不同氮肥用量对设施番茄产量、品质和土壤硝态氮累积的影响

Effects of Different Treatments of Nitrogen Fertilizer on Yield,Quality of Tomato and Soil NO_3^--N Accumulation in Vegetable-Greenhouse

在设施栽培条件下,采用田间小区试验,以番茄为指示植物,研究了不同氮肥用量:农民习惯施氮量(N1,尿素,纯氮1000kg·hm-2)、70%农民习惯施氮量(N2,尿素,纯氮700kg·hm-2)、70%农民习惯施氮量结合调节土壤C/N(N3,尿素,纯氮700kg·hm-2)、50%农民习惯施氮量结合调节土壤C/N和采用滴灌(N4,尿素,纯氮500kg·hm-2)对设施番茄产量、品质和土壤硝态氮累积的影响。结果表明,与农民习惯施用氮肥相比,减施氮肥处理(N2、N3和N4)的番茄产量没有降低,N4处理产量最高,比N1增产9.7%。N2和N4处理氮肥的农学效率和肥料的产投比均显著高于N1处理(P<0.05),其中N4处理最高,为28.9kg·kg-1和12.6,施肥效益最高。不同施氮肥处理间果实Vc含量虽没有显著差异,但N4处理是N1处理的1.2倍。番茄果实的硝酸盐含量随氮肥施用量的增加而增加,两者呈显著的正相关关系(R2=0.8307,P<0.05),N3和N4处理果实硝酸盐含量均显著低于N1处理(P<0.05)。0～100cm土层累积的硝态氮随氮肥施用量的增加而增加,N1处理土层累积的硝态氮含量最高,减施氮肥处理均降低了土壤对硝态氮的累积。土壤硝态氮多累积在0～40cm土层,硝态氮的相对累积量约为50%,这部分残留的氮素可被下季作物吸收利用。果实硝酸盐含量与土壤累积的硝态氮存在显著的相关关系(R2=0.8003,P<0.05),说明土壤硝态氮含量过高能够增加果实对氮素的吸收和积累。在寿光设施蔬菜生产条件下,在农民习惯施氮量基础上减氮30%～50%既可以保证较高产量和较好的果实品质,同时降低土壤中硝态氮累积,从产量、肥料效益和土壤可持续利用角度来看,N4处理更具优势,具有较好应用价值。

Field experiment was carried out to study the effects of different treatments of nitrogen（N） fertilizer on the yield,quality of tomato and soil NO^3--N accumulation in vegetable-greenhouse in Shouguang,Shandong Province,an important greenhouse vegetable production area in North China. There were five treatments：a control receiving no chemical N fertilizer（N0）,habitual N management of the local farmers （100% chemical N,named as N1,1 000 kg N·hm^-2）,70% chemical N fertilizer of N1（named as N2,700 kg N·hm^-2）,70% chemical N fertilizer of N1 combined with maize straw（named as N3,700 kg N·hm^-2）,and 50% chemical N fertilizer of N1 combined with maize straw and drip irrigation（named as N4,500 kg N·hm^-2）. Results showed that under current cultivation conditions,tomato yields could still be ensured even at 30%-50% deduction in N fertilizer input comparing with the local farmer habitual usage. Maximum yield was found in N4 treatment,9.7% higher against the N1 treatment. N2 and N4 treatments were significant higher in N agronomic efficiency and the value of cost ratio than N1 treatment（P〈0.05）. The maximum N agronomic efficiency（28.9 kg·kg^-1） and the value of cost ratio （12.6） appeared in the treatment of N4. There was no significant difference in Vitamin C（Vc） content of tomato among different N fertilizer treatments and N4 treatment got higher Vc content. A close relationship was found between fruit nitrate content and N application（R^2=0.830 7,P0.05）. Tomato nitrate content of N3 and N4 treatment were significantly lower than the habitual N usage（P〈0.05）. High application of N fertilizer（N1） caused high accumulation of NO^3--N within the 0-100 cm soil profile. Deduction of 30%-50% in N input decreased the soil NO^3--N accumulation. Nitrate accumulates mostly in the soil profile of 0-40 cm,relative NO^3--N accumulation account for more than 50%,and which could be utilized in next season. Correlation analysis showed that there were positive relationships between tomato nitrate content and soil NO^3--N accumulation（R2=0.800 3,P0.05）. In conclusion,under current cultivation conditions in Shouguang,high tomato yields,quality and less NO^3--N accumulation could be obtained at 30%-50% reduction in habitual N input,which presents a possible scale to a safety and efficient N fertilizer utilization in greenhouse farming system. N4 treatment is the feasible N management practice.