Effects of soil drying and rate of re-wetting on concentrations and forms of phosphorus in leachate
- 633 Downloads
The drying and re-wetting of soils can result in the modification of the amounts and forms of nutrients which can transfer, via leachate, from the soil to surface waters. We tested, under laboratory conditions, the hypothesis that the rate of re-wetting of a dried soil affects the solubilisation and concentrations of different forms of phosphorus (P) in leachate. A portion of grassland pelostagnogley soil (sieved moist <2 mm) was dried at 35°C and another portion maintained at approximately 40% water-holding capacity. Water (25 ml) was added at ten regularly spaced time intervals in 2.5-ml aliquots to the surfaces of both soils over periods of 0, 2, 4, 24 and 48 h, resulting in different rates of application. The leachate was collected and analysed for dissolved (<0.45 μm) and particulate total P and molybdate reactive and unreactive P. The rate of re-wetting significantly changed the concentrations of P, especially dissolved forms, in the leachate. Dissolved P concentrations were highest in leachate from the 2-h treatment, while particulate P concentrations were highest in the 0-h treatment leachate. In all cases, most P was unreactive and, therefore, likely to be in an organic form. Soil drying decreased microbial biomass, but this could not be directly linked to an increase of P in leachate. These results suggest that changes in patterns of rainfall frequency and intensity predicted by climate change scenarios could significantly affect the quantities of P leached from soils.
KeywordsDrying–re-wetting Phosphorus Leachate Soil microbial biomass
The authors thank Dan Dhanoa for assistance with statistical analyses and Tim Bearder for assistance in the laboratory. This work was funded by the UK Biotechnology and Biological Sciences Research Council (BBSRC) grant BB/C504919/1. North Wyke Research and Rothamsted Research receive grant-aided support from the BBSRC.
- Bartlett R, James B (1980) Studying dried, stored soil samples: some pitfalls. Soil Sci Soc Am J 44:721–724Google Scholar
- Cochran WG, Cox GM (1950) Experimental designs. Wiley, New YorkGoogle Scholar
- Fierer N, Schimel JP (2003) A proposed mechanism for the pulse in carbon dioxide production commonly observed following the rewetting of a dry soil. Soil Sci Soc Am J 67:798–805Google Scholar
- Halverson LJ, Jones TM, Firestone MK (2000) Release of intracellular solutes by four soil bacteria exposed to dilution stress. Soil Sci Soc Am J 64:1630–1637Google Scholar
- Harrod TR, Hogan DV (2008) The soils of North Wyke and Rowden. Revised edition of Harrod TR (1981) Soils in Devon IV: Sheet SS61 (Chulmleigh). Soil Survey Rec No 70. http://www.northwyke.bbsrc.ac.uk/pages/Soils%20of%20NW%20and%20Rowden.htm
- Ministry for Agriculture Fisheries and Food (1986) Method 32: pH and lime requirement of mineral soil. The analysis of agricultural materials. A manual of the analytical methods used by the Agricultural Development and Advisory Service. Reference book 427. Ministry for Agriculture, Fisheries and Food, Her Majesty’s Stationery Office, London, pp 98–101Google Scholar
- Rowland AP, Haygarth PM (1997) Determination of total dissolved phosphorus in soil solutions. J Environ Qual 26:410–415Google Scholar
- Sharpley AN, Hedley MJ, Sivbessen E, Hillbricht-Ilkowska A, House WA, Ryszkowski L (1996) Phosphorus transfers from terrestrial to aquatic systems. In: Tiessen H (ed) Phosphorus in the global environment. Wiley, Chichester, pp 171–199Google Scholar
- Snars KE, Swain A, Brookes PC, Blackwell MSA, Murray PJ, Williams J, Haygarth PM (2006) Modification to fumigation–extraction to permit better analysis of field soils and ease of measurement. In: Proceedings of 3rd International Symposium on Phosphorus Dynamics in the Soil–Plant Continuum, Uberlandia, Brazil, 14–19 May 2006, Embrapa Milho e Sorgo, Set Lagoas, MG, Brazil, pp 64–66Google Scholar
- Turner BL, Baxter R, Whitton BA (2003a) Nitrogen and phosphorus in soil solutions and drainage streams in Upper Teesdale, northern England: implications of organic compounds for biological nutrient limitation. Sci Total Environ 314:153–170. doi: 10.1016/S0048-9697(03)00101-3 PubMedCrossRefGoogle Scholar
- Wild A (1988) Russell's soil conditions and plant growth, 11th edn. Longman Scientific and Technical, HarlowGoogle Scholar