Preparation Of Control-Released Potassium And Effects Of Control-Released Nitrogen And Potassium Humic Acid Blending Fertilizer On Garlic Growth And Soil Nutrients

At present,garlic cultivation has many problems,such as large amount of fertilizer,low nutrient utilization rate,mismatch between target yield and nutrient supply,and high lab cost.On the one hand,controlled-release fertilizer can meet the needs of nutrients in the whole growth period of crops,solve the problem of insufficient nutrients in the middle and late stages of crops,and has the advantages of saving time and lab.On the other hand,humic acid can promote growth,increase yield and promote crop yield and quality.However,the research of controlled-release fertilizer is mostly focused on nitrogen fertilizer,and garlic has a high demand for nitrogen and potassium,and the controlled-release of potassium fertilizer is particularly important.However,there are some problems in the controlled-release of potassium fertilizer,such as difficulty in coating and poor release performance.At the same time,there are few studies on the synergistic effect of controlled-release fertilizer and humic acid to solve the shortage of nutrient supply in garlic later growth.In view of the difficulty of coating potassium fertilizer and the insufficient supply of nutrients for garlic growth in the later stage,this study mainly carries out work in the following two aspects.Firstly,three different coated materials(isocyanate,isocyanate + paraffin,isocyanate + paraffin,and isocyanate + paraffin + castor oil)were prepared for controlled-release potassium fertilizer.The release characteristics of potassium were detected and evaluated under hydrostatic extraction at 60℃ and 25℃ to screen the best coated materials.Based on the optimum coating material conditions,three kinds of coating mass fractions(3.3%,3.5%,3.7%)were set up to detect and evaluate the release characteristics of potassium under static water extraction at 60℃ and 25℃.The optimum coating mass fraction was screened and controlled release potassium was obtained.Secondly,a plot experiment was conducted to design five treatments: common humic acid fertilizer,controlled-release nitrogen humic acid mixed fertilizer(55.6% of controlled-release nitrogen),controlled-release potassium humic acid mixed fertilizer(42.1% of controlledrelease potassium),controlled-release nitrogen-potassium humic acid mixed fertilizer(55.6% of controlled-release nitrogen and 42.1% of controlled-release potassium),and controlledrelease nitrogen-potassium humic acid mixed fertilizer with 16.7% reduction.By studying the effects of different treatments on garlic growth characteristics,yield,quality and soil nutrients,the optimum fertilizer types and dosage for garlic planting were selected,which provided scientific basis and theoretical support for garlic high-yield and high-efficiency planting.The main results are as follows:(1)Under the evaluation indexes of potassium release rate of hydrostatic extraction at 25 ℃and 60℃,the composite material of isocyanate + paraffin + castor oil is the best,and the effect of controlled release is better when the mass fraction of the coating material is 3.7%.The release rate of the optimized controlled-release potassium fertilizer was 5.3% at the initial stage of static water at 25℃,and the controlled-release period was more than 80 days,which met the industry standard of controlled-release fertilizer.The release rate of potassium in soil is "S" type.It releases less before overwintering and slowly.It does not release potassium in the overwintering period when the accumulated temperature of soil is less than 0℃.After overwintering period,with the increase of ground temperature,the release of potassium accumulates more quickly.The release of potassium in 70-80 days after overwintering period is the largest,which coincides with the peak period of potassium demand of garlic.It satisfies the demand for potassium in garlic and meets the demand of garlic for potassium is conducive to the formation and improvement of yield.(2)Controlled-release fertilizer reduced nutrient loss caused by rain leaching or surface runoff,increased soil nutrient supply in the later period of garlic growth,and avoided the effect of potassium deficiency on garlic yield and quality in the later period of garlic growth.Compared with common humic acid fertilizer,application of controlled-release nitrogen,controlled-release potassium and mixed fertilizer of controlled-release nitrogen and potassium humic acid can significantly increase garlic yield and garlic bolt yield,and significantly increase garlic content.The optimum treatment is full controlled-release nitrogen and potassium humic acid mixed fertilizer.The yield-increasing effect of controlled-release nitrogen and potassium humic acid mixed fertilizer was better than that of single controlled-release nitrogen or potassium treatment under 16.7% reduction.(3)Compared with common humic acid fertilizer,the application of controlled-release nitrogen,controlled-release potassium and controlled-release nitrogen-potassium humic acid mixed fertilizer can significantly increase the chlorophyll content of garlic leaves,and can also improve the root activity at different stages after the differentiation of self-flowering bud scales.The effect of controlled-release nitrogen and controlled-release potassium humic acid mixed fertilizer is better than that of controlled-release nitrogen and controlled-release potassium.(4)Controlled-release potassium and controlled-release nitrogen-potassium humic acid mixed fertilizers could significantly increase the content of different forms of potassium in soil,among which available potassium increased by 12.85%-13.57%,and potassium supply in soil.Controlled-release nitrogen and controlled-release nitrogen and potassium humic acid mixed fertilizer significantly increased the content of alkali-hydrolysed nitrogen in soil,increasing by 49.66%-51.61%.There were no significant differences in available phosphorus,organic matter content,conductivity and pH value among treatments.(5)Under the experimental conditions,the controlled-release nitrogen and potassium humic acid fertilizer 12,000 kg/ha could improve garlic yield,garlic quality and economic use of soil nutrients.