The effect of particle size on the nutrient leaching of soil was examined experimentally. Theexperimental results agreed well with the theoretical normal distribution curves for sand although the curves of effluents from aggregates were skew and did not fit the theoretical curves. Mean displacement velocity could be obtained from the maximum concentration point of effluent curve of sand, but could not in case of aggregates. The cause of the skewness was assumed to, be a wider velocity distribution ranging from small pores in aggregates to large pores surrounded by aggregates. These aspects, together with the unsaturated condition, will require further theoretical development.

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A new gauge was fabricated on trial by the author for measuring hydraulic potential of soil water. The null method was applied in the design of the gauge as in that of many other gauges for the same purpose.
A new feature of the gauge exists in that the pressure equilibrium is judged by the moveinent of water in the connecting tube. A water level is prepared in the movable pot for equilibrating the potential of soil water to be measured. A part of the tube connecting the piezometer opening and the movable pot is replaced by a glass capillary, and the movement of water in the capillary is observed with a microscope. The water is mixed in advance with Indian ink at a low concentration in order to facilitate the observation of water movement. The carbon particles of ink flow when not in equilibrium, and stop movement when equilibrium is attained by adjusting the movable pot.
By this method a difference of 0.1mm of water pressure can easily be observed. The precision of the method hardly changes even for 100m long connecting tube. Sensibility is lower when ceramic cup piezometer is used, and an alternation of closing and opening of cock can maintain a high sensibility. Experiments proved that the measurement of water pressure and tension in, sand or loam is easily made within 2 or 3 minutes with an error less than 1 or 2 mmAq. This gauge cannot follow rapid pressure fluctuations, but can satisfactorily follow slowly changing pressure with a practically high accuracy.

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This study aims at clarifying the properties of soil water under the adsorbed state. For this purpose, it seems to the writer that making use of dielectrical properties is the most convenient. Then, study was carried in this way.
(1) The following experimental apparatuses were used:
(a) Bridge circuit.
(b) Double resonant circuits.
(2) The sample soil is of kaolinite type, the specific gravity and the specific surface area of which are 2.66 and about 42 m²/g, respectively.
(3) The relation between the packing ratio and capacity of the quite dry soil is linear as shown in Fig. 6 (C=3.02+10.2P). Using Drude's formula, dielectric constant of the quite dry soil only was obtained as 4. 4.
(4) The relation between the packing ratio and capacity of wet soil is also linear. But its dielectric constant cannot be obtained by physical means.
(5) As the packing ratio increases, tan δ of a soil-water system becoms greater even for identical moisture ratio. From these results, the determination of the soil in the same state becomes necessary for physical properties of adsorbed water.
(6) From the viewpoint of dielectric constant, adsorbed water seems to change qualitatively from about the second layer from the surface of soil particle.
(7) It is reflected in tan of soil-water system that the minimum relative humidity for finishing the monolayer water adsorption of soil is about 20%.

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In the previous paper some physical properties of adsorbed water were showo from its dielectrical phenomena. This paper deals with finding out the relations among water content, pF values and physical properties.
Main results of this study are as follows:
(1) All the adsorbed water which exists within 1 or 2 layers on the surface ofsoil particle has almost identical properties.
(2) The relaration time of film water on soil becomes shorter with the increase of water content. The relaration time is of the same order as that of ice.
(3) Properties of the film water are considered to change contineously from, ice-like properties to liquid-like ones.
(4) The water content in which the film water has the same propertics as liquid water coincides, with the water content at pF 2.7-3.0.

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Experimental studies were made on seasonal march and other behaviors of soil and water teniperature under vegetable cover through the whole growing season. The studies revealed the following characteristics on these-
(1) The daily minimum temperature of soil and water were independent of the state of vegetable cover but were dependent on the seasonal march of climate.
(2) On the contrary, the daily maximum temperature of soil and water was affected by both climate and the state of vegetable cover, and particularly by the latter.
(3) The daily amplitude of soil and water temperature was also affected by the state of vegetable cover and the relationship between the amplitude and the state of vegetable cover was given by the following equation:
φ=A_P0/A_B0=αe^-βb+ (1-α)
here, A_P0, A_B0: amplitude of soil surface temperature with and without rice plant, respectively;L: leaf area index;α, β, : constants.
(4) The effect of vegetable cover (L. A. I.=6) affecting on the decrease of the amplitude was nearly equal to that of saturated soil having 13 cm depth.

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This report explains by experiment and theoretical analysis that the qualitatively different forms of flow appear on the angular broad-crested weir by quantitative variation of depth of overflow and of length of weir-crest.
It makes clear the next:
1) The hydraulic meaning of Mostkow's indices classifying the flow, and correction of those.
2) The range of flow in which the minimum depth equal to one half depth of overflow, founded by Doeringsfeld and Barker, occurs.

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In the previous papers (I)-(II), free surface, seepage surface, stream-line, stream-velocity, discharge, and capillary-potential in percolation with the consiceration of capillary zone were reported.
This paper deals with the seepage surface (H_s), discharge (Q_c) with Cauchy's integral theorem applied to the rectangular or sloping dike (1: 2) with capillary zone and the methods by other investigators.
Presumptive boundary conditions of the rectangular dike are shown in Tables 1-4 for Figs. 1-4, and those of the sloping dike (1: 2) are in Tables 1-4 for Figs. 7-10, with the addition of ψ_F≈ψ_F' to Fig. 7, and ψ_G≈ψ_G' and ψ_F≈ψ_F' to Figs. 8-9.
Judging from the results of the applications under the assumptions that the “highest inductive capillary surface”(a tentative name) is linear or quadratic of Y in the rectangular dike, Table 1 for Fig. 1 and Table 4 for Fig. 4 (when it is quadratic) are seemed to be correct assumptions.
Table 3 for Fig. 3 is seemed so, when the width of the dike L is relatively small and the “highest inductive capillary surface” is quadratic of Y.
In the sloping dike (1: 2), Table 1 for Fig. 7, with the addition of ψ_F≈ψ_F', is seemed so, when the “highest inductive capillary surface” is linear of Y.

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This is the study of a new canal lining method which will prevent otherwise inevitable seepage loss quite economically and effectively.
So far many canal lining methods have been developed and applied to practical work but a tremendous length of canal is still remaining unlined.
On the other hand, irrigation water cost is getting higher year after year. Attention must be paid therefore, to guiding the water from the intake facility to each final field reducing percolation loss as much as possible, or keeping low water conveyance loss, in other words.
In this new method plastics film should be laid under the earth surface of canal. In this way this kind of film can be kept perfectly off from the weathering action of sunlight. This will result in a quite long service life of the material. In addition, the Canals constructed in this way can be as stable as ordinary earth canals because of the special setting method of the film.

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