Soils nitrate leaching

The fact that is not radioactive means that it can be used safely in experiments in the field, but it also means that much patient work is needed to obtain results. The approach is demanding in terms of time, equipment, and skilled manpower, but it has made a great contribution to the understanding of the nitrate problem. The results that are outlined here are from experiments made by staff at Rothamsted, but key contributions have also come from Scotland and France. " The majority of the Rothamsted experiments involved winter wheat, but oilseed rape, potatoes, beans, and sugar beet were also grown. The soil is a factor in nitrate leaching, and three types were used, the flinty, silty clay loam at Rothamsted, a sandy loam at Woburn in Bedfordshire and a heavy sandy clay at Saxmimdham in Suffolk. 

Adams PL, Daniel TC, Nichols DJ, Pote DH, Scott HD (1994) Poultry Litter and Manure Contributions to Nitrate Leaching through the Vadose Zone. Soil Sci Soc Am J 58 1206-1211... 

Kirchmann H, Bergstrom L (2001) Do organic farming practices reduce nitrate leaching Comm Soil Sci Plant Anal 32 997-1028... 

Stopes C, Lord El, Phillips L, Woodward L (2002) Nitrate leaching from organic farms and conventional farms following best practice. Soil Use Manage 18 256-263... 

The appropriate parameters to measure the potential for nitrate leaching during the non-vegetative period are the Nmm-N content in soil in autumn and the N-balance. As the latter will be the subject of Chapter 3.3.1, this section will concentrate on the impact of organic farming on the Nmm-N content in the soil. 

Watson, C. A., Fowler, S. M. and D. Wilman (1994). Purchases and sales of N, P and K. Soil In-organic N and Nitrate Leaching on an organic horticultural holding. Biological Agriculture and Horticulture 10 (3) 189-196. 

Eriksen, J., Askegaard, M. and Kristensen, K. 2004. Nitrate leaching from an organic dairy crop rotation the effects of manure type, nitrogen input and improved crop rotation. Soil Use and Management 20 48-54. 

Watson, C.A., Fowler, S.M. and Wilman, D. 1993. Soil inorganic-N and nitrate leaching on organic farms. Journal of Agricultural Science 120 361-369. 

Goulding, K. 2000. Nitrate leaching from arable and horticultural land. Soil Use and Management 16(4) 145-151. 

Bradfield and Cooke [45] have described an ion-chromatographic method employing a UV detector for the determination of nitrate sulfate and phosphate in water extracts of soils (see Fig. 6.4). Soils are leached with water and Dowex 50-X4 ion exchange resin added to the aqueous extract, which is then passed... 

Kramer, Sasha B., John P. Reganold, Jerry D. Glover, Brendan J. M. Bohannan, and Harold A. Mooney. 2006. Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils. Proceedings of the National Academy of Sciences USA 103(12) 4522-4527. 

Sometimes these operationally defined procedures have a sound theoretical basis. For example, it is quite reasonable to suppose that leaching with magnesium nitrate solution will displace zinc from cation exchange sites in soils, or leaching with ammonium acetate will displace exchangeable calcium, magnesium, sodium, and potassium. Flame spectrometry, especially flame AAS, is widely used for the analysis of such extracts. 

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