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| DOI：10.13522/j.cnki.ggps.20180542 |
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| Service Life of the Gravel-sand Mulch in Reducing Soil Evaporation |
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LI Wangcheng, WANG Shuai, WANG Xingwang
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1. College of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China; 2. Engineering Research Center of Water Resource Efficient Utilization of Modern Agriculture in Arid Area, Ministry of Education, Yinchuan 750021, China; 3. Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Yinchuan 750021, China; 4. College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100000, China
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| Abstract: |
| 【Objective】Gravel mulch is an effective method to reduce soil evaporation, but its service deteriorates as time elapses. In this paper we studied the change in capability of a gravel mulch in thermal preservation and evaporation inhibition using satellite imagery.【Method】 The analysis was based on the Landsat satellite data, and the radiative transfer equation was used to inversely calculate the surface temperature (LST) of a gravel-sand mulched field in Xiangshan. Combining with the observed LST, we compared the change in surface temperature of the mulched and bare ground, from which we analyzed the efficacy of the mulch in reducing soil evaporation and its degradation as the mulch was aging.【Result】The mulch was close to the warm edge in the LST-NDVI trapezoidal space and the soil moisture in it was lower than that in the cultivated land; it is close to that in the dry soil. The gravel-sand mulch can attenuate the radiation to reach soil surface, thereby reducing the latent heat flux and consequently soil evaporation. The day-night temperature oscillation in the mulched field was more substantial than that in the bare field. We also found that for watermelon, mulching increased the effective surface cumulative temperature by 10% compared to the bare field. 【Conclusions】 Degradation of the gravel-sand mulch can be divided into pure gravel-sand stage, sand-soil stage and sand-soil connection stage. Based on our results, the effective serviceable life of the mulch is approximately 25~30 years. |
| Key words: gravel-sand mulched field; temperature inversion; mulched field degradation; evaporation inhibition |
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