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

Inglés. 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.

Español; castellano. Objective: To estimate the ammonia volatilization rate, using a texture gradient with increasing doses of ammonium in alkaline soils. Design/Methodology/Approach: The experiment took place in the Análisis Químico de Suelos lab of the Soil Department of the Universidad Autónoma Chapingo. The incubations consisted of 25 g of soil from the former Texcoco lake, with 12.5% clay. The soil was air-dried and sieved with a no. 10 mesh. The soil was mixed with three different concentrations (17.5%, 22.5%, and 32.5%) of bentonite, in order to increase clay content. The mixtures were placed in plastic containers with airtight seals. Twelve-point five mL of an ammonium sulfate solution (with 150, 300, 450, 600, and 750 mg of nitrogen kg soil-1) was added. The ammonia was recovered in a container with a boric acid solution. Volumetry was used to quantify ammonium. A completely randomized design with two factors (clay content and ammonium dose) was used. Data were analyzed with a regression analysis, analysis of variance, and Tukey Multiple Comparison Test, using the SAS OnDemand for Academics software. Results: The ammonia volatilization has a linear trend, with the concentration of the applied nitrogen. The volatilization rate ranged from 0.02 to 0.03 mg of ammonium per milligram of the nitrogen applied per kg soil-1. Significant statistical differences were recorded between the effect of the N dose and the clay content on the ammonia volatilization rate. Study Limitations/Implications: Clay content in the soil and ammonia volatilization rate can be used as an indicator to estimate ammonia losses and the ammonia adsorption capacity of the soil. Findings/Conclusions: Ammonia volatilization is independent from clay content and takes place immediately after its application. It has a linear trend regarding the ammonia dose applied. Ammonia volatilization rate decreases (asymptotic trend) as the clay content increases in the soil.