Appropriate straw and tillage management strategies increase grain yields, and promote atmospheric carbon dioxide (CO2) mitigation through soil organic carbon (SOC) sequestration. However, little is known about economic parameters and carbon footprint (CF, defined as total greenhouse gases emission from the whole life cycle perspective) of intensive wheat (Triticum aestivum L.)-maize (Zea mays L.) double cropping production under different integrated strategies of straw-return and tillage. To quantify the differences of straw-return and tillage integrated strategies in economic parameters and carbon sustainability, a field experiment was established in 2008 in which six integrated strategies were evaluated: straw return of both maize and wheat (MR-WR), MR-WR with subsoiling to ~40 cm depth after maize harvest (MS-WR), single straw return of wheat (MN-WR), single straw return of maize (MR-WN), MR-WN with subsoiling to ~40 cm depth after maize harvest (MS-WN) and no straw return (MN-WN). Results showed that the MS-WR had the greatest grain yields of both wheat and maize, gross revenue and economic profit with increases of 45.5%, 35.6%, 26.5%, and 79.7% relative to the MN-WN, respectively. Compared with the initial SOC level, the SOC stock increased by 22.9% under MS-WR, following by MR-WR (16.0%), MS-WN (11.6%), MR-WN (8.0%), MN-WR (5.1%), and MN-WN (-3.8%). The MS-WR reduced the net CF and net CF per economic profit by 35.4% and 64.1% relative to the MN-WN although it elevated the CF by 25.3%. Therefore, adopting the integrated strategies of both maize and wheat straw return with subsoiling to ~40 cm depth after maize harvest represented an economically and C-friendly optimal field management practice for intensive wheat-maize double cropping production in the Guanzhong Plain or other regions with similar environmental conditions in the world.
Keywords: Economic profit; Net carbon footprint; SOC sequestration; Straw return; Wheat-maize system.
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