|Randolph, P - North Carolina Agricultural And Technical State University|
|Bansode, R - North Carolina Agricultural And Technical State University|
|Hassan, O - North Carolina Agricultural And Technical State University|
|Rehrah, D - Qatar University|
|Ravella, R - North Carolina Agricultural And Technical State University|
|Reddy, M.r. - North Carolina Agricultural And Technical State University|
|Watts, Donald - Don|
|Novak, Jeffrey - Jeff|
|Ahmedna, M - Qatar University|
Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2017
Publication Date: 2/6/2017
Citation: Randolph, P., Bansode, R., Hassan, O., Rehrah, D., Ravella, R., Reddy, M., Watts, D.W., Novak, J.M., Ahmedna, M. 2017. Effects of biochars produced from solid organic municipal waste on soil quality parameters. Journal of Environmental Management. 192:271-280.
Interpretive Summary: Food, agricultural, and landscaping by-products and other solid organic waste products(newspaper, packaging, etc.) are common municipal solid waste streams that are traditionally placed in landfills, which is an unsustainable and environmentally unsound practice. Globally, agricultural soils have significant deficiencies in a host of essential trace elements and macro-nutrients; and these deficiencies can affect the nutritional quality of edible crops with direct consequences for human health. On the other hand, agricultural soil contains hundreds of times more carbon than totals emitted by mans activities, thus accounting for the largest carbon pool on earth. However, human activities have degraded soil and reduced the pool of soil carbon, thereby affecting agricultural productivity with potential negative long-term consequences for the earth to sustain a growing population. Fortunately, these challenges can be mitigated by producing biochars from the pyrolysis of mixed organic solid waste materials. We completed a study to analyze biochars made from several solid organic municipal waste products on soil quality characteristics. We found that the biochars improved the soil pH, water retention, and nutrient concentrations indicating that these waste materials do not have to be land-filled, but could serve as amendments to improve soil quality.
Technical Abstract: New, value-added uses for solid organic waste are needed for environmental and economic sustainability. Fortunately, value-added biochars can be produced from mixed organic solid waste, thereby addressing solid waste management issues, and enabling long-term carbon sequestration. We hypothesize that soil deficiencies can be remedied by the application of municipal waste-based biochars. Select municipal organic wastes (newspaper, cardboard, woodchips and landscaping residues) individually or in a 25% blend of all four waste streams were used as feedstocks of biochars. Three sets of pyrolysis temperatures (350, 500, and 750°Celsius) and 3 sets of pyrolysis residence time (2, 4 and 6 hours) were used for biochar preparation. The biochar yield was in the range of 21 - 62% across all feedstocks and pyrolysis conditions. We observed variations in key biochar properties such as pH, electrical conductivity, bulk density and surface area (which are known to positively improve water and nutrient-holding capacity in biochar-amended soil) depending on the feedstocks and production conditions. The soil pH increased with increases in biochar application rates and increased pyrolysis temperatures. Biochar improved soil electrical conductivity, aggregate stability, water retention and micronutrient contents. Similarly, leachate from the soil amended with biochar also showed increased pH and electrical conductivity. Some elements such as calcium and magnesium, decreased, while nitrate increased in the leachate’s of soils that were incubated with biochars. Cumulatively, biochar applications produced significant improvements to soil water retention, pH stabilization, and increased electrical conductivity of soil for better aggregation. These findings indicate that solid organic municipal wastes hold promising potential as feedstocks for manufacturing value-added biochars with varied physiochemical characteristics, allowing them to not only serve the needs for solid waste management and greenhouse gas mitigation, but also as a resource for improving the quality of depleted soils.