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Mendes A.M.S.,Embrapa Semiarido | Duda G.P.,Federal Rural University of Pernambuco | do Nascimento C.W.A.,Federal Rural University of Pernambuco | Lima J.A.G.,INCRA | Medeiros A.D.L.,Secretaria Municipal de Agricultura
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2010

Soil cultivation using agrochemicals may increase the concentration of availability of heavy metals to plant and cause contamination of the trophic chain as well. This work was carried out to evaluate the influence of length of time under cultivation with melon (Cucumis melo L.) on the heavy metals accumulation and chemical alterations in Ultisol. Melon plantations of one, two and three years were studied. A benchmark area under natural vegetation was used to compare the data obtained. The results showed that the lengthiest time under cultivation altered the chemical characteristics of the soil. An increase in pH and contents of N, P and K was observed for the two soil layers evaluated. On the other hand, Ca contents were decreased by cultivation. The larger the cultivation time the higher the concentration of N, Pb, Cu, and Mn in the soil surface layer, whereas the Fe and Zn concentrations were diminished in both analyzed soil layers, though available concentrations are still regarded as low in soil. Source

Ferreira R.L.F.,Federal University of Acre | Alves A.S.S.C.,Instituto Federal Of Educacao Profissional E Tecnologica Do Acre | Aaujo Neto S.E.,Federal University of Acre | Kusdra J.F.,Federal University of Acre | Rezende M.I.F.L.,Secretaria Municipal de Agricultura
Bioscience Journal | Year: 2014

The objective this is paper was to evaluate the agronomic performance of lettuce cv. Vera in organic crop under different crop station and tillage systems and cover crops in a protected environment. An experiment was conducted in design of randomized blocks with four replicates, in split-plot arrangement. The plots consisted of four planting dates (jan. / feb. - 2006, may / june - 2006, oct. / dec. - 2006 and april / june - 2007) and the split-plot of four tillage systems / coverage soil (conventional tillage using mulch of rice husk, black/white polyethylene, unmulched soil and no-tillage). Soil cover with polyethylene film double-sided black / white increased the fresh weight of shoots, marketable yield and classification of lettuce. Growing lettuce in a greenhouse in maio/jun.-2006, accumulated higher (p <0.05) shoot dry mass. The fresh mass of shoots in the growing period maio/jun.2006 was higher (p <0.05) in cultivation with tillage soil and covered with plastic double-sided black / white, but in out./dez.-2006 the mass fresh was the same on tillage soil covered with plastic and on tillage, however, was higher (p <0.05) in tillage soil discovered or covered with rice husks. Source

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