Water supplied by sprinkler irrigation system for upland rice seed production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Design and management optimization of trickle irrigation systems using non-linear programming

A non-linear model is presented which optimizes the lay-out, as well as the design and management of trickle irrigation systems, to achieve maximum net benefit. The model consists of an objective function that maximizes profit at the farm level, subject to appropriate geometric and hydraulic constraints. It can be applied to rectangular shaped fields, with uniform or zero slope. The software used is the Gams-Minos package. The basic inputs are the crop-water-production function, the cost function and cost of system components, and design variables. The main outputs are the annual net benefit and pipe diameters and lengths. To illustrate the capability of the model, a sensitivity analysis of the annual net benefit for a citrus field is evaluated with respect to irrigated area, ground slope, micro-sprinkler discharge and shape of the field. The sensitivity analysis suggests that the greatest benefit is obtained with the smallest microsprinkler discharge, the greatest area, a square field and zero ground slope. The costs of the investment and energy are the components of the objective function that had the greatest effect in the 120 situations evaluated. (C) 1996 Academic Press Limited

Digital image analysis of root distribution towards improved irrigation water and soil management: Grapevine and date palm study cases

It is presented two study cases about the approach in root analysis at field and laboratory conditions based on digital image analysis. Grapevine (Vitis vinifera L.) and date palm (Phoenix dactylifera L.) root systems were analyzed by both the monolith and trench wall method aided by digital image analysis. Correlation between root parameters and their fractional distribution over the soil profile were obtained, as well as the root diameter estimation. Results have shown the feasibility of digital image analysis for evaluation of root distribution.

Economic viability and selection of irrigation systems using simulation and stochastic dominance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Seedling growth of Schizolobium parahyba on different substrates and irrigation levels

The present study aimed to assess the behavior of seedlings of Schizolobium parahyba (Vell.) Blake growing on different substrates and irrigation levels, and to study the use of urban waste compost in substrates. The experiment was carried out in the College of Agricultural Sciences, Universidade Estadual Paulista (UNESP), Department of Agricultural Engineering, Jaboticabal Campus, state of São Paulo, Brazil. The experimental design used was completely randomized, consisting of 30 treatments in a factorial design with 15 substrates and two irrigation levels in four replicates. The substrates were composed of different materials: urban waste, Plantmax®, dry cattle manure, vermiculite and soil. For the study of seedling growth, the following characteristics were evaluated: height (H), root-collar diameter (D), number of leaves, shoot dry weight, root dry weight, total dry weight, H/D ratio, Dickson's quality index, and the ratio between height and shoot dry weight (H/SDW). Assessments of the first three characteristics were carried out 20, 35, 50 and 65 days after sowing. Results showed that urban waste compost increased the growth of Schizolobium parahyba. There were significant differences for the irrigation levels tested; with better results for 150% ET compared to 100% ET irrigation level.