File(s) under permanent embargo
Spatially and temporally variable urinary N loads deposited by lactating cows on a grazing system dairy farm
More urination events and greater urine volumes per event were recorded in spring 2014 (3.1 L) compared with winter 2015 (1.4 L), most likely influenced by environmental conditions and the greater spring rainfall observed. Mean (range) N concentration (0.71%; 0.02 to 1.52%) and N load (12.8 g cow−1 event−1; 0.3 to 64.5 g cow−1 event−1) did not differ over the two monitoring periods. However, mean (range) daily N load was greater in spring (277 g cow−1 day−1; 200 to 346 g cow−1 day−1) than in winter (90 g cow−1 day−1; 44 to 116 g cow−1 day−1) due to the influence of urine volume. Relatively greater time was spent in paddocks overnight (13.3 h) than in paddocks between morning and evening milking (6.4 h), compared with the mean numbers of urinations in these places (6.4 and 3.8 respectively). The mean N load deposited overnight in paddocks (89.6 g cow−1) was more than twice that deposited in paddocks during the day (43.8 g cow−1), due to the greater N load per event overnight, and was more closely linked to the relative difference in time spent in paddocks than in the number of urination events. These data suggest that routinely holding cows in the same paddocks overnight will lead to high urinary N depositions, increasing the potential for N losses from these places. Further research using this technology is required to acquire farm and environment specific urinary data to improve N management.
History
Publication title
Journal of Environmental ManagementVolume
215Pagination
166-176ISSN
0301-4797Department/School
Tasmanian Institute of Agriculture (TIA)Publisher
Academic Press Ltd Elsevier Science LtdPlace of publication
24-28 Oval Rd, London, England, Nw1 7DxRights statement
Copyright 2018 Elsevier Ltd.Repository Status
- Restricted