Comparison of Soil Organic Carbon Recovery by Walkley-Black and Dry Combustion Methods in the Russian Chernozem

Comparison of carbon and nitrogen determination methods for samples of a Paleudult subjected to no-till cropping systems

“…This difference among samples of distinct management systems was attributed to the greater amounts of chemical stable organic compounds in pasture than in crop residues. This influence of samples from different management on C results could not be however confirmed in a study conducted in a Russian Chernozem (Mikhailova et al, 2003).…”

“…The regressions found between these two methods were practically the same in the three cropping systems (Figures 1a,1b and 1c), showing that results of C recovery by the Walkley-Black method compared to the reference dry combustion method were not influenced by samples originated from different managements. The Walkley-Black C recovery was also not affected by land use and soil management systems for a Russian Chernozem (Mikhailova et al, 2003), but was for a Typic Hapludoll in Argentina Pampa, where the chemical stable compounds of organic matter occurring after the application of some managements has supposedly reduced the Walkley-Black C recovery (Diaz-Zorita, 1999). Table 2 -Soil bulk density within the 27.5 cm layer, determined according to the core method, for treatments of bare soil, pigeon pea plus maize (P+M) and lablab plus maize (L+M) no-till systems, under two nitrogen levels (0 kg N ha -1 -No N, and 180 kg N ha -1 -With N).…”

“…Although the C concentration results given by the Walkley-Black rapid dichromate oxidation method are generally lower than those obtained through the reference dry combustion methods (McGeehan & Naylor, 1988;Mikhailova et al, 2003) a high correlation is commonly found between these two methods (Mikhailova et al, 2003;Pérez et al, 2001). To overcome the problem of incomplete C recovery which leads to the underestimation of C concentrations by Walkley-Black method, the analytical results of this technique are corrected by a factor, commonly reported as 1.30 when no external heat is applied (Nelson & Sommers, 1996).…”

“…To overcome the problem of incomplete C recovery which leads to the underestimation of C concentrations by Walkley-Black method, the analytical results of this technique are corrected by a factor, commonly reported as 1.30 when no external heat is applied (Nelson & Sommers, 1996). A correction factor of 1.63 was proposed for a Russian Chernozem (Mikhailova et al, 2003), while a factor of 1.12 was suggested for subtropical soils of the State of Rio Grande do Sul, Brazil (Tedesco et al, 1995), but with application of external heat.…”

Microbial succession in a fermenting of wild forest noni (Morinda coreia Ham) fruit plus molasses and its role in producing a liquid fertilizer

“…Plant nutrients (primary: N, P, K; secondary: Ca, Mg and micronutrients: Mn, B, Zn) were also determined as follows. Total carbon (C) and organic matter were determined using the Walkley-Black method (Mikhailova et al 2003), while total nitrogen (N) in the form of nitrate was measured using a test kit (Spectroquant Picco) according to the manufacturers instructions (Merck company), and then total carbon/total nitrogen ratio(C/N) ratios were calculated. The amounts of the following elements (P, K, Ca, Mg, Mn, B and Zn) were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) according to the instructions for the instrument.…”