Márcio Mota Ramos

Recovery of drippers clogged by use of water high in iron content

A study was carried out (Reciclean) to evaluate the efficiency of using the phosphoric acid, sodium hypochlorite, a commercial product and mechanical impact for cleaning the drippers in which the clogging was due to the presence of high iron content in water. The experiment was set up in the Vista Alegre Farm, located in Jaboticatubas County - Minas Gerais State. A drip irrigation system was adopted for the accomplishment of the tests. Eight treatments were tested, of which, seven with application of chemical products and one with mechanical impact. In accomplishing the chemical treatments, the phosphoric acid was used at pH 2 and 3, sodium hypochlorite at 100, 50 and 25 mg L-1 chlorine and Reciclean at 50 and 25 mg L-1. According to the results, the following conclusions were drawn: the treatment using the phosphoric acid at pH 2 provided the best results, when evaluating the improvement of uniformity in the irrigation system, since it showed the highest increase in the values of uniformity coefficients (CUD and CUC); however, it is an expensive treatment. The treatment with 25 mg L-1 chlorine presented the best benefit/cost relation, since it showed to be the cheapest besides being the second best in improving the uniformity of the irrigation system. The mechanical impact is a good alternative to recover the drip irrigation systems, principally under organic farming.

Modelo para a determinação do espaçamento entre desaguadouros em estradas não pavimentadas

As estradas nao pavimentadas sao de fundamental importância para o desenvolvimento social e economico do Brasil, sendo a erosao provocada pela agua no leito e nas margens destas estradas um dos principais fatores para sua degradacao. Neste artigo, apresenta-se um novo modelo para a determinacao do espacamento entre desaguadouros em estradas nao pavimentadas e, consequentemente, para a reducao dos problemas associados a erosao hidrica. Utilizando o modelo de ondas cinematicas, determina-se o hidrograma de escoamento superficial no canal de drenagem da estrada e, a partir deste, e calculada a tensao provocada pelo escoamento. Sempre que a tensao cisalhante causada pelo escoamento supera a tensao critica para cisalhamento do solo ocorre o seu desprendimento. A diferenca entre essas tensoes cisalhantes e multiplicada pela erodibilidade do solo e pela area em que ocorre a aplicacao da tensao cisalhante para estimar a perda de solo provocada pelo escoamento. O espacamento maximo entre desaguadouros e obtido, comparando-se a perda de solo provocada pelo escoamento com a perda de solo toleravel. O comprimento maximo do canal e aquele para o qual a perda toleravel e atingida. O modelo permite determinar o espacamento entre desaguadouros considerando as caracteristicas das areas que contribuem para o escoamento e a resistencia do solo. As simulacoes realizadas mostraram que o modelo e sensivel as alteracoes na erodibilidade e na tensao critica de cisalhamento do solo, bem como a declividade do canal, permitindo ainda que, por meio da alteracao no aprofundamento toleravel para o canal, os espacamentos possam ser ampliados ou reduzidos.

Avaliação do manejo de irrigação no Perímetro Irrigado de Pirapora, MG

The objective this paper was to evaluate the water management in the Pirapora Irrigation District in the State of Minas Gerais during 1999 to 2000. The irrigation demands of crops were simulated using the soil water balance for the entire district. The water volumes obtained in the simulations were monthly integrated and compared with the water volumes measured in the field by hydrometers. According to the results it may be concluded that, excessive water application occurred in the district, except for the months of January 1999, January, February, March and April 2000, when the crops were sub-irrigated. Thus, it is necessary to implant an irrigation scheduling program to optimize the water use.

Estimativa da condutividade elétrica da solução do solo a partir do teor de água e da condutividade elétrica aparente do solo

The increase of fertigation techniques has not been followed by researches that generate available information to guide a correct fertigation management. The time-domain reflectometry allows the simultaneously monitoring of soil water content (q) and bulk electrical conductivity (CEa). Literature presents various models which relate TDR readings of q and CEa to soil solution electrical conductivity (CEw). Nevertheless, many researches demonstrate the need for evaluation and calibration of these models under different soil conditions. In this work, six mathematical models were evaluated in order to establish the relationship among q, CEa e CEw. Laboratory experiments were carried out using two soil materials, by means of applying five electrical conductivities combined with five soil water contents in PVC columns. The models allowed a reasonable relationship among q, CEa e CEw with better performance of de RHOADES et al. (1976) e de VOGELER et al. (1996) models for the soils 1 and 2, respectively.

Avaliação da eficiência do uso da energia elétrica no Perímetro Irrigado de Pirapora, MG

The efficiency of electrical energy use was evaluated in the Pirapora Irrigation District, during the years of 1999 and 2000. The irrigation demand was simulated based on the soil water balance, considering an optimum irrigation management. The annual average energy consumption index for the irrigation district was determined using the water irrigation volume applied and the energy consumption in the pumping plants. With the simulated water volumes and the mean annual energy consumption index, the energy consumption was simulated for the condition of an ideal irrigation management. The simulated energy consumption was compared with the real one. According to the results it may be concluded that due to excessive water application the energy consumption was high. Thus, a good irrigation management program is needed to optimize the use of water and electrical energy in the Pirapora Irrigation District.

Produtividade da Brachiaria brizantha cv. Xaraés em diferentes manejos e doses de adubação, períodos de descanso e épocas do ano

Experimentos ja foram conduzidos no Leste do Estado de Minas Gerais visando a avaliacao de gramineas forrageiras onde destacou-se a Brachiaria brizantha cv. Xaraes. Diante disso, decidiu-se intensificar a pesquisa conduzindo-se um experimento em esquema de parcelas sub-subdivididas, tendo nas parcelas um esquema fatorial 2 x 2 (epocas climaticas e manejos de adubacao), nas subparcelas quatro periodos de descanso e nas sub-subparcelas seis niveis de adubacao, no delineamento inteiramente casualizado, com quatro repeticoes. As epocas climaticas foram outono/inverno e primavera/verao. Os periodos de descanso foram de 21, 28, 35 e 42 dias. Os manejos de adubacao foram convencional e fertirrigacao. Para diferenciar as doses de adubacao no tratamento fertirrigado, utilizou-se a aspersao em linha. As doses de adubacao tiveram uma relacao entre nitrogenio e potassio de 1 N: 0,8 K2O e foram de 0, 15, 39, 64, 83 e 100% da referencia (700 e 560 kg de N e K2O). A produtividade de materia seca foi obtida por meio do material seco em estufa ventilada a 60 °C, por 72 h. Verificou-se, em geral, que a estacao seca apresentou menor produtividade de MS; porem, em media, a produtividade obtida na estacao outono/inverno foi de 75% daquela obtida na estacao primavera/verao. Os manejos de adubacao nao influenciaram os valores de produtividade de MS, porem o aumento da dose de adubacao proporcionou efeito linear positivo no capim-xaraes fertirrigado na estacao outono/inverno e quadratico nos demais tratamentos. Os periodos de descanso proporcionaram efeito quadratico apenas no tratamento fertirrigado e estacao outono/inverno