Phosphorus availability for plant uptake in a phosphorus-enriched noncalcareous sandy soil.
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.
Koopmans
G F
GF
Wageningen University and Research Centre (WUR), P.O. Box 47, 6700 AA, Wageningen, The Netherlands. gerwin.koopmans@wur.nl
Chardon
W J
WJ
Ehlert
P A I
PA
Dolfing
J
J
Suurs
R A A
RA
Oenema
O
O
van Riemsdijk
W H
WH
D000327:Adsorption; D000383:Agriculture; D000818:Animals; D000829:Animals, Domestic; D001673:Biodegradation, Environmental; D004787:Environmental Pollution / Q000517:prevention & control; D010758:Phosphorus / Q000032:analysis* / Q000302:isolation & purification / Q000493:pharmacokinetics*; D018570:Risk Assessment; D012822:Silicon Dioxide; D012987:Soil; D013696:Temperature
D012987:Soil; D010758:Phosphorus; D012822:Silicon Dioxide