Efeitos da irrigaÃÃo com esgoto tratado sobre o sistema solo-planta (milho) e induÃÃo da supressividade a doenÃas causadas por nematÃides / Effects of irrigation with treated sewage on soil â plant(maize) system and inducement of suppressiveness to diseases caused by nematodes

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The treated effluents have great potential for application in agriculture, due to certain levels of nutrients and organic material that can improvement the chemical characteristics of soils and thus induce suppressiveness of soils to plant diseases caused by phytopathogens. The objective this word was to provide technical subsidies for the fertirrigation of corn (Zea mays L.) with the effluent of a UASB reactor, operating at real scale, and to evaluate the inducement to suppressiveness of soils to diseases of plants caused by nematodes of the Meloydogine gender. The experiment was conducted in the area of use of treated effluents belonging to Federal University of Pernambuco, located in ETE Mangueira, Recife - Brazil, which had 24 drainage lysimeters. The treatments applied were: irrigation with supply water (T1), irrigation with supply water further application of NPK (T2), irrigation with supply water further infestation Meloydogine incognita (T3), irrigation with supply water further application of NPK and infested with Meloydogine incognita(T4), irrigation with treated effluent (T5), irrigation with treated effluent further application of P (T6), irrigation with treated effluent further infestation with Meloydogine incognita (T7), irrigation with treated effluent further application of P and infested with Meloydogine incognita(T8). The experimental design was completely randomized, with three replications. The irrigation system used was located irrigation by dripping and management of irrigation was carried at variable period by monitoring of the matrix potential of water in the soil at tensiometers. The results showed that the fertirrigation with treated effluent was able to accumulate nutrients and metals in the soil surface layer (0-20 cm). However, statistically significant differences were found among: the concentration of NO3 - of the treatments T4 and T5; the concentration of NH4 + of the treatments T6, T6 and T8 and the treatments submitted to irrigation with supply water; the concentration of P of the treatment T6 and the concentration of P of the treatments T1, T2 and T3; the concentration of K+ of the treatment T5 and the concentration of K+ of the treatments T1 and T3; the concentration of Ca2+ recorded in treatment T8 and the concentration of that element found in all treatments irrigated with supply water. The fertirrigation also increased the concentration of Na+ and Al3+, but the values found are not capable of causing damage to soil, as sodicity, salinity or toxicity for Al. The values of PST found in soil that received the addition of the treated effluent did not reach the critical value of 15% and there were not significant differences among the results of treatments. The results of RAS were also not significant. What confirms the absence of the risk of soil sodicity. The fertirrigation increased the pH of soil, but this did not affect the development of culture. Statistically, there were significant differences among treatments T5, T6 and treatment T2. With respect to organic material, only the treatments T5 and T8 were significantly different of treatment T1. In the case of CTC effective, treatment T8 was the only one to present significant difference with respect to treatments submitted to irrigation with supply water. With regard to concentration of Fe2+ and Zn2+ in soil, the treatment T6 showed significant differences when compared with all treatments subjected to irrigation with supply water. With respect to concentration of Cu2+ of the soil, the results showed that treatments T5 and T8 differed significantly from the T1 and T3. In the case of Mn2+, that occurred among treatments T5 and T8 and treatments T1 and T3. The fertirrigation with the treated effluent was able to accumulate metals and nutrients in leaf tissue of plants. However, there were significant differences among the levels of N found in plants subjected to treatments T5 and T8 and the levels of that element found in plants subjected to the treatments irrigated with Water. In the case of P, that occurred among the treatment T6 and treatment T1 and T3. Regarding the contents of K+ in leaf tissue, there were significant differences among all treatments irrigated with treated effluent and treatments T1 and T3. In respect of metals, both the values of Fe2+ as Zn2+ found in leaf tissue of plants irrigated with treated effluent were not within the range of levels appropriate to the development of corn plants. The plants fertirrigated with the treated effluent showed better development and productivity. But the treatments T6 e T8 showed significant differences when compared with the treatments subjected to irrigation with supply water. The fertirrigation reduced the density of eggs and the FR of Meloidogyne incognita in roots of plants, in addition to improving the resistance of plants to the disease symptoms caused by the nematode. However, only treatment T3 was significantly different when compared with other treatments (T4, T7 and T8), which showed better results. The suppressiveness can be induced by various factors, biotics and abiotics, the results presented in this work were attributed to increases in values of pH, CEes, CTC effective and organic material, Ca2+, Mg2+ and Al3+ in plants irrigated with treated effluent. Moreover, the plants subjected to the treatments irrigated with treated effluent showed higher levels of N and Zn in leaf tissue. There was an increase in concentrations of leached nutrients, mainly of N-NO3 - and Na+. In respect of the elements leached, the concentrations of leached N-NO3 - were higher than the permitted to maintain the quality of groundwater (10 mg N-NO3 -/L, for human consumption; Resolution NÂ 369 of CONAMA/2008). Among the metals, Fe was the element that showed the highest leached concentrations.

ASSUNTO(S)

reÃso engenharia civil supressividade supressiveness corn milho fertirrigaÃÃo engenharia civil fertirrigation

ACESSO AO ARTIGO

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