Vazão de gotejadores instalados em subsuperfície em diferentes solos

Abstract

The irrigation allows a significant increase of the crop productivity, however it is necessary utilize the water in a rational way for this technique be sustainable. Therefore, efficient irrigation systems in water use are being sought increasingly, such as drip irrigation. The drip irrigation can be installed either on the soil surface or in subsurface, and the last one due to its water application characteristics can be even more efficient than superficial system. However, this system has some additional limitations compared to the superficial system, such as the difficulty of maintenance and installation. In addition,the drippers flow can be modified when buried due to soil characteristics, which can lead to reductionin system uniformity. Although there are many studies in this area, few have investigated the flow reduction of drippers installed in small depths, which is a trend observed in irrigated coffee. Thus the aim of the present work was evaluate the flow variation of two different drippers installed in subsurface in four different soil types as well as to study the characteristics of each soil.The work was divided into two experiments, the first sought to characterize physico-hydrical properties of the soils. The second aimed to determine the variation of subsurface flow in each soil with drippers installed at 5 cm depth. For the first experiment, horizontal infiltration tests were conducted to determine the moisture profile in relation to the advance time and also to determine the soil hydraulic diffusivity. The advance time was shorter for sandy loam and longer for loam whereas for diffusivity the highest values were for sandy loam and the lowest for silt loam and clay loam.In the second experiment the subsurface flow was determined by an experimental apparatus built to meet the purpose of the work. There were variations of flow in both emitters. It was concluded that even at small depths these variations must be taken into account.