The relationship between soil pH measurements in calcium chloride and water suspensions

Soil Research ◽  
1992 ◽  
Vol 30 (5) ◽  
pp. 587 ◽  
Author(s):  
IP Little
Keyword(s):  
Linear Relationship ◽  
Soil Water ◽  
New South ◽  
Neutral Red ◽  
Ph Measurements ◽  
Water Suspension ◽  
South Wales ◽  
Water Suspensions ◽  
Sigmoidal Curve ◽  
The Relationship

The relationship between the pH in a 1:5 soil/water suspension and the pH in 0.01 m CaCl2 has always been considered to be linear, but recent findings favour a non-linear relationship. This trend was confirmed with a set of 1342 surface soils from acid to neutral red duplex and gradational soils from the Lachlan Shire in central western New South Wales. The linear relationship was consistent with that found by earlier workers, but inclusion of the second and third powers of pH(w) accounted for significantly more of the variation in pH(ca) resulting in a sigmoidal curve. It is suggested that the deviation from linearity is due to the buffering effect of Al at low pH and to the presence of carbonate at high pH. Several other attributes were shown to influence pH, namely the ionic strength as indicated by the electrical conductivity of the 1:5 soil/water suspension, exchangeable cations (Na, K, Ca,Mg and Al) and Al and Mn extracted with 0-01 m CaCl2, and their effect varied at different pH levels.

Soil-extractable sulfur and pasture response to applied sulfur

1998 ◽  
Vol 38 (6) ◽  
pp. 567 ◽  
Author(s):  
G. C. Anderson ◽  
R. D. B. Lefroy ◽  
G. J. Blair
Keyword(s):  
Dry Matter ◽  
New South ◽  
Growth Period ◽  
Acid Digestion ◽  
Extraction Techniques ◽  
Organic S ◽  
South Wales ◽  
Trifolium Repens L ◽  
Soil Sulfur ◽  
The Relationship

Summary. A glasshouse experiment was conducted to study the correlation between various soil sulfur (S) extractants and pasture response to applied S grown under controlled environmental conditions (glasshouse) as influenced by variations in levels of extractable S. Intact paired soil cores were collected at 2-month intervals from an S x P factorial experiment at 4 field sites on the Northern Tablelands of New South Wales on 11 occasions. Soil samples were collected from each core and the cores placed in the glasshouse. Sulfur was applied to one core of each pair and basal nutrients applied to all cores which were then oversown with white clover (Trifolium repens L. cv. Haifa). The extractable S in the soil was analysed using the following techniques: 0.1 mol Ca(H2PO4)2/L (MCPt); 0.1 mol Ca(H2PO4)2/L, treated with activated charcoal (MCPi); water (H2O); 0.25 mol KCl/L, heated at 40°C for 3 h (KCl-40); 0.25 mol KCl/L, heated at 100°C for 4 h (KCl-100); 0.5 mol NaHCO3/L (NaHCO3); and an acid digestion of the soil (total). Dry matter yield and S content of the pasture shoots were measured for each 2-month growth period. The relationship between the various soil S extraction techniques and the response of pasture to applied S varied over time and was influenced by the level of inorganic S present in the soil and the amount of organic S extracted. When the level of MCPi-extractable S ranged between 2 and 22 µg S/g soil due to the application of fertiliser (summer 1987–88 and autumn 1988), or after a period of high mineralisation rates (spring 1988), the MCPi, MCPt, H2O and KCl-40 techniques had the highest correlation with the increase in S content of the pasture when S was applied. The higher correlation for the MCPt, H2O and KCl-40 techniques than the MCPi technique indicates that plants obtained some S from the organic S pool. In contrast, when the levels of MCPi-extractable S ranged between 2 and 10 µg S/g soil and the rate of mineralisation increased in response to an increase in soil temperature (June 1988 and June 1989) or moisture (September 1989) upon transfer of samples from the field to the glasshouse, the MCPt, H2O and KCl-40 techniques underestimated the available S pool and had lower r2 values than either the KCl-100 or NaHCO3 techniques.

A cone penetrometer for estimating available soil water

1977 ◽  
Vol 17 (88) ◽  
pp. 842 ◽  
Author(s):  
RG Fawcett
Keyword(s):  
Soil Water ◽  
Soil Texture ◽  
New South ◽  
Clay Soils ◽  
Cone Penetrometer ◽  
Cone Penetration ◽  
Swelling Clay ◽  
South Wales ◽  
Water Contents ◽  
Soil Water Contents

The effect of cone diameter (9.5 to 24.4 mm; 9.5 mm shaft) on the entry of penetrometers into swelling clay soils, and the relations between penetration and soil water contents, have been studied in northern New South Wales. Cones with diameters of approx. 14 mm were chosen for calibration tests on farms. The depth of wet soil and the amount of available water within the wetted zone were both related to the depth of maximum cone penetration (r2 values of 0.78-0.98 at sites with relatively uniform profiles of soil texture). Available soil water contents and water potentials were also related to the force needed for cone penetration. The penetrometer will assist in estimating soil water contents in areas where grain yields are related to available fallow water at seeding.

Surface soil water dynamics in pastures in northern New South Wales. 2. Surface runoff

2004 ◽  
Vol 44 (3) ◽  
pp. 283 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge ◽  
S. Harden
Keyword(s):  
Soil Water ◽  
Surface Runoff ◽  
New South ◽  
Ground Cover ◽  
Simulation Modelling ◽  
Runoff Generation ◽  
Grazed Pastures ◽  
South Wales ◽  
Runoff Events

Surface runoff can represent a significant part of the hydrological balance of grazed pastures on the north-west slopes of New South Wales, and is influenced by a range of rainfall characteristic, soil property, and pasture conditions. Runoff plots were established on grazed pastures at 3 sites as part of the Sustainable Grazing Systems National Experiment (SGS NE). Pastures were either native (redgrass, wallaby grass and wire grass) or sown species (phalaris, subterranean clover and lucerne) and a range of grazing management treatments were imposed to manipulate pasture herbage mass, litter mass and ground cover. Rainfall and runoff events were recorded using automatic data loggers between January 1998 and September 2001. Stored soil water in the surface layer (0–22.5 cm) was monitored continuously using electrical resistance sensors and automatic loggers. Pasture herbage mass, litter mass and ground cover were estimated regularly to provide information useful in interpreting runoff generation processes.Total runoff ranged from 6.6 mm at Manilla (0.3% of rainfall) to 185 mm at Nundle (5.7% of rainfall) for different grazing treatments, with the largest runoff event being recorded at Nundle (46.7 mm). Combined site linear regression analyses showed that soil depth, rainfall depth and rainfall duration explained up to 30.3% of the variation in runoff depth. For individual sites, these same variables were also important, accounting for 13.3–33.6% of the variation in runoff depth. Continuous monitoring of stored soil water in relation to these runoff events indicated that the majority of these events were generated by saturation excess, with major events in winter contributing substantially to regional flooding. Long-term simulation modelling (1957–2001) using the SGS Pasture Model indicated that most runoff events were generated in summer, which concurred with the number of flood events recorded at Gunnedah, NSW, downstream of the SGS sites. However, floods also occurred frequently in winter, but the simulations generated few runoff events at that time of the year. These results have important implications for sustainability of grazed pastures and long-term simulation modelling of the hydrological balance of such systems, since runoff generation processes are likely to vary both spatially and temporally for different rainfall events.

Surface soil water dynamics in pastures in northern New South Wales. 1. Use of electrical resistance sensors

2004 ◽  
Vol 44 (3) ◽  
pp. 273 ◽  
Author(s):  
S. R. Murphy ◽  
G. M. Lodge
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Real Time ◽  
Surface Runoff ◽  
Electrical Resistance ◽  
New South ◽  
Water Dynamics ◽  
Continuous Data ◽  
Soil Water Dynamics ◽  
South Wales

Stored soil water may influence both the generation of surface runoff and the rate of evapotranspiration from pastures, which may be significant in northern New South Wales. Continuous data is essential to fully understand these processes in field studies. Electrical resistance sensors were used to capture continuous data and they were calibrated directly for soil water content (SWC), so as to provide quantitative data in real time. Calibration equations (logarithmic regression) were significantly different for a range of installation depths (2.5–20 cm). To�provide quantitative insight into soil water dynamics in studies of stored soil water, surface runoff, and evapotranspiration, real time data were collected at intervals ranging from 4 min to 24 h. Resistance sensors provided estimates of stored soil water (0–30 cm) that differed by up to 29% compared with estimates obtained from using a neutron moisture metre alone. In surface runoff studies, data collected at 4 min intervals showed that runoff was generated when soil water content was high. In studies of evapotranspiration, daily data were used to quantify different evapotranspiration rates (2.3–4.9 mm/day) and progressive depth of drying for a range of treatments. We concluded that data collected in real time using resistance sensors may be used to make better estimates of SWC and so improve the interpretation of surface runoff generation and evapotranspiration data.

A scheme for preliminary study of soil fertility in a district

1970 ◽  
Vol 10 (43) ◽  
pp. 196
Author(s):  
WM McArthur ◽  
K Spencer
Keyword(s):  
Soil Fertility ◽  
New South ◽  
Strong Correlations ◽  
South Wales ◽  
The Status ◽  
Using Data ◽  
Distribution Of Components ◽  
Edaphic Variables ◽  
The Relationship ◽  
Field Plots

A scheme is proposed as a basis for soil fertility studies in areas where little information is available. The first stage consists of sampling the area on a grid and determining the patterns of variation in the status of those nutrient elements likely to be deficient. These patterns are then compared with intensity patterns of environmental (including edaphic) variables. Where the two sets of variables can be quantified, regression analysis may be used to estimate the closeness of the relationship ; otherwise the relationship must be assessed visually from the degree of conformity between patterns. Those environmental variables that relate, causally or otherwise, to the distribution of components of chemical fertility are identified by strong correlations. Information so gained may be used in subsequent agronomic studies, both as a guide to number and location of field plots and as a framework for studies in soil chemistry and pedology. The scheme is illustrated using data derived from studies on the Dorrigo Plateau of New South Wales. Factors relating closely to phosphorus, sulphur, molybdenum, and nitrogen distribution were identified. In no case could one factor be used to predict the adequacy of all nutrients.

Factors influencing herbicide efficacy when removing lucerne prior to cropping

2006 ◽  
Vol 46 (10) ◽  
pp. 1301 ◽  
Author(s):  
S. L. Davies ◽  
A. M. Storrie ◽  
A. S. Cook ◽  
R. A. Latta ◽  
A. D. Swan ◽  
...  
Keyword(s):  
Field Experiments ◽  
New South ◽  
Residual Activity ◽  
Management Guidelines ◽  
Herbicide Treatment ◽  
South Wales ◽  
Root Reserves ◽  
Herbicide Mixtures ◽  
The Impact ◽  
The Relationship

Farmers often experience inconsistent responses when using herbicides to terminate an established lucerne pasture prior to cropping. In an attempt to redress this problem, a series of field experiments were conducted between 1999 and 2002 at various locations in southern and northern New South Wales, the Australian Capital Territory, and south Western Australia that aimed to identify management guidelines that improved the efficacy of herbicide mixtures commonly used to remove lucerne. Collectively, these studies indicated that herbicides were generally less effective when applied either early (less than 2 weeks) or late (6 weeks or more) in the regrowth cycle of lucerne after defoliation. Herbicide efficacy tended to be greatest if applied to regrowth 3–5 weeks after defoliation, which corresponds to a time when the lucerne crown and root reserves are likely to be in the process of being replenished by photoassimilates transported from the shoot. The impact of timing of herbicide application in relation to season was compared at a number of locations. Across all the sites and years, spring herbicide applications were generally the most effective, removing on average 87% of the lucerne (range 53–100%) compared with 72% in summer (24–100%) and 60% in autumn (7–92%). Spring applications were also more consistent in their effect, removing >80% of the lucerne plants in 9 out of 12 experiments, whereas similar rates of removal occurred on 4 occasions in 9 summer applications and only twice in 8 autumn applications. Some of the seasonal variation could be explained by differences in the amount of rainfall prior to herbicide applications. It was assumed that the relationship between rainfall and herbicide efficacy reflected the stimulation of lucerne shoot and root growth by the additional soil moisture before herbicide treatment. Herbicide mixtures that contained ingredients such as picloram that retain residual activity in the soil tended to be more effective and were less influenced by lucerne growth and season than those herbicides with little or no residual activity. However, such chemicals could potentially restrict which crops can subsequently be grown after a lucerne pasture has been removed. It was concluded that >80% of lucerne plants were likely to be removed using herbicides provided that the herbicide treatment was applied to actively growing lucerne 3–5 weeks after defoliation, and when greater than 70–95 mm rain had fallen in the 6–8 weeks prior to application.

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