Drainage and change in soil water storage below the root-zone under long fallow and continuous cropping sequences in the Victorian Mallee

2003 ◽  
Vol 54 (7) ◽  
pp. 663 ◽  
Author(s):  
Mark G. O'Connell ◽  
Garry J. O'Leary ◽  
David J. Connor

A field study investigated drainage and changes in soil water storage below the root-zone of annual crops on a sandy loam soil in the Victorian Mallee for 8 years. It was designed to compare the effects of the common long (18-month) fallow in a 3-year rotation (fallow–wheat–pea, FWP) with a rotation in which the fallow was replaced with mustard (Brassica juncea), viz. mustard–wheat–pea (MWP). Drainage was measured over 2 periods (1993–98 and 1998–2001) using 9 in situ drainage lysimeters in each rotation. The first period of ~5 years was drier than average (mean annual rainfall 298 cf. 339 mm) and drainage was low and variable. Drainage was greater under the fallow rotation (average 0.24 mm/year) than under the non-fallow rotation (average <0.01 mm/year). The result for the fallow rotation did, however, include one lysimeter that recorded substantial drainage (10.6 mm over the 5 years). During the second period of measurement (~3 years), rainfall was above average (mean annual rainfall 356 cf. 339�mm) and drainage was greater. On average, drainage from the fallow rotation was 6.7 mm/year compared with the non-fallow rotation at 4.0 mm/year. There was again substantial variation between lysimeters. One lysimeter under MWP recorded 31.4 mm/year, and as in the earlier drier period, there were many lysimeters that recorded no drainage. During the drier first period (1993–98), changes in soil water storage between 1.5 and 5.5 m depth confirmed the tendency of the fallow rotation to increase deep drainage. Despite increases and decreases in subsoil water storage during the study, the cumulative change in water storage was positive and greatest under FWP (range: 2.8–14.8 mm/year, ave. 9.6 mm/year) compared with MWP (range: 5.3–9.8 mm/year, ave. 7.4 mm/year) cropping sequences. Overall, the long fallow system has the potential to increase deep drainage by approximately 2 mm/year compared with a fully cropped system, over a wide annual rainfall range (134–438 mm). Further, this experiment reinforces the focus for the reduction of fallow practices for dryland salinity control in the Mallee region.

1981 ◽  
Vol 61 (2) ◽  
pp. 425-435 ◽  
Author(s):  
C. S. TAN ◽  
J. M. FULTON

Several years of daily evapotranspiration (ET) data for irrigated early potatoes, corn and processing tomatoes, grown on Fox sandy loam measured by floating lysimeters and estimated by meteorological data were used to evaluate an equilibrium evapotranspiration (ETeq) model. A reasonable relationship was obtained between values estimated by the model and those measured by floating lysimeters. The ETeq model can be used to estimate daily ET over a wide range of soil moisture and foliage cover conditions. ETeq can be estimated from readily available climatic data in the form: ETeq = (0.48 + 0.01 Ta) [(0.114 + 0.365n/N) K↓a − 0.039]; where Ta is the mean daily air temperature (°C); n is sunshine duration (h); N is maximum hours of bright sunshine (h); K↓a is solar energy received at the top of the atmosphere (mm/day). At high soil water storage in the root zone, the ET/ETeq remained constant, whereas, at low soil water storage, the ET/ETeq decreased linearly with decreasing soil water storage. The total crop yields were directly related to growing season accumulated ET.


2007 ◽  
Vol 58 (12) ◽  
pp. 1129 ◽  
Author(s):  
K. Verburg ◽  
W. J. Bond ◽  
J. R. Hirth ◽  
A. M. Ridley

The use of a lucerne phase in crop rotations can reduce water lost as drainage past the root zone under dryland agriculture in southern Australia. During the lucerne phase the perenniality of lucerne and its deep rooting ability allow extraction of soil water from below the root zone of annual crops and the creation of a soil water storage buffer against deep water loss. The longevity of the soil water storage buffer depends on rainfall patterns, management of the crops and summer fallows, as well as the magnitude of the buffer created during the lucerne phase. Results from a previously reported field experiment in north-eastern Victoria (average annual rainfall 600 mm) suggested that a 2-year lucerne phase could be insufficient to prevent drainage under subsequent crops for more than 1 year. Computer simulations were used to explore the implications of climatic variability on the creation and refilling of the soil water storage buffer. After first testing that the simulations described the experimental data satisfactorily, they were then used to extend the results and conclusions of the field experiment. These showed that the outcome of the experimental evaluation was affected by the climatic conditions experienced during the experiment and that a lucerne phase duration of 2 years was not appreciably less effective than a 3-year lucerne phase in reducing drainage past 1.8 m (the depth evaluated in the experiment). This conclusion was, however, sensitive to the depth at which drainage was evaluated and also depended on management factors such as the timing of lucerne removal and weed control during the summer fallows. For example, when drainage was evaluated to the maximum depth of lucerne rooting (3.6 m), lucerne was removed in December rather than April, and weeds were permitted, a third year of lucerne allowed a longer cropping phase without refilling of the profile in 47% of years. As a general recommendation a 3-year lucerne phase might, therefore, be an appropriate option for maximising the prevention of drainage. The large variability in the longevity of the soil water storage buffer (from 3 to > 45 months) and its sensitivity to management suggest, however, that it may be more beneficial to link phase changes to local assessment of the status of soil water storage buffer.


SURG Journal ◽  
2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Archana Tamang

Understanding of the downward flux of water below the plant root zone, known as deep drainage (DD), is significant in agriculture and soil water conservation. It plays a key role to determine the amount of water that travels below the plant root zone and can potentially cause groundwater recharge. The DD in soil varies with location, soil texture, and topography. Thus, the objectives of this study were to determine the unsaturated hydraulic conductivity, soil water storage, and DD for the years 2012 (dry year) and 2013 (wet year) at the University of Guelph’s Arboretum. The depths to the water table data were collected using a Mini Water Level Meter. CS616 sensors were used to determine the soil volumetric water content. The soil temperature was extracted with the use of T107 Temperature Probes. The slug test, based on the Hvorslev method, was performed to determine the field saturated hydraulic conductivity. The soil moisture retention curve was produced based on the data collected in the lab with the use of pressure plate systems, using van Genuchten’s equation. The unsaturated hydraulic conductivity was also determined using van Genuchten’s equation. Darcy’s law was used to determine the specific discharge, which was then converted to the total DD. In general, the soil water storage was 38.5 mm higher in 2013 relative to 2012. The unsaturated hydraulic conductivity was approximately 2 times higher in 2013 than 2012. The average DD was approximately 25 mm higher in 2013. This study provides information needed to better understand the movement and amount of water flux and DD in larger details.


2021 ◽  
Author(s):  
XinRui Luo ◽  
Shaoda Li ◽  
Wunian Yang ◽  
Liang Liu ◽  
Xiaolu Tang

&lt;p&gt;Soil water storage serves as a vital resource of the terrestrial ecosystems, and it can significantly influence water cycle and carbon cycling with the frequent occurrence of soil drought induced by land-atmosphere feedbacks. However, there are high variations and uncertainties of root zone soil water storage. This study applied comparison map profile (CMP), Mann-Kendall test, Theil-Sen estimate and partial correlation analysis to (1) estimate the global root zone (0~1 m) soil water storage, (2) and investigate the spatial and temporal patterns from 1981 to 2017 at the global scale, (3) and their relationships with environmental drivers (precipitation, temperature, potential evaportranspiration) using three soil moisture (SM) products &amp;#8211; ERA-5, GLDAS and MERRA-2. Globally, the average annual soil water storage from 1981 to 2017 varied significantly, ranging from 138.3 (100 Pg a&lt;sup&gt;-1&lt;/sup&gt;, 1 Pg = 10&lt;sup&gt;15&lt;/sup&gt; g) in GLDAS to 342.6 (100 Pg a&lt;sup&gt;-1&lt;/sup&gt;) in ERA-5. Soil water storage of the three SM products consistently showed a decreasing trend. However, the temporal trend of soil water storage among different climate zones was different, showing a decreasing trend in tropical, temperate and cold zones, but an increasing trend in polar regions. On the other hand, temporal trends in arid regions differed from ERA-5, GLDAS and MERRA-2. Spatially, the SM products differed greatly, particularly for boreal areas with D value higher for 2500 Mg ha&lt;sup&gt;-1&lt;/sup&gt; a&lt;sup&gt;-1&lt;/sup&gt; and CC value lower for -0.2 between GLDAS and MERRA-2. Over 1981 to 2017, water storage of more than 50% of the global land area suffered from a decreasing trend, especially in Africa and Northeastern of China. Precipitation was the main dominated driver for variation of soil water storage, and distribution varied in different SM products. In conclusion, a global decreasing trend in soil water storage indicate a water loss from soils, and how the water loss affecting carbon sink in terrestrial ecosystems under ongoing climate change needs further investigation.&lt;/p&gt;


2001 ◽  
Vol 52 (2) ◽  
pp. 247 ◽  
Author(s):  
F. X. Dunin ◽  
C. J. Smith ◽  
S. J. Zegelin ◽  
R. Leuning

In a detailed study of soil water storage and transport in a sequence of 1 year wheat and 4 years of lucerne, we evaluated drainage under the crop and lucerne as well as additional soil water uptake achieved by the subsequent lucerne phase. The study was performed at Wagga Wagga on a gradational clay soil between 1993 and 1998, during which there was both drought and high amounts of drainage (>10% of annual rainfall) from the rotation. Lucerne removed an additional 125 mm from soil water storage compared with wheat (root-zone of ~1 m), leading to an estimated reduction in drainage to 30–50% of that of rotations comprising solely annual crops and/or pasture. This additional soil water uptake by lucerne was achieved through apparent root extension of 2–2.5 m beyond that of annual crops. It was effective in generating a sink for soil water retention that was about double that of annual crops in this soil. Successful establishment of lucerne at 30 plants/m2 in the first growing season of the pasture phase was a requirement for this root extension. Seasonal water use by lucerne tended to be similar to that of crops in the growing season between May and September, because plant water uptake was confined to the top 1 m of soil. Uptake of water from the subsoil was intermittent over a 2-year period following its successful winter establishment. In each of 2 annual periods, uptake below 1 m soil depth began late in the growing season and terminated in the following autumn. Above-ground dry matter production of lucerne was lower than that by crops grown in the region despite an off-season growth component that was absent under fallow conditions following cropping. This apparent lower productivity of lucerne could be traced in part to greater allocation of assimilate to roots and also to late peak growth rates at high temperatures, which incurred a penalty in terms of lower transpiration efficiency. The shortfall in herbage production by lucerne was offset with the provision of timely, high quality fodder during summer and autumn. Lucerne conferred indirect benefits through nitrogen supply and weed control. Benefits and penalties to the agronomy and hydrology of phase farming systems with lucerne are discussed.


Agriculture ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 888
Author(s):  
Katori Miyasaka ◽  
Takafumi Miyasaka ◽  
Jumpei Ota ◽  
Siilegmaa Batsukh ◽  
Undarmaa Jamsran

In recent years, Mongolia has witnessed an increase in not only wheat fields, which have been present for a long time, but also rapeseed fields. This has led to increasing concerns about soil degradation due to inappropriate cultivation. This study aims to determine the impacts of rapeseed production on soil water storage in Mongolia. The soil water content and matric potential were measured in wheat and rapeseed fields and adjacent steppe rangeland for five years, including crop production and fallow years, and the soil water storages in the fields were compared. The results demonstrated that the matric potential below the root zone in the rapeseed field and both rangelands was drier than the wilting point, whereas the potential in the wheat field was usually almost the same or wetter than this point. The comparison of the amount of soil water storage during the fallow year with that of the adjacent rangeland showed it to be 5–10% higher for the wheat field and almost equal for the rapeseed field. Field management must consider the fact that rapeseed fields use more water than is required by wheat fields and that less water is stored during fallow periods.


1979 ◽  
Vol 19 (97) ◽  
pp. 233 ◽  
Author(s):  
WK Anderson

The potential, or energy-limited evapotranspiration, and the actual, or soil water-limited evapotranspiration functions of sunflower were estimated by lysimetry and field soil water measurements. The functions show that peak water demand by the crop is in the immediate post-anthesis period and that sunflower is capable of restricting its water use when some 70% of the maximum available water remains in the root zone. With the aid of these functions, weekly estimates were made of the water use of thirteen commercial sunflower crops in northern New South Wales. Estimated water use ranged from 150 to 320 mrn and water use efficiencies from 1.9 to 10.5 kg seed mm-1 water used. Highest yields and water use efficiencies were associated with a combination of high total water supply (soil water at sowing plus rainfall during growth of 380 mm or more) high water use (220 mm or more) and low evaporative demand (below 780 mm of pan evaporation). Based on the water use characteristics of the crop the optimal sowing time in most areas is mid summer. However, spring sowings may be preferable for winter rainfall areas where soil water storage capacity is high and there is only a small component of summer rain. Crops sown in spring, even with high stored soil water (up to 200 mm) failed to yield as well as those sown in summer with much lower soil water storage.


2007 ◽  
Vol 64 (3) ◽  
pp. 215-220 ◽  
Author(s):  
Isabeli Pereira Bruno ◽  
Adriana Lúcia da Silva ◽  
Klaus Reichardt ◽  
Durval Dourado-Neto ◽  
Osny Oliveira Santos Bacchi ◽  
...  

The use of climatological water balances in substitution to complete water balances directly measured in the field allows a more practical crop management, since the climatological water balances are based on data monitored as a routine. This study makes a comparison between these methods in terms of estimatives of evapotranspiration, soil water storage, soil available water, runoff losses, and drainage below root zone, during a two year period, taking as an example a coffee crop of the variety Catuaí, three to five years old. Climatological water balances based on the estimation of the evapotranspiration through the methods of Thornthwaite and Penman-Monteith, can reasonably substitute field measured balances, however underestimating the above mentioned variables.


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