Kinetics of ammonium volatilization in the form of ammonia in soils through a textural gradient

Abstract

Objective: Estimate the ammonium volatilization rate through a textural gradient

Design/methodology/approach: The experiment was carried out at the Universidad Autónoma Chapingo in the Soil Chemical Analysis laboratory of the Soil Department. Incubations of 25 g of soil from the former lake of Texcoco with 12.5% clay were carried out, which was air-dried and sieved to 10 mesh. It was mixed with 3 concentrations of bentonite (17.5%, 22.5% and 32.5%). The mixture was deposited in a hermetically sealed plastic container, to which 12.5 ml of an ammonium sulfate solution was added at the following nitrogen concentrations: 150, 300, 450, 600, 750 mgKg S^-1. The ammonia was captured in a container with a boric acid solution. Ammonia quantification was performed with titration. Nitrogen losses show a linear trend between the applied nitrogen concentration and the amount of recovered ammonia.

Results: The volatilization rate ranged from 0.02 to 0.03 mg of ammonia per milligram of nitrogen applied per kgS^-1. It was found that there are highly significant statistical differences regarding the clay content on the ammonium volatilization rate.

Limitations on study/implications: The ammonium volatilization rate can be used as an indicator for the estimation of ammonium losses trough ammonia.

Findings/conclusions: Ammonia volatilization losses occur immediately after application. Nitrogen losses show a linear trend between the applied nitrogen concentration and the amount of recovered ammonia. The volatilization rate presents an asymptotic trend with the increase in clay content.