Nitrogênio na solução do solo e aspectos nutricionais e fisiológicos do milho cultivado após 12 anos sob fontes orgânicas e mineral

Abstract

Animal manures are frequently utilized in agriculture as a source of nutrients, especially nitrogen (N). The objective of this work was to evaluate how the application of manure from different animal breeding systems during twelve years and 19 applications interferes in the soil solution dynamics and forms, as well as in the physiological and physiological state of maize plants. The study was conducted in an experiment conducted from 2004 to 2017 in Santa Maria, Rio Grande do Sul, Brazil. The treatments consisted in the application of swine slurry (DLS), cattle slurry (DLB), swine deep-litter bedding (CSS), mineral fertilization (NPK), Control, without application of nutrients. The determination of the concentrations of inorganic N (NID) (NO3 - +NH4 +) and organic N (NOD) dissolved in the soil solution was performed in situ by means of voltage lysimeters, prior to sowing and application of treatments (time 0) and at 5, 20, 35, 55, 80, 120 days after emergence of the culture (DAE). At these same times, plants were collected for evaluate the concentration of N in the tissue and the photosynthetic activity and the rate of transpiration were analyzed. N productivity and efficiency indexes for maize were also evaluated. The NID in the soil solution was the predominant N in all treatments, ranging from 53 to 80% of Total Dissolved Nitrogen (NDT). NPK was the only treatment that maintained high concentration of NO3 - in the soil solution up to 35 DAE and provided higher grain yield and physiological parameters favor and nutritional in maize plants. Among the organic sources, the use of DLB allowed greater grain yield and better indicators of physiological and nutritional parameters, but did not maintain availability of N in the solution of the soil adequate to the plants.