Ms. Coyne et al., GROSS NITROGEN TRANSFORMATION RATES IN SOIL AT A SURFACE COAL-MINE SITE RECLAIMED FOR PRIME FARMLAND USE, Soil biology & biochemistry, 30(8-9), 1998, pp. 1099-1106
Organic wastes were used to increase N fertility at a surface mine rec
lamation site, with the ultimate goal to stimulate microbial activity
and improve the reclaimed soil's chemical and physical properties. Gro
ss N transformation rates are indicators of microbial activity but are
undocumented in such reconstructed ecosystems. We measured gross nitr
ification, N mineralization and N immobilization in waste-amended and
unamended soil using N-15 pool dilution techniques. Measurements were
made in June, July and November 1993 at the reclamation site in wester
n Kentucky, and compared to net N transformation rates. The premise th
at organic waste amendment stimulates microbial activity in reclaimed
soils was supported by the data. Gross N mineralization, nitrification
and immobilization rates were as much as 4.5 times greater in waste-a
mended soil than unamended soil. Gross N mineralization and nitrificat
ion rates and gross NH4+ and NO3- immobilization rates were significan
tly greater than net rates in waste-amended and unamended soil. There
was net immobilization of NH4+ and NO3- in waste-amended soil, whereas
there was net N mineralization in unamended soil. This was consistent
with using substrates containing high C-to-N ratios. Reclamation prac
tices created soil environments in which gross N transformation rates
were of the same magnitude as those measured for less disturbed soil e
cosystems. (C) 1998 Elsevier Science Ltd. All rights reserved.