Effect of Cropping and Fertilization on Plant and Soil Phosphorus
- F. Selles ,
- C. A. Campbell and
- R. P. Zentner
Knowledge regarding the effects of long-term cropping practices and fertilization on the fate of P applied to the soil is required to aid in the prediction of how such practices influence the quality and sustainability of the environment. A 24-yr crop rotation experiment, conducted on a Swinton silt loam (Aridic Haploboroll) in southern Saskatchewan, was used to determine uptake of P by crops, its distribution in grain and straw, and the rate of change and nature of the residual P in the soil. Phosphorus concentration in the grain relative to that in the straw was 7:1 to 12:1 for spring wheat (Triticum aestivum L.), 6:1 for flax (Linum usitatissimum L.), and 5:1 for lentil (Lens culinaris Medikus) and fall rye (Secale cereale L.). Grain P concentration was lowest in cereal crops (3.6 g kg−1) and highest in flax and lentil (4.4 g kg−1). Phosphorus removed annually with the grain increased with P fertilization and decreased with an increase in fallow frequency; it was 4.8 to 5.3 kg P ha−1 for continuous wheat, 3.5 to 3.8 kg P ha−1 for fallow-wheat-wheat, and 3.1 kg P ha−1 for fallow-wheat. Trend analysis showed that fertilizer P increased the Olsen P levels in soil at rates of 1.0 to 1.7 kg ha−1 yr−1, but in the systems receiving no P, Olsen P remained constant and did not decline as suggested by a P balance sheet. Residual fertilizer P accumulated in labile forms, dominated by sorbed P and microbial P, rather than in forms dominated by Ca phosphate precipitates or other organic forms.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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