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

This Article Full Text (PDF) 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 Fenn, L. B. Articles by Matocha, J. E. Search for Related Content PubMed Articles by Fenn, L. B. Articles by Matocha, J. E. Agricola Articles by Fenn, L. B. Articles by Matocha, J. E.

Ammonia Losses from Surface-Applied Nitrogen Fertilizer as Controlled by Soluble Calcium and Magnesium: General Theory¹

ABSTRACT

Ammonia volatilization from soils after surface application of urea or inorganic N was reduced by Ca and Mg nitrates or chlorides. Sulfates were only slightly effective. Suppression of NH₃ loss was a result of two chemical reactions: (i) precipitation of CO₃ by Ca, thus preventing permanent (NH₄)₂CO₃·H₂O (AC) formation, and (ii) Ca depression of soil pH by depression of the dissociation of the CaCO₃-Ca(OH)₂ buffer system. Soil pH values as low as 6.5 were recorded in calcareous soil and 3.9 and 4.5 in the acid soils after addition of Ca. Soil pH values in the presence of Ca reached approximate neutrality in 24 hours even in acid soils. Soil pH without Ca but with AC increased to > 9.0 in every soil. Addition of AC plus Ca reduced the pH of calcareous soil to 5.3 and raised it to 5.7 in acid soils. Calcium carbonate precipitation eventually occurred in acid soils, preventing high NH₃ losses. Evidently, CaCO₃ precipitated on the surface of acid soils after the pH reached a certain critical value and, as expected, the pH was maintained near that of the pure CaCO₃ system.

¹ Contribution from the Texas Agric. Exp. Stn., Texas A&M Univ.

² Associate Professors, Texas Agric. Res. Center, 1380 A&M Circle, El Paso, TX 79927; and Professor, Texas Agric. Res. and Extension Center, P. O. Box 10607, Corpus Christi, TX 78410.

Received for publication February 21, 1978. Accepted for publication September 22, 1978.

This article has been cited by other articles:

				M. L. Silveira, V. A. Haby, and A. T. Leonard Response of Coastal Bermudagrass Yield and Nutrient Uptake Efficiency to Nitrogen Sources Agron. J., April 4, 2007; 99(3): 707 - 714. [Abstract] [Full Text] [PDF]