Figure captions
FIGURE 1 Monthly rainfall and evaporation in the growing period (2015-2018).
FIGURE 2 Field planting and management showing straw interlayer burial, irrigation and sowing.
FIGURE 3 Changes of SOC (a), TN (b) and C:N ratio (c) in straw interlayers relative to the CK for different soil depths during 2015-2018. The changes (%) were calculated as (Value in Treatment – Value in CK) / Value in CK × 100. CK: no straw interlayer; SL6: 6 Mg straw ha-1 as an interlayer; SL12: 12 Mg straw ha-1 as an interlayer; SL18: 18 Mg straw ha-1 as an interlayer. Values are mean (± SE).
FIGURE 4Contents of soil organic carbon (SOC) (a) and total nitrogen (TN) (b), and C:N ratio (c) in the soil profile under straw interlayers in 2015-2018. CK: no straw interlayer; SL6: 6 Mg straw ha-1 as an interlayer; SL12: 12 Mg straw ha-1 as an interlayer; SL18: 18 Mg straw ha-1 as an interlayer. Values are mean (± SE).
FIGURE 5 Storages of soil organic carbon (SOC) (a) and total nitrogen (TN) (b) under straw interlayers in 2015-2018. CK: no straw interlayer; SL6: 6 Mg straw ha-1 as an interlayer; SL12: 12 Mg straw ha-1 as an interlayer; SL18: 18 Mg straw ha-1 as an interlayer. Different small letters show a significantly difference (p < 0.05) between straw interlayers in each year. Values are mean (± SE).
FIGURE 6 Stratification ratio of soil organic carbon (SOC) (a) and soil total nitrogen (TN) (b) under straw interlayers.CK: no straw interlayer; SL6: 6 Mg straw ha-1 as an interlayer; SL12: 12 Mg straw ha-1 as an interlayer; SL18: 18 Mg straw ha-1 as an interlayer. Different small letters show a significantly difference (p < 0.05) between interlayers in each year. Values are mean (± SE).
FIGURE 7 Correlations of soil organic carbon (SOC), total nitrogen (TN), C:N ratio, stratification ratios with soil moisture, soil salinity and crop yield from 2015 to 2018.