Long-term crop rotation and fertilizer effects on phosphorus transformations. I. In a Chernozemic soil

• Published in: Canadian journal of soil science 1992-11, Vol.72 (4), p.569-579
• Main Authors: McKenzie, R. H., Stewart, J. W. B., Dormaar, J. F., Schaalje, G. B.
• Format: Article
• Language: English
• Subjects: abonos fosfatados; abonos nitrogenados; alberta; chernozem; chernozems; continuous cropping; cultivo continuo; culture continue; disponibilidad de nutrientes; disponibilite d' element nutritif; ecological soil types; engrais azote; engrais phosphate; fosforo; nitrogen fertilizers; nutrient availability; phosphate fertilizers; phosphore; phosphorus; rotacion de cultivos; rotation culturale; rotational cropping; tipos ecologicos de suelos; type de sol ecologique
• ISSN: 0008-4271; 1918-1841
• DOI: 10.4141/cjss92-047

The objective of this study was to determine effects of different cropping systems and nitrogen (N) and phosphorus (P) fertilizers on soil P fractions and transformations in long-term rotation plots on a Chernozemic soil at Lethbridge, Alberta. Continuous wheat, wheat-wheat-fallow, and wheat-fallow crop rotations and fertilizer application significantly affected the amount and distribution of phosphorus among labile and stable inorganic (Pi) and organic (Po) forms as determined by a sequential fractionation procedure. Without N and P fertilizer, the proportion of total soil P in more labile forms that were sequentially extractable with an anion exchange resin (resin-Pi), sodium bicarbonate (bicarb-Pi and Po) and sodium hydroxide (NaOH-Pi and Po) were reduced to a greater extent in continuous wheat than in wheat-wheat-fallow and wheat-fallow rotations. The addition of P fertilizer significantly increased total P and all Pi fractions, with the greatest change in more labile Pi forms (resin, bicarb and NaOH), but had no effect on labile Po forms. In contrast, N fertilizer addition increased the proportion of P in labile Po fractions in all rotations, and decreased the proportion of P in labile Pi forms. The combination of fertilizer N and P generally increased both Pi and Po labile forms. The continuous wheat rotation, coupled with N and P fertilizer inputs, had the most positive effect on P cycling and transformations. Key words: Soil P transformations, Chernozemic soils, P bioavailability, sequential extraction