The objective of this work was to evaluate metribuzin bioactivity as a function of adding swine liquid manure doses and organic matter produced from crushed sugar-cane. It was conducted ten experiments using entirely randomized experimental design with four replicates in greenhouse conditions at the Departamento de Fitotecnia da Universidade Federal de Viçosa/MG. Five substrates were evaluated: washed sand, Yellow-Red clayish-sandy Podzolic soil, from Ponte Nova - Minas Gerais State, mixed with 0, 20, 40 and 60 m3 ha-1 doses of swine liquid manure and 0, 30 60 and 90 t ha-1 doses of organic matter associated to ten doses of metribuzin. This herbicide was applied using a CO2 pressurized costal sprayer after sowing five seeds of the indicator plant (Cucumis sativus L.) AG. 221 caipira hybrid in each vase. The vases were irrigated three times a day using a rainfall simulator and the substrate moisture was maintained about 80% of field capacity. Fourteen days after applying treatments, the haversting of experiments was realized, followed by determination of fresh biomass of the indicator-plant aerial part. The herbicide concentrations resulting in 50% inhibition of the test-plant growth (I50) were calculated from equations adjusted by regression analysis. The adsorption relations and adsorption increasing were calculated as a function of the addition of swine manure and organic matter doses. Metribuzin adsorption increased linearly with the addition of swine liquid manure and organic matter to soil. The greater adsorption occurred with the addition of organic matter. Also, it was observed that for the highest dose of swine liquid manure (60 m3 ha-1), the adsorption relation was 4.79, and in relation to soil without organic matter the adsorption increasing was 28.01%. However whit the addition of the organic matter highest dose (90 t ha-1), the adsorption relation was 6.63 and the increase in adsorption was 32.51%.
Adsorption; substrates; herbicide; indicator plant