Resumo

TARCHETTI DINIZ, Lidia et al. Effect of nitrogen fertilization on soil microbial biomass in an Oxisol cultivated with irrigated barley in the Brazilian Cerrado. Acta Agron. [online]. 2016, vol.65, n.2, pp.137-143. ISSN 0120-2812.  https://doi.org/10.15446/acag.v65n2.46432.

The aim of this study was to evaluate the effect of different nitrogen doses and five period of sample collection, on soil microbial biomass - nitrogen (SMB-N), total nitrogen (total N) and percentual ratio of the microbial biomass and total N (SMB-N/total N) in a Oxisol cultivated with barley (Hordeum vulgare L.). The experiment was installed in June, 2005, in an area located at Embrapa Cerrados, Federal District. The experimental design was a randomized block, with three replicates. The plots received doses of nitrogen: 20 - 40 - 80 kg ha^-1 N and a control without it and the subplots were period of soil sample. Three applications of N were realized: 10 kg ha^-1 on the 5^th day (06/14) after sowing; the rest of N was parceled in two applications with fertigation, on tillage, on the 27^th (07/08) DAP, e no 43^rd (07/22) DAP. Soil samples layer (0 - 10 cm deep) were collected for (SMB-N) determination and total N in six periods: 02 days before of the first fertigation; 02 days after of the first fertigation; 04 days before of the last fertigation and 04 days after of the last fertigation; on flowering stage and after harvesting. There was effect of the doses of N and the period of soil collection on the SMB-N, total N and in the ratio SMB-N/total N. The average values of total N revealed steadier in short-term (cycle of the culture) and this was not a good parameter to evaluate the behavior and N transformations in the soil-plant system

Palavras-chave : Cerrado; Hordeum vulgare L; Microbial biomass; Nitrogen; Soil quality.

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