Adsorption and leaching characteristics of ammonium and nitrate from paddy soil as affected by biochar amendment

Abstract

Biochar plays a key role in nitrogen cycling, potentially affecting nitrogen adsorption and leaching when applied to soils. The laboratory experiments were conducted to investigate the adsorption characteristics of rice straw biochar (RSBC) to ammonium (NH<sub>4</sub><sup>+</sup>) and nitrate (NO<sub>3</sub><sup>–</sup>) and the influence of RSBC on leaching characteristics of NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> at different soil depths using multi-layered soil columns. The results showed that the adsorption characteristics were significantly fitted with Freundlich and Langmuir adsorption isothermal curve models. The Freundlich isotherm model indicated that RSBC has relatively higher adsorption capacity and adsorption intensity to NH<sub>4</sub><sup>+</sup> than NO<sub>3</sub><sup>–</sup>. Moreover, the Langmuir isotherm model showed that the maximum adsorption capacity of RSBC to NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>–</sup> were 31.25 and 10.00 mg/g, respectively. The leaching experiments showed that the contents of NH<sub>4</sub><sup>+</sup> in the leachates from the soil columns showed significant differences at different depths depending on the application amount of RSBC. Compared with CK (0% RSBC amendment), the overall cumulative losses of NH<sub>4</sub><sup>+</sup> via leaching were decreased by 23.3, 35.1 and 13.7% after adding 2, 4 and 6% RSBC, respectively. Correspondingly, the contents of residual soil NH<sub>4</sub><sup>+</sup> in the soil column were increased significantly with the RSBC amendment at different depths. However, the losses of NO<sub>3</sub><sup>–</sup> via leaching from the soil columns could not be retarded obviously by RSBC. Therefore, the application of an appropriate biochar rate is beneficial to retard the losses of soil NH<sub>4</sub><sup>+</sup> from paddy soil.

The Role of Biochar and Perlite in Improving some Chemical Properties of Clay Loam Soil and Sandy Loam Soil

“…With values of 6.53 and 5.83 mg L -1 , compared with the comparison treatment of 7.46 mg L -1 , with decreases of 12 and 21%, the values of nitrates washed from the soil decreased significantly with the use of the two percentages of perlite, with values of 6.76 and 6.30 mg L -1 , with decreases of 9 and 15%. The use of two ratios of biochar led to a reduction in the amount of nitrate leaching from the soils, due to the adsorption of nitrates on the surfaces of the biochar, and because the charge of biochar is of the pH-dependent type, and this is consistent with what was shown by [22], and the use of the two ratios of perlite led to a reduction in nitrate values The soil washed from the soil in an amount less than the two percentages of biochar, due to the fixation of ammonium inside the perlite mineral and its slow release and hindering the chemical conversion to nitrates and thus reducing the amount of washed nitrates, and this is consistent with what [23] found. Table 7.…”

How do biochar size fractions and organic fertilizers interactively influence nitrous oxide emission from a tropical vertisol?

“…The chemical nature of BC (particularly high cation exchnage capacity [CEC]), contributes to its unique property of adsorbing NH 4 ‐N and other plant nutrients (Ahmad et al., 2021). BC has a number of polar or nonpolar substances, which have a strong affinity to bind different inorganic ions including phosphate, NO 3 − , and NH 4 + (Lv et al., 2021). The mechanisms attributed to adsorption of NH 4 + include negatively charged surface (X. F. Tan et al., 2021), occurrence of acidic functional groups to form amides and amines (Bamdad et al., 2021); binding to cationic species sites on the surface of BC (J. Xie et al., 2021); and π‐π electron donor–acceptor interactions (Zhao & Zhou, 2019).…”

Effects of Amendments on Physicochemical Properties and Respiration Rate of Soil from the Arid Region of Northwest China

“…In recent years, soil amendments have been reported to be a highly effective approach for increasing the fertility and microbial activity of the soil, particularly in low-fertile soil of arid region [7][8][9]. Biochar (BC), a carbon-rich amendment, has received wide attention in agriculture research areas, it can sequester carbon and obtund climate change, impeding soil nutrients' loss caused by leaching and improving soil quality [10,11]. Biochar Sustainability 2021, 13, 5332. https://doi.org/10.3390/su13105332 https://www.mdpi.com/journal/sustainability amendment can substantially increase organic matter, nutrients, microbial activity and decrease bulk density and soil aggregation [12,13].…”