Effect of scraping frequency in a freestall barn on volatile nitrogen loss from dairy manure.
The objective of this investigation was to evaluate the effect of scraping frequency (2x vs. 6x daily) on N volatilization from manure on the floor of a dairy free-stall barn. Three trials (crossover design) were conducted in the summers of 2001 and 2002, and in the winter of 2003. Nitrogen volatilization was estimated from the change in the N:P ratio in excreta at the time of excretion to the time when manure was scraped from the barn. Total N loss was considered a maximum estimate of NH3-N loss, because small amounts of nonammonia N may be volatilized. Nitrogen was determined after manure subsamples were lyophilized; P content was measured by direct current emission spectroscopy of ashed subsamples of manure. Lactating dairy cows were fed high-protein (18.5 to 19.3% crude protein), alfalfa-based diets. Average milk yield was 31.9 (SD = 7.4) kg/d. Scraping frequency had no effect on N loss in summer 2001. An average of 41% of excreted N, or 238 +/- 19.0 g of N/d per cow, was volatilized. For the trial in summer 2002, nitrogen volatilization was reduced from 50% of the excreted N with 2x to 46.7% with 6x, equivalent to 265 and 248 g of N lost/d per cow, respectively. Scraping had no effect on N volatilization during the winter trial. An average of 17.7% of excreted N was volatilized during the winter, equivalent to 109 +/- 11.0 g of N lost/d per cow. Scraping frequency of manure had little or no effect on N loss from manure in a freestall barn. Nitrogen loss during the winter was less than half of the loss during the summer.
Moreira
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VR
Department of Dairy Science, University of Wisconsin, Madison 53706, USA. VMoreira@agcenter.lsu.edu
Satter
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LD
D000393:Air Pollutants / Q000032:analysis / Q000737:chemistry; D000641:Ammonia / Q000032:analysis / Q000737:chemistry; D000818:Animals; D002417:Cattle; D003612:Dairying / Q000379:methods*; D004032:Diet; D005260:Female; D005612:Freeze Drying; D006799:Housing, Animal; D007774:Lactation; D008372:Manure / Q000032:analysis*; D008892:Milk / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis* / Q000737:chemistry; D010758:Phosphorus / Q000032:analysis; D012621:Seasons; D013696:Temperature; D014835:Volatilization
D000393:Air Pollutants; D008372:Manure; D010758:Phosphorus; D000641:Ammonia; D009584:Nitrogen