Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/14/2002
Publication Date: 11/14/2002
Citation: AVILA, M., BARAK, P., POSNER, J.L., LAIRD, D.A. ACCELERATED AGING OF AGRICULTURAL SOILS AND THE COUPLING OF THE NITROGEN AND PROTON CYCLES. AGRONOMY ABSTRACTS. 2002. CD-ROM. MADISON, WI.
Technical Abstract: Agroecosystems currently utilize about one third of the soils of the world and, in these soils, crop management introduces new variables to the biogeochemical cycles governing soil development. N fixation related to human activities now accounts for about half of the global N budget and has greatly enhanced the role of the N cycle in soil biogeochemistry. Microbial oxidation of ammoniacal N in soils generates acidity far greater than does acid rain, leading to base cation leaching, loss of CEC, and accelerated mineral weathering, measurable over decades. Soil acidification reflects imbalanced N cycling in soils related to the oxidation status of N inputs, the cation/anion balance of nutrient uptake by crops, the net export of reduced N by crop harvest, and the leaching of nitrate and other anions. When acidity is neutralized by soil constituents, chemical changes in the soil properties -- including saturation of the exchange complex with exchangeable acidity, depletion of base cations through leaching with anions, and the loss of cation exchange sites due to pH-dependent CEC or mineral weathering -- determine the ability of soil to further neutralize acidity.