Direct Determination Of The System Measurement Accuracy Improvement Measures On Soil Organic Matter

The system of soil organic matter gauges is a kind of laboratorial system which was developed by us in 2002. Comparing with Traditional organic matter gauges, some disadvantages such as chemical preprocessing, intricate operations and high costs, etc were overcome by the system, however, It is needed to dry the soil before the measuring, and making the measuring system more precise for the use of the system in agricultural production. This dissertation aimed at the further studies of the system, on the basis of the of a series of experiments, try to solve two problems, the following gains were made: 1. We found that configuration of soil reflective spectrum at the wavelength of 600nm has a strong correlative relation with organic matter content, and add one light signal of 600nm wavelength in the system, combined it with the light signal of 400nm wavelength which was used originally to calculate out the index of the "band degree", the index was also been used in the predicting the organic matter content in soil, and the more precise results of predict the organic matter content were obtained. After added the index of "band degree"to the system, its'measuring relative error decreased from 70% to 31%. 2. In order to achieve the aim of measuring soil organic matter content directly without drying it, we studied the influence of soil water to the reflective spectrum of soil surface and the measuring method of soil water, gained the primary improvement of the system in the future. Soil Water has strong absorption peaks at the wavelength of 1450nm and 1940nm, has unobvious absorption peaks at the wavelength of 1200nm and 1770nm, water content can be estimated by measuring and processing the light signals of absorption peaks. Through studies, we got a conclusion : add light signals of wavelength of 1200nm and 1450nm to the system, at the same time, using InGaAs detectors may be a better improvement for the system. As a result, the study provided some meaningful basis for the future designing and manufacturing of the soil organic matter gauge.