Author(s)

Nguyen Thi Hong Thinh¹, Vu Hoai¹, Ha Lan Anh¹, Vo Thi Anh¹, Truong Viet Chau¹, Trinh Van Giap¹, Tran Minh Tien²

¹Isotope Hydrology Laboratory, Institute for Nuclear Science and Technology, Hanoi, Vietnam.
²Soils and Fertilizers Research Institute, Hanoi, Vietnam.

In this study, the experiments on field were conducted to examine the change in the content of soil organic carbon (SOC), its C-13 stable isotope composition (δ ¹³C) and some main physical, chemical parameters (soil moisture, pH, soil density, content of humic, fulvic, total N, total P, total K) in alluvial soil of Dan Phuong region—Vietnam at a depth of 0 - 30 cm when we changed the regime from 2 maize -1 rice crop to 2 rice - 1 maize crop per 1 year. In addition to analyzing the main parameters in soil, C content and its δ ¹³C value in parts of rice and maize (root, stem and leaf) were also analyzed to assess the contribution of plant residues on soil organic carbon content after harvest. The experiment was carried out in 2016-2017 on the field with the traditional farming method of local farmers along with the tropical monsoon weather conditions of the North-Vietnam. The results showed that SOC had positive correlation with total N, total P parameters and negative correlation with δ ¹³C values of soil samples at two layers (0 - 15 cm and 15 - 30 cm). The average of total dry biomass (stem, stump + roots and leaf parts) per 1 rice and 1 maize crop was 10.64 Mg/ha and 9.09 Mg/ha, respectively. The average of δ ¹³C value of rice (C₃ plant) was -29.78‰ and its value of maize (C₄ plant) was -12.61‰. The new plant (rice) contributes to the total soil organic carbon content from 11.31% to 44.14% at the 0 - 15 cm layer and from 6.55% to 11.31% at the 15 - 30 cm layer in one-year experiment period.

Soil Organic Carbon (SOC), C-13 Stable Isotope, Maize and Rice Crop, Soil Properties

Thinh, N. , Hoai, V. , Anh, H. , Anh, V. , Chau, T. , Giap, T. and Tien, T. (2019) Study the Changes in Soil Organic Carbon of Rice-Maize Cropping System in the Top Layer of Alluvisol Soil in Dan Phuong: A Study of C-13 Stable Isotope Composition (δ¹³C). Journal of Environmental Protection, 10, 1361-1372. doi: 10.4236/jep.2019.1010080.