scholarly journals Assessment and kinetics of soil phosphatase in Brazilian Savanna systems

2016 ◽  
Vol 88 (2) ◽  
pp. 1035-1044 ◽  
Author(s):  
ADÃO S. FERREIRA ◽  
SUÉLLEN P. ESPÍNDOLA ◽  
MARIA RITA C. CAMPOS
Keyword(s):  
Kinetic Parameters ◽  
Phosphatase Activity ◽  
Conventional Tillage ◽  
Brazilian Savanna ◽  
No Tillage ◽  
Brachiaria Brizantha ◽  
Lower Affinity ◽  
Universal Buffer ◽  
Kinetics Of ◽  
Soil Phosphatase

The activity and kinetics of soil phosphatases are important indicators to evaluate soil quality in specific sites such as the Cerrado (Brazilian Savanna). This study aimed to determine the activity and kinetic parameters of soil phosphatase in Cerrado systems. Soil phosphatase activity was assessed in samples of native Cerrado (NC), no-tillage (NT), conventional tillage (CT) and pasture with Brachiaria brizantha (PBb) and evaluated with acetate buffer (AB), tris-HCl buffer (TB), modified universal buffer (MUB) and low MUB. The Michaelis-Menten equation and Eadie-Hofstee model were applied to obtain the kinetic parameters of soil phosphatase using different concentrations of p-nitrophenol phosphate (p-NPP). MUB showed the lowest soil phosphatase activity in all soils whereas AB in NC and NT presented the highest. Low MUB decreased interferences in the assessment of soil phosphatase activity when compared to MUB, suggesting that organic acids interfere on the soil phosphatase activity. In NC and NT, soil phosphatase activity performed with TB was similar to AB and low MUB. Km values from the Michaels-Menten equation were higher in NC than in NT, which indicate a lower affinity of phosphatase activity for the substrate in NC. Vmax values were also higher in NC than in NT. The Eadie-Hofstee model suggests that NC had more phosphatase isoforms than NT. The study showed that buffer type is of fundamental importance when assessing soil phosphatase activity in Cerrado soils.

Kinetics of methane oxidation in selected mineral soils

2012 ◽  
Vol 26 (4) ◽  
pp. 401-406 ◽  
Author(s):  
A. Walkiewicz ◽  
P. Bulak ◽  
M. Brzeziñska ◽  
T. Włodarczyk ◽  
C. Polakowski
Keyword(s):  
Kinetic Parameters ◽  
Methane Oxidation ◽  
Agricultural Soils ◽  
Organic Soils ◽  
Lower Affinity ◽  
Landfill Cover ◽  
Laboratory Conditions ◽  
Haplic Podzol ◽  
Mineral Soils ◽  
Kinetics Of

Abstract The kinetic parameters of methane oxidation in three mineral soils were measured under laboratory conditions. Incubationswere preceded by a 24-day preincubationwith 10%vol. of methane. All soils showed potential to the consumption of added methane. None of the soils, however, consumed atmospheric CH4. Methane oxidation followed the Michaelis-Menten kinetics, with relatively low values of parameters for Eutric Cambisol, while high values for Haplic Podzol, and especially for Mollic Gleysol which showed the highest methanotrophic activity and much lower affinity to methane. The high values of parameters for methane oxidation are typical for organic soils and mineral soils from landfill cover. The possibility of the involvement of nitrifying microorganisms, which inhabit the ammonia-fertilized agricultural soils should be verified.

Effect of No-Tillage and Conventional Tillage Systems on the Chemical Composition of Soil Solid Phase and Soil Solution of Brazilian Savanna Oxisols

2000 ◽  
Vol 163 (4) ◽  
pp. 411-419 ◽  
Author(s):  
Juliane Lilienfein ◽  
Wolfgang Wilcke ◽  
Lourival Vilela ◽  
Samuel do Carmo Lima ◽  
Richard Thomas ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Soil Solution ◽  
Solid Phase ◽  
Conventional Tillage ◽  
Brazilian Savanna ◽  
No Tillage ◽  
Tillage Systems ◽  
Soil Solid Phase

scholarly journals Soil phosphorus availability and uptake by mycorrhizal and non-mycorrhizal plants in an onion no-tillage system

2021 ◽  
Vol 51 (10) ◽  
Author(s):  
Bárbara Santos Ventura ◽  
Edenilson Meyer ◽  
Monique Souza ◽  
André Steiner Vieira ◽  
Juliana do Amaral Scarsanella ◽  
...  
Keyword(s):  
Acid Phosphatase ◽  
Phosphatase Activity ◽  
Cover Crops ◽  
Acid Phosphatase Activity ◽  
Soil Phosphorus ◽  
Conventional Tillage ◽  
Phosphorus Availability ◽  
No Tillage ◽  
Oilseed Radish ◽  
Tillage System

ABSTRACT: Onion is an important vegetable crop, predominantly grown under conventional tillage system management. Alternatively, the vegetable no-tillage system uses cover crops to form a residue layer, which improves soil physical, chemical, and biological attributes. Aiming to understand the interaction of mycorrhizal and non-mycorrhizal cover crops, phosphatase activity, and soil phosphorus availability and uptake by plants, a no-tillage vegetable production system experiment with onion was carried out in Ituporanga, Southern Brazil. The treatments were black oats (Avena strigosa); rye (Secale cereale); oilseed radish (Raphanus sativus); rye + oilseed radish; black oats + oilseed radish, and a control with spontaneous plants. Additionally, two plots, a conventional tillage system area and a forest, both adjacent to the experiment, were evaluated. We measured cover crop biomass, onion yield, acid phosphatase activity, and resin-extracted phosphorus in the soil, shoot and root phosphorus content, and root colonization in cover crops, spontaneous plants, and onions. The treatments with cover crops had the highest plant biomass in winter and onion yield. Available soil phosphorus and acid phosphatase activity were higher in no-tillage plots than in the conventional tillage system area. The presence of non-mycorrhizal oilseed radish was associated with decreased colonization of rye and onion roots by arbuscular mycorrhizal fungi. No-tillage areas with cover crops or spontaneous plants in winter accumulated more phosphorus than conventional tillage system areas. The conventional tillage system showed adverse effects on most soil attributes, as shown by a Principal Component Analysis.

Influence of medium on alkaline hydrolysis of succinic acid monomethyl and monopropyl esters

1980 ◽  
Vol 45 (11) ◽  
pp. 2873-2882
Author(s):  
Vladislav Holba ◽  
Ján Benko
Keyword(s):  
Succinic Acid ◽  
Kinetic Parameters ◽  
Alkaline Hydrolysis ◽  
Specific Interactions ◽  
Nonaqueous Media ◽  
The Media ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of alkaline hydrolysis of succinic acid monomethyl and monopropyl esters were studied in mixed aqueous-nonaqueous media at various temperatures and ionic strengths. The results of measurements are discussed in terms of electrostatic and specific interactions between the reactants and other components of the reaction mixture. The kinetic parameters in the media under study are related to the influence of the cosolvent on the solvation sphere of the reactants.

Kinetics of temperature-programmed reactivation of a hydrodesulphurization catalyst

1983 ◽  
Vol 48 (12) ◽  
pp. 3340-3355 ◽  
Author(s):  
Pavel Fott ◽  
Pavel Šebesta
Keyword(s):  
Carbon Dioxide ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Thin Layer ◽  
Kinetic Parameters ◽  
Diffusion Region ◽  
Reaction Heat ◽  
Gaseous Products ◽  
Temperature Programmed ◽  
Kinetics Of

The kinetic parameters of reactivation of a carbonized hydrodesulphurization (HDS) catalyst by air were evaluated from combined thermogravimetric (TG) and differential thermal analysis (DTA) data. In addition, the gaseous products leaving a temperature-programmed reactor with a thin layer of catalyst were analyzed chromatographically. Two exothermic processes were found to take part in the reactivation, and their kinetics were described by 1st order equations. In the first process (180-400 °C), sulphur in Co and Mo sulphides is oxidized to sulphur dioxide; in the second process (300-540 °C), in which the essential portion of heat is produced, the deposited carbon is oxidized to give predominantly carbon dioxide. If the reaction heat is not removed efficiently enough, ignition of the catalyst takes place, which is associated with a transition to the diffusion region. The application of the obtained kinetic parameters to modelling a temperature-programmed reactivation is illustrated on the case of a single particle.

scholarly journals The crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Blessing Mhlanga ◽  
Laura Ercoli ◽  
Elisa Pellegrino ◽  
Andrea Onofri ◽  
Christian Thierfelder
Keyword(s):  
Crop Rotation ◽  
Southern Africa ◽  
Cropping Systems ◽  
Conservation Agriculture ◽  
Conventional Tillage ◽  
Yield Stability ◽  
No Tillage ◽  
The Stability ◽  
Stability And Resilience

AbstractConservation agriculture has been promoted to sustainably intensify food production in smallholder farming systems in southern Africa. However, farmers have rarely fully implemented all its components, resulting in different combinations of no-tillage, crop rotation, and permanent soil cover being practiced, thus resulting in variable yield responses depending on climatic and soil conditions. Therefore, it is crucial to assess the effect of conservation agriculture components on yield stability. We hypothesized that the use of all three conservation agriculture components would perform the best, resulting in more stable production in all environments. We evaluated at, eight trial locations across southern Africa, how partial and full implementation of these components affected crop yield and yield stability compared with conventional tillage alone or combined with mulching and/or crop rotation. Grain yield and shoot biomass of maize and cowpea were recorded along with precipitation for 2 to 5 years. Across different environments, the addition of crop rotation and mulch to no-tillage increased maize grain by 6%, and the same practices added to conventional tillage led to 13% yield increase. Conversely, adding only mulch or crop rotation to no-tillage or conventional tillage led to lower or equal maize yield. Stability analyses based on Shukla’s index showed for the first time that the most stable systems are those in which mulch is added without crop rotation. Moreover, the highest yielding systems were the least stable. Finally, additive main effects and multiplicative interaction analysis allowed clarifying that mulch added to no-tillage gives stable yields on sandy soil with high rainfall. Similarly, mulch added to conventional tillage gives stable yield on sandy soil, but under low rainfall. This is the first study that highlighted the crucial role of mulch to enhance the stability and resilience of cropping systems in southern Africa, supporting their adaptability to climate change.

Kinetics of bumetanide-sensitive Na+-K+ co-transport in erythrocytes of essential hypertensive patients

1985 ◽  
Vol 69 (5) ◽  
pp. 607-611 ◽  
Author(s):  
Pietro Delva ◽  
Mario De Gasperi ◽  
Maurizio Degan ◽  
Grazia Covi ◽  
Alessandro Lechi
Keyword(s):  
Kinetic Parameters ◽  
Transport System ◽  
Clinical Data ◽  
Laboratory Data ◽  
Cation Transport ◽  
Hypertensive Patients ◽  
Apparent Affinity ◽  
Normotensive Subjects ◽  
Kinetics Of

1. Outward bumetanide-sensitive Na+-K+ co-transport was studied in the erythrocytes of 51 subjects, 24 normotensive subjects and 27 hypertensive patients, matched for sex and age. 2. Three kinetic parameters of this cation transport system were considered: velocity of efflux at saturating internal sodium (Nai) concentrations (Vmax.), apparent affinity for sodium (K50%) and index of co-operativity among Nai sites (Hill's n). 3. We correlated these values with clinical and laboratory data determined routinely in hypertension. 4. There were no significant differences between normotensive and hypertensive subjects for the values considered and we did not find any significant correlations between co-transport and clinical data.

scholarly journals Microbial biomass and activity at various soil depths in a Brazilian oxisol after two decades of no-tillage and conventional tillage

2010 ◽  
Vol 42 (12) ◽  
pp. 2174-2181 ◽  
Author(s):  
L.C. Babujia ◽  
M. Hungria ◽  
J.C. Franchini ◽  
P.C. Brookes
Keyword(s):  
Microbial Biomass ◽  
Conventional Tillage ◽  
No Tillage

KIH-485 and S-metolachlor Efficacy Comparisons in Conventional and No-Tillage Corn

2006 ◽  
Vol 20 (3) ◽  
pp. 622-626 ◽  
Author(s):  
Patrick W. Geier ◽  
Phillip W. Stahlman ◽  
John C. Frihauf
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Conventional Tillage ◽  
Palmer Amaranth ◽  
Effective Control ◽  
No Tillage ◽  
Green Foxtail

Field experiments were conducted during 2003 and 2004 to compare the effectiveness of KIH-485 and S-metolachlor for PRE weed control in no-tillage and conventional-tillage corn. Longspine sandbur control increased as KIH-485 or S-metolachlor rates increased in conventional-tillage corn, but control did not exceed 75% when averaged over experiments. Both herbicides controlled at least 87% of green foxtail with the exception of no-tillage corn in 2004, when KIH-485 was more effective than S-metolachlor at lower rates. Palmer amaranth control ranged from 85 to 100% in 2003 and 80 to 100% in 2004, with the exception of only 57 to 76% control at the lowest two S-metolachlor rates in 2004. Puncturevine control exceeded 94% with all treatments in 2003. In 2004, KIH-485 controlled 86 to 96% of the puncturevine, whereas S-metolachlor controlled only 70 to 81%. Mixtures of atrazine with KIH-485 or S-metolachlor generally provided the most effective control of broadleaf weeds studied.

Kinetics of Nitrite Reduction by Zinc Metal: Influence of Metal Shape on the Determination of Kinetic Parameters

2010 ◽  
Vol 82 (7) ◽  
pp. 648-656 ◽  
Author(s):  
L Limousy ◽  
P Dutournie ◽  
D Hadjiev
Keyword(s):  
Kinetic Parameters ◽  
Nitrite Reduction ◽  
Zinc Metal ◽  
Kinetics Of ◽  
Metal Shape
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