Influence Of Fertigation On Labyrinth Channels Emitters Clogging Under Muddy Water Irrigation

Integrated drip irrigation and fertilizer technology is developing rapidly, but it also causes the problem that the technology has an acceleration effect on emitter clogging. For emitters with the same flow channel structure, fertigation concentration and temperature of irrigation water has a significant effect on emitter clogging, and the effect is influenced by the particle gradation obviously. In order to explore the influence of integrated drip irrigation and fertilizer technology under muddy water irrigation on emitter clogging and the process of blockage formation, periodic intermittent drip irrigation experiments were carried out on labyrinth channels emitters under muddy water containing 3 different particle gradation, 4 fertigation concentrations, they are 1.2, 0.6, 0.4 and 0 g L-1 respectively, to analysis the acceleration effect of the fertigation concentration and influence of particle gradation on emitter clogging, and a suitable range of fertigation concentration was found in the experiment. Tests were done in winter and summer respectively, and the water temperature was high relatively in summer and low in winter to analysis the influence of the water temperature on emitter clogging. The extent of clogging of each emitter and the position of blockages were counted, also the structure of the blockages were observed and ingredients of the blockages were measured by emission scanning electron microscopy(FESEM) to take deep analysis on clogging mechanisms. Sediment deposited in the drip tap was collected and particle gradation was determined to analyze the Siltation degree of each particle size. In this paper we find the following conclusions:1) Adding soluble fertilizer in the irrigation water can has an obvious acceleration effect on emitter clogging, and effect was more obvious in fertilizer solution with high concentration When the application rate of fertilizer was 1.2g L-1, the effective irrigation times of muddy water with three different particle gradations decreased by 36.4%,77.8%and 78.8% respectively; when the application rate of fertilizer was 0.4g L-1, the effective irrigation times of muddy water with three different particle gradations decreased by 9.1%,33.3%and 14.3% respectively. The acceleration effect on emitter was most non-obvious when the concentration of fertilizer solution was less than 0.4g L-1.So when the sediment concentration is about 1 g L-1, the fertigation concentration would better be around 0.4g L-1.2) When keeping the fertigation concentration a constant, the clogging rate differed dramatically under different particle gradation, which showed that the acceleration effect of fertigation was influenced by particle gradation.3) Irrigation water temperature changed with different season was an important factor on emitter clogging. But irrigation water temperature did not change the general trend of emitter clogging caused by fertigation and particle gradation. It showed that emitter had a high anti-clogging ability with high water temperature in summer. The impact of water temperature on accelerative effect was more obvious without fertigation compared to fertigation, the greater the concentration of fertilizer was, the lower influence of temperature on emitter clogging was.4) It showed that after adding fertilizer in irrigation water, the flocculation of particles in muddy water was enhanced and the formation of stable and compact aggregates was promoted, which was the major cause of acceleration effect of emitter plugging; Fertigation had an obvious influence on blockage structure, and the surface structure of blockage was more complicated after fertigation, the gap of aggregates decreased and complete clogging was the major formation and the effect was related to particle gradation.5) Particle gradation was an major factor on emitter clogging. The tests showed the gradation in which the particle(0.034-0.067mm) content was larger than 50% caused emitter clogging easiest, The accelerative effect of fertigation was the most obvious for gradation B in which the particle(0.034-0.067mm) content was larger than 50%. So when using this technology, messures should be taken to filter the particle(0.034-0.067mm).