Characterization of Biochars and Their Application Rates on Soil Moisture Retention in Light Textured Soil of Assam

Abstract

“Biochar” is a relatively new term, yet it is not a new substance. Biochar, product of thermal decomposition or incomplete combustion of biomass or bio-wastes under limited oxygen supply, are fine-grained highly porous charcoal substances that are distinguished from other charcoals in its intended use as soil amendments. The state of Assam produces surplus quantities of biowastes and leaves behind bulk quantity of wastes soon after harvest of the main crop(s) remain unutilized annually and these farm wastes have the potential of further reutilization through production of biochar, which may effectively be used in sustainable production system. Characterization of biochar with respect to physico-chemical properties determines the suitability of biochar to conserve soil moisture, which is again regulated by kind and source of feed stock materials. Keeping these aspects in view, a study on characterization of biochars prepared from four different feed stocks, namely rice straw, rice husk, toria stover, and bamboo leaves was conducted at Assam Agricultural University during 2014-15 and 2015-16 to validate its efficiency to conserve soil moisture for longer time. After determining the physicochemical properties of the four biochars, a set of pot culture experiment in poly house taking toria as test crop was conducted with four biochars. Four hundred gram of soil (preferably light textured) in 500 g capacity of plastic pot replicated thrice was designed statistically (factorial CRD) with four doses of biochars (0, 0.5, 1.0, and 1.5% wt/wt). Initially, a moisture level at field capacity was maintained and periodical volumetric soil moisture content (upto 70 days) was monitored to evaluate their efficiency. Gravimetric soil moisture content decreased significantly with the progress in days of experimentation irrespective of types of biochar used. However, increase in biochar doses increased the soil moisture content significantly over the one where no biochar was applied. Highest efficiency to conserve soil moisture over the days of study period was due to the application of bamboo leaves biochar.