This experiment was designed to determine if tannin concentration and nitrogen (N) content of field-applied dairy cow manure influences greenhouse gas (GHG) emissions from soil, soil N mineralization, and plant productivity. The study was conducted at the U.S. Dairy Forage Research Center farm in Prairie du Sac, WI. Field experiments were set up with six randomized complete blocks with two factors (tannin concentration at 3 levels and N fertilization at 2 levels), plus a control (no manure application) treatment in each block. To begin the experiment, three experimental diets with differing tannin concentrations (0, 0.4, and 1.8% tannin as dry matter intake), were fed to Holstein dairy cows for three months. Manure collected at the end of the three month period was field-applied at two N application rates (240 and 360 kg N ha-1). Manure was broadcast and disk-incorporated on May 15, 2014, in fields that were not irrigated and had no tile drainage. This was followed by tillage using a rototiller. Maize (corn for silage) was planted on May 20, 2014. Corn silage was harvested on September 17, 2014, leaving 20 cm-high residue (stubble). GHG flux measurements took place starting May 15, 2014, with GHG sampling every 7-21 days until harvest. Soil chamber dimensions for flux measurements were 15.24 cm (height), 76.2 cm (length), 42.3 cm (width).

In May 2014, soil was collected for analysis of physical characteristics. Cores 90 cm deep and 10 cm diameter were collected using a Giddings probe and analyzed at the UW Soil and Forage Lab (complete methods at http://uwlab.webhosting.cals.wisc.edu/wp-content/uploads/sites/17/2015/0...). According to the USDA NRCS classification system, soils at the site are St. Charles Silt Loam, fine-silty, mixed, superactive, mesic Typic Hapludalfs, with more than 1.5 m depth to an impermeable layer.

The data are presented as a spreadsheet file with seven sheets: (1) experimental design, (2) soil physical characteristics, (3) gas fluxes, (4) soil nitrogen at 0-10 cm depth, (5) soil nitrogen at 10-20 cm depth, (6), chemical characteristics of dairy manure, (7) crop yield and biomass characteristics. There is also a data dictionary spreadsheet file with a separate dictionary sheet for each data sheet.

Weather data for the field site (not presented here) can be found at: http://www.wunderground.com/personal-weather-station/dashboard?ID=KWIMER...