Effect of Tithonia diversifolia on Compost Pile Heat Built-Up and Physico-Chemical Quality Parameters of Chimato Compost

Abstract

The study objective was to identify blending ratio of T. diversifolia and maize stalks that optimizes compost pile's heat built-up, precursor to compost maturity. In this study, 0%, 20%, 40%, 50%, 60%, 80% and 100% of T. diversifolia biomass were blended with maize stalks, and then composted using chimato composting technology. Temperatures were measured to determine heat built-up. TKN, nitrate-N and C/N ratios were determined using standard methods. Results showed high and more prolonged peak temperatures in compost piles with T. diversifolia content of 0%, 20% and 40% implying occurrence of more prolonged decomposition that generated prolonged heat. Resultant composts contained large amounts of non-compost materials (> 37%) and less dark colour indicating high level of immaturity. High but less prolonged peak temperatures were observed in compost piles with 50% and 60% T. diversifolia suggesting shortened active and rapid microbial activities that generated less heat. Their composts were very dark in colour and yielded least amounts of non-compost materials (< 17%) which indicated high level of maturity. Significantly large quantities of TKN and nitrate-N and low values of C/N ratios were obtained in chimato composts whose compost piles registered high but less prolonged peak temperatures. Optimal blending composition of 50% and 60% of T. diversifolia to maize stalks are judged to have significantly improved moisture content and porosity of feedstock which intensified and shortened active microbial activities leading to generation of optimal heat in chimato compost piles as well as retain optimal TKN, nitrate-N and C/N ratios in resultant composts.

Effect of heat build-up on carbon emissions in chimato compost piles

“…Secondly, prolonged stay in high thermophilic phase is symptomatic to prolonged generation of large amounts of heat (WERL, 2005;Mlangeni, 2013) likely to increase kinetic energy of chemical species in the compost piles. The prolonged stay in the thermophilic phase cause chemical species such as carbon dioxide (CO 2 ), methane (CH 4 ), ammonia (NH 3 ) and nitrogen oxides (NO x ) acquire kinetic energy that significantly increases chemical species' random motions in the compost piles.…”

“…Use of nitrogen rich ingredients such as Tithonia diversifolia biomass is recommended . Temperature progression of chimato compost piles made using 80 and 100% of T. diversifolia was reported to rapidly increase to high thermophilic peak temperature (54.5 and 55°C respectively) before rapidly dropping down to mesophilic phase (35.0°C) (Mlangeni, 2013). Temperature progression of chimato compost piles made using 60 and 50% of T. diversifolia was reported to experience prolonged stay in the high thermophilic phase peak temperature (65.0 and 70.0°C), respectively, symptomatic to well matured compost (Biddlestone and Gray, 1987;Biddlestone and Gray, 1987;Darlington, 2010).…”

“…Well matured and stable composts gradually decompose (Biddlestone and Gray, 1987;Christensen and Peacock, 1998).Compost piles that mature into well matured and stable composts usually meet certain minimum blending composition of nitrogen rich ingredients and carbon rich ingredients (WSU, 2010;. Such requirements make ingredients to be digested very fast by microbes and the compost pile stays in high thermophilic stage for relatively short time (Mlangeni, 2013).…”

“…Too high temperatures deactivate mesophilic microbes whereas a longer duration of high temperatures accelerates losses of methane (CH4), carbon dioxide (CO 2 ) and nitrogen loss as ammonia NH 3 and nitrogen oxide through volatilization (Carr, 1998;CAW, 2012). Heat built-up in compost pile is dependent on quality of ingredients used in constructing the compost piles (Mlangeni, 2013), whereas quantity of CO 2 , methane and other nitrides diverted is dependent on type, stability and quality of composts. High quality ingredients such as T. diversifolia enhances rapid and active microbial activity that break down chemical bonds of compounds and transforms chemical energy (Biddlestone and Gray, 1987;WSU, 2010) contained in the bonds to heat, which raises the temperature of the compost pile (Mlangeni, 2013).…”

“…Heat built-up in compost pile is dependent on quality of ingredients used in constructing the compost piles (Mlangeni, 2013), whereas quantity of CO 2 , methane and other nitrides diverted is dependent on type, stability and quality of composts. High quality ingredients such as T. diversifolia enhances rapid and active microbial activity that break down chemical bonds of compounds and transforms chemical energy (Biddlestone and Gray, 1987;WSU, 2010) contained in the bonds to heat, which raises the temperature of the compost pile (Mlangeni, 2013). Blending maize stalks with T. diversifolia of greater than 40% ensures availability of both carbon and nitrogen in sufficient amounts to enhance optimal active and rapid microbial activities.…”