| The problem of soil degradation has been worsening in recent years,especially the increasingly growing of soil acidification and soil salinization.To restore the degraded soil,the application of soil conditioners is one of the most effective measures.This research examined the changes in nutrient content of five kinds of soil conditioners,which were made from selected materials including calcium-magnesium phosphates,Maifan stones and humic acids of weathered coal,and were ground by a ball mill.On the basis of the findings,how the compatibility of humic acids with calcium-magnesium phosphates and Maifan stones influenced soil pH and nutrient availability in three kinds of soil could be studied through the soil culture experiment.Moreover,the test of fertilizer efficiency of pakchoi in red soil verified the effects of different soil conditioners.The aim of this research is to provide theoretical guidance for the conditioning of humic acids on soil conditioners and the optimization of nutritional function.Specific research results can be listed as follows:(5)The compatibility of humic acids with calcium-magnesium phosphates and Maifan stones reduced the alkaline of calcium-magnesium phosphates and Maifan stones,and significantly increased the content of water soluble magnesium,silicon,and phosphorus.However,the content of water soluble calcium decreased by 180.07 mg/kg,with a drop rate of 108.6% after the compatibility of 10% humic acids and 90% calcium-magnesium phosphates.(2)During the whole culture period,the pH value of red soil varied between 0.04 and 0.33 units,while the variation range of pH value of Jiaodong brown soil was between 0.12 and 0.63 units,and the range of the pH value of the Fluco-aquic soil varied between-0.17 and 0.1 units.The addition of 1g/kg of calcium-magnesium phosphates had the best effect on reducing soil acidity,while humic acids can reduce soil alkalinity.(3)Soil culture tests showed that the utilization of five soil conditioners had an obvious effect on the content of effective calcium,magnesium,silicon and phosphorus in soil.Calcium-magnesium phosphates could significantly improve the content of effective calcium,magnesium,silicon and phosphorus in three kinds of soil,with the average growth rate of 4.43%~13.11%,10.25%~103.79%,1.53%~52.11%,and 12.64%~230.28%,which indicated the condition got better as the quantity of addition increased.Maifan stones could improve the content of effective calcium and magnesium content in these soil,but it had no influence on the effective silicon content of alkaline tidal soil,and it reduced the effective phosphorus content of Fluco-aquic soil;Humic acids could improve the different content of available phosphates in different soil,and its condition improved with the addition amount of 1g/kg.After humic acids were compatible with calcium-magnesium phosphates and Maifan stones,the influence on the content of effective calcium and magnesium in soil had the tendency of a dynamic change,which could improve the content of effective silicon in acidic soil.(4)In the experiment of pakchoi,different soil conditioners could promote the growth of pakchoi,and improve the quality of the pakchoi seedlings.The processing effect achieved the best when humic acids and calcium-magnesium phosphates were compatible under the condition of 2 g/kg addition.Compared with CK treatment,the SPAD values of pakchoi leaf and biomass increased by an average of 12.75% and 25.91% respectively,and there was a significant difference.The content of soluble sugar,soluble protein and Vc in pakchoi leaves increased by 17.91%,5.37% and 18.83% respectively,and the nitrate content increased by 1.63%. |
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