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Arid Land Geography ›› 2022, Vol. 45 ›› Issue (4): 1165-1175.doi: 10.12118/j.issn.1000-6060.2021.477

• Earth Information Sciences • Previous Articles     Next Articles

Inversion and validation of soil salinity based on multispectral remote sensing in typical oasis cotton field in spring

LIU Xuhui1,2(),BAI Yungang2(),CHAI Zhongping1,ZHANG Jianghui2,DING Bangxin2,3,JIANG Zhu2   

  1. 1. College of Resources and Environment, Xinjiang Agricultural University, Urumqi 830052, Xinjiang, China
    2. Xinjiang Research Institute of Water Resources and Hydropower, Urumqi 830049, Xinjiang, China
    3. College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100, Shaanxi, China
  • Received:2021-10-15 Revised:2022-01-01 Online:2022-07-25 Published:2022-08-11
  • Contact: Yungang BAI E-mail:454949752@qq.com;xjbaiyg@sina.com

Abstract:

This study aimed to explore an effective method for extracting soil salinity from cotton fields in oasis and determine the characteristics and spatial distribution of soil salinization on a regional scale to provide reference for soil salinization control. The 31st Regiment of the 2nd Division of Xinjiang Production and Construction Corps was taken as the research area; Landsat 8 OLI multispectral images and field measurements of soil salinity in spring 2019 and 2021 were taken as data sources; and the band group, spectral index group, and total variable group were taken as the model input variable group. Multiple stepwise regression (MSR), partial least squares regression, extreme learning machine, support vector machine, and back propagation neural network (BPNN) were used to construct a remote sensing inversion model of soil salt based on the three input variable groups. Precision evaluation was conducted, and the effects of input variables and modeling methods on model accuracy were explored. The best inversion model of soil salt in spring was determined through comparison and quantitatively inverted surface soil salt content. Results showed that (1) the study area was mainly composed of non-salinized soil and slightly salinized soil, and the coefficient of variation of total samples was 0.67, implying moderate variability. The relationship between spectral reflectance and soil salinization is as follows: serious soil salinization leads to great spectral reflectance. (2) Significance tests were conducted on coastal band(b1), blue(b2), green(b3), and red(b4) and the salinity indices of SI1, SI2, SI3, SI4, S3, S4, and S5 (P<0.01). The obtained correlation coefficients were all above 0.4, which can represent soil salinity to a certain extent. (3) Among the six linear regression models, the MSR model established on the band group had the best inversion effect, and the BPNN inversion model established on the full variable group had the highest accuracy. (4) According to the inversion results, the soil in spring 2019 and 2021 was mainly nonsalinized soil accounting for 55.55% and 64.62% of the total tillage area, respectively, followed by mild salinized soil accounting for 44.31% and 35.17%, respectively. Soil salinization in 2021 was reduced compared with that in 2019.

Key words: multispectral remote sensing inversion, soil salinity, spectral reflectance, variable group, machine learning