Adsorption Characteristics of Three Types of Soils on Biogas Slurry Ammonium Nitrogen

Abstract

Using farmland to digest biogas slurry is an effective measure to overcome the bottleneck of sewage treatment in livestock and poultry farms. However, there is limited research on the soil adsorption characteristics of biogas slurry ammonium nitrogen (NH4+-N). In addition, the maximum adsorption capacity (Qm) of farm soil is unclear. In this study, three typical farmland tillage layer soils (silty loam, loam, and sandy loam) were used to analyze adsorption characteristics through adsorption kinetics experiments (adsorption for 0.25, 0.5, 1, 2, 4, 6, 12, 18, or 24 h with NH4+-N concentrations of 42.90 mg/L) and thermodynamic experiments (adsorption for 3 days with NH4+-N concentrations of 54.25, 88.66, 105.85, 133.71, 178.80, 273.54, and 542.87 mg/L). The Qm value was fitted by models, and its relationship with soil properties was discussed. The results showed the following: 1) the adsorption of biogas slurry NH4+-N by the three types of soils was a composite kinetic process that comprised two stages of rapid and slow reactions. Rapid adsorption predominantly occurred within 0–1 h, and the adsorption capacity accounted for 35.24%–43.55% of the total adsorption. The ExpAssoc equation produced a good fit for the adsorption kinetic behavior in the three soil types. 2) The equilibrium adsorption could be described by the Langmuir equation, the Freundlich equation, the PlPlatt model, and the Langevin model isotherm, among which the Langevin model had the best fit, with a coefficient of determination R2 close to 1. The theoretical saturated Qm fitting results of NH4+-N were 1038.41–1372.44 mg/kg in silty loam, 840.85–1157.60 mg/kg in loam, and 412.33–481.85 mg/kg in sandy loam. The optimal values were 1108.55, 874.86, and 448.35 mg/kg for silty loam, loam, and sandy loam, respectively. 3) The Qm value was significantly positively correlated with soil organic matter, total nitrogen, available phosphorus, available potassium, cation exchange capacity, and particle content of 0.02–0.002 mm (p < 0.01), but significantly negatively correlated with soil pH (p < 0.05). This study can provide a reference for the safe application of biogas slurry on farmland.

Biogas Slurry Significantly Improved Degraded Farmland Soil Quality and Promoted Capsicum spp. Production

“…It is different from the traditional approaches such as seed soaking, foliar fertilizer, base fertilizer, top dressing fertilizer, hydroponics and animal feed [ 39 , 40 , 41 ]. To ensure the environmental safety of this approach, the soil maximum adsorption on biogas slurry ammonium nitrogen was researched [ 42 ], and the aging characteristics and fate analysis of biogas slurry ammonium nitrogen disposal in soil were also researched by simulation experiments [ 43 ] before this study.…”

A Brief Correspondence on Glyphosate Remediation using Microbes and Mineral Sources

“…Meanwhile, on the two transient charge soils, the effects of phosphate on glyphosate adsorption were more important than on the permanent charge soil. Previous studies revealed significantly enhancement in crop growth and yield due to application of phosphorus in glyphosate contaminated soils Wang et al [15]. As phosphate and glyphosate were applied to the soils in various orders, the adsorption concentrations of glyphosate…”

“…on the soils varied, as follows: GPS-soil > GPS-P-soil = GPS-soil-P > P-soil-GPS, implying that glyphosate, phosphate, and the soils had a complex relationship Wang et al [15]. Using these products raises the plant's biomass while reducing the harmful effects of toxins in the environment.…”

An Analysis of Miscible Displacement and Numerical Modelling of Glyphosate Transport in Three Different Agricultural Soils

“…As a small molecule with three polar functional groups (carboxyl, amino, and phosphonate), glyphosate is strongly sorbed by soil minerals after application [7,9,23,[28][29][30][31] and has a half-life of 3-174 days in soil minerals and 5-91 days in water [32]. Even though the carboxylic group can also contribute to glyphosate sorption in soil, it usually occurs through the phosphonic acid group (organic compounds that contain C-PO(OH) 2 or C-PO(OR) 2 ) [3,7,28,33,34]. Considering soil glyphosate contact time variations and soil phosphate accumulation, three different glyphosate applications were applied.…”