Soil Water Relations Research Articles

Water relations of winter wheat: 2. Soil water relations

SummaryVolumetric soil water content and soil water potential were measured beneath a winter wheat crop during the 1975 growing season. Almost no rain fell between mid-May and mid-July and the soil dried continuously until the potential was less than – 20 bars to a depth of 80 cm. Evaporation was separated from drainage by denning an ‘effective rooting depth’ at which the hydraulic gradient was zero.Rates of water uptake per unit length of root (inflow) were calculated for the whole soil profile and for individual soil layers. Generally, inflow decreased throughout the period of measurement from a maximum of 2·5 × 10–3 to a minimum of 0·66 × 10–3 ml water/cm root/day. Values in individual layers were frequently higher than the mean inflow and the importance of a few deep roots in taking up water during a dry season is emphasized. A similar correlation between inflow and soil water potential was found to apply for the 0–30 cm and 30–60 cm layers during the period of continual soil drying. This relationship represents the maximum inflow measured at a given soil water potential; actual inflow at any particular time depends upon the interrelationship of atmospheric demand, soil water potential and the distribution of root length in the soil.

Chiseling Influences on Soil Hydraulic Properties

AbstractChiseling is now more frequently used for primary tillage in the drylands of eastern Oregon and Washington. Improved measures of chiseling effects on soil water relations are needed to evaluate water intake and infiltration benefits, especially as related to depth of chiseling. Hydraulic conductivity (K) and soil water desorption characteristic (SWDC) were field measured in the 120‐cm soil profile of a Walla Walla (mesic typic Haploxeroll) silt loam before and after chiseling 43‐cm deep.The test Walla Walla soil is layered. Cation exchange capacity, exchangeable Ca2+, clay content, and organic matter all changed at the 30‐cm depth; dry bulk density decreased with depth above 45 cm and was constant below 45 cm; K was 10 to 1,000‐fold lower in depths above 30 cm; water contents in the SWDC (−50 to −200 mbar range) were lower in upper 30‐cm layer.Chiseling affected both the SWDC and K in the upper 30 cm, especially at 10 and 20‐cm depths, but had no influence on these measurements at 40 cm. Both water potential at constant water content in the SWDC and K were increased especially in the −50 to −300 mbar range. Failure of chiseling to improve water relations in the mild duripan extending from 30 to 45 cm suggests the need for addition of plant residue or chemical amendments into the chisel slots.Water contents and hydraulic heads during drainage showed that chiseling could reduce evaporation by reducing water content and diffusivity. Overall soil profile hydraulic resistances showed relative average K up to 15 times greater as a result of chiseling 43 cm deep, but nearly similar accelerated internal drainages were projected for simulated chiseling to 25‐cm depth vs. chiseling to 43 cm.

Desert Termite1 Control in a Shortgrass Prairie: Effect on Soil Physical Properties2

Control of the desert termite Gnathamitermes tubiformans (Buckley) in a shortgrass prairie in W Texas resulted in an improvement in the watershed value and soil-water relationships for forage plants. The percentages of > 1-mm soil aggregates were greater on termite-free soils, whereas percentages of < 1-mm aggregates were greater on termiteinfested soils. Organic carbon, forb production, and litter accumulation increased significantly on termite-free soils. Capillary pore space was normally higher in termite-free soils, while non-capillary pore space was normally higher in termite-infested soils. Termite control had no effect on total pore space, hydraulic conductivity, and bulk density in the soil studied. Rainfall infiltration was greater on termite-free soils after the 1st 15 min of a simulated rainstorm. Runoff and sediment load were greater on termite-infested rangeland than on termite-free rangeland. Evapotranspiration was greater on termite-free soils during a 7-day period following rainfall application. However, termite-free soils retained more moisture during dry periods than termite-infested soils.

Small soil containers as experimental tools: Soil water relations

Abstract Container soil water relations are reviewed relative to the extrapolation of container experiments to the field. The use of soil mixtures for the experimental control of container soil water relations is also discussed.

Fifty Years of Progress in Water Relations Research

Many of the basic concepts dealing with soil and plant water relationships were in existence 50 years ago, but were inadequately presented in the textbooks of that time. There has been a marked increase in the amount of work done in this field during recent decades, but much of it involves advances in understanding the concepts already in existence. Three of the most important advances in the field of water relations are: (a) acceptance of the term, water potential, to describe the free energy status of water in soil and plants; (b) marked improvement in methods of measuring water potential and stomatal resistance; and (c) use of the concept of water flow in the soil-plant system as analogous to flow of electricity in a conducting system.A number of interesting and important problems remain to be studied. Of these, probably the most important is to learn why mild water stress of less than - 10 bars can affect various enzyme-mediated metabolic processes. Plant scientists in applied fields also need to learn more about the causes of differences in ability to tolerate drought among plants of various kinds. There is uncertainty concerning the relative magnitude of the resistances to water flow in various parts of the soil-plant system and concerning the causes of the apparent changes in resistance to water flow with increase in rate and with time of day. More information also is needed concerning the role of growth regulators synthesized in roots and the importance of the older, suberized roots in the absorption of water and mineral nutrients.

Establishment of Early Successional Plant Populations on Forest and Prairie Soil

Seed germination and plant community development on adjacent forest and prairie soils (Typic Hapludalf and Typic Halplaquoll) were studied to elucidate the causes of variation in plant community composition during the first growing season after crop harvest. The number of plant individuals in July on the forest soil was three times larger than on the prairie soil. Abutilon theophrasti, Chenopodium album, Polygonum pensylvanicum, and Setaria faberii occurred in large numbers on the forest soil but were considerably less important on the prairie soil. Ipomoea hederacea predominated on the prairie soil. The seed load after abandonment on the forest soil was larger than on the prairie soil both before and after overwintering. Total numbers of plants that reached maturity were significantly higher (at the 5% level) on the forest soil than on the prairie soil. Population levels were generally constant throughout the growing season. Diversity peaked in June and was higher on the prairie soil than on the forest soil throughout the growing season. Germination of Ambrosia artemisiifolia, Lactuca scariola, and Polygonum was enhanced by moist soil conditions, whereas germination of Amaranthus hybridus was higher under dry soil conditions. Lactuca and Polygonum were the most sensitive to water stress and Abutilon and Setaria the most tolerant. It appears that the kinds and numbers of plants that become established in an abandoned field are a function of the number of germinable seeds present in the soil and the seed—soil water relationships. Of the soil parameters that may control seed germination, there is strong evidence to suggest that soil moisture the extreme upper portion of the profile is the major factor.

Vegetation of the Big Horn Mountains, Wyoming, in Relation to Substrate and Climate

The vegetation of the Big Horn Mountains is typical of the Central Rocky Mountain region; a lower Juniperus osteosperma zone is followed by Pinus ponderosa, Pseudotsuga menziesii, Pinus contorta, and Picea engelmannii—Abies lasiocarpa zones. Rock or geologic substrate type has a strong influence on forest vegetation. On sedimentary areas forests cover less that 50% of the area and are composed of Pseudotsuga menziesii or Picea engelmannii—Abies lasiocarpa. On granitic substrates forests cover over 80% of the surface and are composed chiefly of Pinus contorta with Picea engelmannii—Abies lasiocarpa at higher elevations. Populus tremuloides is present but unimportant as a vegetation type. Most of the rainfall comes during March, April, and May; precipitation is less than 30 mm per month during summer. Thus soil—water relationships are important in determining vegetation pattern. Precipitation comes from the east, which allows forest vegetation to reach lower elevations on the east than on the west slope.

ERZİNCAN OVASI TOPRAK VE SU KAYNAKLARININ SULAMA YÖNüNDEN PROBLEMLERİ VE GELİŞTİRİLME İMKANLARI ÜZERİNDE BİR ARAŞTIRMA

ERZİNCAN OVASI TOPRAK VE SU KAYNAKLARININ SULAMA YÖNüNDEN PROBLEMLERİ VE GELİŞTİRİLME İMKANLARI ÜZERİNDE BİR ARAŞTIRMA

The Wool-like Covering of the Roots of Lannea alata. I. The Origin and Morphology of the Wooly Coat

Lannea alata (Engl.) Engl., Anacardiaceae, a tree or shrub of East Africa, has roots covered with dense wool-like hair. Cork cambium of the root produces a closely appressed cork from which the hairs (modified cork cells) arise. Cork cells and wooly hair are rich in sterol and carotin-oid-like compounds and have thick walls. It is suggested that the root wool plays a role in the soil-air, soil-water relations of Lannea alata and other plants.

Plant and Soil Water Relationships: A Modern Synthesis. Paul J. Kramer

Previous articleNext article No AccessNew Biological BooksPlant and Soil Water Relationships: A Modern Synthesis. Paul J. Kramer Donald AylorDonald Aylor Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 45, Number 2Jun., 1970 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/406558 PDF download Crossref reports no articles citing this article.

R. N. Yong, R. D. Japp and S. J. Windisch. Soil water relationships and their engineering applications. 53 pp. (Sept. 1968)

R. N. Yong, R. D. Japp and S. J. Windisch. Soil water relationships and their engineering applications. 53 pp. (Sept. 1968)

The composition of several arid spinifex grasslands of central Australia in relation to rainfall, soil water relations, and nutrients

The study was restricted to communities of Triodia basedowii (hard spinifex) and Plectrachne schinzii (feathertop spinifex), which occur on extensive tracts of featureless sand plains. Measurements of plant cover, size, and weight were made at four sites at the northern, southern, eastern, and western extremities of their distribution as well as centrally. Soil profiles were examined and samples taken for laboratory analyses and nutrition trials in pots. P. schinzii communities are dominant north of lat. 22°S. and T. basedowii communities south of this latitude. The communities are dominated by the spinifex species, which make up 96 to 98% of the standing crop. The tussocks cover about one-third of the soil surface, the remainder being bare. A sparse layer of small trees, shrubs, and subshrubs is always present. The soils are uniformly red, deep, and sandy with clay contents exceeding 13 % only in a few northern and eastern soils. Nitrogen and phosphorus contents are very low and did not exceed 0.022% and 0.015 % respectively. Growth of oats and sorghum in pots was markedly affected by lack of phosphorus (nitrogen was not tested). The small range of available water is offset by deep penetration of moisture in the soils. The uniformity of vegetation and soils was the outstanding feature. Significant differences between areas were found for plant height (due to P. schinzii) and weight per unit area of stand. The latter could not be related to the climatic differences between areas, and may be an historical feature related to fire. The vegetation is a stable edaphic climax subject to and adapted to repeated burning.

Yields of maize, sorghum varieties and sorghum hybrids in the East African Lowlands

1. Sorghum is capable of giving substantial yields under dry conditions where maize fails.2. Sorghum can consistently out-yield maize in some areas under conditions of apparently adequate or excessive rainfall.3. Low soil nutrient status, and/or poor soil water relations, interacting with the amount of rainfall were probably responsible for the low maize yields where precipitation in the growing season exceeded 15 in.4. Some hybrids originating in the U.S.A. may be of immediate value in dry areas of East Africa. Such hybrids are generally susceptible to bird damage and are more susceptible to Atherigona indica infuscate than local material. Hazera 726 shows less susceptibility to both these pests and is recommended for dry areas.

ON THE WATER RELATION IN LIMESTONE AND DIABASE VEGETATION IN THE LEEWARD ISLANDS OF THE NETHERLANDS ANTILLES

In a same macroclimate on the islands of the Leeward Group of the Netherlands Antilles two types of vegetation are chiefly found. A vegetation pertaining to the dry evergreen formation series on limestone and a vegetation on diabase belonging to the seasonal formation series. Study was made of the water relation at the end of the rainy season during which transpiration, water deficit, suction pressure and soil water were investigated. From the course of transpiration curves it was concluded that water relations in diabase soil are more sever than those in the limestone. Water deficit in plants, growing on diabase appears to be much higher than those of limestone. Suction pressure divergates strongly in both cases. In the upper soil layers the amount of water that can be taken up by plants is small both in limestone and diabase. In deeper layers of the limestone soil there is more water than in diabase of the same level. Vegetation on diabase is determined by a sufficient amount of water in the soil during the rain season and a great drought during the other months. On the other hand in limestone the amount of water in the soil is larger during a longer period. Because of the higher suction pressure of this soil only plants developing a higher suction pressure can occur.

VEGETATION AND HABITAT OF THE SALT MARSHES AND BEACH PLAINS IN THE SOUTH-WESTERN PART OF THE NETHERLANDS

This paper contains a survey of ecological and phytocoenological investigations on maritime vegetation, carried out in the SW Netherlands. After an outline of the nature of the Dutch coasts and of former investigations on salt-marsh vegetation, special attention is devoted to a cybernetic approach to this vegetation and its habitat as realizations in space and time. From an ecological point of view stability and instability in the environment appears to be of essential importance. Starting from this approach estuarine phenomena, the genesis of salt marshes and different physical and chemical properties of the soil (texture, carbonate contents, soil-water relations, salinity and supply of organic matter) are discussed, as well as their connections with some features of the vegetation. Using the same strain of thought, a survey of the vegetation is given, at the same time starting from the principles of classification according to the French-Swiss School of Braun-Blanquet.

SOIL OXYGEN AND WATER RELATIONSHIPS TO RICE GROWTH

SOIL OXYGEN AND WATER RELATIONSHIPS TO RICE GROWTH

Soil water relations and relative turgidity on leaves in the wheat crop

Trials were conducted in 1961 and 1962 at Wagga in southern New South Wales to investigate the yield physiology of the wheat crop. Various cultural treatments were applied to a single variety (Heron). The increases in evapotranspiration and associated reductions in total soil moisture content caused by early sowing, by heavier fertilizer applications, and to a lesser extent by a heavier rate of sowing were reflected in an increased plant moisture stress (reduced leaf relative turgidity) at a given time in the spring. At a given stage of development, however, relative turgidity was not much affected by time of sowing, and in fact post-flowering plant moisture stress increased with later sowing. There were only small treatment effects on the estimated depth and density of rooting. Relatively little water was extracted by crops from below 40 in.; dense crops reduced the soil moisture content throughout the root zone to less than the –15 bar value. Leaf relative turgidity at sunrise showed a consistent inverse relationship to soil moisture content in the root zone. Leaf turgidity (sunrise) was maintained at 100% until root zone moisture levels approached the –15 bar value.

The effects of sand type and fine particle amendments on the emergence and growth of subterranean clover (Trifolium subterraneun L.) with particular reference to water relations

Twelve types of sandy soil exhibited considerable differences in ability to promote emergence? of subterranean clover when compared under suboptimal soil water conditions. These differences resulted from interactions between soil water relations, mechanical impedance, and aeration. Water requirements for satisfactory emergence of subterranean clover in a coarse sand were studied in the laboratory. Highest emergence was achieved when a water content of 10% by weight (–10 cm water potential) was maintained for at least 4 days. Very little emergence occurred when the water content was maintained at 2% by weight ( –120 cm water potential). A sustained water content of about 10% for 4 days was infrequently achieved in the field under natural rainfall conditions. Initial establishment and subsequent maintenance of subterranean clover on coarse sands in the field can be critically limited by the effects of poor soil water relations on emergence. Incorporation of 2.5% by weight of three fine particle amendments in the topsoil produced spectacular improvements in emergence and establishment. Fly ash was superior to clay, which in turn was superior to finely ground silica. This was due in part to beneficial effects on nodulation and growth. Incorporation of fine particle material in the soil layer below the seed zone required less material to produce the same response as uniform mixing throughout the topsoil.

Basic Soil Study

It has been the author's experience that too many biology students study life forms in a manner which leads one to believe that soil, the basic commodity, may be considered superfluous. In this paper I discuss several techniques for effective soil study. These techniques are simple to perform, and because of this simplicity ought to be available to all students concerned with the life sciences. There are certain basic facts that should be part of the understanding of any student of biology. Such might be broadly grouped under the following: 1. Some of the less obvious relations of soil to life. 2. Soil-water relations. 3. Physical characteristics of soil. 4. Facts about the soil profile. 5. Relative alkalinity and acidity as related to plant growth and availability of certain plant nutrients.

Diurnal energy and water exchanges in bulrush millet in an area of high solar radiation

The diurnal energy and water relationships of a crop of bulrush millet ( Pennisetum typhoides S. et H.) were examined in an area of high solar radiation at Katherine, N.T., Australia (latitude 14.3°S). The vertical distribution of the components contributing to the net upward water flux was evaluated by a simple heat-budget method from vertical profiles of net radiation, water vapour and temperature, as well as soil heat flux. The physiological response of the plant to diurnal changes in the environment was measured in terms of relative leaf water content, photosynthetic activity and stomatal aperture. The average illumination within the crop was obtained from light readings made with a flat surface and an omnidirectional photometer in vertical profiles during the day. The total dry matter and leaf area in the crop profile were determined from stratified samplings. Soil water relationships were also evaluated. At the time of the study, the soil water content in the surface 150 cm of soil was approaching the −15 bar value. A decrease in transpiration and an increase in sensible-heat loss demonstrated a marked influence on the energy balance by stomatal closure during the middle of the day. During the recovery period in the afternoon, transpiration increased, at a time when net radiation was decreasing, by gaining advected sensible heat from the atmosphere and also from the lower leaf layers. The fraction of net radiation utilized for transpiration generally decreased with depth into the plant canopy. It is postulated that both physiological and meteorological factors contribute to this phenomenon. The maximum proportion of direct evaporation from the soil in relation to the total evaporation appeared to be about 10%.