Effects Of Substituting Organic Fertilizer For Chemical Fertilizer On Garlic Growth And Soil Quality

Excessive use of chemical fertilizers in crop production will damage soil properties on the one hand,and reduce crop yield and quality on the other hand.The substitution of organic fertilizer for chemical fertilizer plays an important role in improving crop quality and soil properties.Therefore,it is one of the key issues that must be studied at present to study the reasonable substitution ratio and reasonable application amount of organic fertilizer.In this study,Ledu purple garlic was used as the main experimental material.A total of 7 fertilization treatments,including 20%organic fertilizer replacement nitrogen fertilizer,40%organic fertilizer replacement nitrogen fertilizer,60%organic fertilizer replacement nitrogen fertilizer,80%organic fertilizer replacement nitrogen fertilizer,100%organic fertilizer replacement nitrogen fertilizer,conventional fertilization and no fertilization,were set up in the experiment of organic fertilizer replacement nitrogen fertilizer and the amount of organic fertilizer was 7500 kg/hm²,12000 kg/hm²,16500 kg/hm²,21000 kg/hm²,25500 kg/hm²,30000 kg/hm²,no fertilization total replacement of organic fertilizer fertilizer in 7 experiments.Field experiments were carried out to study the effects of substituting organic fertilizer for chemical fertilizer on the growth and development conditions,yield and quality of garlic and soil quality,in an attempt to provide theoretical basis for rational fertilization of garlic in Ledu area.The research conclusions are as follows:（1）The effect of substituting organic fertilizer for chemical fertilizer on the growth and development of garlicCompared with conventional fertilization（T₆）,the plant height and pseudostem length of garlic were significantly increased by organic fertilizer replacing 40%nitrogen fertilizer（T₂）,while pseudostem diameter and leaf width of garlic were not increased,but there were no significant differences with conventional fertilization.There was no difference in dry matter accumulation and nitrogen accumulation in garlic leaves,pseudostems and bulbs among different treatments at seedling stage,while T₂treatment significantly increased dry matter accumulation and nitrogen accumulation in garlic organs at moss extraction stage and harvest stage.T₂treatment significantly increased nitrogen use efficiency of garlic by 58.02%compared with conventional fertilization.The plant height and pseudostem length of garlic were prominent when the amount of organic fertilizer was 21000～25500 kg/hm².With the increase of organic fertilizer application rate,the dry matter accumulation and nitrogen accumulation of garlic leaves,false stems and bulbs showed no significant difference at seedling stage,but the dry matter accumulation and nitrogen accumulation of garlic organs at moss extraction stage and harvest stage showed a trend of first increasing and then decreasing,and the organic fertilizer application rate was 21000～25500 kg/hm².Nitrogen use efficiency was the same.（2）The effect of substituting organic fertilizer for chemical fertilizer on garlic yield and qualityCompared with T₆treatment,T₂treatment could significantly improve bulb yield and quality,bulb yield and soluble sugar,vitamin C and soluble protein contents by15.93%,38.05%,25.42%and 63.56%,respectively.Meanwhile,it also increased economic benefit.With the increase of the application amount of organic fertilizer,the yield and economic benefit of garlic bulb increased firstly and then decreased.The yield and economic benefit of garlic bulb were the best when the fertilizer rate was21000～25500 kg/hm²,and the bulb quality was also at a better level.（3）Effect of substituting organic fertilizer for chemical fertilizer on soil quality of garlicCompared with T₆treatment,T₂treatment significantly improved the stability of soil aggregates in soil physical properties,reduced the nitrate nitrogen residue in soil chemical properties,increased soil nutrients,significantly increased the number of soil microorganisms in soil biological properties,and increased the activities of soil urease and catalase.With the increase of the application amount of organic fertilizer,the soil quality increased firstly and then decreased.The physical,chemical and biological properties of soil were the best when the amount of organic fertilizer was 21000～25500 kg/hm².In conclusion,from the perspective of sustainable agricultural industry,in the production process of garlic in Ledu area,organic fertilizer is recommended to replace 40%nitrogen fertilizer（T₂）to replace customary fertilization（T₆）,that is,fertilizer dosage:N:198 kg/hm²,P₂O₅:279 kg/hm²,K₂O:93 kg/hm²,combined with6600 kg/hm²organic fertilizer;In the case of replacing chemical fertilizer with organic fertilizer,the recommended application amount of organic fertilizer is21000-25500 kg/hm².This can guarantee the yield at the same time,improve quality,improve soil quality,is an effective way to achieve zero growth of fertilizer,for the sustainable development of agriculture in Ledu area is of great significance.