Urea Hydrolysis of Tea Soils as Influenced by Incubation Period, Soil pH, and Nitrification Inhibitor

2007 ◽  
Vol 38 (17-18) ◽  
pp. 2295-2307 ◽  
Author(s):  
S. Venkatesan ◽  
V. Sudhahar ◽  
V. K. Senthurpandian ◽  
S. Murugesan
Keyword(s):  
Incubation Period ◽  
Soil Ph ◽  
Nitrification Inhibitor ◽  
Urea Hydrolysis ◽  
Hydrolysis Of

NITROGEN TRANSFORMATIONS NEAR UREA IN SOIL WITH DIFFERENT WATER POTENTIALS

1988 ◽  
Vol 68 (3) ◽  
pp. 569-576 ◽  
Author(s):  
YADVINDER SINGH ◽  
E. G. BEAUCHAMP
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Incubation Period ◽  
Relative Rate ◽  
Soil Water Potential ◽  
Nitrification Inhibitor ◽  
Silt Loam ◽  
Nitrogen Transformations ◽  
Water Potentials ◽  
Initial Soil

Two laboratory incubation experiments were conducted to determine the effect of initial soil water potential on the transformation of urea in large granules to nitrite and nitrate. In the first experiment two soils varying in initial soil water potentials (− 70 and − 140 kPa) were incubated with 2 g urea granules with and without a nitrification inhibitor (dicyandiamide) at 15 °C for 35 d. Only a trace of [Formula: see text] accumulated in a Brookston clay (pH 6.0) during the transformation of urea in 2 g granules. Accumulation of [Formula: see text] was also small (4–6 μg N g−1) in Conestogo silt loam (pH 7.6). Incorporation of dicyandiamide (DCD) into the urea granule at 50 g kg−1 urea significantly reduced the accumulation of [Formula: see text] in this soil. The relative rate of nitrification in the absence of DCD at −140 kPa water potential was 63.5% of that at −70 kPa (average of two soils). DCD reduced the nitrification of urea in 2 g granules by 85% during the 35-d period. In the second experiment a uniform layer of 2 g urea was placed in the center of 20-cm-long cores of Conestogo silt loam with three initial water potentials (−35, −60 and −120 kPa) and the soil was incubated at 15 °C for 45 d. The rate of urea hydrolysis was lowest at −120 kPa and greatest at −35 kPa. Soil pH in the vicinity of the urea layer increased from 7.6 to 9.1 and [Formula: see text] concentration was greater than 3000 μg g−1 soil. There were no significant differences in pH or [Formula: see text] concentration with the three soil water potential treatments at the 10th day of the incubation period. But, in the latter part of the incubation period, pH and [Formula: see text] concentration decreased with increasing soil water potential due to a higher rate of nitrification. Diffusion of various N species including [Formula: see text] was probably greater with the highest water potential treatment. Only small quantities of [Formula: see text] accumulated during nitrification of urea – N. Nitrification of urea increased with increasing water potential. After 35 d of incubation, 19.3, 15.4 and 8.9% of the applied urea had apparently nitrified at −35, −60 and −120 kPa, respectively. Nitrifier activity was completely inhibited in the 0- to 2-cm zone near the urea layer for 35 days. Nitrifier activity increased from an initial level of 8.5 to 73 μg [Formula: see text] in the 3- to 7-cm zone over the 35-d period. Nitrifier activity also increased with increasing soil water potential. Key words: Urea transformation, nitrification, water potential, large granules, nitrifier activity, [Formula: see text] production

Urea hydrolysis and inorganic N in a Luvisol after application of fertiliser containing rare-earth elements

Soil Research ◽  
2003 ◽  
Vol 41 (4) ◽  
pp. 741 ◽  
Author(s):  
Xingkai Xu ◽  
Zijian Wang ◽  
Yuesi Wang ◽  
Kazuyuki Inubushi
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Substantial Reduction ◽  
Application Rate ◽  
Urea Hydrolysis ◽  
High Rate ◽  
Short Term ◽  
N Content ◽  
N Fertilisers ◽  
Hydrolysis Of

In recent decades, Chinese agriculturists have used rare-earth-containing fertilisers as basal fertilisers together with N fertilisers (e.g. urea). We studied urea hydrolysis and its hydrolysis products in a laboratory experiment using urea-N fertiliser with rare earths at rates from 0.5 to 50% (w/w). The results indicated that application of rare earths at a high rate could result in a short-term inhibition of urea hydrolysis and an increase in soil (NH4+ + NO3– + NO2–)-N content. When the application rate of rare earths was higher than 5% of the applied urea-N (corresponding to 10 mg/kg soil), soil exchangeable NH4+-N content increased significantly following the hydrolysis of the applied urea. Increasing the application rate of rare earths appeared to reduce the content of soil urea-derived (NO3– + NO2–)-N. A substantial reduction in soil pH was found immediately after application of rare earths and urea. We conclude that application of rare earths at >10 mg/kg may lead to a substantial increase in the content of urea-derived N in the soil, via the inhibition of urea hydrolysis and nitrification.

scholarly journals Extensive destruction of newly synthesized casein in mammary explants in organ culture

1982 ◽  
Vol 202 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Huthama Razooki Hasan ◽  
David A. White ◽  
R. John Mayer
Keyword(s):  
Incubation Period ◽  
Soluble Protein ◽  
Milk Protein ◽  
Fatty Acid Synthetase ◽  
Total Soluble Protein ◽  
Signal Peptides ◽  
Dual Isotope ◽  
Intracellular Degradation ◽  
Hydrolysis Of ◽  
Specific Particle

1. Explants of mammary glands of mid-pregnant rabbits that had been cultured for 18h in the presence of insulin, prolactin and cortisol were incubated at 37°C for 2h in Medium 199 containing l-[4,5-3H]leucine. After a wash procedure at 4°C, explants were re-incubated at 37°C in fresh medium and the radioactivity of casein polypeptides isolated by isoelectric focusing (at pH 4.6) was followed with time. Casein radioactivity rose during the first hour of re-incubation, but fell markedly during the subsequent hour. 2. Loss of radioactivity represented casein degradation, since less than 10% of newly synthesized casein was found in the incubation medium. 3. Such a loss of radioactivity was not due solely to hydrolysis of signal peptides, since similar results were obtained when l-[5-3H]proline, which is not part of casein signal peptides, was the radiolabelled precursor. 4. A dual-isotope experiment using l-[U-14C]proline and N-[3H]acetyl-d-mannosamine gave similar profiles of radioactivity loss from isoelectrically focused casein, indicating that degradation of mature casein was occurring. 5. Analysis of total pellet and particle-free-supernatant fractions prepared by centrifugation of explant homogenates at 115000gav. for 1h did not show loss of radioactivity on re-incubation. Total pellet-protein radioactivity remained constant, whereas total soluble-protein radioactivity increased during the 2h re-incubation period. 6. Radioactivity in a specific particle-free-supernatant polypeptide, the subunit of fatty acid synthetase, mimicked that of the total soluble protein. 7. Addition of cycloheximide (20μg/ml) during the re-incubation period completely blocked the incorporation of radioactivity from l-[5-3H]proline into casein and the subsequent fall, indicating that observations were being made on newly synthesized casein. 8. Addition of chloroquine (50μm) did not prevent the increase in radioactivity from l-[5-3H]proline into casein during the first hour of re-incubation, but did prevent the loss of radioactivity in the second hour. 9. The intracellular degradation of a newly synthesized milk protein is discussed in relation to the known intracellular degradation of other secretory polypeptides.

A Rapid Procedure to Evaluate the Effect of Pesticides on Nitrification

Weed Science ◽  
1973 ◽  
Vol 21 (5) ◽  
pp. 397-399 ◽  
Author(s):  
R. P. Thorneburg ◽  
J. A. Tweedy
Keyword(s):  
Incubation Period ◽  
Soil Microorganisms ◽  
Nitrification Inhibitor ◽  
Rapid Screening ◽  
Distilled Water ◽  
Laboratory Procedure ◽  
Rapid Procedure ◽  
Short Period

A laboratory procedure for evaluating the effect of pesticides on nitrification in soil proved to be simple to perform, reproducible, and offers a procedure for rapid screening of a large number of chemicals in a short period. The recovery of added nitrate by extracting with distilled water was essentially 100% complete. The conversion of added ammonium to nitrate by the soil microorganisms was nearly complete after the 2-week incubation period. Nitrification in soil treated with several different herbicides and insecticides was determined by our procedure. A nitrification inhibitor, N-Serve3 (2-chloro-6-trichloromethyl pyridine) was included as a standard. None of the herbicides or insecticides inhibited nitrification and the N-Serve completely inhibited nitrification during the 2-week incubation.

EFFECTS OF CATECHOL AND P-BENZOQUINONE ON THE HYDROLYSIS OF UREA AND ENERGY BARRIERS OF UREASE ACTIVITY IN SOILS

1984 ◽  
Vol 64 (1) ◽  
pp. 51-60 ◽  
Author(s):  
J. S. TOMAR ◽  
A. F. MacKENZIE
Keyword(s):  
Activation Energy ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Key Words ◽  
Urease Activity ◽  
Urea Hydrolysis ◽  
Urease Inhibitors ◽  
Soil Urease ◽  
Hydrolysis Of ◽  
Hydrolysis Of Urea

The effects of the urease inhibitors, catechol and p-benzoquinone, and temperature on the hydrolysis of urea in five soils were investigated in a laboratory study. Urea hydrolysis decreased significantly with the amount of inhibitors applied and increased significantly with each 5 °C increase in temperature from 5 to 25 °C. The effectiveness of inhibitors generally decreased with increases in temperature from 5 to 25 °C. The correlation of hydrolysis of urea with organic matter contents of the soils was highly significant (r = 0.67** to 0.86**). Both catechol and p-benzoquinone tended to increase the energies and entropies of activation of soil urease and the effect was enhanced with a decrease in soil organic matter. It is suggested that an increase in the activation energy of the soil urease as a result of inhibitor use was related to an increase in the effectiveness of the inhibitor. Key words: Urease inhibitors, urea hydrolysis, energy of activation

Fate of Bacillus thuringiensis in soil: effect of soil pH and organic amendment

1970 ◽  
Vol 16 (8) ◽  
pp. 677-680 ◽  
Author(s):  
S. M. Saleh ◽  
R. F. Harris ◽  
O. N. Allen
Keyword(s):  
Bacillus Thuringiensis ◽  
Incubation Period ◽  
Soil Ph ◽  
Organic Amendment ◽  
Acid Soils ◽  
Microbial Populations ◽  
Vegetative Cells ◽  
Soil Microbial ◽  
Neutral Ph

Bacillus thuringiensis spores germinated, grew, and sporulated in soils of neutral pH amended with alfalfa or casein. Numbers of viable spores of B. thuringiensis increased 100-fold and more than one million spores/g soil were maintained throughout a 3-month incubation period. B. thuringiensis spores apparently germinated but the resulting vegetative cells did not survive in acid soils amended with alfalfa or casein. It appears that B. thuringiensis spores can remain viable for long periods of time in soil and that the organism can compete successfully under conditions favoring the bacillus component of soil microbial populations.

scholarly journals Optimisation of the Enzymatic Hydrolysis of Blood Cells with a Neutral Protease

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Yanbin Zheng ◽  
Qiushi Chen ◽  
Anshan Shan ◽  
Hao Zhang
Keyword(s):  
Amino Acids ◽  
Enzymatic Hydrolysis ◽  
Incubation Period ◽  
Blood Cells ◽  
Substrate Concentration ◽  
Neutral Protease ◽  
Degree Of Hydrolysis ◽  
Hydrolysis Conditions ◽  
Optimized Conditions ◽  
Hydrolysis Of

For utilizing the blood cells (BCs) effectively, enzymatic hydrolysis was applied to produce the enzymatically hydrolyzed blood cells (EHBCs) by using a neutral protease as a catalyst. The results of the single-factor experiments showed optimal substrate concentration, enzyme to substrate ratio (E/S), pH, temperature, and incubation period were 1.00%, 0.10, 7.00, 50.00°C, and 12.00 h, respectively. The optimized hydrolysis conditions from response surface methodology (RSM) were pH 6.50, E/S 0.11, temperature 45.00°C, and incubation period 12.00 h. Under these conditions (substrate concentration 1.00%), the degree of hydrolysis (DH) was 35.06%. The free amino acids (FAAs) content of the EHBCs (35.24%) was 40.46 times higher than BCs while the total amino acids (TAAs) content was lower than BCs. The scores of lysine (human 0.87; pig 0.97), valine (human 1.42; pig 1.38), leucine (human 1.50; pig 1.90), tyrosine (human 0.84; pig 1.09), and histidine (human 2.17; pig 2.50) indicated that the EHBCs basically fulfilled the adult human and pig nutritional requirements. The calculated protein efficiency ratios (C-PERs) of the EHBCs were 3.94, 6.19, 21.73, and 2.04. In summary, the EHBCs were produced successfully with optimized conditions and could be a novel protein source for humans and pigs.

Effects of Thiourea on Metals Availability and Maize Physiological Characteristics in Acid Soils from South China

2014 ◽  
Vol 1073-1076 ◽  
pp. 340-349
Author(s):  
Si Luo ◽  
Wen Wang ◽  
Xi Hong Zhou ◽  
Qing Ru Zeng
Keyword(s):  
Soil Ph ◽  
Acid Soils ◽  
Urea Hydrolysis ◽  
Physiological Characteristics ◽  
Maize Seedlings ◽  
Toxicological Effects ◽  
Fe Uptake ◽  
Mda Content ◽  
Mn Content ◽  
Pot Culture

It has been confirmed that thiourea (TU) was effective in inhibiting urea hydrolysis and nitrite formation. However, few studies focused on the toxicological effects and environmental impacts of TU. In this study, the influences of TU on the soil pH and available metals contents were reported. The addition of thiourea to the urea-treated soils led to a slower decrease or even increase in soil pH. The application of thiourea had slight influence on the content of available Cu in soils. Mn content increased with increasing TU concentration, however, the changes of Zn and Al contents were opposite. Pot culture experiments were conducted to investigate the effects of TU on the physiological characteristics of maize seedlings, including the plant growth, chlorophyll (CHL) content, metal ions uptakes and malondialdehyde (MAD) content in the leaves. 1 mmol kg-1 soil thiourea significantly inhibited the growth of maize seedlings. The application of thiourea enhanced the Mn accumulation in leaves, and negatively affected the Fe uptake, which thereby inhibited the biosynthesis of CHL. There was not any noticeable difference in MDA content in plants treated with 1-2.5 mmol kg-1 soil thiourea. An obvious increase of MDA content was found at 5 mmol kg-1 soil thiourea.

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