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China's northeast region soil salinization is a very serious problem, a serious impediment to the development of agricultural production, mainly due to the saline-alkali soil of the area Sodic Soil, governance is difficult. The test to the the Songnen Plain Daqing soda meadow saline as the research object, using a randomized complete block design, construction site surface layer (0 ~ 20cm) using four different thicknesses building black fertile soil on the soil of the different degrees of alkalization direct coverage processing, 2cm, 4cm, 6cm and 8cm, and set the control treatment (not covered), while pasture reseeding. Pasture growth conditions (grass height, total coverage, total output), soil physical properties (soil bulk density, natural moisture content), soil chemical properties (pH, soil conductivity, cation exchange capacity, exchangeable sodium ion basicity , total alkalinity, organic matter, soil available nutrients) were measured. Pasture growth conditions and soil physical and chemical properties of contrast, the evaluation of different the cover thickness effects of soda meadow saline vegetation recovery, screening out the appropriate the alkalinization degree of soil cover thickness provides a desalination germination surface pasture precious black maximize resource utilization, soda meadow saline green coverage to maximize the overall goal. The results showed that: different thickness covering processing, can improve soil physical and chemical properties of ground vegetation condition has improved to varying degrees. With the increase in the thickness of repair coverage is more obvious effects. When the cover thickness of 6cm and 8cm from the soil chemical properties in terms of alkali soil in terms of severe or moderate alkali soil, soil pH can be decreased to less than 8.5; soil basicity sharp decline, a decrease of CO32 ions more than 80%; measurement results the total alkalinity also will be dropped; soil cation exchange capacity and soil organic matter has improved to some extent. View from pasture growth status, with a the alkalinization degree of soil cover thickness of 6cm and 8cm from the landscape point of view was no significant difference between the two; different alkalization degree of soil, the overall look is moderate alkalization forage crops are growing well in the soil, but with increasing cover thickness in two alkalization degree of soil on pasture growth status gap is getting smaller and smaller, the statistical analysis showed that when the cover thickness 8cm, no significant difference between the two. The black covering thickness is the dominant factor decide everything changes. Regression analysis showed that: two alkalization degree of soil on the growth index of forage and cover thickness significantly positive association, in line with the variation of cubic curve, that is in the black soil cover thickness (the test of 2cm and 4cm) grass growth in poor condition, and smaller changes, more changes of a sudden when the cover thickness increases to a certain value (the test of 6cm and 8cm), forage growth conditions, and after the change has stabilized. Soil the basicity coverage thickness was highly significant negative linear correlation. Cover thickness and soil pH, electrical conductivity showed a the quadratic curve very significantly negatively correlated linearly with soil organic matter highly significant positive correlation. The purpose of this test is to find a suitable cover critical thickness, combined with pasture recovery status and soil properties change status, moderately alkali soil, black soil covering thickness should not be less than 6cm in severe alkali soil cover thickness should be low At 8cm.
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