Entupimento de gotejadores em função da aplicação de superfosfato simples e ácido nítrico

Abstract

RESUMO:O superfosfato simples (SS) é uma alternativa aos adubos fosfatados que são utilizados via fertirrigação, como o ácido fosfórico, que provoca acidificação do bulbo úmido no solo, e o monofosfato de amônio purificado, que apresenta maior preço. No entanto, não se conhece o efeito de tal adubo no funcionamento de emissores, principalmente nos gotejadores, nem se é possível controlar o entupimento por SS por meio de aplicações de ácido. Assim, desenvolveu-se este trabalho com o objetivo de avaliar a possibilidade da utilização do superfosfato simples via gotejamento, como alternativa ao uso de outros adubos fosfatados, e a tentativa de controle do entupimento utilizando ácido nítrico. O trabalho foi desenvolvido em bancada de ensaios de gotejadores, localizada no Laboratório de Hidráulica da ESALQ/USP. Foram aplicadas doses de 50; 75 e 100% da solubilidade do superfosfato simples (SS), em 26 tubogotejadores de diferentes marcas comerciais, e ao fim de 360 horas de irrigação, foi aplicado ácido nítrico com pH 2, na tentativa de desentupir os gotejadores mais sensíveis. Diante dos resultados, foi possível inferir que o uso do superfosfato simples pode ser feito via fertirrigação, e o ácido nítrico, aplicado segundo esta metodologia, não proporcionou a desobstrução dos emissores. PALAVRAS-CHAVE:adubos fosfatados, gotejamento, obstrução de emissores. DYNAMIC BLOCKAGE OF DRIPPERS AS A FUNCTION OF THE APPLICATION OF SUPER SIMPLE PHOSPHATE AND NÍTRIC ACID IN LOCALIZED IRRIGATION ABSTRACT:The super simple phosphate (SS) is an alternative to the phosphorous fertilizers which are used through fertigation, as the phosphoric acid, which triggers acidification of the wetted volume in the soil, and the monophosfato of purified ammonium, that has a higher price. However, the effect of such fertilizer in the emitters function, mainly in the drippers, is not known neither if it is possible to control the blockage for SS through acid applications. Thus, this study was developed in order to evaluate the possibility of the use of super simple phosphate trough drip irrigation, as an alternative to the use of other phosphorous fertilizers, and the attempt of controlling the blockage with nitric acid. The work was carried out in bench of drippers rehearsals, located at the Hydraulic laboratory in ESALQ-USP. Doses of 50; 75 and 100% of the super simple phosphate (SS) were applied in 26 emitter tubes with different commercial marks, and after 360 hours the nitric acid with a pH of 2 was applied, in the attempt of clearing the most sensitive drippers to the blockage. With the results it was possible to infer that: the use of super simple phosphate can be done by fertigation without causing damages to the system and the nitric acid, applied according to this methodology, did not provide the clearance of the emitters.

Performance of pressure-compensating emitters using treated sewage effluent for irrigation

“…According to the criterion of sensitivity of the emitters to the reduction in flow rate proposed by Barros et al (2009), the dripper G2 is characterized as sensitive from 500 h of operation on; G3, from 600 h of operation on, i.e., until 400 h, it did not show sensitivity to the reduction in flow rate. According to the same authors, only G3 showed Qr variation higher than 10% and CVQ above 5.50%, being characterized as sensitive to the reduction in flow rate.…”

“…Since there is not a norm to characterize the susceptibility of the dripper to clogging, the criterion suggested by Barros et al (2009) was adopted as the main analysis of the sensitivity of the emitters to clogging by the TSE, which is separated into three categories according to the sensitivity to clogging.…”

Obstruction of drippers as a result of application of moisturized whitewash in irrigation water

“…In the G6 model, before applying the acid, the values of Qr remained low, 6.17% (Qr <10%, Barros et al, 2009) and CV values were good, 4.89% (CV <10%, HILLEL, 1982). In models G2, G3 and G5, the graphs showed that the Qr values remained with a low range, and CV values are considered good values according to HILLEL (1982).…”

“…Agríc., Jaboticabal, v.31, n.5, p.887-894, set./out. 2011 From the data, a classification of models was made according to the proposal of BARROS et al (2009) to compare the sensitivity of the emitters to the application of Ca(OH) 2 .…”

“…We compared the means of CV during the experiment and relative flow rate in relation to the beginning of the experiment, and classified according to BARROS et al (2009) as: -Non-sensitive (Qr <10% and CV <5.5%) emitters G2 and G5; -Sensitive (Qr <20% and CV <15%) emitters G1, G3, G4 and G8, and as -Very sensitive (Qr > 20% and CV> 15%) emitters G6, G7 and G9.…”