Effects of urea rates, farmyard manure, CaCO3, salinity and alkalinity levels on urea hydrolysis and nitrification in soils

Soil Research ◽  
1988 ◽  
Vol 26 (2) ◽  
pp. 367 ◽  
Author(s):  
V Kumar ◽  
DS Yadav ◽  
M Singh
Keyword(s):  
Constant Temperature ◽  
Farmyard Manure ◽  
Urea Hydrolysis ◽  
Urea Concentration ◽  
Hydrolysis Rate ◽  
Nitrification Rate ◽  
Indian Soils

The effects of urea concentration, farmyard manure, CaCo3, pH and EC levels on urea and nitrification rates in different Indian soils at constant temperature (25 � 1�C) and moisture (50% WHC) were studied. The hydrolysis rate of urea was not proportional to the amount of urea added. In all cases, hydrolysis was completed within 6 days, except with 16.64 dS m-1 EC and 4% and 8% CaCO3 treatments. An increase in CaCO3, pH and EC levels inhibited urea hydrolysis. The NH4+ concentration increased up to 6 days and then decreased up to 24 days, with a corresponding increase in the NO3- concentration. The maximum NO2- concentration was observed at 12 and 18 days and decreased at 24 days. However, accumulation of NO2- continued up to 24 days at higher CaCO3, EC and pH levels. An increase in urea levels decreased the rate of nitrification. The nitrification rate was fast in the presence of farmyard manure and slow at the higher CaCO3, pH and EC levels.

scholarly journals Influence of hydrolysis rate of urea on ruminal bacterial diversity level and cellulolytic bacteria abundance in vitro

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5475 ◽  
Author(s):  
Pengpeng Wang ◽  
Shengguo Zhao ◽  
Xuemei Nan ◽  
Di Jin ◽  
Jiaqi Wang
Keyword(s):  
Bacterial Diversity ◽  
Early Period ◽  
Urea Hydrolysis ◽  
Hydrolysis Rate ◽  
Acetohydroxamic Acid ◽  
Urease Inhibitor ◽  
Cellulolytic Bacteria ◽  
Total Bacteria ◽  
Ammonia Formation

The objective of this experiment was to evaluate the effects of urea hydrolysis rate on ruminal bacterial diversity level and cellulolytic bacteria abundance in vitro. To control urea hydrolysis rate, urea and urease inhibitor (acetohydroxamic acid, AHA) were supplemented to a 2 × 2 factorial design, with urea supplemented at 0 or 20 g/kg dry matter (DM) of substrate, and AHA equivalent to 0 or 450 mg/kg DM of substrate. Ruminal fluid was collected from three Chinese Holstein dairy cows, fed a TMR, and incubated at 39 °C for 12 h after the addition of urea and AHA. Rumen fermentation parameters, which indicated the rate of ammonia formation (including ammonia-nitrogen (NH3-N) and urea-nitrogen concentrations, urease activity, and microbial crude protein) were measured by chemical analysis. Bacterial diversity was analyzed by denaturing gradient gel electrophoresis (DGGE). Total bacteria and cellulolytic bacteria abundance was detected by quantitative PCR. Results showed that AHA addition significantly decreased the rate of ammonia formation when urea was supplemented. Urea and AHA supplementation significantly increased the bacterial community diversity level according to the Shannon–Weiner index of 16S DGGE images. Furthermore, ruminal bacterial profiles were separated by ammonia release rate when urea was supplemented, according to the DGGE and hierarchical cluster analysis. Urea supplementation reduced the abundance of cellulolytic bacteria, such asRuminococcus albus,R. flavefaciens,Fibrobacter succinogenes, andButyrivibrio fibrosolvens, but inhibition of urea hydrolysis by AHA addition alleviated the reductions during the early period of incubation. In conclusion, slow release of ammonia induced by urease inhibitor influenced the ruminal bacterial diversity level and lessened the inhibition of total bacteria growth at the incubation of 12 h andF. succinogenesduring the early period of incubation.

Kinetics and thermodynamics of urea hydrolysis in the presence of urease and nitrification inhibitors

2020 ◽  
pp. 1-11
Author(s):  
Ahmed A. Lasisi ◽  
Olalekan O. Akinremi
Keyword(s):  
Soil Temperature ◽  
Half Life ◽  
Nitrification Inhibitor ◽  
Inhibitory Effect ◽  
Urea Hydrolysis ◽  
Hydrolysis Rate ◽  
Effect Of Temperature ◽  
Nitrification Inhibitors ◽  
Urease Inhibitor ◽  
N Losses

Urease inhibitor [N-(n-butyl) thiophosphoric triamide (NBPT)] and nitrification inhibitor (NI) (3,4-dimethylpyrazole phosphate) have been used to reduce nitrogen (N) losses from urea-based fertilizers. This study evaluated the effect of temperature, NBPT, and NI on kinetic and thermodynamic properties of urea hydrolysis in six soils. Soils were amended (250 kg N·ha−1) with urea (UR), NBPT treated urea (URNBPT), or NBPT + NI treated urea (URDI), incubated at 5, 15, or 25 °C, and destructively sampled eight times during an 18 d incubation. We measured urea hydrolysis rate by the disappearance of urea with time and determined the rate constant (k; d−1) assuming first-order kinetics. Our results showed that k increased with temperature in the order of 0.07 (5 °C), 0.12 (15 °C), and 0.20 (25 °C) across soils and inhibitor treatments. In addition, k declined in the order of UR (0.19) > URDI (0.11) > URNBPT (0.08) across soils and temperatures. Although urease inhibitor, NBPT, increased the half-life of urea from 3.8 to 8.3 d across soil–temperature, the addition of a NI significantly reduced the half-life of NBPT treated urea by approximately 2 d across soil–temperature. Thermodynamics parameters showed that urea hydrolysis was nonspontaneous, and enthalpy and entropy changes were not significantly different among inhibitor treatments in five of the six soils. We conclude that the often-reported greater ammonia volatilization from URDI than URNBPT may not only be due to the persistence of ammonium in the presence of NI but also because NI reduced the inhibitory effect of NBPT on urea hydrolysis.

Effect of organics on nitrogen transformations in soil under different moisture regimes

2008 ◽  
Vol 56 (3) ◽  
pp. 285-293
Author(s):  
M. Mavi ◽  
B. Singh ◽  
R. Setia
Keyword(s):  
Wheat Straw ◽  
Rice Straw ◽  
Crop Residues ◽  
Farmyard Manure ◽  
Poultry Manure ◽  
Field Capacity ◽  
Urea Hydrolysis ◽  
Green Manures ◽  
Untreated Soil ◽  
Organic Manures

Awareness of the environmental aspects of the quality of crop production has increased in recent decades, leading to renewed interest in organics such as crop residues, green manures and organic manures. The effect of organics on urea transformation was investigated by conducting a laboratory incubation experiment in alluvial clay loam soil (Typic Ustifluvents) at 33±1°C with two moisture levels (1:1 soil:water ratio and field capacity). The rate of urea hydrolysis decreased as the time of incubation increased and the disappearance of urea N was associated with a corresponding increase in the (NH 4+ + NO 3− )-N content in soils treated with crop residues (rice straw and wheat straw), organic manures (poultry manure and farmyard manure) and green manures (cowpea and sesbania). In untreated soil, the time taken for the complete hydrolysis of the applied urea (200 μg urea N g −1 soil) was more than 96 h at both the moisture levels, whereas in amended soils it was completed in 48 h. The rate of urea hydrolysis was more rapid at field capacity than at the 1:1 soil:water ratio. Urea hydrolysis was higher in sesbaniatreated soils, followed by cowpea, poultry manure, farmyard manure, rice straw and wheat straw at both the moisture levels. At field capacity, 85.5% urea was hydrolysed in sesbania-treated soil as compared to 32% in untreated soil after 24 hours of incubation, while at the 1:1 soil:water ratio the corresponding values were 81.5 and 27.5%. Urea hydrolysis followed first order reaction kinetics at both the moisture levels.

Effect of temperature and moisture on kinetics of urea hydrolysis and nitrification

Soil Research ◽  
1987 ◽  
Vol 25 (2) ◽  
pp. 185 ◽  
Author(s):  
DS Yadav ◽  
V Kumar ◽  
M Singh ◽  
PS Relan
Keyword(s):  
Sandy Loam ◽  
Field Capacity ◽  
Urea Hydrolysis ◽  
Hydrolysis Rate ◽  
Effect Of Temperature ◽  
Activation Entropy ◽  
Clay Loam ◽  
Moisture Regimes ◽  
Loam Soil ◽  
Kinetics Of

The effects of temperature and moisture regimes on kinetics of urea hydrolysis in soils of Hisar (Typic Camborthids) and Hansi (Typic Ustochrepts) were studied. The rate constant (K) for first-order reaction increased with temperature from 10 to 35�C. Energy of activation (Ea), activation free energy (�F*) and activation entropy (�S*) between 10 and 35�C were 33.8, 81.8 kJ mol-1 and -176.55 K-1I in a sandy loam soil, and 29.2, 81 -6 kJ mol-I and - 155.3 J K-I in a clay loam soil, respectively. The hydrolysis rate was not a linear function of moisture content but increased with field capacity (F.C.). The rate of hydrolysis in both the soils followed the order: 20% F.C. < 40% F.C. < 80% F.C. = 100% F.C. The rate for flooded soil was between those for 20% and 40% F.C. for sandy loam, and between 40 and 80% F.C. for the clay loam. The added urea was completely hydrolysed in 3 days at all moisture regimes except 20% F.C.; maximum NH4+-N was found at the third day, then decreased thereafter. The time at which NO2- first appeared varied with treatments, but then it persisted throughout the 24-day incubation in all treatments.

Urea hydrolysis rate (UHR) calculation normalizes the 13C-urea breath test for age, sex, height, and weight

1998 ◽  
Vol 114 ◽  
pp. A179 ◽  
Author(s):  
P.D. Klein ◽  
H.M. Malaty ◽  
D.Y. Graham ◽  
S. Czinn ◽  
S. Emmons ◽  
...  
Keyword(s):  
Breath Test ◽  
Urea Breath Test ◽  
Urea Hydrolysis ◽  
Hydrolysis Rate ◽  
13C Urea Breath Test
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