The trend of carbon sequesteration is observed when straw of sugarcane in not burned and merely left on the ground. In the management of straw, experiments were conducted in Australia; the content of carbon in the soil was found to be 20 % higher when depth was considered to be 0-0.1 m. This was studied, 2 years after the green cane management beginning, in unburned areas and compared with the burned areas (Wood 1991). In a long-term experiment of nearly 55 years, burned sugarcane and unburned sugarcane in the southeastern part of Brazil were com­pared, and carbon concentration of 22.34 g kg-1 in the cane with straw maintenance and nearly 13.13 g kg-1 in burned cane in 0.2 m soil depth was reported (Canellas et al. 2003).

Razafimbelo et al. (2006) explained that the increase in soil stocks of carbon in the 0-0.1 m layer after six years of management of green cane is almost 15 %, compared to the management with burned cane. A study was conducted in Australia’s adjacent burned areas in 1996 which revealed that for 4 years there was no change in the carbon stocks. Compared to that, a steady increase in carbon concentration was observed in unburned plots (Vallis et al. 1996). Another experiment conducted in the southeastern part of Brazil reported that in 12 years, due to maintenance of straw on the field, an average of 0.32 mg ha-1a-1 was accumulated in the first 0.2 m depth of an Oxisol. During the first 4 years increase from 1.2 to 1.9 mg ha-1a-1 was reported for the 0-0.4 m layer. After 8 years of up-gradation to mechanical harvest along with crop maintenance on the fields, nearly a 30 % increase in carbon stocks was signified (Galdos and Cerri 2009). The conclusion drawn from these observa­tions deduced the results that since the adoption of proper green cane management system, potential increase in soil stocks for carbon can be expected. In the related experiments conducted in Australia and Brazil, involving the measurement of car­bon concentration in burned and unburned areas, there was no significant difference in the given treatments after 12 months (Blair et al. 1998). An analysis on the man­agement and carbon concentration in Australia described that higher concentration in soil carbon was observed to be higher in areas of green cane after 4-6 years. As far as areas that have been recently converted to this management are concerned, no significant increase in carbon concentration has been observed for 1-2 years (Robertson 2003).

In a long-term experiment carried out in South Africa for 60 years, it was noted that between burned and unburned areas, carbon concentration in the 0-0.1 m layer of soil was higher in the latter but no marked difference was observed in the 0.1-0.2 and 0.2-0.3 m layers (Graham et al. 2001). Carbon stock in these areas was as high as 70 mg ha-1 in the first 0.2 m (Six et al. 2002). In Brazil, a review related to litter impact on soil was conducted which involved the evaluation from 12 sites. The estimate showed a mean annual rate of carbon accumulation of 1.5 mg ha_1 a-1 (Cerri et al. 2011). From the above findings, a conclusion can be drawn that the system of sugarcane harvest without burning accumulates stores more carbon in the soil when compared with the system which involves burning. But this accumulation is variable and dependent upon the texture of the soil, for instance, rate of mean annual carbon accumulation was approx. three times greater than the sandy soil (Leal et al. 2013).

The soil texture and carbon stock and concentration correlation is well estab­lished, especially considering clay content and clay along with slit content (Silver et al. 2000; Hao and Kravchenko 2007). Climatic conditions also impart an effect on the soil carbon accumulation (Blair et al. 1998). Other than that, nitrogen fertil­izer management (Graham et al. 2001) and the level of soil disturbance during the replanting operation have also been shown to aid in this accumulation. It has been noted that soils have a finite capacity to act as a carbon sink. This leads to the reach­ing equilibrium with respect to the management (Six et al. 2002). When carbon stock experiment was carried out with corn cultivation and corn stover, the amount of soil carbon stocks varied depending on the system that was used (Wilhelm et al.

2007) . Above all, sugarcane ground maintenance tends to increase carbon stocks in mid and/or long terms. However, when carrying out experiment for understand­ing the optimal straw amount for carbon stock maintaining or increasing pur­poses, conditions such as local soil, climate, and crop management need to be taken into account.