In-situ detection device for detecting water and fertilizer content in crop cultivation substrate and detection method thereof

An in-situ detection method of detecting water and fertilizer content in a crop cultivation substrate, the in-situ detection method being carried out by an in-situ detection device for detecting water and fertilizer content in the crop cultivation substrate, wherein the in-situ detection device comprises a water and fertilizer in-situ collector and a spectral analysis device;

• the water and fertilizer in-situ collector is pre-buried in the crop cultivation substrate and used to collect water and fertilizer in the crop cultivation substrate in real time to obtain a measurement sample;
• the spectral analysis device is used to emit a laser with a specific wavelength to detect and analyze content of nitrogen, phosphorus, and potassium in the measurement sample collected by the water and fertilizer in-situ collector;
• and a continuous sampling system for continuously transporting the measurement sample is provided between the water and fertilizer in-situ collector and the spectrum analysis device;
• wherein the in-situ detection method comprises:
• pre-burying the water and fertilizer in-situ collector in the crop cultivation substrate;
• penetrating the water and fertilizer in the crop cultivation substrate into a water and fertilizer collection box of the water and fertilizer in-situ collector through a filtration and permeation layer on the water and fertilizer collection box;
• and enabling the water and fertilizer to enter a water and fertilizer storage box of the water and fertilizer in-situ collector through a communicating pipe to obtain the measurement sample;
• enabling the continuous sampling system to continuously transport a reference sample and the measurement sample to a measurement reference light-source-circuit and a measurement sample light-source-circuit in a multi-mode laser splitter, respectively;
• enabling a laser light source of the spectrum analysis device to emit light with a specific wavelength and transmitting the light to the multi-mode laser splitter;
• enabling the multi-mode laser splitter to split the light into a measurement reference laser-beam and a measurement sample laser-beam;
• enabling the measurement reference laser-beam to be transmitted along the measurement reference light-source-circuit to a reference transmittance cuvette, so as to irradiate the reference sample;
• enabling the measurement sample laser-beam to be transmitted to a sample transmittance cuvette along the measurement sample light-source-circuit, so as to irradiate the measurement sample;
• enabling a reference photodetector of the measurement reference light-source circuit to detect absorbance when the measurement reference laser-beam irradiates the reference sample in the reference transmittance cuvette, so as to obtain reference absorbance;
• enabling a sample photodetector of the measurement sample light-source-circuit to detect absorbance when the measurement sample laser-beam irradiates the measurement sample in the sample transmittance cuvette, so as to obtain sample absorbance;
• obtaining signals of both the reference absorbance and the sample absorbance;
• obtaining actual sample absorbance, through a formula that the sample minus the reference absorbance is the actual sample absorbance;
• and calculating content of corresponding nutrient elements in the measurement sample according to the actual sample absorbance;
• wherein the water and fertilizer in-situ collector comprises the water and fertilizer collection box and the water and fertilizer storage box;
• the communicating pipe is provided between the water and fertilizer collection box and the water and fertilizer storage box;
• the water and fertilizer collection box is used to collect water and fertilizer in the crop cultivation substrate in real time, to obtain the measurement sample;
• and the measurement sample is transported into the water and fertilizer storage box through the communicating pipe;
• wherein a top collection port of the water and fertilizer collection box is provided with the filtration and permeation layer for filtering soil of the crop cultivation substrate;
• and a float liquid-level-detection switch is arranged in the water and fertilizer storage box;
• wherein the spectrum analysis device comprises the laser light source;
• the laser light source is connected with the multi-mode laser splitter by a quartz fiber;
• the multi-mode laser splitter is installed with two light source circuits;
• and the two light source circuits comprise the measurement reference light-source-circuit and the measurement sample light-source-circuit;
• wherein the measurement reference light-source circuit comprises a first collimator lens, the reference photodetector is arranged at a side of the first collimator lens, and the reference photodetector and the first collimator lens are spaced apart;
• and the reference transmittance cuvette is arranged between and spaced apart from the first collimator lens and the reference photodetector;
• wherein the measurement sample light-source-circuit comprises a second collimator lens, the sample photodetector is arranged at a side of the second collimator lens, and the sample photodetector and the second collimator lens are spaced apart;
• and the sample transmittance cuvette is arranged between and spaced apart from the second collimator lens and the sample photodetector;
• wherein the continuous sampling system comprises a first peristaltic pump and a second peristaltic pump;
• a liquid inlet end of the first peristaltic pump is communicated with the water and fertilizer storage box, and a liquid outlet end of the first peristaltic pump is communicated with a liquid inlet of the sample transmittance cuvette;
• a liquid inlet end of the second peristaltic pump is communicated with a reference sample pool, and a liquid outlet end of the second peristaltic pump is communicated with a liquid inlet of the reference transmittance cuvette.