Douglas Roberto Bizari

Consumo de água e produção de grãos do feijoeiro irrigado em sistemas plantio direto e convencional

The inappropriate use of water resources in agriculture, to get higher yields, has caused negative impacts on soil water storage, reducing the efficiency of irrigated productive systems. The aim of this research was to study water use through crop coefficients for sprinkler-irrigated beans at different development stages, in addition to the production of grains and their components, in no tillage and tillage crop systems. Irrigation management was monitored with tensiometers to maintain the soil water content level between 28% (at the moment of irrigation) and 31% (field capacity). The crop evapotranspiration level (ETc) was obtained from the soil water balance and the reference evapotranspiration (ETo) using the Penman-Monteith method. The results indicate that bean crop coefficients show lower values in the no tillage system than in the conventional tillage system, during flowering and pod formation stages. The bean plants in no tillage system are more efficient in relation to water use than the conventional tillage system, because in this system, the bean crop shows higher grain yield with lower water consumption.

Contribuição da estrutura interna na perda de carga de filtros de areia utilizados na irrigação

A dinâmica de operacao dos filtros de areia afeta o desempenho hidraulico do sistema de irrigacao, elevando a perda de carga e alterando a altura manometrica total do sistema. Buscando entender parte dessa dinâmica, o objetivo deste trabalho foi determinar o efeito da estrutura interna de filtros de areia na perda de carga de tres modelos de equipamentos fabricados no Brasil, sem a presenca do elemento filtrante e utilizando agua limpa. Adicionalmente, com o ajuste do modelo matematico exponencial aos dados experimentais, procurou-se estabelecer comparacoes entre os tipos de estrutura dos filtros avaliados. Os ensaios foram realizados em um modulo experimental construido no Laboratorio de Hidraulica e Irrigacao da FEAGRI/UNICAMP. Os resultados mostraram que a estrutura hidraulica interna dos filtros determinou comportamentos hidraulicos diferenciados e que os tipos de estruturas (placa difusora e drenos) alteraram o padrao de operacao dos modelos ensaiados. A funcao matematica proposta representou, significativamente, o fenomeno fisico de perda de carga para as condicoes do experimento.

Reflectometria no domínio do tempo em estudos de lixiviação de potássio em colunas de solo não-saturado

The aim of this research was to evaluate the advantages of using unsaturated soil columns equipped with TDR probes (Time Domain Reflectometry) coupled to an automated system of data acquisition for monitoring water and potassium movement in soils. The research was conducted in acrylic columns of 0.35m of internal diameter and 1.05m of length filled with air-dried soil. The use of TDR technique allowed obtaining time-space network at short time intervals, indicating levels of soil moisture and electric conductivity (Ce) at different depths. The results may represent an important help for the works on the proposition and validation of mathematical models that describe numerically these processes, contributing to a better understanding of the dynamics of water and potassium in soils.