الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 166 |  |  |
| | | from | 166 | | |
Abstract
Changes in precipitation patterns in recent years resulted in flooding or ponding of
many farm lands in the North Central Region of the United States. In this work,
field_moist soils and their air_dried counterparts were incubated at 30oC under
waterlogged conditions for times ranging from 3 to 15 days, and the amounts of
NH4
_N released was determined. Results showed that the rates of NH4-N released
were greater in air-dried than in field_moist soils. The mineralization rates of the
field_moist soils were significantly correlated with organic C (r = 0.59*), organic N (r
= 0.69*), Cmic (r = 0.62*), and Nmic (r = 0.63*). The corresponding r values for the
air_dried soils were 0.76**, 0.87**, 0.84**, and 0.85***, respectively. Estimation of the
amounts of N mineralized per hectare of field_moist soils in one day ranged from 2.2
to 4.9 kg (avg. = 3.3). Those values for air_dried soils ranged from 5.2 to 26.2 kg
(avg. = 15.5). The rates of hydrolysis of six enzyme substrates studied were
significantly correlated with the rates of NH4
_N released in the field_moist soils.
With the correlation coefficients (r) in parentheses, the relationships were amidase
(0.82**), arginase (0.90***), asparaginase (0.86***), glutaminase (0.88***),
β_glucosidase (0.83**), and β_ glucosamindase (0.84**). Q10 values ranged from 1.2 to
1.4 (avg. = 1.3) for the field_moist soils and from 1.0 to 1.3 (avg. = 1.1) for air_dried
soils. This study showed that microbial biomass and a number of hydrolases play a
major role in hydrolysis of N in flooded soils.