Optimization of increasing biochar doses with soil–plant–microbial functioning and nutrient uptake of maize

Biochar is an industrial product made from organic wastes thought pyrolysis process and its application to soil–plant systems is known to result several benefits. Care should be however needed to select the appropriate doses, as a function of soils and environmental conditions. The aim of the study was to examine the effect of increasing (0.5-, 1-, 2.5-, 5- and 10 m m%) biochar doses on some agrochemical and biological parameters of sandy soil, in an ecological farming system where there are particularly few opportunities to retain soil nutrients, enhancing biological activity. Wood-derived biochar (pyrolyzed at 600 °C) was mixed with soil. The nutrient content of the test plants was determined photometrically and by atomic adsorption after selenium–sulfuric​ acid digestion. Soil biological activity was determined by fluorescein diacetate enzyme (FDA) activity, while the microbial number was determined by the Most Probable Number (MPN) method. Our hypothesis was that appropriate biochar doses needed for improvement of general soil quality parameters, through the better soil-biological activities. Meanwhile the nutrient uptake of plants was measured and the biomass production of maize, the microbial abundance of key-important microorganisms and enzyme activities of fluorescein diacetate (FDA) was also assessed. Biochar applications were significantly increased biomass and yield of maize compare to the untreated control. Dose limit application of positive effect was also find in Arenosols. The increasing biochar doses might increase enzyme activities and can improve several microbial groups biomass which suggests a selection pressure of biochar to microbial population in soil and resulted in significantly higher root mass. Overall, the application of biochar (at a dose of 1%) was found to be effective on weakly humus (calcareous) sandy soils in terms of yield.