USING GEOSTATISTICS TO DETERMINE SPATIAL VARIABILITY OF NUTRIENTS WITHIN A POULTRY HOUSE

Authors: Owens, Phillip; Miles, Dana; Rowe, Dennis

Submitted to: Feedinfo News
Publication Type: Popular Publication
Publication Acceptance Date: 6/1/2004
Publication Date: 6/1/2004
Citation: Owens, P.R., Miles, D.M., Rowe, D.E. 2004. Using geostatistics to determine spatial variability of nutrients species in a poultry house. Feedinfo News Service. Available: http://www.feedinfo.com/console/PageViewer.aspx?page=94041.

Interpretive Summary: Manure nutrient management calls for sampling poultry litter for nutrient composition prior to field applications. The new Confined Animal Feeding Operations (CAFO) rules propose broiler (meat-type chicken) house sampling guidelines to derive nutrient load concentrations, which may be used to determine fertilizer application rates or nutrient accountability upon litter transfer to a third party. Unanswered questions remain such as: how best to perform sampling of litter within the house, what is representative data, and how many samples are needed? Developing better sampling techniques may provide needed information for implementing sound poultry house manure management practices. This research found that nutrients within a poultry house vary across the poultry house as well as down the poultry house. Data from pooled samples yielded values that were within ranges reported in other studies; however, the contour plots illustrated problems associated with characterizing nutrient concentration variability in broiler litter. The method of house sampling could dramatically affect the outcome of the nutrient analysis and land application. The geostatistical estimates and contour plots may allow determination of multi-factor chemical and physical properties of the litter that lead to ammonia volatilization, pathogen survival and nutrient accumulation. If consistent patterns are observed within poultry houses, best management practices can be established to minimize the potential for negative impacts.

Technical Abstract: The objective of this study was to determine the variability of nutrient species within a poultry house using geostatistical contour plots. This research was conducted in the summer on a tunnel ventilated poultry house that was 146 m by 12.8 m. Prior to sampling, the litter had twenty-eight flocks of chickens grown on it with decaking between each flock. The house was sampled on a grid for a total of 36 sampling points. The litter was sampled at day 1 to determine pH, total N (TKN) and nutrient species. The data indicated a higher average concentration of TKN and ammonium in the cooling cell end of the house and decreased toward the fan exhaust end of the house. The average nitrate data also yielded higher concentrations at the cool cell end of the house and decreased toward the exhaust end of the house. The data from the geostatisitical contour plots illustrated higher TKN and ammonium in the brood end of the house, which corresponded with the lower pH (8.6 vs. 7.5) also in the brood end of the house. The contour plots of the nitrate data illustrated highest concentration near the sidewall of the brood end of the house, which corresponded to the areas with the highest litter moisture. The water extractable P data did not indicate definite trends within the house following analysis of the data. These geostatisical estimates of the nutrient concentrations indicated an anisotropic distribution of the nutrients along the house and illustrated spatial variability of nutrient species within the poultry house.