Crop Recovery of Fertilizer P from Soils Low in Soluble P. (Pot Experiments with Rye Grass)

Abstract

16 Danish mineral soils, depleted in P by cropping for 10 years, were used in a pot experiment to investigate the capacity of rye grass to recover new fertilizer P from application of 4 and 8 mg P per 100g soil. In the year of P application the recovery of P in rye grass amounted to 58 and 45%, in the next two years 19 and 11%, respectively. Based on this result the P fixation was thus 23 and 44% respectively. It may therefore be concluded that on P-depleted limed soils the effect of P fertilizer is highest if applied annually.

Key Words:

• soil
• phosphorus
• P-fixation
• P-uptake
• lime
• ecology