| Influence of bulk density and water content on soil electrical conductivity |
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| DOI：10.7606/j.issn.1000-7601.2022.03.20 |
| Key Words: volumetric conductivity pore water conductivity volumetric water content soil bulk density |
| Author Name | Affiliation | | ZHANG Yiqing | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China | | WANG Wen’e | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China | | HU Mingyu | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China | | LING Gang | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China | | HU Xiaotao | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China | | PENG Xiongbiao | Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A＆F University,Yangling Shaanxi, 712100, China |
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| Abstract: |
| Soil electrical conductivity can indirectly reflect the nutrient or salt content in the field. Monitoring the soil electrical conductivity can help understand the transport and utilization of soil nutrients and salt. In this study, through the soil column infiltration test under the conditions of 2 soil bulk densities and 5 water contents, the 5TE sensor was used to continuously monitor soil volumetric water content, volume conductivity, temperature, and other parameters, and analyze the influence of bulk density and water content on soil conductivity. The results showed that both water content and conductivity first increased, then gradually decreased, and finally tended to be flat during the infiltration process. The time when the conductivity began to decrease was slightly earlier than the time when the water content began to decrease.When the volumetric water content was constant, the conductivity of pore water increases linearly with the increase of volumetric conductivity. With the increase of water content, the increase rate of pore water conductivity with volume water conductivity was slower. When the volume conductivity was constant, the conductivity of pore water decreased gradually with the increase of water content, and the decrease range was 9.52%~55.51% when the bulk density was 1.35 g·cm-3, and the decrease range was 9.72%~54.62% when the bulk density was 1.3 g·cm-3.When the conductivity of pore water was constant, the volume conductivity increased with the increase of water content, the increase was 10.51%~124.75% when the bulk density was 1.35 g·cm-3, and the increase was 10.76%~120.35% when the bulk density was 1.3 g·cm-3. Under the same water content, for the two bulk density cases, the measured pore water conductivity had a linear relationship with the volume conductivity. When the pore water conductivity was the same, the volume conductivity increased slightly with the decrease of the bulk density. When the water content was 24%, 25%, and 26%, compared with the volume conductivity when the bulk density was 1.35 g·cm-3, the bulk conductivity increased by 1.95%, 2.47%, and 1.44% when the bulk density was 1.3 g·cm-3, respectively. When the total infiltration water was limited, the change of soil water salinity with volumetric water content experienced four stages. With the continuous increase of volumetric water content during infiltration, the soil water salinity could be divided into three stages: salt-free dissolution, rapid increase of salt content and decrease of salt content, and the stage of decrease of both volumetric water content and salt content during water redistribution. At the end of the second stage, the amount of dissolved salt in each working condition reached the maximum value. When the bulk density was 1.35 g·cm-3 and the average volumetric water were 20%, 22.5%, 25%, 28% and 31%, the maximum salt content were 3.54,4.95,7.17,31.73 and 11.85 mS·cm-1, respectively. At the end of the fourth stage, the designed average volumetric moisture content was achieved. The pore water conductivity had a linear relationship with the volume conductivity, and its slope decreased with the increase of water content, which was a quadratic function of water content. The product of water content and pore water conductivity could be used to reflect the salt content of soil solution. |
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