Noel Manirakiza

Calcareous and sandy soils generally have soil fertility problems, and these problems have been revealed to be improved by applying compost and biochar produced from the distinct biomass. However, comparing the effects of compost and biochar originating from the same biomass on soil fertility are still not clearly explained. The comparing impacts of compost and biochar both made from the same biomass on soil fertility status in a wind erosion afflicted calcareous and alkaline sandy clay loam (SCL) soil, were explored using a pot experiment. Compost and biochar were produced from a pioneering Oleaster (Oleaster Angustifolia L.) tree through the windrow composting method and pyrolysis process at 450 °C, respectively. The SCL soil used was treated with compost and biochar at rates of 0%, 1%, 2%, and 4% by weight and thereafter incubated for 2 months. The trial layout was in line with a completely randomized plot design with four replicates. Pursuant to the experimental results, the addition of compost and biochar considerably enriched soil fertility by enhancing soil biochemical properties of SCL soil. SCL soil treated with compost yielded the highest available phosphorous (AP), organic carbon (OC), total nitrogen (TN), NH₄ ⁺-N, NO₃-N, active carbon (AC), potential mineralizable nitrogen (PMN), soil microbial respiration (SMR), electrical conductivity (EC), CaCO_3, extractable cations (Mg, K, Ca, and Na), cation exchange capacity (CEC), and available micronutrients (Mn, Fe, and Zn), which were significantly higher (P < .001) than the SCL soil amended with biochar, suggesting the recalcitrance of biochar on microbial activities. Furthermore, available micronutrients (Mn, Fe, and Zn) were significantly decreased in SCL soil amended with biochar compared with compost amended SCL soil, indicating the sorption potential of biochar. It was concluded that applying Oleaster tree compost is more effective than biochar in improving soil fertility. However, the effects of biochar on carbon sequestration and the findings of this study need to be proven under field demonstration for more conclusive results prior to recommending farmers to apply either compost or biochar in soil management practices.

Crop performance in calcareous and alkaline soils is often limited by low nutrient availability and uptake following poor soil fertility. The positive agronomic effects of compost and biochar originated from a distinct biomass on soil fertility, nutrients uptake and crop growth were previously reported in a wide range of different soil types. However, a little is surfaced about the contrasting effects of compost and biochar produced from the same biomass on soil fertility, nutrients uptake and crop growth in the calcareous and alkaline soils. A greenhouse experiment was carried out with an eye of contrasting the effects of compost and biochar made from the same pioneering Oleaster (Oleaster angustifolia L.) tree on improving these limiting factors for crop performance found in the calcareous and alkaline soils. The calcareous and alkaline soil used was either untreated (control) or treated with compost and biochar at a rate of 1, 2 and 4% w/w. The experimental layout was laid in line with completely randomized plot design in quadruplicate. Across the experiment, compost significantly (p < 0.05) exhibited the striking impacts on soil fertility, nutrients uptake and maize growth than biochar treatments. To put the effects of compost and biochar into perspectives, compost exhibited the highest rally in soil fertility through enriching pH, electrical conductivity (EC), extractable cations (Ca, Mg, K and Na), available micronutrients (Fe, Mn, Cu and Zn), available phosphorous (P), NO₃-N, NH₄-N, total nitrogen (TN) and organic matter (OM), nutrients uptake via enhancing the uptake of total nitrogen, P, K, Ca, Mg, Fe, Zn, Mn and Cu, as well as maize growth via improving leaf chlorophyll content (LCC), plant height (PH), stem girth (SG), aboveground fresh biomass (APFB), aboveground plant dry biomass (APDB), fresh root biomass (FRB) and dry root biomass (DRB) than biochar amendments due to most likely sorption effects of biochar and its recalcitrance to microbial activities. Overall, soil fertility and crop performance increased in the order control < biochar < compost. Based on the findings of this study, it is concluded that compost can be suggested under such type of soils for improving soil fertility and crop performance at the expenses of biochar applications, nonetheless, field demonstration is highly essential for more conclusive results prior to recommending either compost or biochar in soil management practices.

Cevdet ŞEKER & Noel MANIRAKIZA - EFFECTIVENESS OF COMPOST AND BIOCHAR IN IMPROVING WATER RETENTION CHARACTERISTICS AND AGGREGATION OF A SANDY CLAY LOAM SOIL UNDER WIND EROSION, Carpathian Journal of Earth and Environmental Sciences, February 2020, Vol. 15, No. 1, p. 5 - 18; DOI:10.26471/cjees/2020/015/103

Due to intensified agricultural mechanization, soils are exposed to increased levels of degradation. Soil compaction is the beginning of this degradation which further proceeds to decrease organic matter content of soils. Among the various methods applied to solve these problems, the addition of organic matter to the soil has an important place. Thus, agricultural land application of organic wastes, such as biochar and compost, could alter the soil properties to offset the degradation effects. The aim of this research was to determine the effect of compost and biochar application on the soil compaction and its quality score. Biochar and compost of the Elaeagnus tree pruning residues were applied in a field at a similar rate of 0%, 2%, and 4%. Results indicated that the soil penetration resistance (PR) statistically experienced a downward trend compared to the control when applied with compost and biochar. The application of 2–4% biochar and compost lowered soil PR by exactly 8.80%, 9.33%, 18.22%, and 28.89%, respectively, throughout the period of 7 months. Furthermore, the infusion of biochar and compost into the soil significantly increased the soil compaction quality score compared to the control, and the least value of PR was observed for the compost-treated soil at the application rate of 4%. Compost and biochar applications were effective to improve the physical quality of a sandy clay loam soil, making it more suitable for plant development. On the other hand, the effect of compost treatments was more impact than biochar treatments.