Method for determining soil moisture

Abstract

The method for determining soil moisture includes the following steps: measuring an initial electrical conductivity and an initial dielectric constant of a training sample of a soil, adjusting the training sample's water content by adding a fixed amount of water and obtaining a plurality of adjusted electrical conductivities and dielectric constants from the adjusted training sample, entering the initial and adjusted electrical conductivities and dielectric constants into a computing device, obtaining a regression value from the initial and adjusted electrical conductivities and dielectric constants of the training sample, measuring a final electrical conductivity and a final dielectric constant from a real sample of the soil, and determining the soil moisture of the soil using the regression value and the final electrical conductivity and dielectric constant of the real sample.

Claims

1. A method for determining soil moisture, comprising (a) measuring an initial electrical conductivity and an initial dielectric constant of a training sample of a soil; (b) adjusting the training sample's water content by adding a fixed amount of water and obtaining a plurality of adjusted electrical conductivities and dielectric constants from the adjusted training sample; (c) entering the initial and adjusted electrical conductivities and dielectric constants into a computing device; (d) obtaining a regression value from the initial and adjusted electrical conductivities and dielectric constants of the training sample; (e) measuring a final electrical conductivity and a final dielectric constant from a real sample of the soil; and (f) determining the soil moisture of the soil using the regression value and the final electrical conductivity and dielectric constant of the real sample.

2. The method according to claim 1, wherein the step (a) comprises (a1) obtaining a fixed volume of the soil as the training sample, (a2) drying the training sample at 105 degree Celsius for 24 hours within an oven, and (a3) measuring the initial electrical conductivity and the initial dielectric constant of the training sample using a measurement device.

3. The method according to claim 2, wherein the measurement device is a soil moisture meter.

4. The method according to claim 1, wherein the soil comprises at least one of sandy soil, loam, clay soil, peat soil, peat moss, organic cultural soil, coconut bran, peat, coconut peat, coconut soil, cultural soil for cuttage propagation, field soil, easy transplanting soil, coir soil, coir brick, and coconut fiber soil.

5. The method according to claim 1, wherein the fixed amount of water is added in a plurality of stages.

6. The method according to claim 1, wherein the regression value and the soil moisture are calculated by a computing device.

7. The method according to claim 1, wherein a composition of the training sample and its corresponding regression value is recorded for future application.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow diagram showing the steps of a method for determining soil moisture according to an embodiment of the present invention.

(2) FIG. 2 is a schematic diagram showing how soil samples are dried according to the method of FIG. 1.

(3) FIG. 3 is a schematic diagram showing how initial dielectric constants of soil samples are measured according to the method of FIG. 1.

(4) FIG. 4 is a schematic diagram showing how water is added to soil samples according to the method of FIG. 1.

(5) FIG. 5 is a schematic diagram showing measured electrical conductivities and dielectric constants displayed by a computing device according to the method of FIG. 1.

(6) FIG. 6 is a schematic diagram showing how a regression value is obtained by a computing device according to the method of FIG. 1.

(7) FIG. 7 is a schematic diagram showing the determination of soil moisture by a computing device according to the method of FIG. 1.

(8) FIG. 8 is a diagram showing the relationship between electrical conductivities (ECs) and dielectric constants measured from eight soils.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims.

(10) As shown in FIG. 1, a method for determining soil moisture according to an embodiment of the present invention includes the following steps: (a) measuring an initial electrical conductivity and an initial dielectric constant of a training sample of a soil, (b) adjusting the training sample's water content and obtaining a number of electrical conductivities and dielectric constants from the adjusted training sample, (c) entering the measured electrical conductivities and dielectric constants into a computing device, (d) obtaining a regression value from the measured electrical conductivities and dielectric constants of the training sample, (e) measuring an electrical conductivity and dielectric constant from a real sample of the soil, and (f) determining the soil moisture of the soil using the regression value and the measured electrical conductivity and dielectric constant of the real sample.

(11) The step (a) includes the following sub-steps. The sub-step (a1) obtains a fixed volume of the soil as the training sample of the soil. The soil includes at least one of sandy soil, loam, clay soil, peat soil, peat moss, organic cultural soil, coconut bran, peat, coconut peat, coconut soil, cultural soil for cuttage propagation, field soil, easy transplanting soil, coir soil, coir brick, or coconut fiber soil. In the following, five training samples of soils of different combinations are tested to demonstrate the method of the present invention, as outlined in the following table.

(12) TABLE-US-00003 Specific weight Sample# Sandy soil % Loam % Clay soil % (g/cm.sup.3) Soil1 95 5 0 1.5 Soil2 95 14 21 1.4 Soil3 9 21 70 1.2 Soil4 6 79 15 1.2 Soil5 46 26 28 1.4

(13) In sub-step (a2), the training sample 1 is dried at 105 degree Celsius for 24 hours within an oven 2, as shown in FIG. 2. In sub-step (a3), as shown in FIG. 3, the initial electrical conductivity (EC(dS/m)) and the initial dielectric constant (K) of the training sample 1 are determined using a measurement device 3, such as a soil moisture meter.

(14) As shown in FIG. 4, in step (b), a fixed amount of water is added to the training sample 1 in several stages so that the humidity ratio is gradually increased, and a number of electrical conductivities and a second dielectric constant are determined using the measurement device 3 at each stage. As shown in FIG. 5, in step (c), the initial and subsequently obtained electrical conductivities and dielectric constants are entered into a computer device 5 such as a computer. As illustrated, it can be seen that, when electrical conductivity is higher, the dielectric constant is also higher. Then, as shown FIG. 6, step (d) obtains a regression value for data whose electrical conductivities are less than a threshold using the computing device 5. In the present embodiment, the threshold is 2 dS/m, and the regression values for the five training samples satisfy the following equations:
Soil1: K=29.76+1.66EC;
Soil2: K=31.29+1.63EC;
Soil3: K=32.98+1.76EC;
Soil4: K=32.65+1.67EC;
Soil5: K=32.78+1.66EC.

(15) Therefore, taking training sample Soil1 as example, for its measured electrical conductivities below 2 dS/m, the regression value is (K1.66EC).

(16) As shown in FIG. 7, in step (e), a real sample 4 is obtained from the soil whose moisture is to be determined and its electrical conductivity and dielectric constant are measured using the measurement device 3. Then, in step (f), the soil moisture of the real sample 4 is determined based on the measured electrical conductivity and dielectric constant of the real sample 4 using the computing device 5. Taking the training sample Soil1 as example, its soil moisture is determined as 5.310.sup.2+2.9210.sup.2(K1.66EC)5.510.sup.4(K1.66EC).sup.2+4.310.sup.6(K1.66EC).sup.3.

(17) Subsequently, the composition of the training sample 1 and its corresponding regression value is recorded for future application.

(18) Therefore, the gist of the present invention lies that a regression value is obtained using a training sample 1 and using the regression value, together with the real sample 4's measured electrical conductivity and dielectric, to determine an accurate soil moisture for the soil from which the real sample 4 is gathered.

(19) While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the claims of the present invention.