HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hettiarachchi, G. M. Articles by Self, P. Search for Related Content PubMed Articles by Hettiarachchi, G. M. Articles by Self, P. Agricola Articles by Hettiarachchi, G. M. Articles by Self, P. Related Collections Flow Phosphorus Nutrient Management

Nutrient Management & Soil & Plant Analysis

Density Changes around Phosphorus Granules and Fluid Bands in a Calcareous Soil

^a Soil and Land Systems, School of Earth and Environmental Sciences, The Univ. of Adelaide, Waite Campus, Urrbrae, SA 5064, Australia
^b CSIRO Land and Water, PMB 2, Glen Osmond, SA 5064, Australia
^c Adelaide Microscopy, The Univ. of Adelaide, Adelaide, SA 5005, Australia

^* Corresponding author (ganga.hettiarachchi{at}adelaide.edu.au)

We employed x-ray computed microtomography (X-ray CT) to observe differences in moisture around fertilizer P granules (monoammonium phosphate, MAP) versus injection zones of fluid P fertilizer (technical grade monoammonium phosphate, TG MAP) in a calcareous soil over time. X-ray CT allows nondestructive visualization of small columns containing soils and fertilizers. We were able to visualize the increase in density around the highly hygroscopic fertilizer granule over time. It appeared that both water flow toward the granule and precipitation of P could be responsible for the development of about 1 mm thick high density zone immediately adjacent to the granule. The mass flow of water toward the granule may have slowed or restricted the diffusion of fertilizer P from the granule, thus increasing the chances for P fixation through precipitation reactions. Also, the granule became less dense with time indicating the progress of granule dissolution. In contrast, injection of fluid fertilizer (TG-MAP) in soil did not result in moisture changes over time as evidenced by a lack of X-ray CT detectable density differences in the soil column. These data support previous findings that, when P is supplied in granular form, P diffusion and isotopic lability in calcareous soils are reduced compared with equivalent liquid fertilizer formulations, probably due to precipitation reactions induced by osmotically induced flow of soil moisture into the fertilizer granule.

Abbreviations: BSE, backscattered electron • MAP, monoammonium phosphate • SEM, scanning electron microscopy • TG-MAP, technical grade monoammonium phosphate • X-ray CT, x-ray computed microtomography

This article has been cited by other articles:

				E. Lombi, K. G. Scheckel, R. D. Armstrong, S. Forrester, J. N. Cutler, and D. Paterson Speciation and Distribution of Phosphorus in a Fertilized Soil: A Synchrotron-Based Investigation Soil Sci. Soc. Am. J., October 27, 2006; 70(6): 2038 - 2048. [Abstract] [Full Text] [PDF]