Enhancing Cation Exchange Capacity of Weathered Soils Using Biochar: Feedstock, Pyrolysis Conditions and Addition Rate

Abstract

The addition of alkaline and high-cation exchange capacity (CEC) biochars is a suitable strategy to increase the CEC of weathered soils. The aim of this study was to evaluate the effect of biochar from different feedstocks and pyrolysis temperatures on the CEC of two contrasting Oxisols. Biochars produced from chicken manure (CM), eucalyptus sawdust (ES), coffee husk (CH) and sugarcane bagasse (SB),plus a control (without biochar), at 350, 450, and 750 °C were mixed with the soils at 2; 5; 10 and 20% (w/w) and incubated for 9 months. Feedstock, pyrolysis temperature and addition rate of biochar were key factors controlling the alteration of soil CEC. The CH biochar pyrolyzed at 350 °C was the most effective matrix at increasing soil CEC. In a rate-dependent way, ES and SB biochars increased C contents of both soils without improving soil CEC. The efficiency of high-ash biochars in enhancing soil CEC in both Oxisols was limited by the alkalization caused by high rates of CH and CM biochars. The increase in CEC is soil-dependent and modulated by high-ash biochar CEC and application rate, as well as by the original soil CEC.

Coffee industry waste-derived biochar: characterization and agricultural use evaluation according to Brazilian legislation

“…Considering that Brazilian soils are predominantly acidic (Quaggio 2000), biochar alkalinity can act as lime and increase soil pH (Singh et al 2017). However, to define the application of coffee residue biochars, the desired final soil pH and the biochar and soil buffering capacities should be considered, since high application rates might alkalinize the soil (Domingues et al 2020), which causes negative effects on plant nutrition. The use of 0.01 mol•L -1 CaCl 2 as the extractor solution appears to be the most appropriate method for biochar pH determination since it reduces the effects of soluble salts and consequently minimizes the analytical error in pH determination and produces more reliable results.…”

Applying Cassava Stems Biochar Produced from Agronomical Waste to Enhance the Yield and Productivity of Maize in Unfertile Soil

“…The CEC was analysed using ammonium acetate extraction (1.0 N NH 4 OAc pH 7.0) [69]. The CEC measured the ion exchange potential at the biochar surface related to the biochar's age [24,73,80]. The total N was analysed using the Kjeldahl method and distillation apparatus.…”

“…Moreover, many anionic functional groups such as carboxylic at the surface area of biochar [30,43,57,62] made the soil suitable for the positive exchange of nutrients dissolved in the soil solution [10,24,68,80]. As a result, mixing CSB into the soil could increase the CEC of soil.…”

The role of biochar in improving soil properties, water retention and potato yield in a Fluvisol under temperate monsoon climate

“…In general, greater changes in soil properties such as decreases in bulk density, and increases in soil porosity and water retention were reported for biochar produced at higher temperature and applied at greater rates than those produced at lower temperature and applied at lesser rates (e.g. Andrenelli et al, 2016;Domingues et al, 2020;Liu et al, 2016). Similarly, larger changes in the soil properties were reported for the coarse-than fine-textured soils for equivalent biochar application rate (Omondi et al, 2016;Razzaghi et al, 2020).…”

“…It also enhances soil fertility by increasing the cation exchange capacity (CEC) of the original soil, thereby retaining nutrients on its surfaces which are available for crop use later as slow-release nutrients, and by reducing leaching losses of mobile nutrients such as nitrate, ammonium, and phosphate (Domingues et al, 2020;Pandit et al, 2018). The ash present in the biochar is also an important source of nutrients, and regulates the availability of nutrients and CEC (Domingues et al, 2020;Kätterer et al, 2019). Rajkovich et al (2012) reported that the ash contents in biochar varied from 0.35% to 59%, which were enriched with K, Ca, Mg and Na in the magnitudes of 0-560, 3-1210, 0-325 and 0-413 mmol kg −1 , respectively.…”