Soil Organic Carbon Build‐up and Dynamics in Rice–Rice Cropping Systems

Abstract

Intensive irrigated rice system is the most important food production system in the world. Continued population growth necessitates increased rice production to meet the increased need of food production through increased rice productivity to ensure food security. In contrast, the recent slowdown in yield growth in intensive irrigated rice‐based cropping systems as a result of deterioration of soil health and decline in productivity level is a serious cause for concern. The objective of this research was to investigate the soil organic carbon (SOC) build‐up and its dynamics in rice–rice cropping system by including a green manure (GM) crop Sesbania rostrata Berm. either during fallow and/or intercrop at 4 : 1 ratio as additive series without changing rice geometry. The results revealed that there is a gradual build‐up of SOC when S. rostrata included and in situ incorporated at flowering stage as a basic means of improving soil quality in rice–rice cropping system. Further, the soil organic matter fractions viz. humic acid and fulvic acid were also improved in all GM‐incorporated systems. In general, the proportion of fulvic acid was higher than humic acid. Cropping system involving three GMs viz. S. rostrata‐rice/S. rostrata‐rice/S. rostrata registered significantly higher SOC and was 10.63 percent higher than traditional rice–rice cropping system (A1). This was followed by S. rostrata‐rice/S. rostrata‐rice system. Although the traditional rice–rice cropping system (A1) also conserved SOC (0.29 and 1.69 % higher than initial during first and second annual cropping cycle, respectively), the magnitude was very low. Repeated application of S. rostrata as GM improved SOC, which formed the basis for sustainable management of soil resources. It can be concluded that S. rostrata would affect the rate of loss of SOC in cropping systems and its ultimate level in soils.

Effects of Conservation Tillage and Nutrient Management Practices on Soil Fertility and Productivity of Rice (Oryza sativa L.)–Rice System in North Eastern Region of India

“…Same treatment (T 2 ) recorded CCS of 0.42 Mg ha −1 after three years at a rate of 141.6 kg ha −1 year −1 with 5.59% CRE. Traditional farming practice increased an average SOC by 2.23% over the initial value, as was also reported by Smith et al [45]. Our results show that the maintenance of TOC concentration and stocks under T 2 may be attributed to the incorporation of 30% rice residue of each crop and application of 5 Mg FYM ha −1 to the first crop at every two-year interval by farmers [43,46].…”

“…Significant differences in SOC concentration (0-40 cm) after four years of tillage and straw retention practices in China followed the order of NT > PT > RT [48]. The positive effect of conservation tillage along with organic manure and residue retention/incorporation in increasing the TOC in paddy soils of India have also been reported [7,43,45,49]. Further, the integrated uses of organics with inorganic fertilizers also have been reported to enhance productivity and SOC concentration over that with the sole application of fertilizer or manure [35,50].…”

“…Our results show that the maintenance of TOC concentration and stocks under T 2 may be attributed to the incorporation of 30% rice residue of each crop and application of 5 Mg FYM ha −1 to the first crop at every two-year interval by farmers [43,46]. Several researchers have indicated beneficial effects of residue incorporation/retention and application of organic manure on the improvement of TOC concentration and stocks in a rice field [45,47]. Agronomic modification by the replacement of CT with NT in WR and replacement of CT with RT in DR (T 4 ) under the same set of FP (T 2 ) significantly increased the TOC (1.9%), TOCS (2.0%), CSR (95.0%), CCS (97.6%) and CRE (115.4%) over T 2 in 0-20 cm depth.…”

The Effect of Camber Bed Drainage Landforms on Soil Nutrient Distribution and Grain Yield of Maize on the Vertisols of the Accra Plains of Ghana

“…rice straw, leads to the formation of waterstable aggregates, which give interspaces to soil as well as good supply of plant nutrients. Organic matter levels could also be increased through crop rotation with leguminous plants; thus, also sequestering carbon in the soil (Ramesh & Chadrasekaran, 2004).…”

Rhizosphere effect has no effect on marker genes related to autotrophic CO2 fixation in paddy soils?

“…Oxygen affected the activity of enzymes invovled in microbial CO 2 fixation, like ferredoxin-dependent 2-oxoglutarate synthase and ATP-citrate lyase, which were quite sensitive to oxygen, while ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) was known for its resistance to oxygen (Berg 2011). Moreover, during the growth period, nutrient uptake, root exudates, and oxygen release can change over space and time (Revsbech et al 1999;Ramesh and Chandrasekaran 2004;Zhang et al 2006), affecting microbial composition directly or indirectly. Soil type, deriving from combined effects of parent material, biology, time, climate, and topography, always influences microbial population size and community structure and sometimes even acts as dominant factor irrespective of rice-planted or unplanted in paddy soil (Chen et al 2010).…”