| Drip irrigation is one of the most advanced irrigation technique. The main reasons for the growth in drip irrigation are the advantages, which it offers over sprinkler and certain conventional forms of surface irrigation. Drip irrigation lends itself to easy adaptation for chemigation and automation, conserves water, and has lower energy and maintenance costs than sprinkler systems. In addition to this, drip irrigation maintains higher soil-water potentials in the root zone, which increases the availability of water to the plant thus enhancing plant growth and yield. Drip irrigation is quite different from other forms of irrigation. Water moves across the soil surface away from the drip emitter until the infiltration rate of the ponded area matches the emitter discharge rate. Beyond this free-water pond water moves into the soil by unsaturated flow. It is very important to research the characteristic and pattern of trickle source infiltration. Drip irrigation under mul:h is a new irrigation method, as utilize the advance of drip irrigation and plastic film cultivation technique. The conditions influenced crop water requirement are changed in drip irrigation under mulch, thus crop water requirement pattern is different from conventional irrigation forms. It is very useful to research field mulched crops water requirement pattern watering with drip irrigation. This research was conducted to: (1) understand the characteristic and pattern of trickle source infiltration, (2) Study mulched crop evapotraspiration for cotton and corn in a arid climate sandy loam soils. According to the researches of the dissertation, the main results are as follows:(1) The shape of wetted soil volume is influenced by soil texture, discharge rate and the total volume of applied water in case of trickle source infiltration. In general, the wetted soil volume is a semi-elliptic cone. The relationship between horizontal and vertical wetting front and infiltration time is remarkable power function. The relationship between wetted soil volume and infiltration time is remarkable stright line, and in case of certain volume of applied water, the wetted soil volume is not influenced by discharge rate. In the process of trick source infiltration, the increased soil water content is a constant value 0.34 for clay loam soil. The distribution pattern of water content in horizontal is similarly with vertical level. The more of the distance away axis, the less of the soil water content, and the decrease is most notable near the wetting front.(2) In case of specified volume of applied water, the shape of wetted soil volume is influenced by discharge rate. The horizontal wetting front in big discharge rate is wider than that of small discharge rate, and the vertical wetting front in big discharge rate is shallower than that of small discharge rate. The horizontal wetting front of 5.3L/h is wider17 percent than 2 L/h, and the vertical wetting front of 5.3 L/h is shallower 20 percent than 2 L/h. The influence of soil bulk density on wetting front is related to discharge rate. In case of big discharge rate, the influence in horizontal is notable. However, in case of small discharge rate, the influence in vertical wetting front is notable,(3) In case of trickle source wetting front overlapping, the infiltration pattern is different from that of single trickle source infiltration. The infiltration rate in wetting front interface is speeder than that under single trickle source. The wetted soil volume shape becomes a strip which parallel lateral. The soil water content distribution under trickle source wetting front overlapping is more than that of single source. The scatter super absorbent polymer in soil surface don't influenced the infiltration process of trickle source, the wetting front is almost coincide with checking treatment.(4) Because of the influence of soil water redistribution, the volume of wetted soil increase and the average soil water content decrease. In case of applied water 330min with a discharge rate 1 L/h, the hori...
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