increased 7%-18% for wheat, oats, and grain sorghum with reduced fertilizer rates. Although these changes were not statistically significant, they do represent benefit through increased profit potential and decreased input cost and production risk. In only 6% of the time was the traditional fertilizer rate the most profitable, compared to 51% for the unfertilized treatment and 43% for the enhanced soil test treatment. These results do not indicate that fertilizer application should be avoided but that fertilizer rates should be carefully chosen considering all sources of plant available nutrients (e.g., mineralization, irrigation water, nutrients deeper in the soil profile) to ensure that fertilizer is applied at the optimal rate.

Keywords

Soil Tests; Crop Yields; On-Farm Profit; Water Quality

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	B. Santos, “Selecting the Right Nutrient Rate: Basis for Managing Fertilization Programs,” HorTechnology, Vol. 21, No. 6, 2011, pp. 683-685.
[2]	USDA-ERS, 2013. http://www.ers.usda.gov/data-products/fertilizer-use-and-price.aspx
[3]	USDA-ERS, 2013. http://www.ers.usda.gov/topics/farm-practices-manage-ent/chemical-inputs/ fertilizer-use-markets.aspx
[4]	D. K. Mueller and D. R. Helsel, “Nutrients in the Nation’s Water—Too Much of a Good Thing?” US Geological Survey Circular, 1996, 24 p.
[5]	L. K. Abbott and D. V. Murphy, “What is Soil Biological Fertility?” In: L. K. Abbott and D. V. Murphy, Eds., Soil Biological Fertility: A Key to Sustainable Land Use in Agriculture, Kluwer Academic Publishers, Dordrecht, 2007, 268 p.
[6]	USDA-NRCS, “Conservation Practice Standard Nutrient Management Code 590,” 2012.
[7]	R. L. Haney, W. F. Brinton and E. Evans, “Soil CO2 Respiration: Comparison of Chemical Titration, CO2 IRGA Analysis, and the Solvita Gel System,” Renewable Agriculture and Food Systems, Vol. 23, No. 2, 2008, pp. 171-176. doi:10.1017/S174217050800224X
[8]	R. L. Haney and E. B. Haney, “Simple and Rapid Laboratory Method for Rewetting Dry Soil for Incubations,” Communications in Soil Science and Plant Analysis, Vol. 41, No. 12, 2010, pp. 1493-1501. doi:10.1080/00103624.2010.482171
[9]	H. L. Golterman, “Reflections on Fractionation and Bio availability of Sediment Bound Phosphate,” Archive Hydrobiology, Vol. 30, 1998, pp. 1-4.
[10]	A. N. Sharpley, “An Innovative Approach to Estimate Bioavailable Phosphorus in Agricultural Runoff by Fe Oxide—Impregnated Paper,” Journal of Environmental Quality, Vol. 22, 1993, pp. 597-601. doi:10.2134/jeq1993.00472425002200030026x
[11]	R. L. Haney, E. B. Haney, L. R. Hossner and J. G. Arnold, “Development of a New Soil Extractant for Simultaneous Phosphorus, Ammonium, and Nitrate Analysis,” Communications in Soil Science and Plant Analysis, Vol. 37, No. 11-12, 2006, pp. 1511-1523. doi:10.1080/00103620600709977
[12]	Z. Rengel, “Genetic Control of Root Exudation,” Plant Soil, Vol. 245, No. 1, 2002, pp. 59-70. doi:10.1023/A:1020646011229
[13]	E. Baudoin, E. Benizri and A. Guckert, “Impact of Artificial Root Exudates on the Bacterial Community Structure in Bulk Soil and Maize Rhizosphere,” Soil Biology and Biochemistry, Vol. 35, No. 9, 2003, pp. 1183-1192. doi:10.1016/S0038-0717(03)00179-2
[14]	R. L. Haney, A. J. Franzluebbers, F. M. Hons and D. A. Zuberer, “Soil Carbon and Nitrogen Mineralization: Influence of Drying Temperature,” Soil Science Society of America Journal, Vol. 68, No. 2, 2004, pp. 489-492. doi:10.2136/sssaj2004.0489
[15]	R. L. Haney, A. J. Franzluebbers, V. L. Jin, M.-V. John son, E. B. Haney, M. J. White and R. D. Harmel, “Soil Organic C:N vs. Water-Extractable Organic C:N,” Open Journal of Soil Science, Vol. 2, 2012, pp. 269-274. doi:10.4236/ojss.2012.23032
[16]	T. Bruulsema, J. Lemunyon and B. Herz, “Know Your Fertilizer Rights,” Crops Soils, 2009, pp. 13-18.
[17]	Minitab, “MINITAB 12,” Minitab Inc., State College, PA, 2000.
[18]	D. R. Helsel and R. M. Hirsch, “Statistical Methods in Water Resources,” Elsevier, New York, 1993.
[19]	C. T. Haan, “Statistical Methods in Hydrology,” 2nd Edition, The Iowa State Press, Ames, 2002.
[20]	USDA-NASS, 2012. www.nass.usda.gov/Data_and_Statistics/Quick_Stats_1.0/index.asp#top
[21]	W. M. Stewart, “News and Views: Fertilizer Contributions to Crop Yield,” 2002. www.ipni.net/ppiweb/ppinews.nsf/0/7DE814BEC3A5A6EF85256BD80067B43C/$FILE/Crop%20Yield. pdf
[22]	OSU, “Soil Fertility Research Highlights,” Oklahoma State University, Stillwater, 2000.
[23]	P. B. DeLaune, D. E. Dittrich and F. M. Hons, “Impact of Drought and High Nitrate Groundwater on Residual Soil Nitrogen,” Proceedings of the Beltwide Cotton Conference, San Antonio, 7-10 January 2013, pp. 876-879.
[24]	C. Buckley and P. Carney, “The Potential to Reduce the Risk of Diffuse Pollution from Agriculture while Improving Economic Performance at Farm Level,” Environmental Science & Policy, Vol. 25, 2013, pp. 118-126. doi:10.1016/j.envsci.2012.10.002
[25]	W. Y. Huang and R. M. Lantin, “A Comparison of Farmer’s Compliance Costs to Reduce Excess Nitrogen Fertilizer Use under Alternative Policy Options,” Applied Economic Perspectives and Policy, Vol. 15, No. 1, 1993, pp. 51-62. doi:10.2307/1349711
[26]	S. B. Phillips, J. J. Camberato and D. Leikam, “Selecting the Right Fertilizer Rate: A Component of 4R Nutrient Stewardship,” Crops Soils, 2009, pp. 14-18.