Soil organic carbon pools and productivity relationships for a 34 year old rice–wheat–jute agroecosystem under different fertilizer treatments

Abstract

Soil organic carbon (SOC) pools are important in maintaining soil productivity and influencing the CO 2 loading into the atmosphere. An attempt is made here to investigate into the dynamics of pools of SOC viz., total organic carbon (C tot ), oxidisable organic carbon (C oc ) and its four different fractions such as very labile (C frac 1 ), labile (C frac 2 ), less labile (C frac 3 ) and non-labile (C frac 4 ), microbial biomass carbon (C mic ), mineralizable carbon (C min ), and particulate organic carbon (C p ) in relation to crop productivity using a 34 year old rice (Oryza sativa L)-wheat (Triticum aestivum L)-jute (Corchorus olitorius L) cropping system with different management strategies (no fertilization, only N, NP, NPK and NPK+ FYM) in the hot humid, subtropics of India. A fallow treatment was also included to compare the impact of cultivation vis-à-vis no cultivation. Cultivation over the years caused a net decrease, while balanced fertilization with NPK maintained the SOC pools at par with the fallow. Only 22% of the C applied as FYM was stabilized into SOC, while the rest got lost. Of the analysed pools, C frac 1 , C mic , C p and C min were influenced most by the treatments imposed. Most of the labile pools were significantly correlated with each other and with the yield and sustainable yield index (SYI) of the studied system. Of them, C frac1 , C min , C mic and C p explained higher per cent variability in the SYI and yield of the crops. Results suggest that because of low cost and ease of estimation and also for upkeeping environmental conditions, C frac1 may be used as a good indicator for assessment of soil as to its crop productivity.

Effect of Long-Term Application of Inorganic and Organics on Soil Aggregate Fractions in Double Rice Cropping System

“…This indicated that smaller particles with greater surface area may be responsible for scavenging a sizable amount of C in micro aggregates. Kong et al, (2005) and Majumder et al, (2007) also reported similar results. However, there was a little influence of increasing C inputs was observed for C associated with aggregates of 250-1000 and < 53 µm size.…”

Effects of enhancing soil organic carbon sequestration in the topsoil by fertilization on crop productivity and stability: Evidence from long-term experiments with wheat-maize cropping systems in China

“…The range of sequestration efficiencies was similar to that observed from the Indian humid subtropical plains at 20-cm depth under a rice-wheat over 20-30 years (7.6-14%, Majumder et al, 2008) and a rice-lentil (Lens culinaris) system (9.9%, Srinivasarao et al, 2012), but lower than that from the temperate region of North America (14-21%, Rasmussen and Collins, 1991) and higher than that from topsoil of subtropical regions under a rice-wheat-jute (Corchorus olotorius L.) system (4-5%, Majumder et al, 2007).…”

Fertilization increases paddy soil organic carbon density

“…However, reported evidence is contradictory. Compared to no fertilization, some studies suggested that SOC content increases under inorganic fertilization, especially for inorganic nitrogen (N) fertilizers (Majumder et al, 2007;Reid, 2008;Tong et al, 2009;Batlle-Bayer et al, 2010). López-Bellido et al (2010) and Luo et al (2010) suggested that the SOC content does not change, and others suggested that the SOC content decreases (Manna et al, 2006;Khan et al, 2007;Li and Zhang, 2007).…”