Rice Yield and Greenhouse Gas Emissions Affected by Chinese Milk Vetch and Rice Straw Retention with Reduced Nitrogen Fertilization

Abstract

Straw retention and fertilization management can affect rice yield and greenhouse gas (GHG) emission in paddy field. To investigate the effect of leguminous green manure and straw retention plus nitrogen (N) fertilizer on rice yield and GHG emissions, field experiments were conducted from 2017 to 2018 and four treatments were designed, including the treatments of Chinese milk vetch (Astragalus sinicus L.) and rice (Oryza sativa L.) straw retention with reduced chemical N fertilizer application amount named RA (6000 kg hm−2 rice straw plus 102 kg hm−2 N fertilizer during early and late rice respectively), RB (6000 kg hm−2 rice straw plus 87 kg hm−2 N fertilizer during early and late rice season respectively), RC (6000 kg hm−2 rice straw plus 72 kg hm−2 N fertilizer during early and late rice season respectively) and control CK (winter fallow, without straw retention, 120 kg hm−2 N fertilizer during early and late rice season respectively). The results showed treatments RA, RB, and RC significantly increased the early rice yield by 15.79, 21.27, and 13.60% (P < 0.05), and RA and RB significantly increased the annual yield by 14.76 and 15.79% (P < 0.05) compared with control CK. For CH4 cumulative emissions, only RB had no significant impact on it (P > 0.05); treatments RA, RB, and RC had no significant effect on N2O cumulative emissions (P > 0.05). Meanwhile, treatments RA and RC significantly increased GWP and greenhouse gas emission intensity (GHGI) (P < 0.05) of CH4 and N2O, but the difference between RB and control CK was not significant (P > 0.05). Therefore treatment RB had the best effect on rice production and GHG mitigation in paddy fields. Core Ideas Straw and vetch retention with reduced N fertilizer were studied on yield and GHGs in double‐cropped rice. Chinese milk vetch and rice straw retention plus reduced N fertilizer significantly increased rice yields compared with control. Effect of Chinese milk vetch and rice straw retention plus 87 kg of N fertilizer on GWP and GHGI was not obvious. Straw and vetch retention can help offset N fertilizer to increase yield and reduce costs, waste, and environment pollution.

Fertilizer timing affects nitrous oxide, carbon dioxide, and ammonia emissions from soil

“…The positive relationship between the average daily temperature and cumulative N 2 O‐N emissions in the unfertilized plots in the fall supports this hypothesis (Figure ). Other studies have reported similar differences (Adair, Barbieri, Schiavone, & Darby, ; Drake, Giasson, Spiller, & Finze, ; Dusenbury, Engel, Miller, Lemke, & Wallander, ; Liu et al., ; McGowan et al., ; Phillips, Tanaka, Archer, & Hanson, ).…”

“…For fertilizer applied in early summer, N 2 O emissions may have been limited by organic‐C substrate availability. Others have seen high emissions following spring freeze thaw cycle (Liu et al., ). However, the amount of fertilizer‐derived N that was emitted as N 2 O was less than 1% of the applied fertilizer.…”

“…Arrows represent when the single rate of fertilizer was applied to each plot. Soil moisture (SM) is provided in the chart and soil temperature is in Figure 1 Darby, 2019; Drake, Giasson, Spiller, & Finze, 2013;Dusenbury, Engel, Miller, Lemke, & Wallander, 2008;Liu et al, 2019;McGowan et al, 2018;Phillips, Tanaka, Archer, & Hanson, 2009). Across all fertilizer application dates, soil moisture was positively correlated to N 2 O ( Figure 5; Table 7).…”

“…However, synchronization has produced mixed impacts on GHG emissions (Burzaco, Smith, & Vyn, ; Venterea & Coulter, ; Eagle, Olander, Locklier, Heffernan, & Bernhardt, ; Ma et al., ). The lack of consistent findings may be attributed to papers that report total losses and not fertilizer derived‐N (Lehman, Osborne, & Duke, ; Johnson & Barbour, ), and sampling methods that do not account for diurnal and seasonal differences in soil temperature, soil moisture, and microbial activity (Liu et al., ; McGowan, Roozeboon, & Rice, ; Shurpali et al., ). Therefore, to resolve why synchronization produces mixed impacts on N 2 O‐N emissions, research was conducted to determine the effect of fertilizer application timing on N 2 O‐N, CO 2 ‐C, and NH 3 ‐N emissions from soil‐applied urea.…”

N2O Emissions Mitigation in Acidic Soil Following Biochar Application Under Different Moisture Regimes

“…Soil pH is a key factor that significantly regulates various soil processes (Liu et al 2019c), and the addition of biochar to acidic soil enhances soil pH, which in turn reduces the production of N 2 O. N 2 OR catalyzes N 2 O to N 2 during denitrification; however, a low soil pH reduces the assembly and function of N 2 OR and prevents the conversion of N 2 O into N, therefore leading to an increase in N 2 O emissions (Bakken et al 2012). Moreover, the biochar applications enhanced the (Obia et al 2015).…”