Water relations of winter wheat: 2. Soil water relations

Gregory, P. J.; McGowan, M.; Biscoe, P. V.

doi:10.1017/s0021859600056665

Cited by 89 publications

(64 citation statements)

References 26 publications

(17 reference statements)

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“…The choice of this target depth was based on the plant's active root depth, which is present from 0.30 to 0.60 m depth from the upper part of the soil. About 92% of the water uptake was extracted from the upper 0-0.60 m of the soil, and 75-80% of the root dry matter was present in this depth (Russell, 1982;Gregory et al, 1978). A plant's root depth determines the depth to which soil water can be extracted.…”

Section: Irrigation Performancementioning

confidence: 99%

Effect of tillage on water advance and distribution under surge and continuous furrows irrigation methods for cotton in Egypt

Ismail

2006

Irrigation and Drainage

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A field experiment was carried out to assess the effect of tillage on water advance and water distribution in the root zone area (0.5 m) under continuous and surge flow irrigation in a cotton field. The experiment was conducted at the Agriculture Experimental Station, Assiut University, Assiut, Egypt. The location was classified as clay soil. The furrows with blocked ends were 76 cm long and 0.70 m wide with 0.0024 m m À1 of slope. To monitor the advance time, six points were established along the furrows at 9, 18, 27, 36, 45 and 76 m from the inlet. In order to study the water distribution along the furrows, soil moisture content was measured using the gravimetric method at 0-0.25 and 0.25-0.50 m depths at the beginning, middle and end of the furrows. A hand hoeing tillage system (HH) was compared with a weed control tillage system (WC) under continuous flow (CF) and surge flow irrigation (SF).Hand hoeing tillage decreased the water advance time compared to weed control tillage either under continuous or surge flow irrigation. Surge flow also decreased the advance time compared to continuous flow. The greatest effect on the advance time reduction resulted from the combined effect of surge flow with tillage (SFHH), which reduced the total supplied water by 22.4 and 25.7% during the first and second irrigation, respectively. The single effect of either tillage (CFHH) or surging (SFWC) also reduced the total amount of supplied water compared to continuous flow with weed control tillage (CFWC), but the reduction was less than that in the combined treatments. Due to tillage and surge effects, soil water was efficiently used and distributed uniformly along the furrow length. Combining surge irrigation and tillage could be an efficient method to use irrigation water efficiently and ensure uniform distribution of soil water. Copyright

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Section: Irrigation Performancementioning

confidence: 99%

Effect of tillage on water advance and distribution under surge and continuous furrows irrigation methods for cotton in Egypt

Ismail

2006

Irrigation and Drainage

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“…A relatively small biomass of roots at depth may be disproportionately important for the functioning of some ecosystems. For example, a study with winter wheat showed that 3% of the root system below 1 m supplied Ϸ20% of water uptake during a summer dry period (50). Another example is the potential importance of hydraulic lift, the passive movement of water through roots from relatively wet, deeper soil layers to relatively dry, shallower ones (51,52).…”

Section: Fig 2 Comparison Ofmentioning

confidence: 99%

Ecosystem rooting depth determined with caves and DNA

Jackson

Moore

Hoffmann

et al. 1999

Proc. Natl. Acad. Sci. U.S.A.

256

218

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Belowground vertical community composition and maximum rooting depth of the Edwards Plateau of central Texas were determined by using DNA sequence variation to identify roots from caves 5-65 m deep. Roots from caves were identified by comparing their DNA sequences for the internal transcribed spacer (ITS) region of the 18S-26S ribosomal DNA repeat against a reference ITS database developed for woody plants of the region. Sequencing the ITS provides, to our knowledge, the first universal method for identifying plant roots. At least six tree species in the system grew roots deeper than 5 m, but only the evergreen oak, Quercus fusiformis, was found below 10 m. The maximum rooting depth for the ecosystem was Ϸ25 m.18 O isotopic signatures for stem water of Q. fusiformis confirmed water uptake from 18 m underground. The availability of resources at depth, coupled with small surface pools of water and nutrients, may explain the occurrence of deep roots in this and other systems.Plant rooting depth influences the hydrology, biogeochemistry, and primary productivity of terrestrial ecosystems (1-7). Progress in determining the maximum rooting depth of species and in identifying the resources taken up at depth is limited by several factors. Access to the soil is difficult, particularly in rocky soils and in deeper layers. In addition, no universal method exists for identifying roots obtained from the soil, especially when only fine roots are available (8-10). There is considerable variation in maximum rooting depth and root biomass distributions, which affects the functioning of ecosystems (11-15). For example, in eastern Amazonia, water uptake from 2-to 8-m soil depths contributes to more than threefourths of the transpiration of evergreen forest in the dry season and helps maintain an evergreen canopy on Ͼ1 million km 2 of tropical forest (1, 16). Characteristics of roots and the soil are also needed in models of biosphere-atmosphere interactions (17). A comparison of 14 land surface parameterizations concluded that rooting depth and vertical soil characteristics were the most important factors explaining scatter among models for simulated transpiration (18, 19), determining the amount of water available to plants and partitioning its uptake from different layers. Conclusions were similar for global soil-moisture dynamics (20,21). Global simulations of net primary productivity and transpiration increased 16% and 18%, respectively, when optimized rooting depths incorporated soil water deeper than 1 m (22).We developed a method for identifying roots based on DNA sequence variation and applied this method to roots collected from caves 5-65 m deep to determine the belowground community structure and maximum rooting depth of the 100,000-km 2 Edwards Plateau of central Texas. The Edwards Plateau and other karst regions in Texas cover one-fifth of the state, with Ͼ3,000 caves identified to date (23, 24). Karst systems, in general, cover 7-10% of land surface area globally and supply a quarter of the earth's population ...

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“…The stored water depth was measured in volume per cent and transformed to millimetres by multiplying the water content with an effective root depth of 0.45 m. The choice of this target depth was based on the plant's active root depth, which is present from 0.30 to 0.60 m depth from the upper part of the soil as found by Russell (1982). Gregory et al (1978) found 92% of the water uptake was extracted from the upper 0-0.60 m of the soil as well as 75-80% of the root dry matter was present in this depth. Rogers and Sothers (1996) stated that the plant's root depth determines the depth to which soil water can be extracted.…”

Section: Cycle Ratiomentioning

confidence: 90%

Water productivity and crop production simulation under surge flow irrigation in short furrows in Egypt

Ismail

Depeweg

2005

Irrig. and Drain.

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This paper describes the simulation results of water productivity and yield production in relation to water supply by either continuous or surge flow irrigation in short fields for clay and sandy soils in Egypt. The input data required by the Cropwat model are meteorological data, plant and soil characteristics and water supply. The meteorological data for the year 1999 were obtained from the Assiut Station, Egypt. Cotton was used as the most important crop for the simulation and its growing characteristics come from the Cropwat model. Soil characteristics and water supply are measured data obtained from field experiments in Assiut. During the simulation all the parameters considered have been kept constant except for the water supply and application efficiency, which are variable. The yield has been determined with Cropwat at the beginning, middle and the end of a furrow as well as for the average stored water depth along the whole furrow. The simulation has been carried out for two different approaches; one based on optimal continuous flow and the other based on optimal surge flow irrigation.The simulation indicates that using an optimal surge flow gives higher crop yields than using an optimal continuous flow. For optimal surge flow irrigation the simulation revealed distinct differences in yield reduction between continuous and surge flow irrigation compared to the results based on optimal continuous flow. Surge flow irrigation is an efficient tool either to produce the same yield with less water than in continuous flow or to produce higher yields than continuous flow by using the same gross irrigation supply. Surge flow irrigation is an effective tool for water saving in short fields as prevails in Egypt. Copyright La simulation montre que l'utilisation de l'écoulement optimal par vagues donne une récolte agricole meilleure que l'écoulement continu. Pour l'irrigation gravitaire par vagues, la simulation a exposé une différence distincte de la diminution de la récolte entre l'irrigation continue ou par vagues en comparaissant avec les résultats basés sur l'écoulement continu optimal. L'irrigation gravitaire par vagues est un moyen efficace soit pour avoir la même récolte avec moins d'eau que dans le cas de l'amenée continue, soit avoir une récolte plus importante que par l'amenée continue en utilisant la même quantité d'eau. L'irrigation gravitaire par vagues est une moyenne efficace pour la rentabilité d'eau dans les parcelles de dimensions réduites, comme c'est souvent le cas en É gypte.

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Water relations of winter wheat: 2. Soil water relations

Cited by 89 publications

References 26 publications

Effect of tillage on water advance and distribution under surge and continuous furrows irrigation methods for cotton in Egypt

Effect of tillage on water advance and distribution under surge and continuous furrows irrigation methods for cotton in Egypt

Ecosystem rooting depth determined with caves and DNA

Water productivity and crop production simulation under surge flow irrigation in short furrows in Egypt

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