Nitrate Utilization by Species From Acidic and Calcareous Soils

Abstract

SUMMARYNitrate utilization by calcicole and calcifuge species has heen measured using a field assay for nitrate reductase. Certain calcifuge species, notably members of the Ericaceae, showed no detectable enzyme activity in the field and very low values in the laboratory even after nitrate feeding. It is concluded that these species have a restricted ability to utilize nitrate. Other calcifuge species and all the species from calcareous soils had detectable nitrate reductase activities in the field and responded to nitrate addition by large increases in enzyme activities. Some of these species were used to compare nitrate utilization in a number of acidic and calcareous soils. Nitrate was utilized in all the soils, but utilization was minimal in ombrogenous peat. A comparison of closely adjacent acidic and calcareous soils showed that nitrate is an important source of inorganic combined nitrogen in at least some acidic soils.

Seasonal Variation in Nitrogen Availability and Utilization in an Acidic and Calcareous Soil

“…see Davy and Taylor, 1974;Runge, 1974;Ellenberg, 1977). Previous work (Havill et al, 1974) has suggested that low nitrate availability is particularly associated with ombrogenous bog sites, where poor aeration and low temperatures, rather than acidity per se, inhibit nitrification. The failure of some workers to detect appreciable nitrate formation in freely drained acidic soils (e.g.…”

“…The activity of this enzyme before and after nitrate addition indicates the degree of nitrate utilization and the species potential to assimilate this nitrogen source respectively Orehamjo, 1972, 1973;Havill, Lee and Stewart, 1974;Havill, Lee and De-Fehce, 1977;Osborne and Whittington, 1981). The in vitro levels of glutamine synthetase and glutamate dehydrogenase were measured to indicate the degree of ammonium utilization by the plants.…”

Nitrate Reductase Activity of Sphagnum Species in the South Pennines

“…This raises the possibility that the ammonium availahility is high enough to inhibit nitrate reductase activity in all but short-term transplants. Havill et al (1974) demonstrated little nitrate utilization by angiosperms on blanket peat. This could not have resulted from ammonium inhibition of the formation of nitrate reductase activity in these plants, since in at least one species {Rubus chamaemorus L.) there was a marked induction of activity on addition of nitrate.…”

NITROGEN METABOLISM IN POTERIUM SANGUISORBA DURING WATER STRESS

“…Experiments have been made on the calcicole Poterium sanguisorba, which can assimilate nitrate and possesses the enzymic potential to assimilate ammonium via both the glutamate dehydrogenase and glutamine synthetase-glutamate synthase pathways (Havill, Lee and Stewart, 1974;Taylor and Havill, 1981). As previous studies concerned with the effect of water stress on nitrogen-assimilating enzymes have tended to concentrate on shoot nitrate reductase (see e.g.…”