| Based on review and summarization the national and international solute transportresearch result, and take KNO3 as a trace element, the unsaturated soil watermovement and solute transport as affected by sprinkler and tlood irrigation is studiedby means of lab and field column experiment, and model analysis in this paper.Considering the wheat absorption on soil water and nutrient, the optimized irrigationamount is present, which has the advantage of high soil nutrient utilization. lt is ofmuch scientific and productive with the feature of raising the utilization, promotingwheat production, lowing fertilizer loss, protecting ecological environment fromchemical contamination in our country, as well as developing irrigation theory. Themain result of the study is as follows:l.Releying on the project aided by European Comlnunity, a large-scale soilcolumn experimental system is set up in Qinwangchuang irrigation district in Gansu.The measuring items in this system is enough and the weather data are auto--recorded,the soil water, salinity and the temperature are timed by computer, which is anadvanced station for field experiment research.2.The major factor affecting the rate of nutriellt absorptiol1 qualltity of tlle wheatare root length density and the concentration of the soil nutrient. The field experimentresult show that root length density function of wheat is L tillering (Z) =98.7l2Z-l.128 intillering stage, and Ljointing, (Z) =l43.90lZ-1.223 in jointing stage. In diftbrent growthstages the root length density of wheat is not the same. Therefore, under sprinkler andflood irrigation pattern and different irrigation amount, the soil nutrient profile is quitedifferent, which causes wheat absorpt nitrogen differently.3.The soil participles show adsorbability to positive ion. According to the laband field experiments, the influence of irrigation patterns and irrigation amount to K+transport is much less than that of soil adsorbability. Therefore, this paper mainlydiscusses NO3 ion profile shape, peak location and peak value as affected by sprinklerand flood irrigation and the irrigation amount.4. That the pore water velocity, hydrodynamic dispersion coefficient, anddispersion degree are different causes the diftbrent characteristics of soil watermovement and solute transport. From the view ofconvection, dispersion and diffusionrole, this paper mainly analyzes the difference of solute transport under sprinkler andflood irrigation. It is the distinguish of solute transport as affected by sprinkler andflood irrigation.Furthermore, this paPer probes into the influence of different sprinklerintensity to soil solute transport .It is result that with the same infiltration wateramount, the smaller the sprinkler intensity is, the larger tlle spatial acculllulatednitrogen absorPtion Z R,,. Especially, when tlle sprinkler intensity is less than0.07mIn/min, the increase extent of Z I(. quickens with the decrease of sprinklerintensity. Therefore, the critic value can be 0.07mm/min between the micro-sprinklerand ordinary sprinkler.5. Meanwhile, this paper studies the influence of different irrigation amount uponsoil solute transport. The result shows that the larger the irrigation amount is, tl1elesser NO, ion profile peak value CInax, the deeper the peak location Zs, as well as themore extensively it distributes. Combining with the distribution law of wheat rootdensity, it is calculated that the rate of spatial accumulated Nitrogen absorption Z Rnis different with different irrigation amount in different wheat growth stages. With thesame irrigation amount, Z Rn in jointing stage is higher than that in tillering stage. Injointing stage, proper supplies of water and nutrient lllake wheat increase theabsorption and utilization rate of fertilizer and tl1en the whcat production is promoted.At the same growth stage, Z R. is distributed in shape of "mushrooln" with thevariation of the irrigation a...
|
PDF Full Text Request