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Decomposition of Biotechnology By‐Products in Soils
Author(s) -
Martinez C. E.,
Tabatabai M. A.
Publication year - 1997
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1997.00472425002600030006x
Subject(s) - soil water , amendment , mineralization (soil science) , chemistry , decomposition , organic matter , environmental chemistry , soil science , environmental science , organic chemistry , political science , law
Recent processes in the biotechnology industry result in many byproducts that have potential values as soil amendment. Laboratory experiments were conducted to evaluate organic C mineralization of various biotechnology by‐products and their effects on glycosidases in soils. A soil sample was mixed with biotechnology by‐product material to approximate a field application of 9 g organic C kg −1 soil (0.9% or 50 Mg C ha −1 ), and incubated under aerobic conditions at room temperature (20 ± 2°C) for 30 d. The CO 2 evolved was trapped in standard KOH solution by continuously passing CO 2 ‐free air over the soil. Results showed that, in general, the amount of CO 2 ‐C initially released increased rapidly, but differed among the biotechnology by‐product materials. Expressed as percentages of total organic C added, the amounts of CO 2 ‐C evolved ranged from 0.5% with DEE in Weller soil (fine, montmorillonitic, mesic Aquic Hapludalfs) to 73.6% with FSL in Grundy soil (fine, montmorillonitic, mesic Aquic Argiudolls). Most of the CO 2 evolution data conformed to a first‐order kinetic equation. The potentially mineralizable organic C values (C o ) of the biotechnology by‐product‐treated soils ranged from 1.2 to 33.4 g C kg −1 soil. The half‐lives of the C remaining in soils ranged from 14 to 239 d. The rate constants of the first and second phases of decomposition ( k 1 , and k 2 ) were significantly correlated ( r > 0.90***) with the percentages of CO 2 ‐C evolved in 30 d. The k 1 values fitted an equation similar to the Michaelis‐Menten kinetic equation with respect to total sugars, and the k 2 values were significantly correlated with the high molecular‐weight organic C fractions (organic C ‐ total sugars, r = 0.42**) in the biotechnology by‐products. The biotechnology by‐products contained considerable amounts of cellulase, α‐ and β‐glucosidase, and α‐ and β‐galactosidase activities, contributing to decomposition of organic C in the biotechnology by‐products in soils. Several biotechnology by‐products are useful as soil amendments.