Lookup NU author(s): Dr Jan Dolfing
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Mining soil phosphorus (i.e., harvesting P taken up from the soil by a crop grown without external P addition) has been proposed as a possible management strategy for P-enriched soils to decrease the risk of P leaching. We performed a pot experiment in a greenhouse where grass was cropped on a P-enriched noncalcareous sandy soil at zero P application over a period of 978 d. We determined the long-term availability of soil P and evaluated the effectiveness of mining soil P to decrease P in different pools. There were two treatments: soil layers in the pots of either 5 or 10 cm thickness. Soils were analyzed at various stages of the experiment. Phosphorus in soil solution and the total pool of sorbed P were estimated using 1:10 (w/v) 0.01 M CaCl2 extracts and acid ammonium oxalate (P-ox), respectively. A desorption isotherm was constructed, which described the relationship between P in soil solution and the total pool of sorbed P for the soils of the 5- and 10-cm treatments. The Langmuir equation gave a very good description of the isotherm. In the long-term, 65% of P-ox in the initial soil can be removed by plant uptake, as was calculated from the Langmuir equation and a critical P concentration in soil solution at which P uptake can just be maintained. Thus, P-ox may be largely plant available. From the strong nonlinearity of the desorption isotherm, it can be understood why the relative decrease of the P concentration in the CaCl2 extracts was much larger than the relative decrease of P-ox. Mining soil P decreased the P concentration in soil solution effectively and, therefore, risk of P leaching from our P-enriched soil.
Author(s): Koopmans GF, Chardon WJ, Ehlert PAI, Dolfing J, Suurs RAA, Oenema O, van Riemsdijk WH
Publication type: Article
Publication status: Published
Journal: Journal of Environmental Quality
Print publication date: 01/05/2004
ISSN (print): 0047-2425
ISSN (electronic): 1537-2537
Notes: Times Cited: 6
Cited Reference Count: 59
J ENVIRON QUAL