Application of Coffee Ground and Woodchip Biochars as a Soil Amendment for Crop Cultivation

Abstract

Application of Coffee Ground and Woodchip Biochars as a Soil Amendment for Crop Cultivation

Crop wastes and biomass from feedstocks cause significant environmental problems and have negative consequences for humans. If used correctly, biomass residues contain a great deal of energy potential. Most crop wastes, particularly agricultural leftovers, may be transformed to biochar utilizing thermodynamic technologies such as a muffle furnace. The derivation of wastes for useful materials as well as biochars is the key tool to helps in controlling and handling of biomass in the area or sites. Generally, the operator at temperature at 400 ˚C to make biochar with fixed carbon contents ranging 52.45, and 78% respectively. Biochar conductions into soil amendment for improving the physicochemical and biological properties of the soil owing to biochar's high organic carbon content, which increases the amount of nutrients in the soil and activates it as a carbon sequestration agent over time. Biochar, in and of itself, is a nutrient source that may affect soil nutrient stores and bioavailability, as well as the microbial community and the environment. The majority of nitrogen (N) in the agricultural system is absorbed by plants through ammonium (NH4+) or nitrate (NO3‒). Ammonium is released through mineralization process while NO3‒ is a product of nitrification process through NH4+ oxidation. This method has two parts: (i) NH4+ was transformed to nitrate (NO2-) through ammonia-oxidizing bacteria; (ii) NO2 was changed to NO3 via nitrite-oxidizing bacteria. Increased nitrate (NO3) leakage into waterbodies has made nitrogen losses from fertilizer techniques a significant environmental problem across the world in recent years. Nutrient leaching is a concern not just for soil function and plant uptake, but it may also lead to nutrient enrichment and eutrophication in water, both of which are harmful to human health. Human absorption of excess NO3, for example, can cause newborn methemoglobinemia and a variety of malignancies. As a result, eliminating excess inorganic N from soil solutions or waterbodies has major ecological and societal consequences. Much further, various physical, chemical, and biological techniques for regulating inorganic nitrogen in the aqueous phase have been presented, with adsorption utilizing biochar being one of the most popular. The primary objective of this research was to demonstrate the application of biochar and the effect of long-term exposure to coffee grounds and wood chips biochar on Pak Choi cultivation in sandy loam soil: (1) to investigate the effects of biochar on adsorption (Park M. H. et al., 2019) and desorption of macronutrients (i.e., N) in the aqueous phase; (2) to study the effect of biochar (biochar-soil mixture) on inorganic nitrogen (N) and plant growth production under plot conditions in the soil phase. (3) to investigate the properties of biochars under long-term exposure or aging in soil environment and (4) to verify biochar effects on crop growth and yield in plot experiment. It is also necessary to study the effect of biochar production on NH4+-N and NO3--N adsorption and desorption to quantitatively explain the relative effect of aging biochar (NH4+-N and NO3--N) on Pak Choi Yields. Furthermore, the kinetics model experiment was important in determining the releasing properties after equilibrium, as well as the long-term exposure characteristics of nitrogen were obtained. The initial pH of soil (6.55) is in a proper range for plant nutrient uptake whereas the initial pH of coffee grounds biochar (CBC), and woodchips biochar (WBC) varied from moderately alkaline to alkaline. CBC and WBC produced similar yields which varied from about 32.49% to 33.93% by weigh, respectively. The percentage of ash content in CBC (2.9%) was lower than ash content in WBC (11.6%), however, its ash contents were in the average ranges. C/N ratio, ranging from about 52 for CBC and 312 for WCB, respectively. CBC and WBC had O/C and H/C ratios close to the recommendation thresholds, indicating well-pyrolysed ranges, enrichment of aromatic structures, and prone to degradation. The CEC of biochars were similar and were in the average ranges while CEC of the initial soil was in suitable for soil to hold and exchange cations in the soil solution, however, main elements in CBC, WBC, and the initial soil were exchangeable Ca, K, Mg, and Na, respectively. The similar strong peaks decreased at ~1,350 cm‒1 and ~1,600 cm‒1 of C=C and ‒COOH for both CBC and WBC were due to carbon condensation. BET specific surface area of biochars of CBC and WBC were large, this showed that SEM of WBC has more chance to enhance exposure of inorganic minerals as it increased in the pore structure comparing to CBC. The Langmuir isotherm model suited the ammonium nitrogen (NH4+-N) adsorption to both CBC and WBC biocahrs better than the Freundlich isotherm model, with higher r2 values. In comparison to CBC, WBC emitted more nitrogen from the surface. The pseudo-first order and pseudo-second order kinetic models fit better NH4+-N and NO3--N adsorption, respectively. As a result, we concluded that both biochar products can be used in situations where NH4+-N adsorption is a problem, while CBC can be used in situations where NO3--N desorption is a problem. However, more study on using biochars to reduce NO3--N pollution is required.