Research On Fertilizer Concentration Monitoring Method And Device Based On EC And PH

China’s agricultural water resources are scarce with the low effective utilization rate of irrigation water in farmland;the amount of fertilizer application is large with the low average utilization rate and the serious pollution.In order to maintain the sustainable and healthy development of agriculture,improve the utilization efficiency of water and fertilizer resources,and reduce the pollution of water and fertilizer to the environment,a precision irrigation model based on the integration of water and fertilizer has emerged.Based on the integration of water and fertilizer technology and the law of water and fertilizer demand for different crops at different growth stages,the development and research of automatic monitoring of the mixing ratio of water and fertilizer to realize the development of precision variable irrigation and fertilization devices and systems is the only way for the development of modern intensive precision agriculture.In the process of water and fertilizer mixing,real-time and accurate monitoring of water and fertilizer mixing concentration is the key to realize automatic and accurate variable irrigation and fertilization,and it is also an indispensable important link in the implementation of precision agriculture.Based on the measurement of the conductivity and p H of the indoor fertilizer solution,this article explores the influence of typical soluble fertilizer types,fertilizer solution concentration,temperature and fertilizer solution mixing ratio on the conductivity and p H of the fertilizer solution.Based on the response of fertilizer solution under different working conditions,an online monitoring strategy of fertilizer solution concentration suitable for integrated water and fertilizer precision irrigation has been proposed;secondly,based on the characteristics of the existing EC and p H testing equipment,based on the existing related monitoring equipment,carry out packaging transformation of existing EC sensors,p H sensors,temperature sensors,pressure sensors,flow sensors,etc.,and integrate autonomous power supply systems and data transmission systems,forming a collection of autonomous power supply,data transmission,irrigation water volume measurement,pipeline water and fertilizer concentration monitoring and feedback.It is an integrated device for online monitoring of water and fertilizer at the end of an integrated irrigation system.The main results and conclusions are as follows:(1)The effect of fertilizer solution mass concentrationρ_f under different types of fertilizers on the conductivity and p H of the fertilizer solution was clarified.The conductivity of potassium chloride,dipotassium hydrogen phosphate,compound fertilizer,diammonium hydrogen phosphate,and potassium nitrate fertilizer solution increases with the increase in the mass concentration of fertilizer solutionρ_f,and the degree of increasing trend was:potassium chloride>hydrogen phosphate Diammonium>potassium nitrate>potassium sulfate>dipotassium hydrogen phosphate>compound fertilizer.The acidity and alkalinity of the dipotassium hydrogen phosphate and urea fertilizer solution increased with the increase of the mass concentration of the fertilizer solutionρ_f(P<0.01),and the degree of increase was:dipotassium hydrogen phosphate>urea;however,the p H of the compound fertilizer solution The value decreased with the increase of fertilizer solution mass concentrationρ_f.(2)The response of the conductivity of different fertilizer solutions to the temperature T of the fertilizer solution was clarified.The conductivity of potassium chloride,compound fertilizer,potassium sulfate,potassium nitrate,dipotassium hydrogen phosphate,compound fertilizer,diammonium hydrogen phosphate fertilizer solution increased with the increase of fertilizer liquid temperature T,and compound fertilizer,diammonium hydrogen phosphate The response degree of potassium hydrogen phosphate,potassium sulfate,and potassium nitrate increased with the increase of the mass concentrationρ_f of the fertilizer solution,and the response degree of potassium chloride decreased with the increase of the mass concentrationρ_f of the fertilizer solution.(3)The influence of the ratio rv on the conductivity and p H of the mixed fertilizer solution was clarified.The conductivity of the mixed fertilizer solution of dipotassium hydrogen phosphate、potassium chloride and diammonium hydrogen phosphate、potassium chloride increased with the ratio rv(dipotassium hydrogen phosphate:potassium chloride and diammonium hydrogen phosphate:potassium chloride).The response degree increased with the increase of the mass concentrationρ_fof the mixed fertilizer solution;the p H value of the mixed fertilizer solution of dipotassium hydrogen phosphate and potassium chloride increased with the increase of the ratio value rv.The trend weakened with the increase of the mass concentration of the mixed fertilizer solutionρ_f,and the ratio value rv had no obvious effect on the p H of the mixed fertilizer solution of diammonium hydrogen phosphate and potassium chloride.(4)A real-time online monitoring strategy for the concentration of mixed fertilizer solution based on the conductivity method was proposed.Based on the EC value-temperature-proportion value-mass concentration data set of diammonium hydrogen phosphate and potassium chloride mixed fertilizer solution,an EC monitoring-based mixed fertilizer solution concentration inversion prediction model was constructed,and a real-time online monitoring strategy of water and fertilizer information based on monitoring the EC value of fertilizer liquid under the premise of known formula was proposed;(5)A real-time online monitoring strategy based on EC and p H for the concentration and mixing ratio of the water and fertilizer integrated mixed fertilizer solution was proposed.According to the difference of the EC value and p H value of the dipotassium hydrogen phosphate and potassium chloride mixed fertilizer solution under different mass concentrations,temperatures,and ratio values,a function of EC value-p H value-temperature T-mass concentrationρ_fof dipotassium hydrogen phosphate and potassium chloride mixed fertilizer liquid and EC value of dipotassium hydrogen phosphate and potassium chloride mixed fertilizer liquid-p H value-temperature T-mixing ratio function was constructed,a real-time online monitoring strategy for the concentration and formula of the mixed fertilizer solution based on monitoring the EC,p H and temperature of the fertilizer solution was proposed.(6)A set of integrated equipment for on-line monitoring of water and fertilizer at the end of the irrigation system was built that integrated independent power supply,data transmission,irrigation water measurement,pipeline water and fertilizer concentration monitoring and feedback.The device was based on the characteristics of the existing EC and p H test equipment,based on the existing related monitoring equipment,through the packaging transformation of the existing EC sensor,p H sensor,temperature sensor,pressure sensor,flow sensor,etc.,and integrated an autonomous power supply system With the wireless data transmission system,a set of integrated water and fertilizer online monitoring and feedback devices at the end of the water and fertilizer integrated irrigation system has been initially constructed.