Soil Enzyme: The State-of-Art

Soil organic carbon allocation and dynamics under perennial energy crops and their feedbacks with soil microbial biomass and activity

“…Highest and lowest soil MBC were observed in reed canary grass and giant knotweed, compared to the benchmark system. Similar observations were made for the basal respiration and also the activities of cellulose 1,4 β‐cellobiosidase and 1,4 β‐glucosidase, which can be regarded as a tracer for the ability of soils for SOM stabilization (Bakshi & Varma, 2011). From the information available to date, no study has dealt with effects on enzyme activities in soils cultivated with dicotyledonous PECs.…”

“…PECs were usually two to three times higher than that of silage maize (3.4% of d.w.), whereas the lignin content of giant knotweed even exceeded 18% of d.w. Cellulose contents varied in a wide range between 19.1% of d.w. (silage maize) and 41.8% of d.w. (tall wheatgrass). In the present study, the elevated activities of cellulose 1,4 β-cellobiosidase and 1,4 β-glucosidase, both catalysing the hydrolysis of oligo-and polysaccharides (Bakshi & Varma, 2011) underpin the lignocellulosic character of the crop residues. It should furthermore be considered that in the tilled soil of the benchmark system, the aeration and accessibility of organic residuals are higher presumably leading to accelerated mineralization rates.…”

The impact of banding urea and enhanced efficiency fertilizers on nitrogen transformations and the implications for nitrogen use efficiency in high-risk environments

“…Granular urea fertilizer typically contains 46% N which is rapidly hydrolysed to ammonium carbonate [(NH4)2CO3] by the extracellular enzyme urease. This enzyme is found in plants, micro-organisms (Bakshi and Varma, 2011) and adsorbed onto soil clay and humic phases (Frankenberger and Johanson, 1982). Equations 2.7 and 2.8 show the chemical reactions of urea hydrolysis to firstly, (NH4)2CO3 and the subsequent break-down to NH4 + , CO2, and water (H2O).…”

“…60% water filled pore space (Sanz-Cobena et al, 2016) so that the reduction of NBPT to NBPTO is restricted due to an increasingly oxygenlimited environment. Increased temperature will also reduce effectiveness of NBPT as result of enhanced enzymatic activity (Bakshi and Varma, 2011) which outpaces the rate of NBPT to NBPTO conversion (Carmona et al, 1990), and in soils of low to slightly alkaline pH, NBPT and NBPTO will degrade more rapidly than in strongly alkaline conditions (Engel et al, 2015).…”

“…Urease is a soil enzyme that facilitates the transformation pathway of urea to NH4 + . It exists either intracellularly or extracellularly on soil clay and humic phases (Bakshi and Varma, 2011). Briefly, urease catalyses reactions between urea and water to form (NH4)2CO3, which in turn consumes protons from the soil solution during the formation of NH4 + .…”