JWARP  Vol.10 No.10 , October 2018
Development and Testing of a Variable Rate Nitrogen Application System through an Overhead Irrigation System
Abstract: Nutrients are injected through overhead irrigation systems at a uniform rate in a process known as fertigation. The highly variable soils in the Southeastern US pose challenges for effective fertigation. Currently, there is no variable-rate fertigation system available to apply the correct amount of N within a field through an overhead irrigation system. Therefore, the objective of this study was to develop and test a variable-rate N application system that works independently of irrigation water flow for site-specific N application. The variable-rate fertigation system (VRFS) was designed to apply different rates N using a pulse width modulation technique. The VRFS utilized the Clemson Lateral Irrigation Control software which controlled the solenoids in each zone by turning the N supply on and off (pulsing) for each zone. In this study, four tests were conducted to determine the uniformity of the VRFS. In test # 1, the pump output showed a linear slope relationship and was the same for water and N. In test # 2, nozzle flow and uniformity were determined using four different irrigation system travel speeds at N application rates of 31, 59, 88, and 113 kg/ha. There was a strong correlation (R2 = 0.9998) between irrigation system speed and N rate. In test # 3, the uniformity across the length of the irrigation system was determined. The nozzles produced an average flow of 31.1, 58.7, 87.6, and 112.7 kg N/ha with an overall average error of 0.1% across all N rates. Results also showed the system was capable of accurately applying N based on prescription maps with an error of less than 1.8%. Test # 4 was conducted to determine the accuracy of the map-based controller system for applying variable rate N. There was a strong correlation between target N and actual N rates (R2 = 0.9999). In summary, the VRFS applied the correct amounts of N within each zone by either manually controlling the pulsing mechanism or utilizing a prescription map to apply different rates throughout the field.
Cite this paper: Williams, P. , Khalilian, A. , Marshall, M. , Maja, J. , Liu, H. , Park, D. and Nafchi, A. (2018) Development and Testing of a Variable Rate Nitrogen Application System through an Overhead Irrigation System. Journal of Water Resource and Protection, 10, 994-1011. doi: 10.4236/jwarp.2018.1010058.

[1]   United States Department of Agriculture (2017) National Agricultural Statistics Service, Crop Production Summary.

[2]   Oosterhuis, D. (2009) Foliar Fertilization: Mechanisms and Magnitude of Nutrient uptake. Proceedings of the Fluid Forum, 15-17 February 2009, Phoenix, AZ.

[3]   Verbree, D., McClure, A. and Leib, B. (2013) Fertigation of Row-Crops Using Overhead Irrigation. University of Tennessee Extension Publication, W303.

[4]   Duffera, M., White J. and Weisz, R. (2007) Spatial variability of Southeastern U.S. Coastal Plain Soil Physical Properties: Implications for Site-Specific Management. Geoderma, 137, 327-339.

[5]   Scharf, P., Lorry, J., Kitchen, N., Sudduth, K. and Davis, J. (2002) Spatial Variability of Optimum N Rate for Corn. American Society of Agronomy, Madison, WI.

[6]   Kablan, L.A., Chabot, V., Mailloux, A., Bouchard, M.è. and Bruulsema, T. (2017) Variability in Corn Yield Response to Nitrogen Fertilizer in Eastern Canada. Agronomy Journal, 109, 2231-2242.

[7]   Jones, M.A. (2008) Utilizing Crop Vegetation Indices (NDVI) Measurements to Potentially Reduce Input Costs Associated with Plant Growth Regulator and Harvest Aid Applications. Proceedings of the Beltwide Cotton Conferences, National Cotton Council of America, 8-11 January 2008, Memphis, TN, 158-161.

[8]   Dexter, A.R. (2004) Soil Physical Quality; Part I. Theory, Effects of Soil Texture, Density, and Organic Matter, and Effects on Root Growth. Geoderma, 120, 201-214.

[9]   Crouse, D.A. (2017) Soils and Plant Nutrients, North Carolina Extension Gardener Handbook. NC State Extension, Raleigh, NC.

[10]   Nafchi, A.M., Maja, J.M., Khalilian, A., Han, Y., Rogers, N., Payero, J.O., Marshall, M.W., Williams, P.B. and Fox, J. (2017) An Electro-Mechanical Controller for Adjusting Piston Pump Stroke On-the-Go for Site-Specific Application of Crop Nutrients. Agricultural Sciences, 8, 949-959.

[11]   Han, Y.J., Khalilian, A., Owino, T.O., Farahani, H.J. and Moore, S. (2009) Development of Clemson Lateral Variable-Rate Irrigation System. Computers and Electronics in Agriculture, 68, 108-113.

[12]   Perry, C., Pocknee, S. and Hansen, O. (2003) A Variable Rate Pivot Irrigation Control System. In: Stafford, J. and Werner, A., Eds., ECPA 2003, Proceedings of the Fourth European Conference on Precision Agriculture, Wageningen Academic Publishers, Wageningen, 539-544.

[13]   Scherer, F., Thomas F., Kranz, W., Pfost, D., Werner, H., Wright, J.A. and Yonts, C.D. (1999) Sprinkler Irrigation Systems. MidWest Plan Service, MWPS-30. 1st Edition, Iowa State University, Ames, IA.