Marcos Vinícius Folegatti

Estimation of in situ hydraulic conductivity function from nonlinear filtering theory

Note: 29(4): 1063-1070 Reference EFLUM-ARTICLE-1993-006doi:10.1029/92WR02593 Record created on 2005-09-08, modified on 2017-02-23

EVAPORATION AND THE FIELD SCALE SOIL WATER DIFFUSIVITY FUNCTION

Note: 29(4): 1279-1286 Reference EFLUM-ARTICLE-1993-003doi:10.1029/93WR00094 Record created on 2005-09-08, modified on 2017-02-23

Estabilidade temporal da distribuição espacial da umidade do solo em área irrigada por pivô central

A heterogeneidade do solo faz com que o armazenamento de agua seja variavel, sendo necessaria uma amostragem intensa, para caracterizar a sua distribuicao espacial em uma area irrigada. Para fins de manejo da irrigacao, e importante o monitoramento da umidade do solo durante o processo de secagem entre duas irrigacoes sucessivas. O presente trabalho tem por objetivos avaliar a estabilidade temporal da distribuicao espacial da umidade do solo, a correlacao da umidade com conteudo de argila e avaliar se ha estrutura de dependencia espacial dessas variaveis. Quanto mais estavel for a distribuicao espacial da umidade e mais estreita a correlacao com a textura, menos intensas poderao ser as amostragens para fins de controle das irrigacoes. Em area irrigada por pivo central, no campus da ESALQ/USP, de solo Podzolico Vermelho-Escuro, a umidade foi medida em pontos espacados de 2,83xa0m ao longo de uma transecao radial, nas profundidades de 0,15 e 0,30xa0m, por meio de uma sonda de neutrons. O conteudo de argila e a densidade global foram tambem medidos. As medidas foram feitas durante um periodo de secagem do solo. A estabilidade temporal das distribuicoes espaciais foi avaliada por meio do coeficiente de correlacao e da tecnica de diferencas relativas. Foi constatada a persistencia no tempo das distribuicoes de umidade, sendo possivel identificar pontos de amostragem cujos valores permitem estimar a media geral da umidade na area, a qualquer momento. A dependencia espacial da umidade foi avaliada por meio de semivariogramas, os quais mostraram que mais de 50% da variacao dos dados pode ser atribuida a variacao estruturada no espaco, cujo padrao se mantem estavel no tempo e varia com a profundidade. Na camada inferior, a correlacao espacial entre umidade e conteudo de argila e descrita por semivariograma cruzado com efeito pepita nulo. A estrutura de dependencia espacial pode ser usada no mapeamento da umidade do solo.

Simulation of growth and development of irrigated cowpea in Piauí State by CROPGRO model

The objective of this work was to adapt the CROPGRO model, which is part of the DSSAT system, for simulating the cowpea (Vigna unguiculata) growth and development under soil and climate conditions of the Baixo Parnaiba region, Piaui State, Brazil. In the CROPGRO, only input parameters that define crop species, cultivars, and ecotype were changed in order to characterize the cowpea crop. Soil and climate files were created for the considered site. Field experiments without water deficit were used to calibrate the model. In these experiments, dry matter (DM), leaf area index (LAI), yield components and grain yield of cowpea (cv. BR 14 Mulato) were evaluated. The results showed good fit for DM and LAI estimates. The medium values of R2 and medium absolute error (MAE) were, respectively, 0.95 and 264.9xa0kgxa0ha-1 for DM, and 0.97 and 0.22 for LAI. The difference between observed and simulated values of plant phenology varied from 0xa0toxa03 days. The model also presented good performance for yield components simulation, excluding 100-grain weight, for which the error ranged from 20.9% to 34.3%. Considering the medium values of crop yield in two years, the model presented an error from 5.6%.

Produtividade do maracujazeiro amarelo sob diferentes níveis de irrigação e doses de potássio via fertirrigação

The objective of this work was to study the effect of four irrigation levels and five K doses applied through fertirrigation by drip irrigation system in the yellow passion fruit (Passiflora edulis Sims f. flavicarpa Deg.) yield. A complete randomized block design in plot subdivided with four replications was used. The treatments resulted from the combination of four irrigation levels [0.25V (926.76 L), 0.50V (1,528.20 L), 0.75V (2,117.28 L) and 1.00V (2,706.36 L), where V is the average volume of water applied in lysimeter with passion fruit plant] with five K doses (0.000, 0.225, 0.450, 0.675 and 0.900 kg plant-1 year -1 of K2O). The commercial yield was affected by irrigation levels, K doses and by the interaction irrigation levels vs. K doses. The majors values of passion fruit commercial yield were obtained with the application of 0.450 to 0.675 kg plant-1 year -1 of K2O, and water levels of 1,528.20 to 2,117.28 L plant-1 year -1, respectively.

Ocorrência de entupimento de origem biológica em sistema de irrigação por gotejamento

O trabalho consistiu de uma avaliacao da uniformidade de distribuicao de agua em uma parcela de um sistema de irrigacao por gotejamento para producao de flores em estufa, com 5 anos de uso, em uma propriedade no municipio de Atibaia, SP. Em uma amostra de 25 gotejadores retirados da parcela, determinou-se, em laboratorio, a curva de vazao-pressao e o coeficiente de variacao de fabricacao, CV, para as pressoes de 50, 100, 150, 200, 250, 300, 350 e 400 kPa. Analises quimica, fisica e de contagem bacteriologica da agua foram realizadas em tres pontos do sistema de irrigacao: na fonte de agua, apos o sistema de filtragem e no final de uma linha de gotejadores no meio da parcela avaliada. O valor do CV foi de 8,2% e os valores de 73% para o coeficiente de uniformidade de aplicacao de agua, 97% para o coeficiente de uniformidade hidraulica e 26% para o coeficiente de performance do emissor, juntamente com os resultados das analises da agua, permitiram evidenciar-se a ocorrencia de entupimento de origem biologica afetando a uniformidade de aplicacao de agua do sistema.

Lâmina de irrigação e aplicação de CO2 na produção de pimentão cv. Mayata, em ambiente protegido

The effect of different irrigation water depth applications and the atmosphere enrichment with CO2 was evaluated. The experiment was carried out with sweet pepper (cultivar Mayata) in two similar plastic greenhouses in Piracicaba, Brazil. In one of them, CO2 was applied with irrigation water, increasing the CO2 concentration in the atmosphere to 800 mmolCO2/mol and in the other greenhouse the irrigation water was not enriched with CO2. In each greenhouse four irrigation water depths were applied, corresponding to 60; 80; 100 and 120% of a reduced pan evaporation (RPA), in a complete randomized block design with ten replications. The CO2 was injected into irrigation pipeline during a period of 40 minutes. Fruits were harvested from ten selected plants, after 90 days of transplanting, evaluating fruit number, length, diameter, pulp thickness, weight and yield (kg/ha). The effect of different irrigation water depths was observed for length, pulp thickness and fruit number per plant in the greenhouse with CO2 application. In the greenhouse with CO2 enrichment and irrigation water depths corresponding to 100% of RPA, differences were observed in length, pulp thickness, fruits numbers per plant and yield of 7.0%, 4.5%, 35.0% and 38.4%, respectively. On the other hand, in the greenhouse without CO2 application, different water depth applications did not affect any parameter. All analyzed parameters presented better results in the greenhouse with CO2 enrichment, except for the fruit pulp thickness. The CO2 application in the plastic greenhouse resulted in increased length, diameter, fruit number per plant, weight and yield of 12.4%, 11.9%, 21.4%, 20.0% and 51,3%, respectively.

Dióxido de carbono aplicado via água de irrigação na cultura da alface

ABSTRACT Carbon dioxide water for lettuce irrigation.The experiment was carried out in Piracicaba, Brazil, in order toevaluate the effects of carbon dioxide, applied with the irrigationwater, on the productivity and quality of the lettuce cultivated inplastic greenhouse. The treatments were designed in two plasticgreenhouses, one was enriched with CO 2 and the other without CO 2 ,where lettuce variety Ver onica was cultivated. The plastic greenhousehad eight plots with 1.2 x 6.0 m and spaced by 0.8 m. The crop wasirrigated with “Rain Tape ” drip with outflow of 1.15 L/h at operatingpressure of 60 kPa. The irrigation was scheduled on a daily basis inorder to apply 50 liters/m 2 /day of CO 2 daily. The seedlings wereproduced in plastic greenhouse by using isopor tray with vermiculiteas substratum. They were transplanted 30 days after sowing date inbeds of 1.2 m width and 6.0 m length, with 0.30 m spaced betweenplants and 0,30 m between lines. After the application of CO 2 (10/02/97 – 11/02/97) plants were harvested. Enrichment of irrigationwater with CO

Reclamation of a salinized soil after cultivation in greenhouse

Overapplication of fertilizers and inadequate irrigation management in greenhouse crops have caused soil salinization, resulting in reduction of crop yields. The aim of this work was to evaluate different depths of leaching and methods of application for reclamation of a salinized soil under greenhouse conditions. Three relative water depths (2/3, 1, 3/2), based on calculated leaching water depth, were applied by drip irrigation and flooding, in a 2 x 3 factorial scheme, with 3 replications. From the obtained results, it may be concluded that the application by drip was more efficient than flooding in leaching the accumulated salts in the soil and the relative water depth and coefficient k of 0.9 and 0.1 for drip and 1.3 and 0.2 for flooding, respectively, should be used.

EFICIÊNCIA DO USO DA ÁGUA PELO MELOEIRO SOB DIFERENTES FREQÜÊNCIAS DE IRRIGAÇÃO

Objetivou-se, com este estudo, avaliar o efeito de cinco frequencias de irrigacao por gotejamento, na maximizacao da produtividade e na eficiencia do uso da agua pelo meloeiro cultivado em solo arenoso de Tabuleiro Costeiro do Piaui. O experimento foi conduzido no Campo Experimental da Embrapa Meio-Norte, localizado no municipio de Parnaiba, PI, latitude 3o5S longitude 41o47W e altitude de 46,8 m. O delineamento experimental foi o de blocos ao acaso, com cinco tratamentos e seis repeticoes, em que os tratamentos foram: frequencias de irrigacao de 0,50, 1,0, 2,0, 3,0 e 4,0 dias. Foram avaliadas as produtividades comercial e total e a eficiencia do uso de agua, constatando-se que a maior produtividade total (77.985 kg ha-1) e a maxima eficiencia do uso da agua (EUAEt) pelo meloeiro (282,83 kg ha-1 mm-1) sao obtidas com frequencia de irrigacao de um dia. As frequencias de irrigacao de 3 e 4 dias, ou superiores, nao sao recomendadas para o meloeiro e, se a agua e escassa, utilizam-se irrigacoes com frequencia diaria.