Crop-available zinc is affected by P-Zn interactions in soils. Orthophosphate (OP) additions may decrease or have no effect, while pyrophosphate (PP) may increase or have no effect on Zn solubility. Mechanisms involved in the interactions are not well understood and need to be quantified on agricultural soils subjected to P fertilization. / Top and sub-samples from three Quebec agricultural soils were equilibrated with OP or PP solutions, then with Zn solutions, and finally with solutions containing neither P nor Zn. The first equilibration evaluated P sorption effects on soil cation exchange capacity (CEC), the second equilibration evaluated Zn sorption (Zn$ sb{ rm s}$) after P sorption, and the third Zn desorption (Zn$ sb{ rm D}$) as related to added P. Subsequently, Zn fractions were extracted sequentially with KNO$ sb3$ (Zn$ sb{ rm KNO3}$), NaOH (Zn$ sb{ rm NaOH}$) solutions and concentrated HNO$ sb3$ + H$ sb2$O$ sb2$ (Zn$ sb{ rm HNO3}$). Autoclaved soils were used for OP and PP comparisons, and non-autoclaved soils were used for OP determinations. / Autoclaving reduced dithionite-citrate extractable Fe and Al materials. In both autoclaved and non-autoclaved soils, one mmole sorbed P as PP or OP resulted in increases in CEC from 0.52-1.24 mmole (+). Comparison between OP and PP in the autoclaved soils indicated that the increased CEC per mmole sorbed was greater with sorbed OP than with PP, while at the same rate of P addition, the absolute increased CEC was more with sorbed PP than with OP due to greater P sorption as PP compared to OP. Both sorbed OP or PP in autoclaved soils and sorbed OP in non-autoclaved soils increased specific Zn sorption in association with oxide materials. The effect was more significant with PP than with OP, as indicated by the observations: (1) P sorption increased Zn sorption but reduced Zn desorption, (2) P sorption reduced KNO$ sb3$- but increased NaOH- and HNO$ sb3$-extractable Zn, and (3) P sorption increased the difference between Zn sorbed and Zn extracted with KNO$ sb3$. These effects were more significant in coarser than finer textured soils. Results suggested that Zn fertilizers should be separated from P fertilizers to avoid enhanced Zn sorption and reduced Zn desorption.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.75928 |
| Date | January 1988 |
| Creators | Xie, Rongjing |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Renewable Resources.) |
| Rights | © Rongjing Xie, 1988 |
| Relation | alephsysno: 000928860, proquestno: AAINL52332, Theses scanned by UMI/ProQuest. |
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