Interactive Effect of Soil Mulching and ISAREG Model Based Irrigation on Watermelon Production

Abstract

Even with the growing scenario of water scarcity, in the Northeastern semi-arid region, the irrigation management is still not properly managed, resulting in the waste of scarce water resources in the region. The ISAREG model has been used in several countries, being able to assist in the simulation of irrigation. In addition, the ISAREG model quantifies irrigation depths at different percentages of storage, increasing irrigation efficiency. Another way to reduce water loss in agriculture is through the use of soil cover, which is a simple technology and whose benefits over crop production and productivity are irrefutable. Added to this is the fact that interactions among these applications can amplify the effects. The objective of this study was to compare the irrigation propositions generated from ISAREG model with the actual irrigation management adopted by the farmers of the Jaguaribe - Apodi Irrigation District, Brazil. In addition, field experiments were performed to assess the influence of different irrigation and soil cover conditions on fruit development and yield of watermelon These field experiments were performed after field surveys with farmers in a randomized complete block design with subdivided plots and four replicates. The treatments consisted of the combination of four irrigation propositions (three ISAREG propositions: M1 = 100%, M2 = 80% and M3 = 60% of Available Water Capacity in Soil, and M4, irrigation depth used by irrigators), and four subplots, the uncovered soil (C0), covers with rice husks (C1), with white mulching (C2) and with black mulching (C3). The data were subjected to analysis of variance, and when significant, regression analysis, averages test and trend graphs were performed. The irrigation depths of 365.2 mm and 410 mm with a black mulching resulted in the highest numbers of fruits per plant (1.6). From the results, it was concluded that the farmers do not practice the correct management of the irrigation, because the farmers irrigated more water to a greater irrigation depth as indicated by the ISAREG model (100% of the Available Water Capacity in Soil) throughout the watermelon cultivation. In general, plants irrigated with 100% of available Water Capacity and on soils covered by rice husk and white mulching showed better productivity.