关键词: 涌泉根灌, 灌水器间距, 湿润体, 双点源交汇入渗, 水氮运移

Abstract:

In order to optimize the relevant technical elements of the bubbled-root irrigation， a dual-point source intersection infiltration test was carried out at Yuanzhishan experimental station of Northwest A&F University to study the influence of different irrigator spacing on the characteristics of the wet body and the law of water and nitrogen transport. Three levels of irrigator spacing （40， 50， and 60 cm） were set in this experiment， the mass concentration of fertilizer solution was 10 g·L^-1， and the flow rate of bubbled-root irrigation irrigator was 5 L·h^-1， the effects of different distance of irrigators on the infiltration characteristics of fertilizer solution， the migration law of wetting front， soil moisture， and distribution characteristics of ammonium nitrogen （NH{}_{\mathrm{4}}^{+}-N） and nitrate nitrogen （NO{}_{\mathrm{3}}^{-}-N）. The research showed that the cumulative infiltration amount and the increased infiltration amount of free infiltration and intersection infiltration under different conditions of the bubbled-root irrigation or the distance of the wetting front in different directions of the bubbled-root irrigation， which all had a positive proportional power function relationship with the distance between irrigators （R²>0.9， P<0.01）. The larger the distance between the irrigators， the smaller the migration distance of the wetting front moving upward and downward on the intersection surface （P<0.05）， and the reduction of soil moisture content on the infiltration side of the intersection was smaller than that on the free infiltration side， the larger the distance between the irrigators， the lower the wetness degree of the intersection surface （P<0.05）. Under the condition of free infiltration， the greater the distance from the water outlet of the irrigator， the decrease of NH{}_{\mathrm{4}}^{+}-N content was more significant （P<0.05）， while the decrease of NH{}_{\mathrm{4}}^{+}-N content on the convergent infiltration side was smaller than that on the free infiltration side. The NO{}_{\mathrm{3}}^{-}-N content varies greatly at different times and positions. After irrigation， the NO{}_{\mathrm{3}}^{-}-N content of the surface soil in the humid area decreased slightly. The longer the water distribution time， the higher the NO{}_{\mathrm{3}}^{-}-N content at different soil depths （P<0.05）. A mathematical model of the cumulative infiltration volume of the bubbled-root irrigation intersection infiltration， the migration distance of the wetting front with time and the distance of the emitters was established. The model parameters K and α， which varied with the distance of the irrigators in a power function relationship， and the value of K decreased with the increase of the distance， while the value of α increased with the increase of the distance. The relationship model about soil moisture content， NH{}_{\mathrm{4}}^{+}-N， NO{}_{\mathrm{3}}^{-}-N contents and the distance of the irrigators was established， and the soil moisture content， soil NH{}_{\mathrm{4}}^{+}-N and NO{}_{\mathrm{3}}^{-}-N contents at any point from the infiltration soil to the distance r from the irrigator center were quantitatively estimated， and the deviation of the estimation results was within ±10%. The results laid a scientific foundation for the further improvement of the water-saving irrigation technology of the bubbled-root irrigation.

Key words: bubbled-root irrigation, irrigation distance, wetting body, double point source convergence infiltration, water and nitrogen transport