Surface Exchange of Ammonia over Grazed Pasture

1997 ◽  
pp. 285-291 ◽  
Author(s):  
M. A. H. G. Plantaz ◽  
A. T. Vermeulen ◽  
G. P. Wyers
Keyword(s):  
Surface Exchange ◽  
Grazed Pasture

Clay liner materials for land disposal of hazardous non-metal wastes

1996 ◽  
Vol 33 (8) ◽  
pp. 71-77
Author(s):  
I. M.-C. Lo ◽  
H. M. Liljestrand ◽  
J. Khim ◽  
Y. Shimizu
Keyword(s):  
Sorption Capacity ◽  
Organic Anion ◽  
Surface Exchange ◽  
Clay Liner ◽  
Effective Removal ◽  
Exchange Constants ◽  
Anionic Species ◽  
Surface Ligand ◽  
Land Disposal

Simple land disposal systems for hazardous and mixed wastes contain heavy metal cationic species through precipitation and ion exchange mechanisms but typically fail by releasing soluble organic and inorganic anionic species. To enhance the removal of anions from leachate, clays are modified with coatings of iron or aluminium cations to bridge between the anionic surface and the anionic pollutants. A competitive surface ligand exchange model indicates that surface coatings of 10 meq cation/gm montmorillonite under typical leachate conditions increase the inorganic anion sorption capacity by at least a factor of 6 and increase the intrinsic surface exchange constants by more than a factor of 100. Similarly, metal hydroxide coatings on montmorillonite increase the organic anion sorption capacity by a factor of 9 and increase the intrinsic surface exchange constants by a factor of 20. For historical concentrations of non-metal anions in US hazardous and mixed waste leachate, sorption onto natural clay liner materials is dominated by arsenate sorption. With cation coatings, anion exchange provides an effective removal for arsenate, selenate, phenols, cresols, and phthalates. Engineering applications are presented for the use of modified clays as in situ barriers to leachate transport of anionic pollutants as well as for above ground treatment of recovered leachate.

Grazed pasture parameters. I. Pasture dry-matter production and availability in a stocking rate and grazing management experiment with dairy cows

1966 ◽  
Vol 67 (2) ◽  
pp. 199-210 ◽  
Author(s):  
A.G. Campbell
Keyword(s):  
Dairy Cow ◽  
Dry Matter ◽  
Grazing Management ◽  
Dry Matter Production ◽  
Small Scale ◽  
Stocking Rate ◽  
Rotational Grazing ◽  
Pasture Production ◽  
Grazed Pasture ◽  
Matter Production

1. Net pasture dry matter production and available pasture dry matter were measured over 3 years in a small-scale replica of the study of the effects of dairy cow grazing management and stocking rate reported by McMeekan & Walshe (1963).2. The four treatments were(i) Controlled rotational grazing, light stocking rate (0.95 cows/acre).(ii) Controlled rotational grazing, heavy stocking rate (1.19 cows/acre).(iii) Uncontrolled, set stocked grazing, light stocking rate (0.95 cows/acre).(iv) Uncontrolled, set stocked grazing, heavy stocking rate (1.19 cows/acre).3. The pasture measurement technique employed measured net pasture production (gains through new growth minus losses from all sources). It is argued that this parameter, rather than absolute pasture production, governs the changes in the dry matter feed supply to the grazing animal.

scholarly journals Ammonia volatilisation from grazed, pasture based dairy farming systems

2021 ◽  
Vol 190 ◽  
pp. 103119
Author(s):  
Andrew P. Smith ◽  
Karen M. Christie ◽  
Matthew T. Harrison ◽  
Richard J. Eckard
Keyword(s):  
Farming Systems ◽  
Dairy Farming ◽  
Grazed Pasture ◽  
Ammonia Volatilisation

scholarly journals Influence of Heterointerfaces on the Kinetics of Oxygen Surface Exchange on Epitaxial La1.85Sr0.15CuO4 Thin Films

2021 ◽  
Vol 11 (9) ◽  
pp. 3778
Author(s):  
Gene Yang ◽  
So-Yeun Kim ◽  
Changhee Sohn ◽  
Jong K. Keum ◽  
Dongkyu Lee
Keyword(s):  
Thin Films ◽  
Oxygen Vacancies ◽  
Elevated Temperatures ◽  
Surface Exchange ◽  
Electrical Conductivity Relaxation ◽  
Exchange Kinetics ◽  
Relaxation Curves ◽  
Kinetics Of ◽  
Oxygen Surface Exchange ◽  
Oxygen Surface

Considerable attention has been directed to understanding the influence of heterointerfaces between Ruddlesden–Popper (RP) phases and ABO3 perovskites on the kinetics of oxygen electrocatalysis at elevated temperatures. Here, we report the effect of heterointerfaces on the oxygen surface exchange kinetics by employing heteroepitaxial oxide thin films formed by decorating LaNiO3 (LNO) on La1.85Sr0.15CuO4 (LSCO) thin films. Regardless of LNO decoration, tensile in-plane strain on LSCO films does not change. The oxygen surface exchange coefficients (kchem) of LSCO films extracted from electrical conductivity relaxation curves significantly increase with partial decorations of LNO, whereas full LNO coverage leads to the reduction in the kchem of LSCO films. The activation energy for oxygen exchange in LSCO films significantly decreases with partial LNO decorations in contrast with the full coverage of LNO. Optical spectroscopy reveals the increased oxygen vacancies in the partially covered LSCO films relative to the undecorated LSCO film. We attribute the enhanced oxygen surface exchange kinetics of LSCO to the increased oxygen vacancies by creating the heterointerface between LSCO and LNO.

A comparison of soil sampling procedures used to monitor soil fertility in permanent pastures

Soil Research ◽  
1984 ◽  
Vol 22 (1) ◽  
pp. 81 ◽  
Author(s):  
DK Friesen ◽  
GJ Blair
Keyword(s):  
Sampling Method ◽  
Nutrient Status ◽  
Temporal Variations ◽  
Cluster Sampling ◽  
Soil Test ◽  
Sampling Strategies ◽  
Grazed Pasture ◽  
The Mean ◽  
Sampling Procedures ◽  
Bray 1

Soil testing programs are often brought in disrepute by unexplained variability in the data. The deposition of dung and urine onto grazed pasture brings about marked variation in the chemical status of soils which contributes to this variability. A study was undertaken to compare a range of sampling procedures to estimate Colwell-P, Bray-1 P, bicarbonate K and pH levels in adjacent low and high P status paddocks. The sampling strategies used consisted of 75 by 50 m grids; whole and stratified paddock zig-zag and cluster (monitor plot) samplings. Soil test means for the various parameters did not vary among sampling methods. The number of grid samples required to estimate within 10% of the mean varied from 121 for Bray-1 P down to 1 for soil pH. Sampling efficiencies were higher for cluster sampling than for whole paddock zig-zag path sampling. Stratification generally did not improve sampling efficiency in these paddocks. Soil test means declined as sampling depth increased, but the coefficient of variation remained constant for Colwell-P and pH. The results indicate that cluster sampling (monitor plots) is the most appropriate procedure for estimating the nutrient status of grazed pastures. This sampling method enables a more accurate measure to be taken of the nutrient status of a paddock and should allow more reasonable estimates to be made of the temporal variations in soil test.

The design and interpretation of experiments to study animal production from grazed pasture

1968 ◽  
Vol 71 (3) ◽  
pp. 327-335 ◽  
Author(s):  
J. B. Owen ◽  
W. J. Ridgman
Keyword(s):  
Simple Model ◽  
Unit Area ◽  
Personal Communication ◽  
Animal Production ◽  
Stocking Rate ◽  
Grazed Pasture ◽  
Stocking Rates ◽  
Pasture Productivity

SUMMARYExperiments designed to assess differences between treatments in pasture productivity as measured by the production of animals are complicated by the stocking rates chosen. The paper attempts toderive a simple model relating production per animal and production per unit area to stocking rate for meat animals, based on biological considerations.A method is proposed which would allow meaningful grazing experiments to be carried out employing only one stocking rate, thus considerably reducing the expense of this type of experimentation.The model is applied to some recent data obtained by Hodgson (1966) and Appleton (1967, personal communication).

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