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| DOI：10.13522/j.cnki.ggps.2020202 |
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| The Impact of Long-term Drip Irrigation on Spatiotemporal Variation in Salt in the Proximity of Soil Surface in a Cotton Field |
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FAN Weihua, XUAN Junwei, LI Baoguo, SHI Jianchu, LIU Yunhua, SHENG Jiandong
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1. Xinjiang Key Laboratory of Soil and Plant Ecological Process, College of Grass and Environmental Sciences, Xinjiang Agricultural University, Urumqi 830052, China; 2. College of Land Science and Technology, China Agricultural University, Beijing 100193, China
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| Abstract: |
| 【Objective】Soil salinity is modulated by soil water movement, and in this paper we studied the spatiotemporal variation of total salt content and its composition in the proximity of soil surface at a field as impacted by long-term drip irrigation and cotton cultivation.【Method】The measurement was taken from a cotton field with an area of 143.52 ha and under drip irrigation at Baotou Lake Farm in Korla City, Xinjiang. Based on the duration of the cotton cultivation and drip irrigation, we divided the area into three sub-areas that had been cultivated with cotton under drip irrigation for 10 years, 14 years and 16 years, respectively, by the end of 2018. Soils were sampled from 111 sites within a grid network from the subareas in 2003 and 2018 respectively, and the total salt content and the salt composition in each sample were analyzed in laboratory.【Result】The long-term drip irrigation had reduced the total salt content, the content of main ions and their coefficients of variation significantly, with soil salinity and its coefficient of variation reduced from 18.08 g/kg and 116.8% in 2003 to 7.35 g/kg and 39.4% in 2018 respectively. The salinity and its ions contents measured from the samples taken in 2003 in the subarea with 10 years of cotton cultivation was significantly higher than that in the subareas with 14 and 16 years of cultivation, while no significant difference was found between them in the samples taken in 2018. The soil desalination rate was positively correlated with initial salinity content at significant level with R2=0.97, but it decreased as the cultivation duration elapsed. The desalination rate after 10 years, 14 years and 16 years of cultivation was 4.75 g/(kg·a), 0.59 and 0.47 g/(kg·a) respectively. Average desalination rate estimated using the Kriging interpolation was 85%, 53% and 51% for the subareas under cotton cultivation for 10 years, 14 years and 16 years respectively.【Conclusion】 For heavily saline soil, 10 years of drip irrigation was sufficient to reduce the spatial heterogeneity of its salinity rapidly due to the desalination by leaching and cotton uptake combined. |
| Key words: soil salinity; archive samples; topsoil; cultivation duration; drip irrigation |
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