Elís Regina Costa de Morais

Classificação da composição iônica da água de irrigação usando regressão linear múltipla

This work was conducted with the objective of developing a methodology for classification of the ionic composition of the irrigation water using multiple linear regression. A Stepwise Regression Analysis model was tested, using electrical conductivity as the dependent variable and analyzed ions calcium, sodium, potassium, carbonate, bicarbonate and chlorides as the independent variables in all tested models. All water samples were collected by the farmers of the region where this work was conducted. The regression models were adjusted using the water analysis database from the ESAMs Analysis Laboratory (Laboratorio de Analises de Agua e Fertilidade do Solo da Escola Superior de Agricultura de Mossoro - LAAFS/ESAM). The linear model, adjusted using the Stepwise Regression Procedure, shows that the degree of model adjustment tested depends upon geological formation of watersheds and whether it is collected in a river or tubular wells. The classification of the water in calcareous region of the Chapada do Apodi is calcic-sodic, calcic or choride if this source was tubular well, piezometric well (drilled in unconfined water denominated in the region as poco amazonas) or surface rivers and lagoons water, respectively. In Baixo Acu region, these waters were classified as sodic, magnesian-sodic or sodic depending if the source collected is a tubular well (drilled in Acu sedimentary geological formation), piezometric well or superficial water, respectivelly.

Nível crítico pelo critério da distribuição normal reduzida: uma nova proposta para interpretação de análise foliar

This study develops a methodology through a statistical method, for the determination of critical level in foliar analysis. The obtaining of the critical level with the continuous distribution of probability is a new proposal for foliar analysis interpretation, based on the reduced normal distribution. For this purpose it is necessary to have data of productivity (P) and of Q, defined as the relationship between P and ni (Q = P/ni), where ni is the content of the nutrient for which critical level is to be found. Initially Pr which represents 90% of the maxim, is calculated with the equation P(90%) = 1.281552s1 + x1 and for the calculation of Q 90% of the maximum value with the equation Q = 1.281552s2 + x2 where x1 and s1 are the arithmetic average and the standard deviation of P and x2 and s2 the average and the standard deviation of Q. The critical level is obtained by NCi = (1.281552s1 + x1)/(1.281552s2 + x2). The critical level methodology of the continuous distribution of probability allowed the calculation, for the coffee crop, of critical values within range of those recommended in the literature.

Estimativa de carbonato de cálcio aplicado via água de irrigação nas regiões da Chapada do Apodi e Baixo Açu, RN

The application of irrigation water with high contents of carbonate and bicarbonate can contribute to pH elevation of the soils after some years of cultivation. This study had as its objective the evaluation of the irrigation water with respect to its carbonate and bicarbonate content, based on the concept of the Equivalent Calcium Carbonate (ECACO3) in the region of the Chapada do Apodi and Baixo Acu in the state of Rio Grande do Norte, Brazil. Considering an irrigation water depth of 400 mm, the results showed that the waters of the region of the Chapada do Apodi presented larger values of ECACO3 compared to those of the region of Baixo Acu. In the region of the Chapada do Apodi, independent of the origin, largest values of ECACO3 were found for the waters of the region of Mossoro, with an average of 765 kg ha-1 and the smallest value was observed for Grossos and Upanema with 626 kg ha-1. For the region of Baixo Acu, independent of the origin of the waters, the region of Ipanguassu presented the highest values of ECACO3 with an average of 654 kg ha-1 whereas the smallest values were found for the region of Carnaubais, with 580 kg ha-1.

Avaliação da evolução da coleta seletiva: usando análise envoltória de dados (DEA)

A geracao excessiva de residuos solidos, revelada nos ultimos anos, tornou-se um fator agravante para o desenvolvimento sustentavel em todo o planeta, o que motivou a agenda 21 a preconizar o tratamento hierarquico para a gestao de residuos, fundamentada na politica dos 3 R´S, com objetivo de amenizar a problematica causada pelos mesmos. No Brasil, a Politica Nacional dos Residuos Solidos, entende que a coleta seletiva seja uma das principais alternativas para a gestao sustentavel dos residuos solidos. Porem, esta vem passando por diversas dificuldades no pais, o que impossibilita a evolucao dos programas implantados nos municipios. Assim, o objetivo deste artigo e demonstrar a evolucao dos programas de coleta seletiva nos municipios do Estado do Rio Grande do Norte, usando Analise Envoltoria de Dados (DEA). Neste, foi possivel identificar que os principais problemas que interferem na evolucao dos programas estao relacionados ao uso excessivo dos insumos e a baixa producao dos programas.

Crescimento da parte aérea e raiz do meloeiro adubado com fertilizante orgânico

Este estudo objetivou avaliar o efeito do fertilizante orgânico no crescimento de raiz e da parte aerea do meloeiro em funcao de graus dias acumulado. Foi instalado um experimento em vasos, em delineamento experimental em blocos casualizados com quatro repeticoes em esquema fatorial 2x6, referente a presenca e ausencia de fertilizante orgânico e seis epocas de amostragens (7; 14; 21; 28; 35 42 dias), totalizando 48 parcelas experimentais. Para cada amostragem determinou-se numero de folhas (NF), area foliar (AF), materia seca de raiz (MSR) e materia seca da parte aerea (MSPA). A taxa de crescimento absoluto (TCA) divergiu em funcao da adubacao para as diferentes caracteristicas avaliadas e na presenca do fertilizante orgânico, verificou-se que as somas caloricas para se obter as maiores TCAmax foram maiores nos tratamento que nao receberam o fertilizante orgânico.