Dynamics of Organic Carbon and Microbial Biomass in Alluvial Soil With Tillage and Amendments in Rice-wheat Systems

Abstract

Rice-wheat cropping systems of the Indo-Gangetic plains (IGP) occupying 12 million ha of productive land are important for the food security of South Asia. There are, however, concerns that yield and factor productivity trends in these systems are declining/stagnating in recent years. Decrease in soil organic carbon is often suggested as a reason for such trends. A field experiment was conducted to study the soil organic carbon (SOC) and soil microbial biomass carbon (MBC) dynamics in the rice-wheat systems. Use of organic amendments and puddling of soil before rice transplanting increased SOC and MBC contents. Microbial biomass carbon showed a seasonal pattern. It was low initially, reached its peak during the flowering stages in both rice and wheat and declined thereafter. Microbial biomass carbon was linearly related to SOC in both rice and wheat indicating that SOC could be used as a proxy for MBC.

Monitoring changes in soil organic carbon pools, nitrogen, phosphorus, and sulfur under different agricultural management practices in the tropics

“…Incorporation of CR resulted into significantly lower MBC status as compared to other integrated treatments. These results are in concurrence with the findings of Banerjee et al (2006). Because of high C:N ratio, incorporation of residues slows down the mineralization process.…”

“…Cropping systems and management practices that ensure greater amount of crop residue (CR) to be returned to the soil are expected to cause a net buildup of SOC stock (Kaur et al 2008;Majumder et al 2008a, b). Besides, tillage intensity (Reicosky et al 1995;Peterson et al 1998;Banerjee et al 2006), addition of manures and fertilizers (Ismail et al 1994;Sanchez et al 2001;Melero et al 2008), crop rotation (Zielke and Christenson 1986;Mandal et al 2008), and climate (Potter et al 1998) are the important factors contribute to the buildup or losses of SOC under arable agriculture.…”

“…In this regard, significance and applicability of living soil organic carbon fraction, i.e., microbial biomass carbon (MBC) have been studied extensively (Haynes 2005;Banerjee et al 2006;Kaur et al 2008), but received criticism because of its susceptibility to environmental stresses (Mazzarino et al 1991). Compared to MBC, nature and significance of non-living labile organic carbon pools are much less understood (Haynes 2005).…”

“…Moreover, much of the current understanding on SOM dynamics and nutrient supply patterns largely emanates detailed studies under controlled conditions (Mtambanengwe and Mapfumo 2008). Barring a few recent reports under tropical environments (Banerjee et al 2006;Rudrappa et al 2006;Majumder et al 2008a, b;Kaur et al 2008;Mandal et al 2008), majority of the studies related to soil organic carbon dynamics under different agricultural management practices and land uses are confined to temperate region (Mandal et al 2008), where SOC content is generally much higher than tropical Indian soils. Out of the above-mentioned studies under tropical and subtropical conditions, surprisingly, only Rudrappa et al (2006) included KMnO 4 -oxidizable SOC in their study as a measure of labile SOC.…”

Effects of Long‐Term Fertilization on Soil Carbon and Nitrogen in Chinese Mollisols

“…In this study, the amount of soil microbial biomass is linearly related to the SOC content ( P < 0.01) (Fig. 6); many reports confirm this relationship (Jedidi et al, 2004; Banerjee et al, 2006; Goyal et al, 2006; Li et al, 2008). The soil Cmic represented 1.3 to 2.9% of the SOC, and the Nmic accounted for 1.7 to 4.1% of the soil TN (Hao et al, 2008).…”