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Nitrate leaching and residual soil nitrogen supply following outdoor pig farming
Author(s) -
Williams J.R.,
Chambers B.J.,
Hartley A.R,
Chalmers A.G.
Publication year - 2005
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.2005.tb00131.x
Subject(s) - leaching (pedology) , arable land , nitrate , environmental science , agronomy , loam , nitrogen , pig farming , denitrification , soil water , zoology , agriculture , chemistry , biology , ecology , soil science , animal production , organic chemistry
. Large nitrogen (N) inputs to outdoor pig farms in the UK can lead to high nitrate leaching losses and accumulation of surplus N in soil. We investigated the residual effects of three contrasting outdoor pig systems as compared to an arable control on nitrate leaching and soil N supply for subsequent spring cereal crops grown on a sandy loam soil during 1997/98 and 1998/99 harvest seasons. Previously, the pig systems had been stocked for 2 years from October 1995 and were designated current commercial practice (CCP, 25 sows ha −1 on stubble), improved management practice (IMP, 18 sows ha −1 on undersown stubble) and best management practice (BMP, 12 sows ha −1 on established grass). Estimated soil N surpluses by the end of stocking in September 1997 were 576, 398, 265 and 27 kg ha −1 N for the CCP, IMP, BMP and continuous arable control, respectively. Nitrate leaching losses in the first winter were 235, 198, 137 and 38 kg ha −1 N from the former CCP, IMP and BMP systems and the arable control, respectively. These losses from the former pig systems were equivalent to 41–52% of the estimated soil N surpluses. Leaching losses were much smaller in the second winter at 21, 14, 23 and 19 kg ha −1 N, respectively. Cultivation timing had no effect ( P >0.05) on leaching losses in year 1, but cultivation in October compared with December increased nitrate leaching by a mean of 14 kg ha −1 N across all treatments in year 2. Leaching losses over the two winters were correlated ( P <0.001) with autumn soil mineral N (SMN) contents. In both seasons, spring SMN, grain yields and N offtakes at harvest were similar ( P >0.05) for the three previous pig systems and the arable control, and cultivation timing had no effect ( P >0.05) on grain yields and crop N offtake. This systems study has shown that nitrate leaching losses during the first winter after outdoor pig farming can be large, with no residual available N benefits to following cereal crops unless that first winter is much drier than average.