Effects of Tillage and Nitrogen Fertilizers on CH4 and CO2 Emissions and Soil Organic Carbon in Paddy Fields of Central China

Abstract

Quantifying carbon (C) sequestration in paddy soils is necessary to help better understand the effect of agricultural practices on the C cycle. The objective of the present study was to assess the effects of tillage practices [conventional tillage (CT) and no-tillage (NT)] and the application of nitrogen (N) fertilizer (0 and 210 kg N ha−1) on fluxes of CH4 and CO2, and soil organic C (SOC) sequestration during the 2009 and 2010 rice growing seasons in central China. Application of N fertilizer significantly increased CH4 emissions by 13%–66% and SOC by 21%–94% irrespective of soil sampling depths, but had no effect on CO2 emissions in either year. Tillage significantly affected CH4 and CO2 emissions, where NT significantly decreased CH4 emissions by 10%–36% but increased CO2 emissions by 22%–40% in both years. The effects of tillage on the SOC varied with the depth of soil sampling. NT significantly increased the SOC by 7%–48% in the 0–5 cm layer compared with CT. However, there was no significant difference in the SOC between NT and CT across the entire 0–20 cm layer. Hence, our results suggest that the potential of SOC sequestration in NT paddy fields may be overestimated in central China if only surface soil samples are considered.

Daycent Simulation of Methane Emissions, Grain Yield, and Soil Organic Carbon in a Subtropical Paddy Rice System

“…DayCent overestimated soil C stocks especially in the first years of the experiment (Table 3). The current SOC stocks observed (2015) corroborate what has been observed in previous studies on tillage systems in paddy rice: an increase in SOC in the topsoil, without significant differences across tillage systems (Nascimento et al, 2009;Cheng-Fang et al, 2012;Huang et al, 2016). Excess water in rice paddies may decrease physical protection of organic matter in soil aggregates in no-tilled flooded soils (Nascimento et al, 2009).…”

No-tillage lessens soil CO<sub>2</sub> emissions the most under arid and sandy soil conditions: results from a meta-analysis

“…However, Hendrix et al (1988) and Oorts et al (2007) found greater CO 2 emissions from untilled compared to tilled soils, with Oorts et al (2007) reporting that notillage increased CO 2 emissions by 13 % compared to tillage. In a further example, Cheng-Fang et al (2012) showed that in central China, no-tillage increased soil CO 2 emissions by 22-40 % compared with tillage. Oorts et al (2007) attributed the larger CO 2 emissions from no-tilled soil compared to tilled soil to increased decomposition of the weathered crop residues lying on the soil surface.…”

“…Jacinthe et al (2002) reported annual CO 2 emissions to be 43 % higher with tillage compared to no-tillage with no mulch, but found a 26 % difference for no-tillage with mulch. Some other authors associated the changes in CO 2 emissions following tillage abandonment to shifts in nitrogen fertilization application and in crop rotations (Al-Kaisi and Yin, 2005;Álvaro-Fuentes et al, 2008;Cheng-Fang et al, 2012). working in North Dakota pointed to CO 2 flux differences between tilled and untilled soils only for fertilized fields, while other studies pointed to the absence of nitrogen impact (Drury et al, 2006;Cheng-Fang et al, 2012).…”

Effects of Irrigation Regime and Nitrogen Fertilizer Management on CH4, N2O and CO2 Emissions from Saline–Alkaline Paddy Fields in Northeast China

“…Zheng et al, evaluated that approximately 3/4 of the annual freeings of N 2 O from the plow land of China was caused by anthropogenic N-input [26]. As more fertilizer is used, higher amounts of N 2 O and CH 4 are emitted [27,28]. Nevertheless, other studies have shown a substantial decrease in CH 4 emissions due to N fertilization.…”