Annual pattern of soil moisture stress under sown and native pastures

1959 ◽  
Vol 10 (4) ◽  
pp. 518 ◽  
Author(s):  
JE Begg
Keyword(s):  
Soil Moisture ◽  
New England ◽  
General Pattern ◽  
Moisture Stress ◽  
Soil Conditions ◽  
Soil Moisture Stress ◽  
South Wales ◽  
Native Pasture ◽  
Available Soil Moisture ◽  
Native Pastures

Soil moisture fluctuations were measured under a phalaris-white clover pasture and under three native pasture types in the New England region of New South Wales over a 4-year period, by means of the gypsum resistance block technique. The results indicate that large differences in available soil moisture occur at times within areas of apparently similar soil type and that these differences are reflected by the different pasture types in the area. Although the lengths of the period during which soil moisture was unavailable differed considerably under the different pastures the general pattern was similar. The months of greatest soil moisture stress were December, January, April, and May, while the period of most favourable soil moisture was from June to November. Thus although most of the rain fell during the period December to May the rain which fell from June to November was more effective in maintaining available soil moisture. The subsoil dried out more rapidly and remained dry for a longer period under the sown pasture than under the native pasture type which the area previously carried, owing to the greater rate of removal of available soil moisture from under the sown pasture. Of the three native pasture types studied, the most favourable soil moisture pattern for plant growth occurred under the Sorghum-Themeda pasture. This pasture type may be a useful indicator of areas with soil conditions favourable for the growth of productive sown pastures.

Nitrogen supplementation of ruminants grazing native pastures in New England, New South Wales

1976 ◽  
Vol 16 (82) ◽  
pp. 630 ◽  
Author(s):  
JP Langlands ◽  
JE Bowles
Keyword(s):  
New England ◽  
New South ◽  
Tritiated Water ◽  
Late Winter ◽  
Dietary Composition ◽  
Linseed Meal ◽  
Nitrogen Supplementation ◽  
South Wales ◽  
Native Pasture ◽  
Native Pastures

The potential for nitrogen (N) supplementation of ruminants grazing native pastures in late winter was examined in two experiments. In experiment 1 the N contents of the diet selected by unsupplemented sheep and cattle, and by cattle receiving a supplement of linseed meal were determined. Dietary composition was not affected by supplementation but sheep selected a diet averaging 1.7 gN/100 g OM which was significantly greater than the corresponding value of 0.96 gN/100 g OM for cattle. Differences in dietary composition between sheep and cattle were also evident in experiment 2 and were confirmed by analysis of rumen liquor. It was concluded that sheep would not respond to non-protein N supplementation but that cattle might be marginally N deficient. In experiment 2 groups of heifers grazing native pasture were offered supplements of either molassesurea containing 2.54 gN/100 g OM, molasses-urea containing 7.66 gN/100 g OM, linseed meal containing 6.64 gN/100 g OM, or linseed meal treated with formaldehyde. Liveweight changes relative to an unsupplemented group were determined, and individual consumptions of supplement were measured using tritiated water. All heifers lost weight and the rate of loss was significantly greater in unsupplemented heifers than in those receiving supplement. Differences between supplemented groups were not significant after liveweight losses had been adjusted to equal energy intakes using covariance analysis.

scholarly journals Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO<sub>2</sub> and water fluxes through combined in situ measurements and ecosystem modelling

2009 ◽  
Vol 6 (8) ◽  
pp. 1423-1444 ◽  
Author(s):  
T. Keenan ◽  
R. García ◽  
A. D. Friend ◽  
S. Zaehle ◽  
C. Gracia ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Forest Canopy ◽  
Moisture Stress ◽  
Mediterranean Ecosystems ◽  
Forest Growth ◽  
Water Fluxes ◽  
Soil Moisture Stress ◽  
Dynamic Global Vegetation Model ◽  
Forest Growth Model

Abstract. Water stress is a defining characteristic of Mediterranean ecosystems, and is likely to become more severe in the coming decades. Simulation models are key tools for making predictions, but our current understanding of how soil moisture controls ecosystem functioning is not sufficient to adequately constrain parameterisations. Canopy-scale flux data from four forest ecosystems with Mediterranean-type climates were used in order to analyse the physiological controls on carbon and water flues through the year. Significant non-stomatal limitations on photosynthesis were detected, along with lesser changes in the conductance-assimilation relationship. New model parameterisations were derived and implemented in two contrasting modelling approaches. The effectiveness of two models, one a dynamic global vegetation model ("ORCHIDEE"), and the other a forest growth model particularly developed for Mediterranean simulations ("GOTILWA+"), was assessed and modelled canopy responses to seasonal changes in soil moisture were analysed in comparison with in situ flux measurements. In contrast to commonly held assumptions, we find that changing the ratio of conductance to assimilation under natural, seasonally-developing, soil moisture stress is not sufficient to reproduce forest canopy CO2 and water fluxes. However, accurate predictions of both CO2 and water fluxes under all soil moisture levels encountered in the field are obtained if photosynthetic capacity is assumed to vary with soil moisture. This new parameterisation has important consequences for simulated responses of carbon and water fluxes to seasonal soil moisture stress, and should greatly improve our ability to anticipate future impacts of climate changes on the functioning of ecosystems in Mediterranean-type climates.

scholarly journals Erratum: Effect of soil moisture stress from flowering to grain maturity on functional properties of Sri Lankan rice flour

2011 ◽  
Vol 63 (6) ◽  
pp. 392-392 ◽  
Author(s):  
Anil Gunaratne ◽  
Upul Kumari Ratnayaka ◽  
Nihal Sirisena ◽  
Jennet Ratnayaka ◽  
Xiangli Kong ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Functional Properties ◽  
Rice Flour ◽  
Moisture Stress ◽  
Sri Lankan ◽  
Soil Moisture Stress

The effects of soil moisture stress on the growth of barley. I. Vegetative development and grain yield

1964 ◽  
Vol 15 (5) ◽  
pp. 729 ◽  
Author(s):  
D Aspinall ◽  
PB Nicholls ◽  
LH May
Keyword(s):  
Grain Size ◽  
Soil Moisture ◽  
Grain Yield ◽  
Stem Elongation ◽  
Moisture Stress ◽  
The Other ◽  
Vegetative Development ◽  
Soil Moisture Stress ◽  
The One ◽  
Periods Of Stress

The effects of soil moisture stress on tillering, stem elongation, and grain yield of barley (cv. Prior) have been studied by subjecting the plants to periods of stress at different stages of development. Soil moisture stress treatments consisted of repeated short cycles of stress, single short cycles (both in large pots), or single long cycles (in large lysimeters). The data collected support the contention that the organ which is growing most rapidly at the time of a stress is the one most affected. Grain numbers per ear were seriously affected by stress occurring prior to anthesis, an effect probably associated with the process of spikelet initiation and, later, with the formation of the gametes. Grain size, on the other hand, was reduced more by stress at anthesis and shortly after. Elongation of the internodes was reduced mostly by stress at or just before earing, and was less seriously affected by earlier or later stress. Tillering, although being suppressed during a drought cycle, was actually stimulated upon rewatering. The effect was greater the earlier the period of stress, and was probably related to nutrient uptake and distribution within the plant.

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