Study On Agricultural Improved Technologies And Water-salt Transfer Rule Of The Saline-alkaline Grassland

As a kind of renewable natural resources, grassland resources had important effect at the aspects of sand fixation, water conservation, preventing soil erosion, etc. The saline-alkaline grassland of song-nen plain which had high economic value and important ecological significance, not only was the natural pasture in our country,but also was the ecological barrier in west of northeast china. For a long time, under the condition of natural factors and human factors, over-grazing and blind reclamation generated the severe consequences of destroying grassland resources, reducing excellent grass, decreasing vegetation coverage and productivity, changing structure of grassland ecosystem, making soil hardening, weakening ecological function, causing ecological imbalance, deteriorating grassland ecological environment, moreover, there had been severe threaten to development of economy and society, production and life of people, and even the healthy development of national economy. Therefore, both deeply research the improvement of the saline-alkaline grassland and the restoration of ecological environment had important practical significance.The paper selected improved methods to the saline-alkaline grassland by experiment, provided effective measures for the restoration of the saline-alkaline grassland, meanwhile, the paper analyzed the dynamic changes of soil water and salt, spatial variability, and the mechanism of the storage and preservation of water, evaluated improved technical measures and effects by evaluation method of ecological restoration.The classification and evaluation were carried out, which based on the types and the distribution rule of the saline-alkaline grassland, the index testing of soil physical and chemical, the investigation of vegetation types, coverage, growth status. Considering that the saline-alkali soil had the particularity of hard and dense, poor storage capacity, soil leanness under the natural condition of drought, less rain, lack water, two key technologies which were improved soil of vibrating deeply-loosening and improved soil preparation the biological and biochemical technology (kangdibao)were selected by field experiment, vibrating deeply-loosening not only improved the soil, but also established the soil reservoir, the loose soil created the condition for the salt leaching. The improved preparation Kangdibao turned the nutrient and trace elements of the soil into the available status which was absorbed by the plant, removaled the physiological nutrient deficiency symptom, ensured normal emergence of the plant in the saline-alkaline soil. Proceeding optimum combination of the above technology, determining the improved project, the experimental results showed that the economical and effective amount of the improved preparation Kangdibao was 7.5-12.5 kg/ hm2 under the condition of vibrating deeply-loosening.According to distribution features of the saline-alkali soil and the influence of the saline-alkali soil for husbandry production in song-nen plain, taking the utilization of precipitation resources as the breakthrough point, taking the improvement of the comprehensive production capacity of grassland as the target, taking the systematic configuration of drainage network as the security, the agronomic technology and biochemical technology were integrated, according to the different type region, the severe, the moderate, and the mild of saline-alkaline grassland were determined, taking the ecological restoration as the emphasis, the technology model of comprehensive treatment and efficient utilization of the saline-alkali grassland was established, which was suitable to the regional characteristics.Using both the water balance and the unsaturated soil moisture motion equation to analyze the mechanism of the storage and preservation of water. The undisturbed soil of the saline-alkaline grassland had the characteristics of hard soil, poor permeability, weak preserving water capacity, and the inhibition for the growth of the grass and the crop, so the produced potentiality of the crop did not adequately play. The experimental results showed that the soil structure with vibrating deeply-loosening was breaked and renewedly combined, the storage and preservation of water was greatly improved in the range of 50 cm loosen.According to the dynamics theory of soil moisture, established the one-dimensional vertical transfer model of soil profile, simulated the movement rule of water-salt under the infiltration of the evaporation for the subsoiling soil and the undisturbed soil, in the further distribution process of simulation analysis, the transfer characteristics of water and salt not only provided the theoretical foundation for the improved measures of the saline-alkaline, but also provided the theoretical foundation to reasonably determine the ecological improvement model.Using the statistical method to research the time and space variation regularity of the moisture, salinity, bulk density, yield of the grass, which were pre and post improvement of the subsoiling soil in the range of 0-40cm and improvement of the range of 1-5 year, through the ArcGIS, using the relevant statistical theory module established the information database and the spatial differentiation model by the soil characteristics in the combination of the graphic data and the attribute data, drawed spatial distribution graph, visually understanded spatial distribution of soil moisture and salt in pre and post soil improvement. Application of Projection Pursuit Classification model (PPC) based on Real-number coding Acceleration Genetic Algorithm (RAGA) to evaluate and analyze the ecological restoration of the saline-alkaline grassland. Respectively proceeding the investigation to the sample evaluation indexes which contained grazing region, vibrating deeply-loosening region, shallow ploughing and light harrowing region, enclosed fence region, every sample had 14 indexes, carrying out the normalization processing for the evaluated index set of the sample, structuring the projective index function, applying RAIGA to optimum the parameters of PPC model, arranging the optimal order of the sample, the result was that vibrating deeply-loosening ranked in front. Secondly, comprehensively weighing the species diversity changes after vibrating deeply-loosening by biodiversity analysis, after analyze and compare with the species richness, the ecological dominance, the diversity index, evenness index, the effect of grassland ecological environment, which was restored by improved technology was ulteriorly revealed.The paper took the experimental data of the laboratory experiment and the field observation as the basis, adopted the methods of the qualitative analysis combining with the quantitative analysis, the macroscopic analysis combining with the microscopic analysis, theoretical research combining with application research, with analyzing and processing the experimental results, determined the key technology and treatment measure for the improvement of the saline-alkaline grassland, established the improved technology model suitable for the saline-alkaline grassland in song-nen plain, systematically analyzed the mechanism of the storage and preservation of water, the movement rule of the water-salt, and spatial variability, evaluated the repairing ecological environment, provided the reference and the scientific basis to the research of ecological restorationin similar area.Innovative points:1.Applying vibrating deeply-loosening to the improvement of the saline-alkaline grassland for the first time, the loose soil after vibrating deeply-loosening storaged natural rainfall, formed soil reservoir, effectively used precipitation resource, meanwhile, created the condition for salt leaching.2.The saline-alkaline soil was scientifically classified and evaluated, to the characteristics and measures demand of the saline-alkaline grassland, formed classification of the control measures to severe, moderate, and mild of saline soil by the optimum combination of single technology, established the comprehensive control technology modle which was suitable for the saline-alkaline grassland of song-nen plain , realized the target of the less input, fast effect, and large output.3. First researched on the redistribution rule of water-salt and the simulation of water-salt transfer to the the subsoiling saline-alkaline soil, filled the gap in the theory of the water-salt motion rule of subsoiling land, provided the reference for the similar research.