化肥减施对日光温室越冬长茬番茄氮肥利用率及去向的影响

Effect of fertilizer reduction on nitrogen utilization efficiency and fate during overwinter long-season tomato production in greenhouse

【目的】我国设施蔬菜过量施肥现象严重,在设施栽培条件下,比较常规施肥与化肥减施增效技术(简称化肥减施)下蔬菜产量(生物量)和氮肥利用率,研究氮素去向,为高效施肥提供依据。【方法】2017—2018年在河北省定兴县龙华村基地的日光温室进行2个试验。试验1根据差减法设计4个处理,包括常规施肥(CF,N–P2O5–K2O为858–594–1284 kg/hm^2)和化肥减施40%(RF,N–P2O5–K2O为608–297–720 kg/hm^2),及其相应的不施化肥氮对照(CFNN和RFNN)。试验2为15N示踪试验,用15N尿素替代普通尿素15NRF和15NCF 2个处理。番茄收获后,取0—20、20—40和40—60 cm土层样品,测定氮素的残留量。分期收获成熟番茄及枯枝落叶,拉秧时取植株地上和地下部分,再分为不同部位,对番茄产量和养分吸收量进行测定。【结果】差减法试验结果表明,RF处理番茄产量、总吸氮量分别较CF显著增加了10.4%、14.8%,化肥氮利用率增加了15.4个百分点。15N示踪试验结果表明,15NRF处理产量、氮吸收量和15N吸收量分别较15NCF处理增加12.1%、25.3%和13.8%,15NRF和15NCF处理的化肥氮利用率分别为36.4%、20.3%。15N示踪法研究还表明,不同土层的全氮含量及15N原子百分超呈自上而下逐渐降低的趋势;15NRF处理的化肥氮损失、番茄氮吸收以及土壤氮残留比例分别为40.4%、36.4%和23.2%,15NCF处理化肥氮损失、番茄氮吸收和土壤氮残留比例分别为59.6%、20.6%和19.6%,化肥氮去向总体表现为损失>番茄吸收>土壤残留;15NRF处理化肥氮损失率较15NCF处理低19.2个百分点;15NRF和15NCF处理0—20 cm土层化肥氮残留量分别占土壤中化肥氮总残留量的88.9%和87.9%。【结论】在施用30 t/hm^2有机肥的前提下,减少农户常规化肥用量的40%并调整氮磷钾比例,番茄产量和氮素吸收量显著增加,土壤残留比例没有明显变化,损失量显著降低,化肥氮利用率提高15个百分点以上。

【Objectives】Excessive application of fertilizers in vegetable production is quite often happened in China.We studied the effects of reduced chemical fertilizers on the yield and nitrogen fertilizer efficiency of tomato grown in greenhouse.We also studied the fate of applied nitrogen after harvest,so as to provide scientific references for rational chemical fertilizer application in this region.【Methods】A fertilizer subtraction and a 15N labeled microplot experiment were conducted simultaneously in a greenhouse from 2017 to 2018 in Dingxing County,Hebei Province.The tomato cultivar used is’Provence’,which is often grown overwinter and for about 8 months.There were four treatments in the fertilizer subtraction experiment,including:the farmers’average N-P2 O5-K2 O input of 858-594-1284 kg/hm^2(CF);the reduced 40%fertilizer treatment(RF),with the N-P2 O5-K2 O input of 608-297-720 kg/hm^2;the left two treatments were the above two deleted nitrogen(CFNN,RFNN).In the 15N labeled experiment,the nitrogen in RF and CF were replaced by 15N labeled urea(15NRF and15NCF).The tomato yield and fallen leaves were collected with the ripe of fruits,and the whole plant and soil samples(0-20,20-40 and 40-60 cm layer)were collected after the final harvest.The N contents were measured and fertilizer utilization efficiencies were calculated.【Results】In the fertilizer subtraction experiment,the yield,total N uptake of RF treatment were significantly increased by 10.4%and 14.8%,and the chemical N recovery rate was increased by 15.4 percentage points,compared with those of CF.In the 15N labeled experiment,the tomato yield,the total N uptake and 15N uptake in 15NRF treatment were increased by 12.1%,25.3%and 13.8%,compared with those of 15NCF.The difference in chemical N recovery rate was significant between 15NRF(36.4%)and 15NCF(20.3%).From the 15N labeled experiment,the total soil N content and 15N atom%content decreased with the soil depths increased.The fertilizer N fate was in order of loss>tomato uptake>soil residue,with detailed ratio of loss,tomato uptake and soil residue of 40.4%,36.4%and 23.2%in the 15NRF treatment,and 59.6%,20.6%and 19.6%in the 15NCF treatment.The fertilizer N loss rate of 15NRF was 19.2 percentage points lower than that of the 15NCF.The fertilizer N residue in the 0-20 cm soil layer of 15NRF and15NCF accounted for 88.9%and 87.9%of the total,respectively.【Conclusions】On the base of applying 30 t/hm^2 of organic fertilizer,reducing 40%chemical NPK nutrient input and adjusting the N-P2 O5-K2 O ratio could achieve significantly higher tomato yield,decrease the nitrogen loss,keep similar nitrogen residue in the soil,and increase chemical N use efficiency more than 15 percentage points.