Tree clearing and dryland salinity hazard in the Upper Burdekin Catchment of North Queensland

Soil Research ◽  
1997 ◽  
Vol 35 (4) ◽  
pp. 785 ◽  
Author(s):  
John Williams ◽  
E. N. Bui ◽  
E. A. Gardner ◽  
Mark Littleboy ◽  
M. E. Probert
Keyword(s):  
Water Balance ◽  
Vegetation Change ◽  
Root Zone ◽  
Simulation Models ◽  
Significant Shift ◽  
Deep Drainage ◽  
Dryland Salinity ◽  
Salinity Hazard ◽  
Red Earth ◽  
Salt Distribution

This paper provides experimental data on the effect of tree clearing, introduction of perennial Stylosanthes based pastures, and the use of native grasses on the water balance of a red earth soil in the Upper Burdekin Catchment near Charters Towers. The water balance simulation models SWIM and PERFECT are used to extend the results and estimate deep drainage for this and other soils in this tropical environment. The analysis illustrates that the soil/climate interaction in the wet/dry tropics has a similarity with the winter-dominant rainfall zone where vegetation change can substantially increase deep drainage beyond the root-zone. Salt distribution in the soil/landscapes of the Upper Burdekin suggests that there is a salinity hazard, should a significant shift in the water balance occur as a result of tree clearing. Therefore, in the Upper Burdekin Catchment of North Queensland, indiscriminate tree clearing is a hazardous form of land management and should only proceed after the risks of dryland salinity have been evaluated and shown to be negligible.

Relationship between yield of grain sorghum (Sorghum bicolor) and soil salinity under field conditions

2001 ◽  
Vol 41 (2) ◽  
pp. 211 ◽  
Author(s):  
I. G. Daniells ◽  
J. F. Holland ◽  
R. R. Young ◽  
C. L. Alston ◽  
A. L. Bernardi
Keyword(s):  
Sorghum Bicolor ◽  
Field Experiments ◽  
Surface Soil ◽  
Root Zone ◽  
Saline Soil ◽  
Grain Sorghum ◽  
Yield Reduction ◽  
Sampling Point ◽  
Dryland Salinity ◽  
Salinity Hazard

Three field experiments using grain sorghum (Sorghum bicolor), an important dryland summer crop on the Liverpool Plains in northern New South Wales, were conducted: (i) to determine the effect of dryland salinity on the yield of commercial crops at 2 sites; (ii) to see if ridging the soil would ameliorate the problem; and (iii) to compare 16 commercial varieties for tolerance to dryland salinity. Grain sorghum was shown to be more severely affected by dryland salinity than most literature would suggest. Over 3 seasons and 2 sites, sorghum yield was reduced by 50% at soil electrical conductivity (saturation extract, ECe) levels as low as 2.8 dS/m whereas advisory literature indicated a salinity threshold (no yield reduction) for sorghum of 6.8 dS/m, and 50% yield reduction at 9.9 dS/m. Current advisory literature is based on research where salinity was artificially imposed after plants were established in non-saline soil. The measurements described in this paper were on sorghum sown into saline soil. Soil and crop management strategies (ridging the soil or choosing a tolerant variety) showed limited potential for improving yields of grain sorghum on saline soil. At one site, the ECe varied widely across the paddock but little down the soil profile at any sampling point. Hence, analysing the surface soil would indicate the salinity hazard. However, at a second site, where ECe levels in the surface soil were low (<2 dS/m) everywhere, ECe at soil depths of 1 m varied widely (from 2 to 15 dS/m) across the paddock. Soil sampling to assess salinity hazard before crop planting should therefore include the entire root zone.

Water Use by Maize at Three Plant Densities

1971 ◽  
Vol 7 (2) ◽  
pp. 161-169 ◽  
Author(s):  
Lloyd A. Downey
Keyword(s):  
Soil Moisture ◽  
Water Balance ◽  
Water Use ◽  
Root Zone ◽  
Ground Cover ◽  
Grain Filling ◽  
Stress Conditions ◽  
Actual Evapotranspiration ◽  
Deep Drainage ◽  
Plant Densities

SUMMARYWater use by maize at three densities was measured by a complete water balance, including soil moisture, rain, applied irrigation and deep drainage in crops irrigated so that relative turgidity at noon remained above 90 per cent (i.e. no-stress conditions). Total evapotranspiration between planting and harvest, 56 cm., was not significantly affected by density, but evapotranspiration was slightly higher at higher densities when ground cover was less than 50 per cent. Actual evapotranspiration rose to 1 cm. per day during anthesis and grain filling. A fifth of the water applied moved beyond the root zone, indicating that work on more permeable soils would be inaccurate if the deep drainage component was ignored.

Comparative assessment of soil water balance under wheat in a subtropical environment with simplified models

1997 ◽  
Vol 128 (4) ◽  
pp. 461-468 ◽  
Author(s):  
V. K. ARORA ◽  
CHARANJIT SINGH ◽  
KULDEEP SINGH
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Root Zone ◽  
Balance Model ◽  
Soil Water Storage ◽  
Water Evaporation ◽  
Deep Drainage ◽  
Water Balance Components ◽  
Area Index ◽  
Empirical Coefficients

Water balance components under wheat were assessed by employing two simple models, differing in their structure and data requirements, namely the soil-plant–atmosphere–water (SPAW) model of Saxton (1989) and the water balance model (WBM) of Arora et al. (1987). A few modifications based on the SPAW model procedure for the estimation of green canopy were used in a modified WBM and its performance was also tested. Soil water loss (the sum of interception evaporation, soil evaporation, plant transpiration and deep drainage) from sowing to harvest, simulated with the WBM, modified WBM and the SPAW model, had a close correspondence with the measured sum of profile water depletion, rainfall and irrigation for values ranging between 18·3 and 42·7 cm. Estimates of drainage with the WBM and modified WBM using empirical coefficients were greater than those calculated using the SPAW model for situations where the upward flow of water into the root-zone was negligible. Estimates of soil water evaporation using the WBM and modified WBM were invariably smaller than those using the SPAW model. A comparison of simulated and measured soil water storage and a correlation analysis of simulated transpiration with measured biomass at harvest showed that the performance of the WBM was the most realistic of the three models. However, it requires the input of leaf area index values to infer green canopy for each water supply regime. In the absence of this information, the modified WBM and SPAW models are more useful for assessing water balance components in cropped soils.

Water use by annual crops. 1. Role of dry matter production

2007 ◽  
Vol 58 (12) ◽  
pp. 1159 ◽  
Author(s):  
P. R. Ward ◽  
D. J. M. Hall ◽  
S. F. Micin ◽  
K. Whisson ◽  
T. M. Willis ◽  
...  
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Western Australia ◽  
Dry Matter ◽  
Soil Evaporation ◽  
Dry Matter Production ◽  
Deep Drainage ◽  
Dryland Salinity ◽  
Annual Crops ◽  
Matter Production

In southern Australia, expanding dryland salinity is the result of increased deep drainage associated with widespread replacement of native perennial vegetation by annual agricultural crops and pastures. Although perennial pastures have been shown to assist in slowing salinisation, their adoption has been slow, and annual crops and pastures are likely to remain as the dominant land use for the foreseeable future. Therefore, understanding the water balance of annual crops and pastures, and how it can be manipulated, is important in trying to manage salinity. In this research we investigate the effect of varying levels of dry matter production on components of the water balance (soil evaporation, transpiration, soil water storage, and drainage) for annual crops at contrasting sites and soil types in south-western Australia. Dry matter production was controlled by fertiliser addition and crop rotation, and varied by a factor of up to 2, depending on seasonal conditions. Deep drainage was zero for most sites and years, but where it was greater than zero, there was no discernible effect due to production level. Out of a total of 14 site/year comparisons, the difference in soil water extraction associated with greater dry matter production averaged 5 mm, and was greater than 20 mm on only 1 occasion. However, high dry matter production was associated with greater transpiration, at the expense of soil evaporation. Manipulating dry matter production is unlikely to have a substantial effect on deep drainage and the expansion of dryland salinity in south-western Australia.

Salt source for dryland salinity - evidence from an upland catchment on the Southern Tablelands of New South Wales

Soil Research ◽  
2001 ◽  
Vol 39 (1) ◽  
pp. 39 ◽  
Author(s):  
R. I. Acworth ◽  
J. Jankowski
Keyword(s):  
New South ◽  
New South Wales ◽  
Dust Storms ◽  
Dryland Salinity ◽  
Heterogeneous Distribution ◽  
Small Catchment ◽  
South Wales ◽  
Bedrock Weathering ◽  
Salt Distribution ◽  
The Last Glacial

A detailed study involving drilling, geophysics, hydrogeochemistry, and groundwater monitoring over a 10-year period has been carried out at a small catchment south-east of Yass on the Southern Tablelands of New South Wales to investigate the source of salt causing dryland salinity. The catchment is within 2 km of the top of a regional groundwater and surface water divide and remains substantially tree covered. The investigations have found a highly heterogeneous distribution of salt, most of which is associated with swelling clay. Dispersion of this clay causes the surface features commonly associated with dryland salinity. There is no hydrogeochemical evidence to suggest evaporative or transpirative concentration of salt in the groundwater. The short flow path from the top of the catchment cannot provide a significant source of salt from bedrock weathering. An alternative model of salt accumulation is proposed with the salt imported into the catchment with silt during dust storms in the arid and windy conditions during the last glacial. The management implications of this model of salt distribution and the associated dryland salinity development are discussed.

Basic Concepts of Modeling Pesticide Fate in the Crop Root Zone

Weed Science ◽  
1985 ◽  
Vol 33 (S2) ◽  
pp. 25-32 ◽  
Author(s):  
R. J. Wagenet ◽  
P.S.C. Rao
Keyword(s):  
Environmental Fate ◽  
Root Zone ◽  
Effective Means ◽  
Simulation Models ◽  
Cost Effective ◽  
Natural Processes ◽  
Modeling Approach ◽  
Efficacy Trials ◽  
Sorption Leaching ◽  
Crop Root

Modeling is increasingly being used as a tool for the evaluation of the environmental fate of pesticides. Sorption, leaching, degradation, and volatilization are some of the processes being integrated through the use of simulation modeling techniques. Several research programs are focusing their attention on such issues (16, 17, 18, 32, 35), with regulatory agencies involved in management of pesticides also taking a modeling approach (3, 7). Because of the extreme complexity of agroecosystems, it is obvious that the use of simulation models will continue to be the most expeditious, reliable, and cost-effective means of integrating the various processes acting upon a pesticide to determine its fate. For example, modeling will help to summarize and interpret efficacy trials and will provide the vehicle for transferring experimental results to unstudied situations, such as the potential environmental fate of an applied herbicide. However, proper development, testing, and responsible use of a modeling approach must be based upon a thorough, comprehensive understanding of interdependent and dynamic natural processes.

Estimating yield of sorghum using root zone water balance model and spectral characteristics of crop in a dryland Alfisol

2007 ◽  
Vol 87 (3) ◽  
pp. 315-327 ◽  
Author(s):  
Uttam Kumar Mandal ◽  
U.S. Victor ◽  
N.N. Srivastava ◽  
K.L. Sharma ◽  
V. Ramesh ◽  
...  
Keyword(s):  
Water Balance ◽  
Root Zone ◽  
Spectral Characteristics ◽  
Water Balance Model ◽  
Balance Model ◽  
Zone Water

Water use efficiency and water use of Mediterranean annual pastures in southern Australia

1999 ◽  
Vol 50 (6) ◽  
pp. 1035 ◽  
Author(s):  
T. P. Bolger ◽  
N. C. Turner
Keyword(s):  
Water Use Efficiency ◽  
Linear Relationship ◽  
Water Use ◽  
Management Practices ◽  
Root Zone ◽  
Annual Rainfall ◽  
High Input ◽  
Deep Drainage ◽  
Pasture Production ◽  
Use Efficiency

There is a perception in the farming and research communities that annual pastures have low produc- tivity and water use, and contribute disproportionately to problems of rising watertables and dryland salinity. Our aim was to determine potential pasture production in relation to water use and the influence of management factors on this relationship. Experiments were initiated at 4 locations along a gradient of 300–1100 mm annual rainfall across the Western Australian agricultural zone. At each site a high input treatment was compared with a low input control. There was a strong linear relationship between water use and pasture production up to 440 mm of growing- season water use. After 30 mm of water use the potential pasture production was 30 kg/ha.mm. An upper limit to pasture production may be reached at about 12 000 kg/ha in this environment due to rainfall distribution patterns and soil water holding capacity in the root-zone. Although pasture production was increased by as much as 3500 kg/ha, water use was generally similar or only slightly more for high input compared with control plots. The marginally higher water use by the high input pastures resulted in an extra 18 mm of water extracted from the subsoil at one location by the end of the third season. A drier subsoil may provide a buffer for storing excess rainfall and reduce deep drainage. Estimated drainage was small at low rainfall sites so even marginal increases in water use by highly productive annual pastures could play a significant role in reducing water loss to deep drainage and mitigating water-table rise and secondary salinisation in low rainfall regions. Management practices aimed at promoting early growth and adequate leaf area should maximise water use, water use efficiency, and yield. The linear relationship defining potential pasture production provides a useful benchmark to farmers.

Control of water leakage from below the root zone by summer-active pastures is associated with persistence, density and deep rootedness

2016 ◽  
Vol 67 (6) ◽  
pp. 679 ◽  
Author(s):  
M. R. McCaskill ◽  
G. A. Kearney
Keyword(s):  
Perennial Ryegrass ◽  
Tall Fescue ◽  
Plant Density ◽  
Root Zone ◽  
Empirical Relationship ◽  
Water Leakage ◽  
Dryland Salinity ◽  
Dry Soil ◽  
Temperate Pastures ◽  
Western Victoria

Temperate pastures that leak water below the root zone have been linked to an increase in dryland salinity in southern Australia through their conservative use of stored water. An experiment was conducted at Hamilton in south-western Victoria to test the hypothesis that deep-rooted, summer-active perennial pasture species can substantially reduce leakage. On topographic crests the experiment compared lucerne and chicory with a traditional perennial ryegrass variety with low summer activity, whereas on the poorly drained valleys the comparison was between tall fescue, kikuyu and a perennial ryegrass variety with high summer activity. Lucerne developed a buffer of dry soil to a depth of at least 5 m. An empirical relationship with June–September rainfall indicated that with this dry buffer, leakage below the root zone would not occur even in the wettest of years. Chicory developed a dry buffer to the depth of measurement (3 m), but plant density gradually declined and leakage started to occur 5 years after sowing. The perennial ryegrass with low summer activity had leakage nearly every year. On the valleys kikuyu was initially the most effective at drying the soil in summer, but its density declined at the expense of annuals and 3 years after sowing it became wetter than the other treatments. None of the pasture options on the valley fully controlled leakage, but both the summer-active perennial ryegrass and tall fescue were persistent and there was little difference in their capacity to extract summer moisture. This study showed that four characteristics were associated with a pasture that controlled leakage – summer activity, persistence, adequate density and deep rootedness. Of the species tested only lucerne satisfied all these criteria.

Simulation of the water balance for plants growing on coarse textured soils

Soil Research ◽  
1975 ◽  
Vol 13 (1) ◽  
pp. 21 ◽  
Author(s):  
BA Carbon ◽  
KA Galbraith
Keyword(s):  
Computer Simulation ◽  
Water Balance ◽  
Simulation Model ◽  
Close Agreement ◽  
Water Storage ◽  
Field Measurements ◽  
Soil Water Storage ◽  
Physical Parameters ◽  
Computer Simulation Model ◽  
Deep Drainage

A computer simulation model* of the water balance for plants growing on coarse soils was developed and tested against field measurements. The inputs for this model are measurable physical parameters. From the close agreement between simulated and observed results, it is suggested that evaporation, soil water storage and deep drainage may be satisfactorily predicted.

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