m. arabfard

Localized irrigation methods can be used to manage low water holding capacity in the sandy soils. In this research, the effects of different irrigation systems including pot, tape and drip irrigation with gravity pressures of 0.5, 1.5 and 3 meters on the sandy soil moisture distribution under watermelon cultivation were compared with the furrow irrigation as the control treatment. The moisture content of the soil at different depths and at the distance of 5 and 20 cm from the plant was measured using the TDR device. Water distribution study showed that in the pot irrigation method, the moisture content of different depths of soil was kept constant by 16% during the irrigation interval, but the highest moisture content was observed in gravitional drip irrigation treatment at the depths of 40, 50 and 60 cm; in contrast, the lowest amount of moisture was observed in the pot irrigation treatment. In tape and gravitional drip irrigation system with gravity pressure, in addition to the adjustment soil moisture up to 15 to 22% within the wetting front, soil moisture can be kept almost constant by pulsed irrigation technique. Therefore, while providing the use of drip irrigation system with minimum water pressure available in most of the agricultural land (0.5 m), using pot irrigation can ensure sandy soil moisture retention and soil for the cultivation of fruits such as watermelon plants.

Knowing the development of plant root area in plant growth duration we aimed to develop the culture of reducing unnecessary expenses in irrigation and, tried to irrigate the plant by as much water as needed in only root zone. So the plant growth divided to 4 monthly stages and by assuming the various root zone depth in different plant growth duration, the plant irrigated with as much water as met the plant need. Based on the results of this research in both gravity drip irrigation and gravity porous pipes irrigation methods, 100% irrigation level had the most effect on two characteristic of productivity and productivity per consumed water in treatments and, deficit irrigation wasn’t effective. Also by reducing the number of plants for each dripper, although because of duplication of number of plants per unit area productivity was increased, but the mean weight and number of corns were decreased and, among the irrigation methods, productivity of gravity drip irrigation in compare with gravity porous pipes irrigation and between amount of irrigation water, full irrigation in compare with deficit irrigation, and the number of plants for each dripper than one dripper for each plant showed more productivity.