Improving available phosphorus in acidic soil using biochar

Abstract

Understanding of phosphorus (P) retention and release mechanisms provides crucial information for the effective management of phosphorus to enhance crop production and sustain soil. In acidic soil, available phosphorus is fixed by aluminum and iron. To overcome this problem, soils are limed to fix aluminum and iron. But this practice is not economical for small scale farmers and also it is not environmentally friendly. This study was conducted to improve phosphorus availability using biochar produced from coffee husk and corn cob to fix aluminum and iron instead of phosphorus. Acidic soil samples were mixed with biochar applied at the rates of 0, 5, 10 and 15 t ha -1 and incubated in laboratory for 2 months at ambient temperature. The results showed significant effects (p<0.01) on selected soil chemical properties by increasing soil pH and reduced exchangeable acidity, exchangeable aluminum, and exchangeable iron in a way that enhanced the availability of phosphorus. Due to the incorporation of biochar the available P level increased to a level ranging 3.64±0.34 -23.21±0.07 mg/kg after an incubation period of 2 months and it increased by 84.3% available phosphorus when coffee husk biochar produced at 500°C temperature was applied at a rate of 15t/ha. Moreover, further field researches are needed to evaluate the effect of biochar on availability, the fate and uptake of available P in soil.

Ameliorative Effects of Coffee Husk Compost and Lime Amendment on Acidic Soil of Haru, Western Ethiopia

“…This gradually neutralizes soil acidity and hence makes fixed phosphorus available in the soil solution. This result was in agreement with Bayu, et al [42] who reported increased soil available phosphorus with application of coffee husk biochar. Therefore, application of coffee husk compost to acid soil could increase available phosphorus contents of soil through releasing of phosphorus in it and also by increasing soil pH which reduces phosphorus fixation.…”

“…In all the treatments except the control, soil pH progressively increased while the exchangeable acidity decreased with increased rates of coffee husk compost and lime. This corroborates with the findings of Taye et al [41], Kasongo, et al [20,22], Nduka, et al [23] and Bayu, et al [42]. It could be attributed to reduction of Al 3+ ions concentration in soil solution and in exchangeable sites because of lime and manure application [18].…”

“…This agrees with the result reported by Tigist, et al [18], who reported application of vermicompost and lime on acid soil had significantly increased soil total nitrogen and organic carbon. Also, Bayu, et al [42] reported highest mean value of organic carbon and total nitrogen with application of 15 t ha -1 of coffee husk biochar amendment on acid soil.…”

Analysis of biochars produced from the gasification of Pinus patula pellets and chips as soil amendments

“…The C content reached for the PL-BC (97,94 wt%) and the CH-BC (97,06 wt%) meets the values set by the European Biochar Certificate (EBC); where a minimum C content of 50 % allows to use a BC as a soil amendment (EBC 2019). Furthermore, Bayu et al(2017) stated that a high concentration of C in the BC favors the properties of the material to be used as a soil amendment since the C availability in the treated soil increases. Additionally, it is highlighted that during the gasification process, the N is transformed into water-soluble compounds, such as the ammonium nitrate (De la Rosa et al 2016), which benefits the fixation of microbial and vegetable N. This favors the biogeochemical cycle of N and reduces nitrous oxide emissions (N 2 O) through nitrification and denitrification (Wang et al 2019).…”

“…Similar results were reported by Díez and Pérez (2019) when characterized BCs derived from the gasification of different forest species (wood chips). Therefore, according to the properties of PL-BC and CH-BC, these BCs can be used as soil amendments, mainly acid ones (Bayu et al 2017). Concerning the CEC, there are alternatives to improve this property, among which it is highlighted the mixing with compost (Nsamba et al 2015).…”