| The technology of water and fertilizer integration is an effective way to solve the problem of low utilization rate of water and fertilizer in the process of agricultural production.The small-scale sprinkler irrigation machine is easy to use and has simple supporting facilities,which plays an important role in the process of water and fertilizer integration.Aiming at the problems of high price of water and fertilizer integrated irrigation facilities and insufficient research and development of intelligent products,this research adopted the method of experimental research and theoretical analysis to study the influence laws of water and fertilizer integrated spraying hydraulic performance of small-scale sprinkler irrigation machine,designed the water and fertilizer integrated automatic control system of small-scale sprinkler irrigation machine,and realized the automatic control of irrigation and fertilization.The main research contents are as follows:(1)The effects of different factors on the uniformity of spray irrigation and fertilization of small-scale sprinkler irrigation machine were studied.The influence of sprinkler working pressure,combination spacing,installation height and fertilizer concentration on the spraying uniformity coefficient and fertilization uniformity coefficient was analyzed.The results showed that within the reasonable working parameters of the system,the working pressure,combination spacing,installation height and fertilizer concentration had significant effects on the uniformity of irrigation and fertilization,and the influence of working pressure and fertilizer concentration on the uniformity of irrigation and fertilization was stronger than that of combination spacing and installation height.(2)The water and fertilizer integration performance of small-scale sprinkler irrigation machine was studied,and the effects of different fertilizer concentration on the hydraulic performance of irrigation and fertilization of small-scale sprinkler irrigation machine were revealed.The results showed that,with the increase of fertilizer concentration in the system,the wetted radius of sprinkler and the kinetic energy of a single droplet variation was little.The combined uniformity coefficient of sprinkler decreased firstly and then increased.Compared with water medium,the average droplets diameter during fertilization increased significantly.In the range of 4to 9m from the sprinkler,fertilizer concentration had a great influence on the application rate.In the range of 0 to 6m from the sprinkler,the water-fertilizer medium droplet velocity was decreased compared with water,while in the range of 6to 8m from the sprinkler,it was increased.(3)The comprehensive evaluation system of water and fertilizer integrated sprinkler irrigation technical indicators for small-scale sprinkler irrigation machine was established.The main technical performance indicators included: wetted radius reduction coefficient,spray uniformity coefficient,application rate variation coefficient and droplet diameter specific gravity coefficient.The comprehensive hydraulic performance under different fertilizer concentrations of 0.09%,0.16%,0.19%and 0.24% were obtained by fuzzy comprehensive evaluation method.The results showed that wetted radius reduction coefficient of the sprinkler was very small when water and fertilizer were sprayed integrally.With the increase of fertilizer concentration,the application rate variation coefficient decreased gradually,and the uniformity coefficient of sprinkler increased.Under the four kinds of fertilizer concentration,the specific gravity coefficient of droplet diameter was more than 99%.(4)The water and fertilizer integrated automatic control system for small-scale sprinkler irrigation machine was designed and its performance was tested.The control system design mainly included: overall structure design,hardware design,software design and touch screen interface design.The soil temperature and humidity sensor was used to detect the soil humidity in time,which was used as a control target.The soil humidity was stabilized in the range suitable for crop growth by controlling the water pump and solenoid valve,and the irrigation control strategy was established.The voltage of fertilizer injection pump was controlled to the amount of fertilizer application,and the control strategy of fertilizer application was established.The soil moisture sensor,automatic and manual functions and control effect were tested.The soil moisture value was measured by soil moisture sensor and compared with drying method.The results showed that,the maximum relative error between the measured value of soil moisture sensor and the measured value of drying method was 3.20%,which indicated that the data transmission of soil moisture was accurate and reliable.The experimental scheme of water and fertilizer integration automatic control system of small-scale sprinkler irrigation machine was designed,which provided conditions for the improvement and perfection of the automatic control system. |
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