Sugarcane biochar as an amendment for greenhouse growing media for the production of cucurbit seedlings

Authors: Webber Iii, Charles; White, Paul; Spaunhorst, Douglas; Lima, Isabel; Petrie, Eric

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2017
Publication Date: 1/15/2018
Citation: Webber III C.L., White Jr, P.M., Spaunhorst, D.J., Lima, I.M., Petrie, E.C. 2018. Sugarcane biochar as an amendment for greenhouse growing media for the production of cucurbit seedlings. Journal of Agricultural Science. 10(2):104-115. https://doi.org/10.5539/jas.v10n2p104.
DOI: https://doi.org/10.5539/jas.v10n2p104

Interpretive Summary: It is very common for Louisiana sugarcane mills to burn a portion of the sugarcane bagasse to produce steam power to run equipment within the mill and/or as a boiler fuel for the clarification, evaporation, and crystallization processes. Even after Louisiana sugar mills use 80 to 90% of the bagasse for fuel production it results in 350,000 to 700,000 mt of bagasse accumulation each year. The conversion of the excess bagasse into biochar is an excellent option with numerous uses. Biochar is the incomplete combustion with limited oxygen of organic material (pyrolysis). Research was conducted to determine the impact of sugarcane biochar as an amendment to soilless planting media for the production of vegetable seedlings. Two biochars were combined by volume with a commercial certified organic soilless growing media into 5 combinations (0%:100%, 25%:75%, 50%:50%, 75%:25%, and 100%:0%, biochars and growing media, respectively). Squash (Cucurbita pepo L.) var. ‘Enterprise’ or cantaloupe (Cucumis melo L.) var. ‘Magnum Hybrid Melon’ were planted in each of the 5 different planting mixtures. The higher heating value (HHV), lower heating value (LHV), and fixed carbon (FitC) were greater for the standard bagasse biochar (SBB), therefore, making it more valuable as a potential fuel source than the pneumatic bagasse biochar (PBB). The physical analysis of the soilless media combinations were excellent, producing low bulk densities (0.11 to 0.14 g/cm3) and high water holding capacities (80 – 87%). As an amendment to the soilless greenhouse growing media, the biochars (SBB and PBB) functioned very well especially at the 25 and 50% levels across both plant species. The squash seedling did respond better at the 75% level than the cantaloupe seedlings, which reflect differences in nutrient requirements. This research did not include weekly supplemental applications of fertilizer, which in future research may compensated for any differences in nutrient requirements. The 100% biochar growing media are not recommended because both plant species often had a decrease in organic matter. Future research should investigate the impact of supplemental fertilizer applications, additional plant species, and different biochar sources on seedling production.

Technical Abstract: Louisiana sugarcane farmers in 2016 harvested 11.7 million mt millable sugarcane from 163,000 ha, producing 1.47 million mg of raw sugar and an estimated 3.5 million mt of bagasse. Even though Louisiana sugar mills use 80 to 90% of the bagasse for fuel production, another 350,000 to 700,000 mt of bagasse accumulates each year. The conversion of the excess bagasse into biochar is an excellent option with numerous uses. Research was conducted to determine the impact of sugarcane biochar as an amendment to soilless planting media for the production of vegetable seedlings. Two biochars were combined by volume with a commercial certified organic soilless growing media into 5 combinations (0%:100%, 25%:75%, 50%:50%, 75%:25%, and 100%:0%, biochars and growing media, respectively). Squash (Cucurbita pepo L.) var. ‘Enterprise’ or cantaloupe (Cucumis melo L.) var. ‘Magnum Hybrid Melon’ were planted in each of the 5 different planting mixtures. The higher heating value (HHV), lower heating value (LHV), and fixed carbon (FitC) were greater for the standard bagasse biochar (SBB), therefore, making it more valuable as a potential fuel source than the pneumatic bagasse biochar (PBB). The physical analysis of the soilless media combinations were excellent, producing low bulk densities (0.11 to 0.14 g/cm3) and high water holding capacities (80 – 87%). As an amendment to the soilless greenhouse growing media, the biochars (SBB and PBB) functioned very well especially at the 25 and 50% levels across both plant species. The squash seedling did respond better at the 75% level than the cantaloupe seedlings, which reflect differences in nutrient requirements. This research did not include weekly supplemental applications of fertilizer, which in future research may compensated for any differences in nutrient requirements. The 100% biochar growing media are not recommended because both plant species often had a decrease in organic matter. Future research should investigate the impact of supplemental fertilizer applications, additional plant species, and different biochar sources on seedling production.chemical interaction between plants, which is referred to as allelopathy, may result in the inhibition of plant growth and development.