Effects of nitrogen addition on soil oxidisable organic carbon fractions in the rhizospheric and bulk soils of Chinese pines in north-western China

Increased atmospheric nitrogen (N) deposition caused by human activities has potentially important effects on ecosystem carbon (C) dynamics and different effects on C fractions with different stabilities and chemical compositions. A better understanding of the responses of different C fractions to N addition is vital for maintaining soil quality and protecting vegetation. In order to investigate the differential effects of N addition on total soil organic carbon (SOC) and four SOC fractions with increasing degrees of oxidisability in Pinus tabuliformis rhizospheric and bulk soils, a 6-year pot experiment was performed testing the effects of the addition of N at rates of 2.8, 5.6, 11.2, 22.4 and 44.8 g [m.sup.-2] [year.sup.-1] compared with a control (CK) group (no N addition). Addition of N addition had significant (P Additional keywords: Pinus tabuliformis, rhizosphere, nitrogen deposition, carbon stabilization.
Introduction Global emissions of reactive nitrogen (N), such as N[H.sub.3], [N.sub.2]O, urea, amines and proteins, have increased three-to fivefold over the past century because of anthropogenic activities such as the [...]