Efeito da moenda fina das amostras de terra na determinação dos teores de azoto total e carbono total e orgânico Influence of soil grinding degree on the determination of total nitrogen, total carbon and organic carbon concentrations.

Abstract

A Norma ISO 11464, relativa à prepara­ção de amostras de terra para análise físico­química, preconiza, para tomas de material inferiores a 2 g, que as mesmas sejam sujei­tas a moenda fina (0,05) os resultados e a moenda fina da amostra não aumentou significati­vamente (p>0,05) a precisão dos mesmos, quer em termos do teor de azoto total quer de carbono total e orgânico, sugerindo ser dispensável a moenda fina das amostras.According to ISO Standard 11464 (Soil quality -Pretreatment of samples for physico­chemical analyses) for test samples below 2 g, the air dried soil sample must be ground to a particle diameter ≤ 0.25 mm, in order to have a homogeneous test sample and, there­fore, minimize the variability of results. This is quite a time consuming task. The aim of this study was to compare the influence of two different degrees of grinding (0.05) effect on C and N concentrations. Grinding the soil to 0.15 mm didn’t increase significantly (p>0.05) the precision of results suggesting that, for the determination of total nitrogen or total and organic carbon, it is not necessary to grind the soil to a fraction less than 2 mm.

Keywords

• análise de solo
• azoto
• carbono
• moenda
• Norma ISO 11464
• carbon
• ISO Standard 11464
• ni­trogen
• soil analysis
• soil grinding