Vol. 10, Issue 11 (2021)

Author(s):
Ravi Kumar Meena, YK Sharma, VP Yadav, Manisha Gaur, MA Khan, ML Meena and Rajesh

Abstract:
Soil Organic Carbon (SOC) is the key parameter which drives various soil functions. It provides integrative benefits in protecting the environment and sustaining agriculture. Some scientists have described SOC as a ‘universal keystone indicator’ in soil fertility management (Ssali, 2000; Loveland & Webb, 2003), making it an appropriate tool for managing heterogeneity with respect to soil fertility among farmer fields. Too much or too little SOC can equally be an environmental threat leading to pollution or loss of biodiversity (Musinguziet al. 2015). The establishment of SOC threshold is one of the measures that can be employed to overcome this problem. However, only few studies have been attempted to discuss minimum or maximum threshold values of SOC above or below which the beneficial effects of SOC is diminished. Janzen et al. (1992) showed that dry matter yields decreased when soil organic carbon level fell below 2%. Biswas et al. (2017) showed critical limits of SOC in two soil orders in rice-rice cropping systems in Indo- gangetic plains; 1.03%-1.16% (Entisol) and 0.5%-0.77% (Alfisol), below and above which yield of rice was significantly affected. On the other hand Musinguziet al. (2015) assigned a minimum critical value of 1.2% SOC in ferralsols of Uganda. An increase in microbial activity was found, indicated by rise in various enzymatic activities within a range of 1.52- 1.82% SOC (Lopes et al. 2013). Similarly, a good correlation was found between SOC and available micronutrients (Mondal et al. 2015). Greenland et al. (1975) concluded that soils in England and Wales with <2% SOC were prone to structural deterioration. The influence of water potential and organic carbon on the sensitivity of soil to mechanical disturbance was shown by Watts and Dexter (1997). Their study showed that soils become more sensitive to mechanical damage when wetter and the most dramatic effect is observed for soils with <1.5% organic carbon. A minimum critical value of 2% was shown above which there was significant increase in CEC (Eshetu et al. 2003). In spite of all past efforts it is difficult to establish a single minimum or maximum SOC threshold value that can be universally or regionally accepted. So this provides scope for development of method that can be used to predict SOC threshold considering all variables.