Urease activity in soils : a review

Abstract

Extensive literature on the unique soil enzyme urease is reviewed and presented to create vigilance among local scientists, and to motivate them to conduct more research on urease activity under Sri Lankan conditions. Soil urease is mainly microbial in origin, and its activity in soils is due to accumulated urease. However, comparison of reported urease activity levels in different soils was extremely difficult as the assay procedures adopted in the various studies were different. Further, this enzyme is remarkably stable in organo-mineral complexes found in soil. Factors affecting urease activity and correlations between urease activity and soil properties are discussed. Problems associated with high urease activity, i.e. gaseous loss of N and plant damage due to ammonia gas and accumulated nitrite, and the effectiveness of most recently found compounds in overcoming these problems are also discussed.

Maize Stover Biochar Accelerated Urea Hydrolysis and Short-term Nitrogen Turnover in Soil

“…The accelerated urea hydrolysis can be explained by the following two reasons: i) Increased urease activity. The enhanced urease activity in the presence of biochar is presumably caused by a combination of different mechanisms: a) biochar provides energy-rich organic compounds (Luo et al 2013;Singh and Cowie 2014) and microbial habitat that promote the growth of microorganisms resulting in the production of microbial urease (Zantua and Bremner 1977); and b) urease activity is optimum under slightly alkaline conditions (Dharmakeerthi and Thenabadu 2013), and biochar is a known liming agent; ii) Soil pH corresponds well to urea hydrolysis rate and nitrification processes (Gao and Cai 2015). This is consistent with the authors' result that the urea hydrolysis rate increased with enhanced biochar pH value (Table 3).…”

Effective Use of Plant-Derived Urease in the Field of Geoenvironmental/ Geotechnical Engineering

“…They are also intracellular as part of the soil biomass [54]. Soil urease activity is related to the vegetation of the soil [55].…”

“…Immobilization changes original enzyme properties like storage stability, kinetic parameter and customizes them for specific applications [76,77]. Furthermore, immobilization of enzymes enhances their thermal stabilities [54]. For example, glucose isomerase denatures at 45°C in solution, however, it is stable for about 1 year even at 65°C when suitably immobilized.…”

Increasing NBPT rates to reduce ammonia volatilization losses from urea applied over sugarcane straw

“…Urease is naturally found in the soil, mostly synthesized by soil microorganisms, although plant residues may supply urease directly to the soil (DHARMAKEERTHI; THENABADU, 1996).…”

“…The low efficiency of NBPT when urea is surface-applied in GCTB systems can be attributed to the high urease activity promoted by the straw layer and the high temperatures of upper soil layers, since urease activity increases as the temperature rises (MOYO; KISSEL; CABRERA, 1989;DHARMAKEERTHI;THENABADU, 1996;TASCA et al, 2011 There is a trend of farmers collect part of the straw for bioenergy production (SORDI; MANECHINI, 2013), but a fraction of the plant material will remain on soil for agronomic reasons. Among the benefits of maintaining the straw on the soil surface are the attenuation of soil erosion by reducing the impact of raindrop, enhancement of water infiltration and reduction of runoff; lower emission of greenhouse gases (compared to burned fields); increase in the soil organic carbon stock and; maintenance of soil moisture along drought seasons (CANTARELLA; ROSSETTO, 2012;CANTARELLA et al, 2013).…”