Submitted to: Interagency Conference on Research in the Watersheds
Publication Type: Proceedings
Publication Acceptance Date: 10/30/2011
Publication Date: 11/2/2011
Citation: Gish, T.J., Daughtry, C.S., Russ, A.L., McKee, L.G., Prueger, J.H. 2011. Improved nitrogen management utilizing ground-penetrating-radar: A nine-year investigation. In: Fourth Interagency Conference on Research in the Watersheds, September 26-30, 2011, Fairbanks, Alaska. p. 94-99.
Technical Abstract: Water availability and efficient use of nitrogen are critical components of a sustainable and profitable agricultural system. Since nitrogen is typically excessively applied, considerable nitrogen may leach to and move through the subsurface. Our hypothesis is that knowledge of the subsurface hydrology can be utilized to reduce nitrogen applications by identifying where these water flow pathways serve as a subsurface irrigation system. This nine year study was conducted at the USDA-ARS Optimizing Production Inputs for Economic Enhancement site (OPE3) in Beltsville, Maryland. Uniform and precision application of sidedressed N were evaluated on two corn production fields, about 4 ha each. For the precision N field sidedressing was determined primarily with a knowledge of the subsurface flow pathways identified with ground-penetrating radar (GPR) and digital surface elevation maps. Field B, received uniform applications of nitrogen with 34 kg N ha-1 applied at planting and then about 134 kg N ha-1 as side-dressing when the corn was about 60 to 80 cm high. The second field, field D, was under precision management -- receiving 34 kg N ha-1 at planting and then 0 to 134 kg N ha-1 as variable-rate side-dressing. The precision N site generally received about 34% less nitrogen than the uniform N application site yet there was no significant reduction in yields. This work demonstrates that knowledge of the subsurface hydrology can improve nitrogen use efficiency and thereby increase farm sustainability.