| Responding process of soil pH to the irrigation and fertilization in vadose |
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| DOI：10.7606/j.issn.1000-7601.2019.02.11 |
| Key Words: vadose zone soil pH irrigation & fertilization variation characteristics response process |
| Author Name | Affiliation | | DI Long | Forestry Industry Development Office of Yulin, Yulin,Shannxi 71900, China | | LIU Xiu-hua | Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education Chang’an University, Xi’an, Shaanxi 710054，China
College of Environmental Science and Engineering，Chang’an University,Xi’an, Shaanxi 710054，China | | HU An-yan | Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education Chang’an University, Xi’an, Shaanxi 710054，China
College of Environmental Science and Engineering，Chang’an University,Xi’an, Shaanxi 710054，China | | XIE Lan-bao | Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education Chang’an University, Xi’an, Shaanxi 710054，China | | LIU Guang-hui | Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education Chang’an University, Xi’an, Shaanxi 710054，China |
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| Abstract: |
| To reveal the variation of soil pH resulted from irrigation and fertilization and the changes in geochemical conditions in vadose zone,we conducted a three-year of irrigation and fertilization field test.Using the monitoring data at different depths of 6 m soil profile before and after irrigation in different seasons,we systematically analyzed the responding process of the soil pH to irrigation and fertilization.The results showed that the pH had low variability in all tests (CV=1.01%~2.28%). Compared with that before irrigation, its mean value and coefficient of variation (CV) changed responsively after irrigation. Before irrigation,the pH of each measured layer had strong spatial correlation,after irrigation due to the impact of water, substrate, and their interaction, the spatial correlation was weakened. The C0/(C0+C) decreased from 7.23 m and 3.54 m (0 d before irrigation) to 3.26 m and 2.76 m (10 d after irrigation), respectively.The pH mainly depended on the soil matrix. With the responding of the soil pH to the irrigation and fertilization, the geochemical conditions (soil moisture content, soil temperature, soil organic matter, redox potertial (RP), etc.), soil matrix, nitrogen concentration (NH+4-N) and their interaction affected the dynamic characteristics of pH. The moisture content or temperature did not have significant impact to pH, but their interaction did. The soil nutrients such as Cl-, soil organic matter (SOM), NO-3-N, NH+4-N and space soil matrix at different depths were the main causes for pH variation.These indicated that irrigation and fertilization processes changed the geochemical dynamics, soil pH, the interaction of nutrients and soil matrix components leading to the biogeochemical reaction that controlled the characteristics of pH at each depth.With the change in soil moisture, NH+4-N was adsorbed as molecule or hydrated formand H+ was released. This resulted in the decrease in soil pH on the 4th day after irrigation.With the release of H+ in the process of ammonia oxidation, the pH lowered significantly after the irrigation on the 10th day and 30th day of irrigation.Due to ammonia oxidation process, the soil nitrate content increased, and its impact on pH enhanced step-by-step after irrigation, the correlation coefficient increased from 0.24(0 d, P<0.05) to 0.41(30 d, P<0.01). While the influence of NH+4-N on pH gradually reduced,the correlation coefficient decreased from 0.43(0 d, P<0.01) to 0.19(30 d, P>0.05). |
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