Net Ecosystem Exchange of Carbon Dioxide in Rice-Spring Wheat System of Northwestern Indo-Gangetic Plains

Abstract

Rice growing under anaerobic conditions followed by spring wheat under an aerobic environment differentially impact the net ecosystem exchange (NEE) of carbon dioxide (CO2) in rice-wheat systems of the north-western Indo-Gangetic Plains (IGP). This is the first estimation of the NEE in a rice-spring wheat sequence via the eddy covariance technique in the north-western Indo-Gangetic Plains, which was partitioned into gross primary productivity (GPP) and ecosystem respiration (RE) and correlated with the environmental variables. Higher CO2 uptake of −10.43 g C m−2 d−1 was observed in wheat during heading as compared to −7.12 g C m−2 d−1 in rice. The net uptake of CO2 was 25% lower in rice. The average daily NEE over the crop season was −3.74 and −5.01 g C m−2 d−1 in rice and wheat, respectively. The RE varied from 0.07–9.00 g C m−2 d−1 in rice and from 0.05–7.09 g C m−2 d−1 in wheat. The RE was positively correlated with soil temperature at 5 cm depth (0.543, p < 0.01) in rice and with air temperature (0.294, p < 0.01) in wheat. The GPP was positively correlated with air temperature (0.129, p < 0.05) and negatively correlated with vapor pressure deficit (VPD) (−0.315, p < 0.01) in rice. In wheat, GPP was positively correlated with air temperature (0.444, p < 0.01) and soil moisture (0.471, p < 0.01). The rate of GPP over the crop duration was nearly the same in both rice and wheat, however, the RE was higher in rice as compared to wheat, thus, the ratio of cumulative RE/GPP was 0.51 in rice and much lower at 0.34 in spring wheat. Rice contributed 46% and 43% to the annual totals of RE and GPP, respectively, while spring wheat contributed 36% and 51%. The NEE of CO2 was higher in spring wheat at −576 g C m−2 d−1 as compared to −368 g C m−2 in rice. Thus, while estimating the carbon sink potential in the intensively cultivated northern IGP, we need to consider that spring wheat may be a moderately stronger sink of CO2 as compared to rice in the rice-wheat system.

Carbon fluxes in spring wheat agroecosystems in India

“…Field observations on carbon fluxes are limited in India, and none are available in the public domain. We obtained field observations of carbon fluxes for the 2013-14 spring wheat growing season from the IARI, Delhi, experimental spring wheat farm (Bhatia et al, 2014: Kumar et al,2021. The farm covering 650 square meters is located at 28 o 40' N, 77 o 12' E. The site has an EC flux tower that gave Gross Primary Production (GPP), Total Ecosystem Respiration (TER), and Net Ecosystem Production (NEP).…”

“…A few studies have looked at carbon fluxes at the site scale over spring wheat agroecosystems in northern India. These include Patel et al (2011) for the 2008-2009 growing season, Patel et al (2021) for the 2014-15 growing season, and Kumar et al (2021) for the 2013-14 growing season.…”

Design of a Portable Analyzer to Determine the Net Exchange of CO2 in Rice Field Ecosystems

“…For example, Chatterjee et al [ 11 ] monitored lowland paddy fields for one year (dry and wet seasons) using eddy covariance (EC) to evaluate variations in NEE and find a suitable model for the better partitioning of NEE with respect to its components, such as gross primary production (GPP) and ecosystem respiration (Reco). Kumar et al [ 12 ] calculated NEE in rice and wheat systems in the northwest Indo-Gangetic plains. This was the first estimation in a rice–wheat spring sequence using EC.…”

Sericulture: Prospect to Address the Global Challenges of Climate Change and Microplastic in Textile Sector

“…The carbon uptake during the photosynthesis and subsequent utilization into the growth and maintenance of the host plants through respiration indicated by the net primary production. The farm net primary production is the outcome of the gross primary production and respiration (Kumar et al, 2021). Some percentage of the photosynthate is secreted into the soil as rhizodeposition, which also can be considered as C sink based on the root depth and tillage operation.…”