Enzymatic activity of a soil profile in the Sudan Gezira

Distribution, salinity, kinetic and thermodynamic characteristics of urease activity in a vertisol profile

“…Musa and Mukhtar (1969) found that, although urease activity in a Sudan Gezira soil (50-60% clay, predominantly montmorillonitic) was essentially similar at 0-5 cm and 5-60 cm and decreased with increasing depths, addition of glucose (2500 ppm C) and NO,-N (100 ppm N) resulted in only 60% increase in activity in the top layer (0-5 cm) but much higher increases in deeper layers (90, 150, 1400 and 700% increase in urease activity at 5-60, 60-90, 90-125 and 125-180 cm depths, respectively). They concluded that microbial activity was markedly stimulated in deeper soil layers following the addition of available carbon and nitrogen, and may be due to regeneration of resting forms of microorganisms washed down from the surface through soil cracks early in the rainy season.…”

Impact of Soil Environment and Agronomic Practices on Microbial/Dehydrogenase Enzyme Activity in Soil. A Review

“…Dehydrogenase activities increase with increasing microbial populations following amendments of soils with nutrients (Ladd and Paul, 1 973) and decrease when soils are dried (Ross, 1970;Pancholy and Rice, 1972). Dehydrogenase activities are related to soil organic matter contents (Lungesen and Mikkelsen, 1974) but vary with the season (Ross and Roberts, 1970;Ross, 1973) and decrease with depth of sample from the soil profile (Musa and Mukhtar, 1969). Activities are best retained by storing undried soil samples in the cold (Ross, 1970) and reduced when soil was stored air-dried at room temperature (Ross, 1970;Ross and McNeilly, 1972), a reduction which tended to increase with storage (Casida et al, 1964;Ross, 1970).…”