The Research Of Measurement Technique Of Farmland Relative Soil Moisture

As the freshwater shortage capacity gets shortage and overusing, it has become an hot topics, of irrigaton technology,that how to make a rational and efficient path to water-using.In China, agricultural irrigation accounts for a significant proportion of freshwater use, and according to statistics, water-saving irrigation technology can effectively Saving 30% to 60%.In view of this, how to shift the agricultural to agricultural informatization、agriculture automation and network, along with the high-tech to improve the water-saving technology and develop automated irrigation,are on the agenda.Relative humidity of soil,as a key indicator of agricultural irrigation,is a core technology both in rational irrigation and farmland research.In order to quickly detect soil moisture, the paper compares the different principles and methods about the pros and cons, advantages and feasibility of proposed capacitance value detecting soil moisture.Based on a system,aimed at pratical using of irrigation,is named as intelligent control system for plant growth and developed by one compay located at Chengdu. This paper has a systematic study relatively on the automation control method and ZigBee wireless transmission.The paper compares the Topp, Jacosen, Malicki, and Dobson’s famous experience or theoretical models, to make the general model improved, so that it is suitable for the electrical characteristics of soil parameters collection and calculation.This paper,focus on the relative value of soil moisture content ranges 30%-100%,then devised a method for measuring the capacitance value of the soil.The dual-band has been chose to collected soil parameters which provided an important theoretical basement about the development of measure soil moisture by using the soil moisture sensor.Using soil capacitance value represents the relative moisture of soil and fitting data regression curves.In simulation,ogarithmic fitting polynomial coefficient of determination and the results are similar, and slightly better than the polynomial fit, while its expression is simple and easy to calculate.In result,the logarithmic fitting has been matched to the date regression for the capacity of data to become converted to soil moisture value.In this paper,the comparison has aslo made between the capacitance method and the frequency domain moisture detector test method widely used currently.The pratical advantage in accuracy is aslo analysised and showed that the combined average error is less than 3%,fully in line with agricultural irrigation humidity detector technology requirements(5%).What’ more,the impact of temperature compensation aslo is taken into account,makes in line with crops grown in different seasonal temperature measurement error due to the actual situation.At the end of the paper,a suggestion has been expressed about choosing a reasonalbe signal resource,then,the reference advice of both the single-frequency and dual-band detection of soil electrical properties test.This paper is provide an new path to soil line detector with high availability, portability, low cost, high stability and other characteristics.The deficiency of this design is the bigger absolute when the moisture is low,the reason may be the samaller capacitance when soil moisture is low so that the resistance parameter palys a major role,and mineral content,metal content and solinity have a big effect on the resistivity.