Nitrate leaching and residual soil nitrogen supply following outdoor pig farming

• Published in: Soil use and management Vol. 21; no. 2; pp. 245 - 252
• Main Authors: Williams, J.R, Chambers, B.J, Hartley, A.R, Chalmers, A.G
• Format: Journal Article
• Language: English
• Published: Wallingford CAB International 01.06.2005
• Subjects: Agronomy. Soil science and plant productions; Animal productions; best management practices; Biological and medical sciences; crop residues; farming systems; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; grain crops; grain yield; leaching; nitrate nitrogen; nutrient availability; nutrient offtake; Physical properties; Physics, chemistry, biochemistry and biology of agricultural and forest soils; sandy loam soils; Soil and water pollution; soil nutrient balance; Soil science; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; stocking rate; swine; Terrestrial animal productions; Vertebrates; Water and solute dynamics; United Kingdom; England; Great Britain; Europe; British Isles; grain nitrogen offtake; Soil transport processes; Soil fertility; Intensive rearing; Soil quality; Nitrates; Outer; Inorganic element; Soil science; Animal production; soil nitrogen supply; Ungulata; Soil chemistry; Pollution by agriculture; Farming animal; Underground leaching; Pollutant behavior; nitrate leaching; Agricultural soil; Land use; Zootechny; Residual effect; Pig; Outdoor pig farming; Vertebrata; Mammalia; Inorganic nitrogen; Environment impact; Artiodactyla; soil mineral nitrogen
• ISSN: 0266-0032; 1475-2743
• DOI: 10.1079/SUM2005318

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.