期刊
NUTRIENT CYCLING IN AGROECOSYSTEMS
卷 92, 期 3, 页码 329-346出版社
SPRINGER
DOI: 10.1007/s10705-012-9493-1
关键词
Whole farm model; Soil model; Nitrogen excretion; Nitrogen leaching
类别
资金
- DairyNZ Inc.
- Ministry of Science and Innovation - Dairy Systems for Environmental Protection [DRCX0802]
- New Zealand Ministry of Business, Innovation & Employment (MBIE) [DRCX0802] Funding Source: New Zealand Ministry of Business, Innovation & Employment (MBIE)
On New Zealand dairy farms, it is the nitrogen excreted directly onto pasture, particularly urine, that drives nitrogen (N) leaching from the farm. A new framework (UPF: Urine Patch Framework) is presented that post-processes the results of a whole farm model and runs a mechanistic soil model to simulate the urine patches. Two alternative methods to simulate the spatial distribution of urine patches were implemented and compared (Grid: spatially explicit, and Probabilistic: based on the probability of different temporal urination patterns). This paper describes the implementation of these two methods in connection with a Whole Farm Model; and compares the N leaching predictions with observed data. Two examples are provided, one analyzing the impact of urine patch overlap and another, the relative risk of N leaching at different times of urinary N deposition. The model showed good correlation and predictive ability between simulated annual N leaching results and observed data [R-2 = 94 %, mean relative prediction error (MRPE) = 10 % for Grid and R-2 = 72 %, MRPE = 20 % for Probabilistic]. The two methods produced similar results across an 8-year period for monthly and annual N leaching (R-2 = 96 %, MRPE = 10 % and R-2 = 86 %, MRPE = 8 %; respectively). Only 8 % of the paddock area was covered with multiple urinations during 1 year, but as much as 39 % of the total urine volume was deposited on overlapped patches. Systematically removing all urinary N for 1 month in either May or June reduced N leaching by approximately 20 %. Avoiding urinary N deposition during autumn or early winter could be highly effective in mitigating N leached during the following winter.
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