عنوان مقاله [English]
Background and objectives
Nowadays, it is believed that carbon distribution and emission between different pools of soil, plant and atmosphere have an essential role in sustainability of agroecosystems, environmental challenges especially global warming and climate change. CO2 is the most important of greenhouse gases that increasing of its concentration in the atmosphere has been caused global warming and climate change (8). Carbon sequestration is increase soil organic carbon (SOC) that improves depth distribution of SOC and stabilize SOC by encapsulating it within soil and the simplest ways to mitigation levels of this atmospheric gas (18, 52).
Materials and Methods
In order to evaluate the potential of carbon sequestration in above ground and below ground organs for canola as an important oil crop in Khorasan Razavi region, an experiment was conducted. Sampling was performed with random-systematic method by using 30 plots of 0.5 m2 and along three transects of 50 m. Conversion coefficients of above ground and below ground organs including silique+ seed, stem, leaf and root of canola were determined with combustion method separately. Sequestration carbon potential for above ground and below ground organs of canola and soil were measured. After the calculation of emission for greenhouse gases including CO2, N2O and CH4 based on emission indices, global warming potential (GPW) were calculated.
The results showed that mean yields of silique+ seed, stem, leaf and root were achieved with 33.46, 36.60, 17.45 and 22.91 kg.ha-1, respectively. The mean carbon sequestration of soil for canola fields was 3.46 t.ha-1. Conversion coefficients and carbon sequestration potential were significantly different between above ground and below ground organs of canola. The highest conversion coefficient was observed in silique+ seed with 51.65%. Total carbon sequestration potential for above ground and below ground organs was obtained 5.12 t.ha-1 that the maximum and the minimum were belonged for stem and leaf with 1.81 and 0.76 t.ha-1, respectively. The highest emission of greenhouse gas was achieved for nitrogen fertilizers with 1.35 ton CO2 and GWP was 0.688 ton CO2 equivalent per ha.
It is therefore concluded that reduction of chemical fertilizer and more use of above ground and below ground residues for canola seems to be a rational ecological approach for sustainable management of agroecosystem with a consequence of reduction in greenhouse gases and mitigation of climate change.