地下滴灌系统施肥灌溉均匀性的田间试验评估

该文对影响地下滴灌系统性能的两个重要因素施肥装置类型和滴灌带埋深进行了田间评估.施肥装置包括国内外常用的压差式施肥罐、文丘里施肥器和比例施肥泵三种类型,滴灌带埋深包括0、15和30 cm 3个水平.结果表明,滴灌带埋深与施肥装置类型对滴头流量和灌水量均匀性的影响均未达到显著性水平(a=0.05),而施肥装置类型对施肥量均匀性的影响达到极显著水平(a=0.01).对给定的毛管埋深而言,压差式施肥罐的施肥量变差系数高于比例施肥泵和文丘里施肥器.对不同施肥装置的施肥量变差系数与灌水量变差系数之间关系的回归分析结果指出,比例施肥泵和文丘里施肥器的施肥量变差系数与灌水量的变差系数相当,但压差式施肥罐的施肥量变差系数比灌水量变差系数大40%左右.因此在进行微灌系统设计时应将施肥装置类型和性能作为一个因素加以考虑,并宜优先选用输出肥液浓度恒定的施肥装置.

Field evaluation of fertigation uniformity for subsurface drip irrigation systems

Field experiments were conducted to evaluate the effects of injector types and lateral depths on fertigation uniformity of subsurface drip irrigation (SDI) systems by simultaneously measuring the distributions of water application, solution concentration, and fertilizer applied. Three conventionally used injectors, a differential pressure tank, a Venturi device and a water-driven piston proportional pump and three lateral depths of 0, 15, and 30 cm. were used in the experiment. The results indicate that injector type and lateral depth had an insignificant effect on emitter discharge and the uniformity of water applied, but the uniformity for fertilizer applied is mainly dependent on injector type. The uniformity for fertilizer applied of the differential pressure tank is lower than that of the Venturi device and the water-driven piston proportional pump. For a given lateral depth, the differential pressure tank generally produced a higher coefficient of variation (Cv) for fertilizer applied than that of the Venturi injector and the proportional pump. The regression analysis between fertilizer Cv and water application Cv was conducted for different injector types. The results indicate that the fertilizer applied Cv is very close to water application Cv for SDI system using a Venturi injector or a proportional pump as an injection device. However, fertilizer Cv for a differential pressure tank is about 40% greater than that for the water application Cv. The injection method and injector performance should therefore be considered in the design of microirrigation systems and the injector devices capable of releasing a constant fertilizer rate are recommended.