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Trade‐offs between soil carbon sequestration and reactive nitrogen losses under straw return in global agroecosystems
Author(s) -
Xia Longlong,
Lam Shu Kee,
Wolf Benjamin,
Kiese Ralf,
Chen Deli,
ButterbachBahl Klaus
Publication year - 2018
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.14466
Subject(s) - straw , agronomy , carbon sequestration , environmental science , soil carbon , leaching (pedology) , reactive nitrogen , nitrous oxide , denitrification , soil water , agroecosystem , nitrogen , chemistry , soil science , ecology , biology , agriculture , organic chemistry
It is widely recommended that crop straw be returned to croplands to maintain or increase soil carbon (C) storage in arable soils. However, because C and nitrogen (N) biogeochemical cycles are closely coupled, straw return may also affect soil reactive N (Nr) losses, but these effects remain uncertain, especially in terms of the interactions between soil C sequestration and Nr losses under straw addition. Here, we conducted a global meta‐analysis using 363 publications to assess the overall effects of straw return on soil Nr losses, C sequestration and crop productivity in agroecosystems. Our results show that on average, compared to mineral N fertilization, straw return with same amount of mineral N fertilizer significantly increased soil organic C (SOC) content (14.9%), crop yield (5.1%), and crop N uptake (10.9%). Moreover, Nr losses in the form of nitrous oxide (N 2 O) emissions from rice paddies (17.3%), N leaching (8.7%), and runoff (25.6%) were significantly reduced, mainly due to enhanced microbial N immobilization. However, N 2 O emissions from upland fields (21.5%) and ammonia (NH 3 ) emissions (17.0%) significantly increased following straw return, mainly due to the stimulation of nitrification/denitrification and soil urease activity. The increase in NH 3 and N 2 O emissions was significantly and negatively correlated with straw C/N ratio and soil clay content. Regarding the interactions between C sequestration and Nr losses, the increase in SOC content following straw return was significantly and positively correlated with the decrease in N leaching and runoff. However, at a global scale, straw return increased net Nr losses from both rice and upland fields due to a greater stimulation of NH 3 emissions than the reduction in N leaching and runoff. The trade‐offs between increased net Nr losses and soil C sequestration highlight the importance of reasonably managing straw return to soils to limit NH 3 emissions without decreasing associated C sequestration potential.