Effects of increased temperatures and rice straw incorporation on methane and nitrous oxide emissions in a greenhouse experiment with rice

Abstract

We investigated the effect of increased temperatures of water and soil, together with the incorporation of rice straw, on emissions of methane (CH4) and nitrous oxide (N2O), and the daily variation in CH4 emissions. Three temperature treatments (floodwater temperature), ambient, ambient +2°C and ambient +4°C, and two amounts of rice straw (0 and 6 t ha−1) were arranged in a randomized complete block design with four replications. The emissions of CH4 and N2O and the soil's redox potential (Eh) were measured weekly for two crop cycles. Daily variation in CH4 emission rates was measured with and without rice straw incorporation in planted and unplanted soil (with no warming treatments) during four growth stages of the crop. Methane emissions increased by as much as 91% with increasing amounts of water and soil temperature (+2 and +4°C), up to 34–35°C. Increases in temperature (+2 and +4°C above ambient) above 34–35°C decreased emissions by 30–36%. A decrease in soil Eh to < −100 mV and in CH4 emissions was observed earlier in the pots containing rice straw than in those without straw. Methane emissions varied daily; they were larger from 11:00 to 14:00 hours, particularly in unplanted soil. They showed positive correlations with the temperatures of both soil and air. In contrast, N2O emissions were negligible throughout the growing season. The emissions of CH4 evidently depend on the background temperature range; in our experiment, CH4 emissions increased up to 34°C and then they decreased above that. Highlights: GHG emissions were measured from flooded rice soil under elevated temperatures. Temperature, straw incorporation and rice plants affected daily variation in methane emissions. An increase in temperature increased methane emission by up to 91%. Increased temperature decreased methane emissions when background temperature was above 34–35°C.

Effects of alternate wetting and drying technique on greenhouse gas emissions from irrigated rice paddy in Central Luzon, Philippines

“…Second, the amount of crop residue incorporation from the previous DS to WS was greater than the opposite, as shown in the greater yield in DS (Table 2). Although smaller rice biomass in WS could cause less CH 4 emission through providing limited substrate supply and emission pathway, the greater residue incorporation would have provided a substantial carbon substrate for rapid development of soil reductive conditions and the resultant greater CH 4 production (Gaihre et al 2016). Third, the considerable volume of rainfall in WS resulted in longer flooding periods under CF than in DS .…”

Role of biochar in managing the irrigation water requirements of maize plants: the pyramid model signifying the soil hydro-physical and environmental markers

“…Moreover, the Egyptian farmers burn these residues in open fields (Hassan et al, 2014); thus, increasing the emissions of greenhouse gases (GHGs) (Sing et al, 2016). This might, in turn, increase the temperature (Gaihre et al, 2016). On the other hand, crop production is generally affected negatively by the corresponding increases in temperature (Mahmoud, 2017).…”

Micrometeorological Studies in Rice: A Review

“…Higher soil temperatures were negatively affect plant growth, while extreme temperatures can stall biological processes of micro-organisms (FAO, 2016). Gaihre et al (2016) concluded that optimum soil temperature for methane emissions in the tropics was between 34 and 35C and reported that temperatures beyond this appears to decreased in methane emissions.…”