The effect of chisel ploughing and inter-row cultivation on soil water content and yield of bulrush millet (Pennisetum typhoides) at Katherine, N.T

1966 ◽  
Vol 6 (20) ◽  
pp. 48
Author(s):  
LJ Phillips ◽  
MJT Norman

A multifactorial experiment comprising combinations of three pre-wet-season chisel ploughing treatments, three wet-season chisel ploughing treatments, and three inter-row cultivation treatments was carried out on bulrush millet (Pennisetum typhoides S. & H.) at Katherine, N.T., in 1963-64, and was repeated in 1964-65. Pre-wet-season ploughing throughout the growth of the nitrogen yield of millet when treatments had very little effect on the dry matter or nitrogen yield of millet crop. Increasing the depth of wet-season ploughing increased the dry matter and sampled at 7 and 12 weeks after sowing, but at the final sampling, 18 weeks after sowing, only the differences in dry matter yield were maintained. Responses in dry matter and nitrogen yield were obtained to one inter-row cultivation, but not to a second. Differences in dry matter yield due to wetseason ploughing and inter-row cultivation were associated with differences in soil water content measured in the 1-4 feet profile in 1964-65.

1988 ◽  
Vol 28 (2) ◽  
pp. 249 ◽  
Author(s):  
S Fukai ◽  
P Inthapan

Several physiological responses were compared, under irrigated and water-stressed conditions, in an attempt to explain the reasons for the greater reduction in dry matter production of rice compared with maize and sorghum in a water-limiting environment. Leaf water potential and leaf rolling were determined weekly, soil water profiles and root length density twice, and leaf osmotic potential once during a long dry period. Root length density of rice was at least as high as that of maize and sorghum in the top 0.6 m layer of soil in both the wet and dry trials. There was no difference in water extraction among the 3 species from this layer, while rice extracted less water than did the other species from below 0.6 m. High variability among replicates precluded any conclusion being drawn regarding root length in the deeper layer. Leaf water potential, measured in the early afternoon, was consistently lower in rice than in maize and sorghum, even when soil water content was high, indicating high internal resistance to the flow of water in the rice plants. The low leaf water potential in rice was accompanied by low osmotic potential, and this assisted in maintenance of turgor and dry matter growth when soil water content was relatively high. As soil water content decreased, however, leaf water potential became very low (less than - 2.5 MPa) and, for rice, leaves rolled tightly.


1939 ◽  
Vol 30 (2) ◽  
pp. 259-284 ◽  
Author(s):  
T. A. M. Nash

1. The female tsetse extrudes her larva on soils ranging from fairly heavy clay to coarse sand; the presence or absence of organic matter seems to be immaterial.2. The soil temperature varies greatly in different breeding-grounds in the dry season, but little in the rains.3. The soil water content varies greatly in different breeding-grounds in the rains, but little in the dry season.4. The soil water content in some of the breeding-grounds falls so low in the dry season that there can be no doubt that the atmosphere in these soils is below saturation.5. Evaporation measured at 5 inches above ground-level varies little from site to site; bigger and important differences occur at greater heights above the ground where the screening effects of thicket become operative.6. The seasonal changes are so great at Gadau that no one breeding-ground can satisfy the female's requirements throughout the year; instead, different breeding-places are selected for different seasons.7. The cycle for G. morsitans is as follows: In the rains breeding occurs under palm fronds and logs in the open woodland. In the early dry season breeding continues in the open woodland, but shifts from the palm and log sites to the small thickets; breeding also starts in the more open parts of the forest islands. At the beginning of the very hot weather all the thickets of the open woodland are evacuated, and breeding is confined to the densest parts of the forest islands. In the early rains the movement is reversed: breeding shifts out into the open woodland, and in the heavy rains is confined to the log and palm sites.This cycle fits in closely with the cycle for the seasonal concentration and dispersal of the adult population (Nash 1937, pp. 85–90).8. The major wet season breeding-ground of G. tachinoides is unknown, but the cycle is believed to be as follows: In the early dry season breeding shifts from the log, palm, and probably from the unknown site, to the small thickets and forest islands, and becomes maximal in the cold season. Breeding now decreases in all sites, suggesting that none is really suitable—a surmise which is strengthened when tremendous breeding activity starts in the river-bed, as soon as it becomes available at the beginning of the hot season. In the early rains this site is destroyed and breeding is believed to commence in the unknown site, as it certainly does under the logs and palms.


2006 ◽  
Vol 57 (3) ◽  
pp. 297 ◽  
Author(s):  
I. R. P. Fillery ◽  
R. E. Poulter

The effect of including phases of long-growing-season annuals and herbaceous perennial pastures on water use was examined at 2 sites (deep sand and duplex soil) in Western Australia. Herbaceous perennials used were lucerne (Medicago sativa), and a mix of C3 grasses comprising phalaris (Phalaris aquatica), tall wheat grass (Thinopryum ponticum), and tall fescue (Festuca arundinacea) (perennial grass treatment). The long-season annual treatment was a mix of yellow and pink serradella (Ornithopus sp.) and Casbah biserrula (Biserrula pelecinus). These treatments were compared with annual-based pasture that was a mixture of subterranean clover with capeweed and Brassica species, and annual crops. Pasture treatments were first sown in 1998. High senescence of C3 grasses over the 1998–99 summer and poor germination of serradella/Casbah biserrula in the autumn of 1999 necessitated the re-seeding of the long-season annual and the perennial grass treatment in 1999. Wheat was sown in 1998, lupin in 1999, and barley in 2000 in an annual crop treatment. Soil water content to 1.5 m was measured hourly using frequency domain reflectometer probes, and a neutron probe was used monthly to measure changes in soil water to 5 m. Herbage production and species composition were determined. In each year of the study, annual pasture species senesced by November. About 20 lucerne plants/m2 persisted through the first summer–autumn in deep loamy sand and 40 lucerne plants/m2 in a duplex soil. Perennial C3 grass species did not survive the summer–autumn in sufficient density and distribution to evaluate their effect on soil water. Annual dry matter (DM) production in lucerne-based and subterranean clover-based pasture was not significantly different. Dry matter production in lucerne between 1 December and the following May–June, when germination of annual-based pastures occurred, was 1.2–1.9 t/ha at one site and 0.2–1.6 t/ha at another site. Long-season annual pastures produced significantly more DM than either lucerne or subterranean clover-based pastures in one season at one site but produced significantly less DM than either lucerne or subterranean clover-based pasture at another site in another season. Long-season annual-based pastures extracted amounts of soil water to a depth of 5 m similar to subterranean clover-based pasture when these were grown on deep sand and a duplex soil. In contrast, lucerne removed an additional 128 mm of water to 5 m, with 70 mm of this water being drawn from 2.5–5 m, compared with subterranean clover-based pasture. Lucerne was comparatively less effective in extracting water from a duplex soil where rooting depth was restricted to 2 m by a saline watertable. Early germination of annual pastures appeared to reduce drainage compared with a crop treatment where weeds were killed in autumn and early winter ahead of seeding. The need for studies at landscape scales that include concurrent measurements of groundwater levels and changes in soil water content to a depth of at least 5–6 m under perennial-based production systems is highlighted.


1970 ◽  
Vol 10 (47) ◽  
pp. 710 ◽  
Author(s):  
MJT Norman ◽  
LJ Phillips

At Katherine, N.T., stocking rates of 1.33, 1.00, and 0.67 Shorthorn steers an acre for a period of 18 weeks in the wet season beginning January were imposed on established pastures sown to Townsville sty10 (Stylosanthes humilis) alone but subsequently invaded to varying degrees by annual grasses. The experiment was repeated over three years. There were no significant differences in mean liveweight gain per head over three years ; hence liveweight gain per acre at the heaviest stocking rate was approximately twice that at the lightest rate. The mean dry matter yield of grass increased significantly with decreasing stocking rate, but there were no significant differences between stocking rates in Townsville stylo dry matter yield, nitrogen yield, or phosphorus yield. Correlation coefficients were calculated using data from individual paddocks and years. There was a highly significant positive correlation between liveweight gain per head and pasture nitrogen yield, and between liveweight gain per head and pasture phosphorus yield.


Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1844 ◽  
Author(s):  
Francisco Del Toro-Guerrero ◽  
Enrique Vivoni ◽  
Thomas Kretzschmar ◽  
Stephen Bullock Runquist ◽  
Rogelio Vázquez-González

In this research, we examined temporal variations in soil water content (θ), infiltration patterns, and potential recharge at three sites with different mountain block positions in a semiarid Mediterranean climate in Baja California, Mexico: two located on opposing aspects (south- (SFS) and north-facing slopes (NFS)) and one located in a flat valley. At each site, we measured daily θ between 0.1 and 1 m depths from May 2014 to September 2016 in four hydrological seasons: wet season (winter), dry season (summer) and two transition seasons. The temporal evolution of θ and soil water storage (SWS) shows a strong variability that is associated mainly with high precipitation (P) pulses and soil profile depth at hillslope sites. Results shows that during high-intensity P events sites with opposing aspects reveal an increase of θ at the soil–bedrock interface suggesting lateral subsurface fluxes, while vertical soil infiltration decreases noticeably, signifying the production of surface runoff. We found that the dry soil conditions are reset annually at hillslope sites, and water is not available until the next wet season. Potential recharge occurred only in the winter season with P events greater than 50 mm/month at the SFS site and greater than 120 mm/month at the NFS site, indicating that soil depth and lack of vegetation cover play a critical role in the transport water towards the soil–bedrock interface. We also calculate that, on average, around 9.5% (~34.5 mm) of the accumulated precipitation may contribute to the recharge of the aquifer at the hillslope sites. Information about θ in a mountain block is essential for describing the dynamics and movement of water into the thin soil profile and its relation to potential groundwater recharge.


2013 ◽  
Vol 27 (3) ◽  
pp. 351-357 ◽  
Author(s):  
A. Pérez-Vázquez ◽  
G. Hernández-Salinas ◽  
C. Ávila-Reséndiz ◽  
O.A. Valdés-Rodríguez ◽  
F. Gallardo-López ◽  
...  

Abstract The purpose of this study was to evaluate growth, chlorophyll content, and photosynthesis in Jatropha at different levels of soil moisture. Plants were cultivated in containers and the treatments of the soil water content evaluated were: 0% (without watering), 20, 40, 60, and 80% soil water content. Plant height was statistically similar for all treatments, but the number of leaves differed significantly. Total dry matter and chlorophyll at 40, 60, and 80% soil water content were statistically similar, but different from 0 and 20% soil water content. Leaf area at 40, 60, and 80% soil water content was statistically different from 0 and 20% soil water content. The photosynthetic rate, transpiration and stomatal conductance at 60 and 80% soil water content were statistically similar but different from 0 and 20% soil water content. Water stress affected growth, chlorophyll content, photosynthetic rate, transpiration, and stomatal conductance.


2008 ◽  
Vol 12 (2) ◽  
pp. 1-25 ◽  
Author(s):  
Diana C. Garcia-Montiel ◽  
Michael T. Coe ◽  
Meyr P. Cruz ◽  
Joice N. Ferreira ◽  
Euzebio M. da Silva ◽  
...  

Abstract Water distributed in deep soil reservoirs is an important factor determining the ecosystem structure of water-limited environments, such as the seasonal tropical savannas of South America. In this study a two-dimensional (2D) geoelectrical profiling technique was employed to estimate seasonal dynamics of soil water content to 10-m depth along transects of 275 m in savanna vegetation during the period between 2002 and 2006. Methods were developed to convert resistivity values along these 2D resistivity profiles into volumetric water content (VWC) by soil depth. The 2D resistivity profiles revealed the following soil and aquifer structure characterizing the underground environment: 0–4 m of permanently unsaturated and seasonally droughty soil, less severely dry unsaturated soil at about 4–7 m, nearly permanently saturated soil between 7 and 10 m, mostly impermeable saprolite interspaced with fresh bedrock of parent material at about 10–30 m, and a region of highly conductive water-saturated material at 30 m and below. Considerable spatial variation of these relative depths is clearly demonstrated along the transects. Temporal dynamics in VWC indicate that the active zone of water uptake is predominantly at 0–7 m, and follows the seasonal cycles of precipitation and evapotranspiration. Uptake from below 7 m may have been critical for a short period near the beginning of the rainy season, although the seasonal variations in VWC in the 7–10-m layer are relatively small and lag the surface water recharge for about 6 months. Calculations using a simple 1-box water balance model indicate that average total runoff was 15–25 mm month−1 in the wet season and about 6–9 mm month−1 in the dry season. Modeled ET was about 75–85 mm month−1 in the wet season and 20–25 mm month−1 in the dry season. Variation in basal area and tree density along one transect was positively correlated with VWC of the 0–3-m and 0–7-m soil depths, respectively, during the wettest months. These multitemporal measurements demonstrate that the along-transect spatial differences in soil moisture are quasi-permanent and influence vegetation structure at the scale of tens to hundreds of meters.


2016 ◽  
Vol 20 (77) ◽  
pp. 59-70 ◽  
Author(s):  
Sh. Zand-Parsa ◽  
S. Parvizi ◽  
A. R. Sepaskhah ◽  
M. Mahbod ◽  
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