Quantitative estimation of nitrogen, phosphorus and potassium flow in dairy farms
1997
Tsuki, M. (National Agriculture Research Center, Tsukuba, Ibaraki (Japan)) | Harada, Y.
As livestock production in Japan becomes more intensive, livestock wastes cause serious environmental problems. To solve these problems, the flow of nitrogen (N), phosphorus (P) and potassium (K) in dairy farms was estimated quantitatively during the period 1979 to 1991. The input of N, P and K to dairy farms increased year by year. On the other hand, the proportion of self-supplying feeds to the total input decreased. In 1991, about 5% of N input was contained in self-supplying feeds in Hokkaido and about 19% in other areas. The ratio of N:P:K was 50:7:43 in the former, and 54:8:38 in the latter. The proportions of animal wastes to the total output were 77%(N), 69%(P) and 94%(K) in Hokkaido, and 78%(N), 71%(P) and 93%(K) in other areas. The N loading onto cropland was almost constant during this 13-year period. In other areas than Hokkaido, N loading onto cropland increased year by year in dairy farms which operate a small area of cropland (0.5ha) or lack cropland. These results indicate that the number of dairy farms with large number of cows but with a small area of cropland or without cropland is increasing
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