The Effect Of Planting Years And Fertilization On Soil Fetrility And Biological Activity Of Platycodon Grandiflorum

The soils collected from the field of different planting years and different fertilizationswere used as experiment materials. The content of soil total nitrogen, Olsen phosphorus,available potassium, organic matter, available iron, available Manganese, available copperand available zinc were measured. And then, the amount of microbial and activities of soilenzymes were determined. Then the correlation between soil fertility and soil biology activitywas analyzed. Last, the reasons leading to successive cropping obstacle were obtain. And theoptimum ratio of N: P: K to preserve soil fertility of Platycodon grandiflorum and to relievesuccessive cropping obstacle of Platycodon grandiflorum. In addition, the effect ofPlatycodon grandiflorum’s extracting solution and different planting years’ soil on the growth,yield and the active ingredient concentration was studied by pot experiment. The thesisoffered theoretical direction for Platycodon grandiflorum’s high production and superiorquality successively.1. The soil pH value decreased after Platycodon grandiflorum planted, but the amount ofbacteria and amount of fungi increased. After Platycodon grandiflorum planted, the activitiesof soil enzyme first increased and then decreased in0-20cm of soil, but in20-40cm theactivities decreased first and then increased. In0-20cm, the content of soil total nitrogen,Olsen-P and organic matter increased first and then decreased, but the content of availablepotassium, nitrate nitrogen and ammonium nitrogen decreased. In20-40cm, the content ofsoil total nitrogen and organic matter increased, but the content of Olsen-P, availablepotassium and nitrate nitrogen decreased first and then increased. Planting Platycodongrandiflorum did not have significant effect on the content of soil microelement. Theamounts of fungi, the activities of urease and catalase have significant correlation with soilfertility after planting Platycodon grandiflorum. Short term continuous cropping did not have significant effect on soil fertility and soil enzyme activities, while long term one made the soilelement deficiency and soil enzyme activities decreased. But continuous cropping did nothave significant effect on the content of soil microelement. The successive cropping obstacleof Platycodon grandiflorum was not caused by deficiency of microelement, it may caused bydecreased soil enzyme activities and deficiency of nitrogen, Olsen-P and potassium. Thefertility of Platycodon grandiflorum soil can be reflected by the amount of fungi, activity ofurease and catalase.2. Fertilization increased the amount of bacteria and actinomycetes, but decreased theamount of fungi, consequently enhance the soil fertility. And fertilization enhanced theactivities of invertase and urease. Fertilization decreased the pH value of soil, but it increasedthe content of total nitrogen, organic matter, nitrate nitrogen, Olsen-P, available potassium,and available iron, manganese, copper and zinc. Fertilize NPK together had the mostsignificant effect. The content of nitrogen, phosphrous and potassium had significantcorrelation with available iron and manganese. The content of available iron, availablemanganese, total nitrogen and organic matter had significant positive correlation with theactivities of soil enzyme. Fertilize NPK together, particularly N3P3K1had the most suitableeffect to maintain the fertility of soil. The soil biological activities can be used to reflect thesoil fertility, for the significant correlation between soil fertility and soil biological activities.3. The pot experiment indicated that neither the extracting solution of Platycodongrandiflorum nor the soil of successive cropping had significant inhibiting effect on the heightand stem diameter of Platycodon grandiflorum. But the two factors interactions inhibited thegrowth of Platycodon grandiflorum. The autotoxins of Platycodon grandiflorum andsuccessive cropping soil may lead to the successive cropping obstacle of Platycodongrandiflorum. Consequently, Crop rotation and cleaning stubble of Platycodon grandiflorumcan be used to relieve successive cropping obstacle of Platycodon grandiflorum in fieldproduction.