Study On The Appropriate Ratio Of Slow-Controlled Release Nitrogen To Conventional Nitrogen In Winter Potato

In terms of the problem that the nitrogen releasing from conventional compound fertilizer does not match the potato nitrogen requirement with“one base exemption”technology under the black plastic film mulch of Guangdong winter potato,this research adopted the fertilizer in the farmers(N level is 329.4 kg·hm^-2,N:P₂O₅:K₂O=1:0.88:1.42)to reduce the application amount of nitrogen and phosphorus and increase the amount of potassium application,that is,the N level is 240 kg·hm^-2,N:P₂O₅:K₂O=1:0.5:2,consisted of six slow-controlled release urea nitrogen（N）and conventional urea nitrogen different ratio treatment:T1（Slow-controlled release N:Conventional N=10%:90%）;T2（Slow-controlled release N:Conventional N=20%:80%）;T3（Slow-controlled release N:Conventional N=30%:70%）;T4（Slow-controlled release N:Conventional N=40%:60%）;T5（Slow-controlled release N:Conventional N=50%:50%）;T6（Slow-controlled release N:Conventional N=60%:40%）;as well as other two treatments:T8（conventional fertilizer treatment）and T9（only phosphorus and potassium fertilizer application）;at the same time,set up T10（without fertilizer treatment）.Under the condition of 9000.0 kg·hm^-2organic fertilizer,the analysis were performed to the effects of different urea treatments on accumulation and distribution of fresh weight and dry matter,nitrogen,phosphorus and potassium absorption and distribution,yield,economic benefit,nitrogen fertilizer efficiency parameters and tuber quality of potato.The results revealed the optimal ratio of nitrogen,phosphorus and potassium in winter potato of Guangdong,which is suitable ratio of slow-release urea N to conventional urea N for high-yield,high-quality and high-efficiency production of the potato,as well as the ratio of slow-release urea to conventional urea is suitable for winter potato in Guangdong province.In order to solve the problem of nitrogen-based fertilizer management in the winter-made potato film“one base free exemption”technology,the theoretical basis and technical support were provided to replace available nitrogen with slow-controlled release nitrogen.The main findings were shown as follows:（1）During the growth period of potato,the accumulation of nitrogen and phosphorus in potato stems and leaves showed a single-peak curve,while potassium showed a double-peak curve.Nitrogen and phosphorus reached the peak at 31d and 43～55d after seedling emergence,respectively.The first peak appeared at 19～31d after seedling emergence,and the second peak occurred 55～67d after seedling emergence.The accumulation of nitrogen,phosphorus and potassium in the tubers showed an S-type uptrend with the growth and development process until harvest..Among the various organs of potato,the accumulation of potassium was the highest among the three elements of NPK,followed by nitrogen,and phosphorus was much lower than the accumulation of nitrogen and potassium.（2）The distribution rates of nitrogen,phosphorus and potassium in potato stems and leaves reached the highest at 7d after seedlings.As the potato growth period progressed,the aerial part of the potato and the photosynthetic system were established,and the growth and development center began to transfer to the tubers.Nitrogen,phosphorus and potassium began to transfer to the tubers for the formation and expansion of tubers until the senescence and shedding of the leaves and the wilting of the stems in the late growth stage,and the distribution rate of NPK in the stems and leaves gradually decreased.The distribution rate of NPK in tubers is lower in the early stage of growth,.but increasing with the growth period.（3）The reduction and control of nitrogen release in the potato tuber fresh weight,dry matter accumulation and its proportion and tuber quality were reduced with conventional fertilizer treatment,and there was no significant difference between the farmers’habit treatment.（4）There was no significant difference between the reduced-volume controlled-release nitrogen treatment and the conventional nitrogen treatment and the farmer treatment with the total yield,marketable potato yield,marketable potato rate,total output value and economic benefit.The total yield of T3 treatment was the highest in each treatment,reaching 50199.5 kg·hm^-2;while the yield of marketable potato produced by T4 reached47470.3 kg·hm^-2,which was the highest for each treatment,followed by T3,and reached46680.88 kg·hm^-2.In terms of marketable potato rate,the marketable potato rate of T6treatment was the highest in each treatment,reaching 95.39%,which was the same as that of T7;compared with the conventional fertilizer production value and economic benefit,T1～T6 treatment increased by 5.40～16.09%,9.01～28.54 respectively%,part of the treatment increased by 5.24～7.53%and 1.06～15.44%compared with the habits of growers,respectively.The total output value and economic benefit of T4 treatment were the highest in each treatment,reaching 106527.78 yuan·hm^-2respectively,65085.88 yuan·hm^-2.（5）Slow-controlled release of urea has a certain impact on the total output value of the potato and economic benefits.Compared with the conventional urea treatment,the total output value and economic benefits increased by 5.40～16.09%and 9.01～28.54%,respectively.The partial treatment increased by 5.24～7.53%and 1.06～15.44%compared with the farmer treatment.The total output value and economic benefit of T4 treatment were the highest among the treatments,reaching 106527.78 yuan·hm^-2and 65085.88yuan·hm^-2respectively.（6）There was no significant difference in agronomic efficiency,partial productivity,physiological efficiency and utilization rate of nitrogen fertilizers with conventional fertilizers,and the partial productivity and utilization rate of nitrogen fertilizers were significantly higher than those of farmers.The agronomic efficiency,partial productivity and physiological efficiency of nitrogen fertilizer treatment were the highest,reaching112.73 kg·kg^-1,209.16 kg·kg^-1and 656.89 kg·kg^-1,respectively,while T4 was only lower than T3,reaching 112.26 kg·kg^-1,respectively,208.69 kg·kg^-1,577.52 kg·kg^-1.In addition,the nitrogen utilization rate of T1～T6 treatment is higher than that of T7 and T8.（7）In terms of the total output,commercial potato yield,economic benefit,fertilizer efficiency parameters and quality,based on planting mode of“one base exemption”with black plastic film,the application of 9000.0 kg·hm^-2organic fertilizer with N level of 240kg·hm^-2and N:P₂O₅:K₂O=1:0.5:2,the ratio with 30%～40%of slow-controlled release urea N was the suitable ratio of slow-controlled release urea N to conventional urea N in slow-controlled release and compound fertilize for high yield,high quality and efficient production of winter potato in Guangdong Province.