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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #222980
Title: Physical Properties and Microbial Activity in Forest Residual Substrate

Author
item BOYER, CHERYL - AUBURN UNIVERSITY
item GILLIAM, C - AUBURN UNIVERSITY
item FAIN, G - AUBURN UNIVERSITY
item GALLAGHER, T - AUBURN UNIVERSITY
item Torbert, Henry - Allen
item SIBLEY, J - AUBURN UNIVERSITY

Submitted to: Southern Nursery Association Research Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/6/2008
Publication Date: 8/6/2008
Citation: Boyer, C.R., Gilliam, C.H., Fain, G.B., Gallagher, T.V., Torbert III, H.A., Sibley, J.L. 2008. Physical Properties and Microbial Activity in Forest Residual Substrate. In: Proc. Southern Nurs. Assoc. Res. Conf. August 6-7, 2008, Atlanta, GA. 53:42-45.

Interpretive Summary: Many growers in the horticulture industry have expressed concern that switching from a pine bark-based substrate to one with a significant wood content will increase microbial activity, resulting in nitrogen (N) immobilization. This study evaluated four growth substrates (pine bark, peat moss and two hammer mill screen sizes of clean chip residual or CCR) in a simulated 60-day production cycle. Physical properties of each substrate were different, though pine bark and CCR had more air space and less container capacity than peat moss. Results of the incubation study indicate that CCR has only slightly more microbial activity than pine bark. Peat moss had the least microbial activity. This data shows that while there is a slight but significant difference between pine bark and CCR the disparity is minimal and will likely have nominal effects for fertilizer requirements as growers switch to crop production in CCR.

Technical Abstract: Many growers in the horticulture industry have expressed concern that switching from a pine bark-based substrate to one with a significant wood content will increase microbial activity, resulting in nitrogen (N) immobilization. This study evaluated four growth substrates (pine bark, peat moss and two hammer mill screen sizes of clean chip residual or CCR) in a simulated 60-day production cycle. Physical properties of each substrate were different, though pine bark and CCR had more air space and less container capacity than peat moss. Results of the incubation study indicate that CCR has only slightly more microbial activity than pine bark. Clean chip residual consistently had the greatest amount of microbial respiration among the substrates over the course of the incubation (0-60 days). Pine bark and peat moss were different from each other and less than CCR treatments for microbial respiration. There was no difference in microbial respiration across N rates for peat moss and peat moss had the least microbial activity. This data shows that while there is a slight but significant difference between pine bark and CCR the disparity is minimal and will likely have nominal effects for fertilizer requirements as growers switch to crop production in CCR.