Effects Of Chemical Fertilizers Partialy Substituted By Organic Fertilizers On Potato Dry Matter Accumulation And Distribution And Soil Biological Characters

Yellow River Irrigation Areas of Middle Gansu Province is one of the main processingpotato growing regions and is important of seed potatoes breeding base in the NorthwestChina. Over here potato industry play a important role in increasing farmers’ payoffs andpromoting all-round development of the rural economy. However， non-adequatefertilization，especially long-term overuse of chemical fertilizer，severely leads to thedecrease of soil organic matter and deterioration in soil physical-and chemical-as well asbiological properties. This practice results in the severe decline in tuber yield and also hurtthe healthy development of the potato planting industry locally. Field experiment wasconducted to evaluate the effects of chemical fertilizer partialy substituted by organicfertilizers on potato dry matter accumulation and distribution，and soil biological charactersincluding soil microbial communities，soil enzyme activities and microbial functiondiversity. The aim of the study was to improve fertilizer management approach in intensivepotato production system. Eight treaments were set up using completely the randomizdeblock design with four repeats，including：T1:CK，non-fertilization；T2:100%chemical fertilization（100%CF）；T3:100%CF+200kg/667m2organic fertilizer（100%CF+200kg/667m2OF）；T4:100%CF+200kg/667m2bio-organic fertilizer（100%CF+200kg/667m2BOF）；T5:80%CF+200kg/667m2OF；T6:60%CF+400kg/667m2OF；T7:80%CF+200kg/667m2BOF；T8:60%CF+400kg/667m2BOF.1）Except for T3，there were almost no change in tuber yield between the treatmentswith chemical fertilizer partialy substituted by organic fertilizers and the treatment with100%CF. T7had the highest tuber yield31110.75Kg/hm2across fertilization treatments， indicating that the potato production systems200-400kg/667m2organic fertilizer orbio-organic fertilizer can replace20%-40%of the local conventional fertilizer usage inTiaoshan Farm.2）There were obvious changes in potato dry matter accumulation among fertilizationtreatments. Logistic equation was set up for estimating dry matter accumulation of potatoplants， indicating that the average rate(Vmean) and the duration(△t) in dry matteraccumulation during quickly accumulative period were crucial for potato dry matteraccumulation and tuber yield formation. Significant changes in Vmeanand△t were observedacross fertilization treatments. Logistic equation parameters of the whole plant dry matteraccumulation,T2were the highest of the Vmeanin all treatments.Compared with CKsignificantly increased Vmeanby98.71%，but the△t were lowest in all treatments. suggestingthat change in Vmeanwas the important reason for tuber yield increase under100%CFtreatment. Dry period of rapid accumulation of dry matter and dry matter Vmean averagegrowth rate of the rapid accumulation of synergistic increase△t is the duration of thewhole plant dry matter accumulation and tuber production increased foundation, which isreduced fertilizer and organic fertilizer fertilizer treatment is still able to maintain100%ofmajor fertilizer processing mechanism and flat compared tubers production. Tuber drymatter accumulation of data on Logistic equation was also indicated that the process of birthtuber dry matter accumulation and dry matter accumulation during the whole plant showedsimilar patterns3）Distribution of dry matter in the presence of different fertilization treatments are alsosignificant differences in aboveground vegetative organs (stems and leaves) and economicorgans (tubers) of dry matter accumulation in potato late growth scissors size formeddistinct, stem dry matter accumulation the mass balance of the time there is a significantdifference. All treatment to80%CF+scissors largest T7treatment200kg/667m2BOF,indicating replaced with bio-organic fertilizer200kg/667m220%of the regular amount offertilizer can promote growth of potato late vegetative organs to the tuber dry matter partitioning. Reduced fertilizer and manure or bio-organic fertilizer with each treatment,the dry mass balance of100%of the time compared to the average processing fertilizer T2ahead15d, especially T7treatment earlier20d, which indicates that the organic fertilizerpromotes vegetative organs fat dry matter allocated to economic organs as soon as possible.4）Compared with the100%chemical fertilizer T2, all processing of organic fertilizerto replace part flowering fertilizer increased soil tuber enlargement and starch accumulationnumber of culturable bacteria, reducing the number of culturable fungi to improve the soilbacteria/Fungal ratio. Described in the long-term fertilizer intensive potato cultivationsystem, the amount of organic fertilizer inputs can regulate microbial flora composition andstructure.5）Soil microbial community is an integral part of the soil ecosystem as it regulatessoil nutrient cycling，decomposition of organic matters and formation of humic substances.In the research，Biolog Eco Plate was performed to evaluate the effect of fertilizermanagement on soil microbial function diversity. The treatments with organic fertilizerreplacement significantly improved soil microbial activities and the efficiency of carbonsources utilization for soil microorganisms compared to100%CF treatment. After168hours of soil incubation，the treatments with chemical fertilizer partialy substituted byorganic fertilizers significantly increased the efficiency of carbon sources utilization by19.06%-72.61%relative to100%CF treatment.5）Compared with100%chemical fertilizer treatment T2, replacing part of the fertilizerfertilizer all changed in different periods of soil urease, dehydrogenase, catalase, invertaseactivity, but change due to the difference of the types of soil enzymes and growth period.6）The results under different treatments microbial functional diversity measured usingBiolog Eco Plate technology show,100%chemical fertilizer lowest microbial functionaldiversity T2, and less than no fertilizer control T1. All processing of organic fertilizer toreplace part of a significant increase in fertilizer use intensity potato planting soil microbialactivity and microbial carbon source. After soil cultivation168hr, organic manure fertilizerhandling more completely replace chemical fertilizer treatment increased19.06%-72.61% in the microbial community carbon source utilization. And in microbial functional diversityindex, organic manure fertilizer handling more fully replace part of the processing ofchemical fertilizers also increased by2.53%compared to-18.50%.In conclusion，producers could maintain the same level of tuber yield obtained bytraditional chemical fertilizer management practice in the intensive potato productionsystem via chemical fertilizer partialy substituted by organic fertilizers while improving soilbiological properties，especially in increase of soil enzyme activities，amendment of soilmicrobial community structure and improvement of soil microbial function diversity.Overall, Field test results showed a year, T7treatment, which uses bio-organic fertilizer200kg/667m2substitute80%of the local conventional fertilizer to reduce by20%theamount of fertilizer and bio-organic fertilizer combined application of200kg/667m2best.