Moisture Constants Research Articles

Selection Criteria for Grain Yield and Moisture in Maize Yield Trials

Grain yield and moisture in maize (Zea mays L.) are positively correlated, and must be considered simultaneously. Typically, breeders desire to identify better‐yielding hybrids within each of several maturity groups. Data from 28 multiple‐location yields trials were used to (i) compare five indices for ability to identify hybrids that are high yielding for their maturity; (ii) investigate the validity of assumptions used in developing estimated indexes; and (iii) investigate possible relationships between effectiveness of indexes and violations of assumptions. Selection criteria evaluated included: BSE, a base index; S‐H, a Smith‐Hazel index; Y/M, the ratio of yield and moisture; REG, yield adjusted for the regression of yield onto moisture; and DSG, a desired gains index designed to hold moisture constant. Departures from normality for distribution of grain yield means and for moisture were detected in 18 and 32% of the experiments, respectively. The regression of yield onto moisture varied considerably across experiments, with a mean coefficient of 12.5 kg ha−1 yield per g kg−1 moisture. Selection differentials of REG, BSE, and DSG for yield were 92, 91, and 89% respectively of that resulting from direct selection for yield, but changes for moisture were considerably less than those for selection based on yield. The Y/M selection differential for yield was only 64% of that of yield, and had a large decrease in grain moisture. No association between the success of an index and nonnormality was observed. Both BSE or REG are recommended for identification of hybrids that are high yielding for their maturity. However, these or other indices employed should be carefully evaluated in the context of the breeder's circumstances and objectives.

On the basic equation of sorption and the isosteric heat

Precise derivations are given for the basic equation of sorption, -RT ln r = Δh -T Δs. and for the isosteric heat. The prefix Δ indicates the change from sorbed liquid to free liquid. The above basic equation is interpreted as an equilibrium moisture constant (emc) equation. It is shown how Δs/R varies with temperature under the assumption that Δh/l is a function of moisture content only. The above ratios are the obvious non-dimensional expressions for Δh and Δs and these are evaluated for wood as typified by klinki pine (Araucaria klinkii Lauterb.).

Flotability and Dielectric Characterization of the Intrinsic Moisture of Coals of Different Ranks

Abstract The flotability of Argonne Premium coals varying in rank has been correlated with the intrinsic moisture content and dielectric properties of the intrinsic water. It is shown that as the coal rank increases the intrisic moisture and dielectric constant of the coals decreases. The nature of intrinsic water present in the coal of different ranks has been characterized using a dielectric mixture model. The water present in lignite is different from that of sub-bituminous and bituminous coals. The flotability of coals of various ranks is explained in terms of the nature and extent of the intrinsic water

Statistical equations for estimating field capacity, wilting point and available water capacity of soils from their saturation percentage

SummaryStatistical equations were derived for estimating three soil moisture constants, i.e. field capacity (FC), wilting point (WP) and available water capacity (AWC), from soil saturation percentage (SP), which is an easily determinable parameter. The regression equations were evaluated from a data set obtained on 438 soil samples collected from different horizons of 111 profiles of the Indogangetic Plains in northern India, having a wide variation of texture and other physico-chemical properties. The three soil moisture constants were positively correlated with logarithms of SP (r = 0·985 for FC v. In SP, 0·979 for WP v. In SP, and 0·914 for AWC v. In SP). The regression equations were thetested on an independent set of experimental data on 57 samples collected from 14 representative soil profiles of the study area. Values of the three moisture constants of this data set, predicted from the regression equations, were in exceptionally good agreement with the observed values. The mean estimation error (the error of the estimated value relative to the measured value) was only 0·55% for FC, 0·12% for WP and 0·67% for AWC.

Physical properties and moisture retention characteristics of some nigerian soils

Measurements were made of physical characteristics of 119 samples from 23 profiles derived from two parent materials in Nigeria. The laboratory analyses included texture, plasticity and shrinkage characteristics, and a range of soil moisture constants including saturation point and moisture retention at various suctions. Simple and multiple correlation coefficients and regression analyses were conducted to investigate the possibilities of obtaining estimates of soil moisture retention from the textural analysis. Clay and sand contents are correlated with various soil moisture constants. The textural analysis may therefore be used to estimate moisture holding capacity at different suctions for these and similar soils with a predominantly uniform clay mineralogy, dominated by kaolinite and sesquioxides. Moisture retention curves indicate that the “field capacity” for most of these soils is better estimated at 60 or 100 cm of water suction rather than at 0.3 bar. A plot of the pF curves indicated only slight differences between moisture retention at 2 or 3 bar suction and at 15 bar suction.

Influence of Calcium on the Physical properties of Soil

Forty soil samples were collected from various parts of South India and were subjected to the determination of important physical properties of soil and various forms of calcium. Exchangeable calcium exhibited high degree of correlation to the clay content. Total calcium and exchangeable calcium showed close correlation with volume expansion on wetting. Moisture constants like water holding capacity and sticky point were correlated with various forms of calcium. Black soils which contained high calcium were found to bo extremely impermeable compared to red soils. Aggregate stability was observed to be markedly high in black soils, which were richer in calcium and clay.

Hygroscopicity as a valuable complement in soil analysis, 2. Correlation between maximum hygroscopicity and some physico-chemical characteristics of Ap-horizons with different textures

Hitherto, an extensive series of analyses is needed to characterize soil samples. According to the data described in the literature, as well as data obtained from our own experiments, the use of maximum hygroscopicity or “Hy” is finally evaluated. By means of statistical analysis, the correlation between pairs of properties was studied for different Ap-horizons from Quaternary deposits at various locations representing the main soil types of Belgium. A few samples (approximately 10) are from secondary origin with CaCO 3 contents of about 40%. The regression equations resulting from this study enable us to calculate definite figures for different soil characteristics such as clay content, C.E.C. (cation-exchange capacity) and especially for moisture constants at 15 atm and 1 3 atm as well as for the available water capacity. The results obtained demonstrate that “hygroscopic water” may be used as a valuable complement in soil analysis.

Effects of total suctions in the soil solution during the Summer on the growth and fruiting of young Satsuma orange trees

Experiments were carried out to clarify the combined effects of various water regimes and fertilizer rates on the growth and fruiting of young Satsuma orange trees during two months, from July to August in 1969. Four and five year old plants grown in the Wagner′s pots (1/2000 are), filled with a loam soil, were used as materials.At regular intervals, watering were done to maintain the appropriate levels of soil moisture by determining the water content in each plot at the depth of 10cm according to the volumetric method. The water suctions were calculated to express this force on the energy scale, pF and bar using soil moisture constants as shown in Table 2.To make the plots with different osmotic suctions in the soil, the mixed fertilizers on various levels were supplied. Thereafter, separate fertilizers were done by determining the electrolytic conductivity of salts solution prepared from the saturated soil in each plot at regular intervals to maintain the definite osmotic suction. The osmotic suctions (P) in bar were estimated by the calculation from the values of the electrolytic conductivity (EC) of saturation extracts in mmhos/cm according to the following equation.P=0.36×ECTotal suction in the soil solution can be obtained as the sum of water suction and osmotic suction. The ranges of total, water and osmotic suction in the soil solution under different treatments are shown in Table 1.Results obtained are as follows:1. The trees reached their full growth when the total suction in soil solution did not exceed 2.5 bar as the sum of water suction of 0.5 bar and osmotic suction of 2.0 bar. Above its critical pressures, the trees showed a tendency to inhibit their growth. In this case it appeared that the water suction was more important than the osmotic one.2. The suction in soil solution had the same effect on the fruit growth as described above. Index of fruit shape was also affected by the soil water suction, showing the tendency of increasing the ratio of vertical diameter to cross diameter with increasing the water suction. The full development of fruit color was shown in the plots with lower total suctions, especially the lowest osmotic suction, while incomplete coloring in plots of higher water suctions. Percent of fruit rind was high in the treatments with higher total suctions.3. Soluble solids in fruit juice were higher in plots with total suctions below 3 bar than the ones in the other plots. On the contrary, citric acid was high in content in plots with higher total suctions and therefore tastes due to lowered sugaracid ratio showed bad quality.4. Both water saturation deficit and diffusion pressure deficit as measures of internal water status in leaves showed the tendency of increasing their values with increasing water and osmotic suctions in soil solutions. Leaves exposured at higher values of water suctions accompanied by increased solute suctions in soils showed a marked drop in both photosynthesis and transpiration. The suctions in such conditions had the same effect on the viability of fine roots, which were going to rot in very bad conditions.5. The content of nitrogen, phosphorous and potassium in leaves was high at higher osmotic suctions, while the case with calcium was the reverse.In conclusion, to give the best possible growth and fruiting of Satsuma orange trees, it is important to keep the water suctions below 0.5 bar and the osmotic suctions below 2.0, in other word total suctions below 2.5 bar in the soil solution by adjusting watering and fertilizer rate during the summer. The upper critical range of 2.5-3.0 bar as the total suction in the soil solution may be shown from our experiments.

Relationship of texture to some important soil moisture constants

Correlation coefficients between grain size separates and three soil moisture constants (1/3 A.T.P. (atmospheric percentage), 15 A.T.P. and A.W.C. (available water capacity)) are presented for 79 soil samples collected from fourteen profiles in the semi-arid regions of Hissar district (India). Silt is the major factor contributing to moisture held at 1/3 A.T.P. while clay bears a highly positive and significant correlation with 15 A.T.P. Upto about 50% of clay+silt there is a linear increase in A.W.C. with increase in clay+silt content. Beyond this there is a tendency for A.W.C. to decrease. The same trend occurs in samples containing more than 25% clay. It is suggested that calcium carbonate, if present in appreciable quantities, should be taken into account when inferring moisture constants from textural data.

Soil Moisture and Soil Temperature Changes with the Use of Black Vapor‐Barrier Mulch and Their Influence on Pineapple (Ananas comosus (L.) Merr.) Growth in Hawaii

AbstractAs the mulching practice in pineapple culture in Hawaii has developed over the last 50 years, a number of functions have been assigned to the action of the mulch. This study gives primary consideration to the effect of soil moisture and soil temperature changes upon pineapple growth. Soil moisture changes were determined from field samplings and lysimeter studies at Wahiawa, Oahu. Changes in the soil moisture budget with the mulch were so slight that the variability of field sampling precluded assessment without excessive replication. Coefficients of variability for samples taken at the plant butt were 3 to 5% of a moisture constant (e.g., 15‐bar point) for a soil series or within a single field. Moisture use, measured by semicontained hydraulic lysimeters, was reduced by the mulch when the soil was very wet but changed little when the soil moisture ranged from field capacity (0.15‐bar) to the 15‐bar point.The mulch raised the average soil temperature about 1.6C during the winter. The measured one‐third increase in the plant growth was nearly identical with the increase calculated from the growth‐response of pineapple to temperature.

The Relationship of Soil Water with Soil Moisture Constants

Investigation of soil moisture constants, physical properties of soils and their relationships will be of much use for an understanding of the moisture characteristics of the soils. The classification of soil moisture in relation to plant is a realistic approach. The range of soil water from wilting coefficient to field capacity is of greater importance due to its availability for crop growth and production. which has been designated as 'available range. The range of soil water from wilting coefficient' to 'ultimate wilting point' and that from ultimate wilting point to zero have been named as "moisture unavailable to plants" respectively. Soil moisture constants viz., water holding capacity, moisture equivalent, wilting point, ultimate wilting point, their inter-relationships and relationship with soil water are discussed in this paper.

Influence of soil moisture content on germination and emergence of seeds

This study was designed to clarify the relations of germination and emergence of several kinds of seeds to moisture content of soils, with special reference to their moisture constants and moisture supplying capacities.Seeds were planted in the soils having different moisture contents in the depth of one cm from the surface, and numbers of emerged seeds were counted daily. After the final count, seeds remaining in the soil were exposed and number of germinated seeds were counted. Physical properties of soils used were shown in Table 1.1. Minimum moisture content allowing germination of radish, rape, and sunflower seeds was close to P. W. P. (permanent wilting percentage) in the fine sandy clay loam (alluvial soil) and the fine sandy loam (volcanic ash soil), but was higher than P. W. P. in the coarse sand (river sand). Minimum moisture content allowing emergence of these seeds was a little higher than that for germination (Fig. 1).Critical moisture levels for carrot seed were higher than those for other seeds (Fig. 1). This may be due to the lower moisture absorbing power of carrot seed than that of other seeds (Table 3).2. Average number of days required for emergence of each seed was found to be almost the same in the range down to a certain critical moisture content of the soil, below which number of days increased with the decrease of moisture content. This critical point was close to the minimum capillary moisture content in each soil (Fig. 4, Table 5).3. Pre-soaking treatment decreased minimum moisture content allowing germination and emergence of pea seed, but had little effect to tomato seed, which was much smaller in size than pea seed (Fig. 5).4. Basing on the above mentioned results, it may be concluded that minimum moisture content allowing germination or emergence of seeds are determined primarily by the moisture tension of the soil, but, at the same time, it is affected by the moisture absorbing power of seed, amount of moisture which should be absorbed by the seed for its germination or emergence, and moisture holding capacity or moisture supplying power of soil.

Studies on the composts for raising seedlings of vegetable crops in hot beds. VII.

In the previous works standard formulas of the composts for raising seedlings of forced vegetables have been proposed. Composts were made of soils (volcanic ash soil, clay soil and fine sand), and organic material (leaf-mold) with optimal fertility. Suitable components differed from sorts of vegetable crops. For cucumbers, the 1 volcanic ash soil-3 leaf-mold mixture (in volume), for tomatoes 2-2 mixture, and for egg-plants 3-1 mixture were most favourable, respectively.The purpose of this study was to determine the physical properties of these composts, and to find the relation between these properties and plant growth.In the first experiment, moisture constants of the mixtures, varying in their proportion of soil and organic material, were determined. From pF-curves of soil water, it was evident that, with increasing proportions of leaf-mold to the soil, macropore spaces were increased markedly. On the other hand, amount of available water were decreased in both volcanic ash soil and clay soil except in fine sand.In the next steps, physical changes in the mixtures which received daily watering at the field for four weeks were observed. The actual volume of solid and liquid phases in each mixture was increased, accompanied with decreasing air capacities, because the sedimentation of the soil particles into macropores occured, and the mixtures became compact considerably during experimental periods. Addition of leaf-mold to the soil was effective for reducing soil compression, though the 3-1 mixture showed more compact than 4-0 component (no leaf-mold added) at the end of experiment.Last of all, the permeabilities of the mixtures to water and to air were measured in the laboratory, after daily watering for four weeks. Both properties indicated similar tendencies, though there were great differences concerning to the soil types. There were noticeable improvements in the water-and air-permeability when leaf-mold was added to the soil. However, just as in the case of the former experiment, 3-1 mixture showed lower rate than other mixtures.It appears from these results that the application. of bulky organic matter to the soil altered remarkably physical characteristics of the composts. And also, it was suggested that their properties may affect on the growth of vegetable seedlings, particularly, on the development of their root. And it was considered that suitable components were determined by mutual relationship between nature of plant root and physical properties of mixtures, and consequently they differed with sorts of vegetable crops.

The nonsteady state of the water table in drained land

The interesting papers by Maasland [1959] and Isherwood [1959] on the nonsteady state of the water table probably develop the discussion of this topic as far as is useful at present. The purpose of this note is to draw attention to an assumption implicit in all work of this kind which needs further examination before progress becomes possible. The assumption is that there is such a quantity as a constant specific yield f, namely the volume of soil water released per unit surface area per unit fall of the water table. Nonsteady-state moisture profiles. Moisture profiles above a water table which is falling after rainfall cessation may be described, in crude semi quantitative terms only, in some such manner as proposed in Figure 1 [see Luthin, 1957, p. 33]. One may suppose an initial stage indicated by the full line and subsequent stages of which the broken line indicates an example. If one supposes that all such profiles are similar, being merely displaced vertically, then the yield of water, which is transported across the water table, is given by the shaded area between the profiles, and this, in turn, by a simple geometrical argument, is equal to the rectangular area f dh where dh is the fall of the water table and f is the difference between saturation and field capacity, to use a somewhat elusive concept. As so defined the specific yield / is evidently a soil moisture constant. This naive treatment simply ignores and avoids the difficult problem of the water movement and moisture profile development in the unsaturated soil above the water table, a problem in the field of nonlinear diffusion [Luihin, 1957, chap. I]. It is easy to demonstrate some common cases where such a treatment is greatly in error.

Influence of Temperature Upon Soil Moisture Constants and Its Possible Ecologic Significance

Holscher, C. E. 1945. The effects of clipping bluestem wheatgrass and blue grama at different heights and frequencies. Ecology 26: 148-156. Hull, A. C., Jr. 1944. The relation of grazing to establishment and vigor of crested wheatgrass. Jour. Am. Soc. Agron. 36: 358-360. . 1954. Rating seeded stands on experimental range plots. Jour. Range Management 7: 122-124. Joy, C. R., et al. 1954. A comparison of grass growth on different horizons of three grassland soils. Jour. Range Management 7: 212-214. Klages, K. H. W. 1942. Ecological crop geography. The Macmillan Co. 615 pp. Lister, P. B. and F. X. Schumacher. 1937. The influence of rainfall upon tuft area and height growth of three semi-desert range grasses in southern Arizona. Jour. Agr. Res. 54: 109-121.

Título en español.

Los suelos tropicales de la región húmeda de Puerto Rico que se usaron en esta investigación fueron agrupados en dos categorías: (a) Lateríticos y (b) no-lateríticos. Se presentan ecuaciones de regresión que pueden servir para predecir, a base del contenido de arcilla de los suelos exclusivamente, las constantes estudiadas, a saber: Saturación máxima, capacidad de campo, equivalente de humedad, punto de marchitez permanente y coeficiente de higroscopicidad. Se obtuvieron índices de correlación altamente significativos en cada caso para suelos lateríticos. En suelos no-lateríticos la correlación fué también altamente significativa en todos los casos con excepción de la correlación entre la saturación máxima y el contenido de arcilla.

Capillary Movement of Soil Water in Circular Irrigation as three Dimentional Diffusion

This paper intends, by the theory of three dimentional diffusion, to determine the watercontent capillarily held and its change in the ground, where was fast irrigated through a circular area. The theoretical formulae have been derived, considering the special conditions of soil moisture constants as a change of a capillary conductivity in soil.One of these formulae to show a watercontent at any depth beneath the center of an irrigated circle, is as follows:w=100βQ/2√πkte-z2/4kt⋅(1-e-a2/4kt)where w=watercontent %(wt.), β=apparent specific gravity, Q=applied waterquantity cc/cm2, k=capillary conductivity cm/sec, t=time after irrigation sec., z=depth beneath the soil surface cm. a=radius of irrigation area cm.The discrepancy between the formula and the corresponding experiments has been explained principally by the presence of the field capacity. But a lot of problems, especially on the functional relation of capillary conductivity to soil moisture, remain still unsolved.

The Effects of Cropping and Manure Applications on Some Physical Properties of a Heavy Soil in Eastern Nebraska

SummaryA study was made of the effects of cropping and manure applications on some of the physical properties of a heavy soil in eastern Nebraska. The results may be summarized as follows: 1.The addition of manure had no appreciable effects on the consistency constants, the moisture constants, the volume weight, or the aggregation. 2.For the first six-inch depth, the values for the uncultivated soil exceeded the average values for the cropped soil as follows: (a) the upper plastic limit, 9.8 per cent; (b) the lower plastic limit, 6.9 per cent; (c) the plasticity number, 2.9 per cent; (d) the scouring point, 7.4 per cent; (e) the moisture equivalent, 6.9 per cent, (f) the hygroscopic coefficient, 1.2 per cent; and (g) the maximum water capacity, 16.2 per cent. 3.The average “state of aggregation” for the cultivated soils was seventy-three per cent of that for the uncultivated soil. The great difference was in the aggregates larger than 0.5 mm. The cultivated soil had only 12.8 per cent as many aggregates larger than 0.5 mm., as were found for the uncultivated soil. 4.Air-drying the soil greatly decreased the size of the aggregates.

Studies in Tropical Soils. III. The Shrinkage Behaviour of Lateritic and Kaolinitic Soils

V. Summary1. This article describes the comparative results of the determination of shrinkage constants (Haines’ method) and of certain soil moisture constants for a series of clay soils representative of three important classes, namely,tropical red soilsderived from igneous rocks and from limestone,kaolinitic soilsand materials, andgrey and yellow soils, mainly derived from aqueous sedimentary rocks.2. An attempt is made to interpret the data in terms of Wilsdon's micro-reticular hypothesis of soil colloidal structure, and to explain the physical significance of some of the constants measured, particularly sticky point moisture (S), loss on ignition (I), water uptake from aqueous vapour (H, R), and Haines’ “residual shrinkage” moisture content (d).3. The results indicate thattropical red soils closely resemble kaolinitic materials in their shrinkage behaviour and moisture relations, but that they are intermediate between this type and grey and yellow soils, which exhibit characteristic high total shrinkage, marked residual shrinkage and high adsorptive capacity for moisture and for cations.4. A brief review of recent literature concerning the mineralogy of clay minerals (based on X-ray analysis and optical examination) is offered in support of these findings.5. The need of detailed mineralogical investigations of the products of weathering of rocks under humid tropical conditions is urged. Such study might reveal the causes of the characteristic and peculiar field properties of tropical red soils which appear to have been neglected by soil physical-chemists.

The relations between certain soil moisture constants and the determination of the vesicular coefficients of soils

1. Evidence is produced to show that the free water in a soil is 21.2. Wilsdon's modification of the Briggs-Shantz equation is discussed, viz., M = xH + 21, in which x = the vesicular coefficient. From this equation the vesicular coefficient of any soil can be found from the values of M and H.3. The values thus obtained agree for clay soils with those found by Hardy's method from the moisture at the point of maximum plasticity.4. The vesicular coefficient of a soil is greater than that of its subsoil.5. The total bound water = (M – 21), and the vesicular water = M – (21 + H). The vesicular water expressed as a percentage of the plastic soil is equal to the cubical shrinkage coefficient.