title: Applying nitrogen site-specifically using soil electrical conductivity maps and precision agriculture technology.
abstract: Soil texture varies significantly within many agricultural fields. The physical properties of soil, such as soil texture, have a direct effect on water holding capacity, cation exchange capacity, crop yield, production capability, and nitrogen (N) loss variations within a field. In short, mobile nutrients are used, lost, and stored differently as soil textures vary. A uniform application of N to varying soils results in a wide range of N availability to the crop. N applied in excess of crop usage results in a waste of the grower"s input expense, a potential negative effect on the environment, and in some crops a reduction of crop quality, yield, and harvestability. Inadequate N levels represent a lost opportunity for crop yield and profit. The global positioning system (GPS)-referenced mapping of bulk soil electrical conductivity (EC) has been shown to serve as an effective proxy for soil texture and other soil properties. Soils with a high clay content conduct more electricity than coarser textured soils, which results in higher EC values. This paper will describe the EC mapping process and provide case studies of site-specific N applications based on EC maps. Results of these case studies suggest that N can be managed site-specifically using a variety of management practices, including soil sampling, variable yield goals, and cropping history.
authors.affiliation: Veris Technologies, Salina, KS 67401, USA. lunde@geoprobesystems.com
authors.forename: E D
authors.initials: ED
authors.lastname: Lund
authors.forename: M C
authors.initials: MC
authors.lastname: Wolcott
authors.forename: G P
authors.initials: GP
authors.lastname: Hanson
mesh_terms: D000383:Agriculture / Q000379:methods* / Q000639:trends*; D000538:Aluminum Silicates / Q000737:chemistry; D000077215:Clay; D018556:Crops, Agricultural / Q000254:growth & development; D004553:Electric Conductivity; D007615:Kansas; D008145:Louisiana; D008377:Maps as Topic; D008922:Mississippi; D009566:Nitrates / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D009658:North Dakota; D012987:Soil / Q000032:analysis*; D013672:Technology / Q000639:trends; D014867:Water / Q000737:chemistry; D014881:Water Supply
chemical_list: D000538:Aluminum Silicates; D009566:Nitrates; D012987:Soil; D014867:Water; D009584:Nitrogen; D000077215:Clay