| In order to explore the effects of biochar addition combined with nitrogen fertilizer on Soil improvement and nitrogen utilization in flue-cured tobacco,we carried out a pot experiment with 15 N trace technique and a field trials in a modern tobacco agriculture science and technology park of Henan Agricultural University Xuchang campus in 2016 and 2017.Four treatments were set up: Conventional fertilization(CK),Conventional fertilization + biochar(T1),Nitrogen fertilizer reduced by 30% + biochar(T2),Nitrogen fertilizer reduced by 60% + biochar(T3).The main results are as follows: 1.Effects of biochar addition combined with nitrogen fertilizer on Soil characteristicsThe soil bulk density and non water stabilized aggregates and water stabilized aggregates have Significant changes when biochar addition combined with nitrogen fertilizer.oil bulk density decreased by 11.74%,11.93 and 15.73%,The average weight diameter of the water stabilized aggregates increased by 40.83%,27.97% and 16.84%,>2mm-particle aggregates improved more significant.The results of field experiment and pot experiment showed that the application of biochar addition combined with nitrogen fertilizer could improve the soil CEC.in pot experiment,compared with CK,CEC improved 25.35%,28.03%,14.47%,24.45% and 55.17% in five times when nitrogen fertilizer reduced 30% combined with biochar.Conventional fertilization combined with biochar has the greast effect on CEC in field experiment.Conventional fertilization combined with biochar reduce the 15 N loss,improved the content of NH4+-N,NO3-N and available nitrogen in soil,and has a significant level in the late growth period of flue-cured tobacco.NH4+-N,NO3-N,available nitrogen(AN)improved 74.42%,14.27%,14.89%.There was no significant difference in the content of inorganic nitrogen and AN in T2 soil,and the content of three kinds of nitrogen in T3 soil was always low.T2 treatment can increase the content of available phosphorus(AP)and available potassium(AK)significantly in soil,and also improve the content of Fe,Mn,Cu and Zn in soil.biochar addition combined with nitrogen fertilizer were significantly inhibited the mineralization of organic nitrogen in soil after transplanting 1-60 d,and decreased by 56.63%,38.37% and 10.36% compared with the CK,but the mineralization of organic nitrogen was increased by 28.73%-66.57% after transplanting 60-120 d.the highest rate of nitrogen mineralization of biochar addition combined with nitrogen fertilizer has been delayed about 15 d compared with CK.the early mineralization was increased with the decrease of nitrogen fertilizer dosage,while the latter was the reverse when Application of Biochar.After transplanting 45 d and after,the activity of urease,sucrose enzyme and catalase was significantly improved when biochar addition combined with nitrogen fertilizer.the activity of urease and catalase was increased obviously when nitrogen was reduced 30%,and the activity of sucrose enzyme was not significantly different from CK.When the nitrogen reduction was 60%,The activity of three kinds of enzymes in soil decreased obviously.Soil microbial biomass carbon(SMBC)content increased by 8.43%-21.01%,and microbial biomass nitrogen(SMBN)content increased 6.35%~33.68%.2.Effects of biochar addition combined with nitrogen fertilizer on growth and nitrogen utilization of flue-cured tobaccoThe biochar addition combined with nitrogen fertilizer improved the root vigor by 12.04%~50.81% in different periods,nitrate reductase was improved by 16.16%~49% on 45 d after planting.the activity of glutamine synthetase increased by 16.36%-67.31%.The content of chlorophyll and the net photosynthetic rate of tobacco were also improved.The root vigor,chlorophyll content and net photosynthetic rate of reduced 30% nitrogen were not significantly different from CK.dry matter accumulation of flue-cured tobacco root,stem and leaf accords with logistic curve equation,fitting degree is more than 0.97.dry matter accumulation of tobacco enters the fast accumulation period after transplanting 45 d.the Conventional fertilization combined with biochar enhances the dry matter accumulation rate of fluecured tobacco significantly.dry matter accumulation of T2 was significantly higher than ck after transplanting 90 d.When the accumulation rate of nitrogen was at the peak of 50 d,T1 and T2 was higher than CK.From the point of view of nitrogen uptake,biochar addition combined with nitrogen fertilizer promote the absorption and accumulation of two kinds of nitrogen sources,and the accumulation of fertilizer nitrogen was higher than that of soil nitrogen in the early stage.From the point of view of different nitrogen sources,the main absorption of nitrogen fertilizer in the early stage of flue-cured tobacco,mainly absorbed soil nitrogen.The nitrogen utilization rate and the residue of fertilizer and nitrogen in the soil were improved by biochar addition combined with nitrogen fertilizer,and the dependence of flue-cured tobacco on soil nitrogen was decreased.3.Effect of Effect of biochar addition combined with nitrogen fertilizer on the quality of cured tobacco leaves on the quality of cured tobacco leavesbiochar addition combined with nitrogen fertilizer reduce the content of sugar,increase the content of nicotine,potassium and chlorine,improve the ratio of potassium to chlorine in flue-baked tobacco.the nicotine content of T2 is moderate,the chemical composition is relatively harmonious,and the content of neutral aromatic substance is higher.The content of neutral aromatic substances was lower and the content of the newly implanted two was decreased obviously when biochar addition combined with Conventional fertilization fertilizer. |
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