Effects of conservation tillage practices on rice yields and greenhouse gas emissions: Results from a 10-year in situ experiment

Abstract

A long-term continuous in situ field experiment was conducted in the Yangtze River Delta region of China to quantify the effects of different rice-based conservation tillage (CT) practices on greenhouse gas (GHG) emissions and rice yields, compared to a conventional rice-wheat rotation system (RW). Four representative rice-based CT practices were evaluated: no-tillage rice-wheat rotation (RT), rice-winter fallow (RF), and rice-green manure rotation with low (RM-LN) and high nitrogen (N) fertilizer inputs (RM-HN). The RW, RT, and RF treatments were implemented continuously from 2012 to 2021. The RM-LN treatment was implemented from 2012 to 2016, followed by the RM-HN treatment in the same plots from 2017 to 2021. The results indicated that, compared to the RW treatment, the RT, RF, RM-LN, and RM-HN treatments resulted in decreases in total GHG emissions during the rice-growing season by 11.5 %, 40.2 % (P < 0.01), 41.0 % (P < 0.05), and 35.2 % (P < 0.05), respectively, within the corresponding years of implementation. When compared to the RW treatment, the RT and RM-LN treatments significantly reduced rice yields by 6.7 % (P < 0.01) and 8.7 % (P < 0.01), respectively. In contrast, the RF and RM-HN treatments had no significant impact on rice yields relative to RW across the corresponding years. Consequently, relative to the RW treatment, the RF and RM-HN treatments achieved reductions in rice yield-scaled greenhouse gas intensity (GHGI) of 31.3 % (P < 0.05) and 34.0 % (P < 0.05), respectively, across the corresponding years, while maintaining rice yields. These findings suggest that RF and RM-HN are effective CT practices for mitigating GHG emissions from rice paddies in the Yangtze River Delta region.