Effects Of Fertilization On Growth Of Potato And Soil Nutrients In Different Continuous Years

Continuous cropping causes the change of soil nutrients,physical characteristics and microorganism system, and the uptake of plant to soil nutrients, the crop quality and yield also be influenced. Dingxi city of Gansu province ,which located at the semiarid areas of northwest losee plateau, is suitable to potato planting. Recently, the total local potato planting area was more than 24×10~4ha, have be one of main industries in this area. However, as the increasing of plant area, the potato replanted areas also be increased, the local potato industry was suffered the disease which caused by the replanting, how to solve this problem was became one of the most important methods to sustain the local potao industry. The local popular potato cultivar named Longshu 3 be used as the experimental material, the adjacent terraced fields which continuous cropping for 0 year (crop rotation), 3 years, 5 years respectively and under same soil types and management were chosen as experimental objects, treated by the different generation of tubers, different fertilization methods and chemical amendments, to study the influence of different treatments on potato growth and soil nutrients status of different replanted years, to find the way to decrease the replanted disease from seeds, chemical amendments and fertilization. The main conclusions of the study were summarized as follows:1,on flowering period, the photosynthetic rate (P_n) of potato leaves decreased as the increase of replanted years, the P_n of potato leaves in 3 years and 5 years continuous replant field are 23.2% and 17.1% lower than 0 year respectively under first-generation species+OPT treatment. The P_n of potato leaves in 3 years and 5 years continuous replant field are 13.7% and 18.7% lower than 0 year respectively under first-generation species+FP treatment. The P_n of potato leaves in 3 years and 5 years are 13.7% and 18.7% lower than 0 year respectively under elite seed potato+FP treatment. The P_n of potato leaves in 3 years and 5 years are 10.3% and 22.2% lower than 0 year respectively under first-generation species+FP+chemical amendments treatment's. Stomatal condncatance (Gs) declines with increasing replanted years, the Gs of potato leaves in 3 years and 5 years are 22.8% and 30% lower than 0 year respectively under first-generation species+OPT treatment. The Gs of potato leaves in 5 years is 30.38% lower than 0 year under first-generation species+FP treatment. The Gs of potato leaves in 3 years and 5 years are 38.9% and 26.5% lower than 0 year respectively under elite seed potato+FP treatment. The Gs of potato leaves in 3 years and 5 years are 28.1% and 33.1% lower than 0 year respectively under first-generation species+FP+chemical amendments treatment. Leaves'transpiration rate (Tr) declines with increasing replanted years, the Tr of potato leaves in 3 years and 5 years are 29.5% and 31.9% lower than 0 year respectively under first-generation species+OPT treatment. The Tr of potato leaves in 3 years and 5 years are 28.9% and 41.1% lower than 0 year respectively under first-generation species+FP treatment. The Tr of potato leaves in 3 years and 5 years are 52.7% and 41.6% lower than 0 year respectively under elite seed potato+FP treatment. The Tr of potato leaves in 3 years and 5 years are 30.4% and 28.6% lower than 0 year respectively under first-generation species+FP+chemical amendments treatment. The Tr of potato leaves in 3 years and 5 years are 30.4% and 28.6% lower than 0 year respectively under first-generation species+FP+chemical amendments treatment. Continuous cropping causes potato's fatal growing period photosynthesis decrease and influence potato's growth.2,Potato's nitrogen content is highest in replanted 0 year+elite seed potato+OPT treatment, its 7.57% and 14.71% higher than replanted 3 years'and 5 years'. Replanted 5 years+first-generation species+FP treatment's total nitrogen is the lowest, its 10.97% and 16.54% lower than replanted 3 years'and 0 year's, this treatment's plant is lower and leaves rolls and areas decrease. Potato's phosphorus content is decreasing with replanted years, and the content is highest in replanted 0 year+elite seed potato+OPT treatment, its 15% and 23.6% higher than replanted 3 years'and 5 years'; the content is lowest in replanted 5 years+first-generation species+FP treatment's, its 41.9% and 47.9% lower than replanted 3 years'and 0 year's, and 55.9% lower than the highest treatment. Potato's potassium content is highest in replanted 0 year+elite seed potato+ OPT+chemical amendments treatment, its 12% and 19.2% higher than replanted 3 years'and 5 years'; and the content of elite seed potato and first-generation species show a similar result that both of them are the lowest under replanted 5 years+ FP+ chemical amendments treatment. Replanted 5 years+first-generation species+FP+ chemical amendments treatment's total potassium is 38.7% and 27.1% lower than replanted 0 year's and 3 years'. Replanted 5 years+elite seed potato+FP+chemical amendments treatment's total potassium is 34.2% and 20.7% lower than replanted 0 year's and 3 years'. The results show that increasing of replanted years cause plant's N,P,K content, and use elite seed potato optimize fertilizations and add chemical amendments could ease unfavorable effect of nutrients absorption and utilization by replant disease.3,Status of soil nutrients in different replanted years are as follows: total nitrogen is highest in replanted 5 years+first-generation species+FP treatment, and lowest in replanted 0 year+elite seed potato+OPT treatment; total phosphorus is highest in replanted 5 years+first-generation species+FP+chemical amendments treatment, and lowest in replanted 0 year+elite seed potato+OPT treatment; total potassium is highest in replanted 5 years+first-generation species+OPT treatment, and lowest in replanted 5 years+first-generation species+FP treatment. Organic matters is highest in replanted 5 years+elite seed potato+OPT+chemical amendments treatment. Available nitrogen is highest in replanted 3 years+elite seed potato+OPT treatment. Available phosphorus is highest in replanted 5 years+elite seed potato+OPT+chemical amendments treatment, and increase with replanted years. Available potassium is highest in replanted 3 years+first-generation species+FP+chemical amendments treatment, available potassium content decreases with replanted years under FP treatment, but OPT treatment has no change. Total nitrogen phosphorus and potassium are all highest in replanted 5 years field, available nutrients are highest in replanted 3 years field besides available phosphorus. The results show that the increase of replanted years cause soil nutrients increase and plant nutrients decrease, so one of replant disease mechanisms may be replanted years restrict plant to uptake soil nutrients.As leaves'photosynthesis of replanted 3 years and 5 years'treatments are lower than 0 year's treatment, available nutrients content decline, cause potato's total nitrogen phosphorus and potassium decrease, the yield decrease with increasing replanted years, the yield of replanted 0 year+elite seed+OPT+chemical amendments treatment was the highest of 2402.13kg/mu, replanted 5 years+first-generation species+FP treatment's yield is the lowest of 999.17kg/mu. In sum, continuous cropping broke the balance of soil nutrients, total nitrogen and phosphorus accumulate, total potassium decrease obviously, available nutrients content in soil show a decline trend, these factors restrict potatoes to absorb nutrients, but scientific fertilizations, choose species and add chemical amendments could lighten replant disease of potato's plant in different degree.