Effects of biochar application on soil potassium dynamics and crop uptake

Abstract

Biochar has been suggested as a possible means for enhancing soil fertility, including soil potassium (K). However, understanding of the effects of biochar on soil K dynamics remains limited. In this study, a pot trial was conducted to investigate the influence of biochar application (0, 5, 10, and 25 g kg−1 soil) on soil K dynamics and crop K uptake under a winter wheat–maize rotation in two types of soil (an Alfisol, which contained a high initial available K and an Entisol, which contained a high abundance of 2 : 1 K‐bearing minerals). Changes in soil K in various forms following biochar application and cropping were determined, and their contributions to plant K uptake were evaluated. Soil microbial activity, especially the development of K‐dissolving bacteria (KDB), was evaluated to obtain insights into its effects on the weathering of K‐bearing minerals in the soils. During the wheat growth period, crop K uptake was more enhanced (13.6–40.5% higher) in the Alfisol than in the Entisol due to the higher availability of water‐soluble and exchangeable K, while K fixation occurred in the Entisol because of the higher content of 2 : 1 K‐bearing minerals. During the maize period, crop K uptake was generally higher in the Entisol soil due to the release of non‐exchangeable K. In addition, biochar application enhanced the growth of KDB in both soils, which was associated with changes in soil pH and water‐soluble K. However, improved mineral K release was observed only in the Entisol. It is concluded that biochar application could be a feasible soil amendment to improve soil K availability, but crop K uptake responses may vary depending on soil types. Soils abundant in 2 : 1 K‐bearing minerals tend to prolong biochar effects on crop K uptake. Biochar application enhanced the growth of KDB, which may facilitate mineral K weathering in soils with abundant K‐bearing minerals.

Biochar Application for Rice Cultivation in Salt-Affected Soils

“…Previous research indicated that biochar increases the amount of exchangeable K because of increasing the soil CEC [35,45]. However, in this study, the amount of exchangeable K was reduced (except for RHB-1), presumably as the biochar increased the uptake of K by the plants [43,46].…”

“…A number of studies have indicated that mixing biochar with soil can effectively improve the soil's physical and chemical properties [30][31][32][33], with biochar also improving the drainage, aeration, and water retention in clay [34], sandy [35,36], hard and compact [17], acidic [28,37], alkaline [38,39], and saline soils [4,[40][41][42]. Biochar can increase the nutrient uptake ability of plant roots [43][44][45][46].…”

Biochars produced from coconut palm biomass residues can aid regenerative agriculture by improving soil properties and plant yield in humid tropics

“…Similar higher SOM values were reported by Sukartono et al (2011) when coconut shell biochar was added with manure to soil. Increased potassium availability in soil is another common effect of biochar reported by many others (Wang et al 2018).…”

“…Microbiome studies from three different European sites (UK, France and Italy) after application of same biochar indicated a shift towards copiotrophic ecology and increased mobility of ammonium and phosphates and, therefore, an increased availability of these two nutrients to crops (Jenkins et al 2016). Biochar application not only increased the potassium availability in soils directly, but also enhanced the growth of potassium solubilizing bacteria which could then solubilize K-containing minerals in soils with high K contents (Wang et al 2018).…”

Potential short-term negative versus positive effects of olive mill-derived biochar on nutrient availability in a calcareous loamy sandy soil

“…It has been reported that a high quantity of K in BCs could enhance the bioavailable pool of K in the soil [50]. Application of BCs might also improve soil mineral K release by enhancing the activity of K-dissolving bacteria and facilitating K uptake by crops [51]. Syuhada et al [52] found that the K content in corn tissue was significantly higher but its tissue content of N, Ca, and Mg was lower in BC-amended plants than that of the control.…”