Study On Appropriate Amount Of Controlled Release Nitrogen And Controlled Release Period Of Winter Potato In Guangdong

As the mulching mode of winter potato cultivation in Guangdong changed from straw mulching to black film mulching,the fertilization method also changed from the previous“basic fertilizer plus multiple top dressing”（referred to as“one base multi top dressing”）to“one-time base fertilizer without top dressing”（Referred to as“one base no top dressing”）.This fertilization method has the problem that the supply period and supply of conventional fertilizer nutrients do not match the nitrogen demand of potatoes at different growth stages.Therefore,exploring the supply of fertilizers suitable for the nutrient requirements of potato at all growth stages has become the key science and practice problem to be solved under the new model.The entry point of this experiment is slow and controlled release nitrogen fertilizer.Under the application of 9000.0 kg·hm^-2as decomposed poultry manure,the total nutrient content and fertilizer ratio is N 240.00kg·hm^-2,N:P₂O₅:K₂O=1:0.5:2,set 8 treatments:T1（coated urea with longevity of 60days:normal urea=30%:70%）,T2（coated urea with longevity of 60 days:normal urea=40%:60%）,T3（coated urea with longevity of 90 days:normal urea=30%:70%）,T4（coated urea with longevity of 90 days:normal urea=40%:60%）,T5（100%normal urea）,T6（only missing Nitrogen fertilizer）,T7（only apply organic fertilizer）,T8（no fertilizer）.The effects of different fertilization treatments on potato growth status,nutrient absorption characteristics,tuber yield and quality,economic benefit and fertilizer utilization rate were studied,to explore the suitable period and proportion of nitrogen fertilizer for Guangdong winter potato under the“one base no top dressing”fertilization model.The main research findings as follows:（1）Compared with normal urea,combined treatment of slow and controlled release urea and normal urea increased the nitrogen accumulation of the whole plant in the late potato growth period,a relative increase of 15.62%～43.32%,and also increased the accumulation of tuber dry matter,a relative increase of 15.07%～25.86%,T4（the longevity of nitrogen fertilizer for 90 days,the ratio of slow-controlled release urea to conventional urea is 40%:60%,same as below）is the best treatment.（2）Compared with normal urea,combined treatment of slow and controlled release urea and normal urea increased the tuber fresh weight per plant and the commercial potato rate,which in turn increased tuber yield and economic efficiency.The relative increase in yield was 5.38%～10.29%,and the relative increase in income was 11.84%～21.13%.T4 is the best treatment,its output reaches 48392.59 kg·hm^-2,and the net income reaches 64091.15yuan·hm^-2.（3）The morphological parameters and tuber quality parameters of the combined application of slow and controlled release urea and normal urea were not significantly different from those of conventional urea（p>0.05）.Among them,T4 had the highest Vc content,up to 16.69 mg.100g^-1,the content of reducing sugar is relatively low,0.078%.（4）Compared with normal urea,combined treatment of slow and controlled release urea and normal urea improved the agronomic efficiency of nitrogen fertilizer,a relative increase of 34.68%～66.34%,the relative productivity of nitrogen fertilizer increased by 5.38%～10.29%,the recovery rate of nitrogen increased by 9.88%～17.19%,the combined efficiency of nitrogen,phosphorus and potassium fertilizers has increased by 36.93%～70.57%,T4 is the best treatment,respectively reached 47.19 kg.kg^-1,201.63 kg.kg^-1,21.09%,12.98 kg.kg^-1.