ABSTRACT Reducing greenhouse gas emissions and increasing agronomic productivity by sustaining soil organic matter and refining soil fertility have become the main concerns for agricultural scientists. There is a new approach to decrease greenhouse gas emissions, soil C sinks, and improve soil quality using biochar. Soil acidification is improved by applying lime or other acid-neutralizing materials. Additionally, Ca and Mg can increase by applying lime. The availability of Ca, Mg, and K in the soil is significantly affected by the application rate of biochar spread separately or combined with chemical fertilizers. Soil nutrients and maize (Zea mays L.) yield are highly influenced by the use of lime and biochar. Biochar can improve the ecosystem by reducing soil CO2 emissions from agricultural practices. The inconsistent results and clarifications from various studies highlight the importance of relating the impact of different biochar rates on CO2 emissions and maize yield. This review summarizes the properties of biochar, provides the scientific reference for its application to achieve high and good quality maize and reduce CO2 emissions.

ABSTRACT: Heavy metal pollution of the soil environment has become a major source of concern and continues to pose serious health problems to both humans and ecological systems worldwide. Phytoremediation is a biological treatment whereby plants are used to remove pollutant from the environment. An experiment was conducted to evaluate the potential of Melastoma malabathricum as a phytoremediator to absorb heavy metals from soil contaminated with sewage sludge. Melastoma malabathricum seedlings were planted on six different growth media: T0 - Control (100 % soil), T1 (80 % soil + 20 % sewage sludge), T2 (60 % soil + 40 % sewage sludge), T3 (40 % soil + 60 % sewage sludge), T4 (20 % soil + 80 % sewage sludge) and T5 (100 % sludge). There were differences found in both growth parameters and plant biomass. The highest growth performance such as plant height and number of leaves was found in T3. Iron was highly accumulated in the roots, Cu in the stems in T3, while Pb was accumulated in leaves in T5. The results showed the lowest Translocation Factor (TF) and highest Bioconcentration Factor (BCF) values in relation to the following elements: Cu, Fe, Mn, Pb and Zn. Melastoma malabathricum roots are able to uptake and translocate the elements into the plant's shoots. Therefore, it can be considered a good accumulator plant due to its capability of concentrating contaminants in aerial tissue. Melastoma malabathricum were thus found to be suitable for absorbing heavy metals in contaminated soils, and this species can also be considered an effective phtyoremediator of contaminated soil and mitigator of soil pollution.