Effects Of Combined Application Of Biochar And Nitrogen Fertilizers On Soil Properties,Growth And Quality Of Flue-cured Tobacco

Effects of combined application of biochar and nitrogen fertilizers on soil main characteristics,the growth and quality of flue-cured tobacco,and nitrogen utilization rate were studied through 2014(Experiment I),2015(Experiment II)experiments for two years,in order to solve the problems of Tobacco soil environment deterioration,deterioration of leaf quality caused by over application of nitrogen fertilizer in tobacco fields.Experiment I included 9 treatments according to the nitrogen amount(N1-22.5 kg·hm-2,N2-37.5 kg·hm-2and N3-52.5 kg·hm-2)and the amount of biochar(C0-0 t·hm-2,C1-2.4 t·hm-2 and C2-4.8 t·hm-2)two factors,Experiment II set 5 treatments: no nitrogen fertilizer,conventional fertilization,conventional fertilization + biochar(2.4 t·hm-2),conventional nitrogen reducing nitrogen 15% + biochar(2.4 t·hm-2),and conventional fertilizer reducing nitrogen30%+ biochar(2.4 t·hm-2).The main results were as follows:1 Effects of combined application of biochar and nitrogen fertilizers on soil characteristics.(1)Effects of combined application of biochar and nitrogen fertilizers on soil enzyme activity,MBC,organic carbon and bulk densit.The results of Experiment I showed that,under low nitrogen level,adding 2.4 t·hm-2biochar significantly increased soil urease activity in the whole growth period of flue-cured tobacco;low nitrogen and medium nitrogen levels,with the application of biochar could significantly increase the activity of soil catalase in the early and late growth stage of flue-cured tobacco,and under the condition of medium nitrogen level,the activity of catalase increased with the increase of the amount of biochar;under the three nitrogen levels,the whole performance of the soil invertase activity was inhibited by the application of biological carbon.Low nitrogen and medium nitrogen levels,adding 2.4 t·hm-2biochar significantly increased the MBC content at late growth stage of flue-cured tobacco,the content of MBC was the highest under the medium nitrogen level;the application of biochar and nitrogen fertilizer could significantly increase the content of soil organic carbon in the whole growth period of flue-cured tobacco.Under low nitrogen and medium nitrogen levels,the application of 2.4 and 4.8 t·hm-2could reduce soil bulk density,treatment N1C2 decreased the most,up to 12.3%;under the high nitrogen level,the application of 2.4 t·hm-2 could also reduce soil bulk density,but the effect was not significant in the two cases.(2)Effects of combined application of biochar and nitrogen fertilizers on soil alkali hydrolysis nitrogen content.The results of Experiment II showed that the treatments of conventional fertilization +biochar and reducing nitrogen 15% + biochar could improve rhizosphere soil alkali hydrolyzable nitrogen,up to 7.64%,reduce the fertilizer leaching,and improve soil fertility,to ensure the required nitrogen by the growth of tobacco leaf.2 Effects of combined application of biochar and nitrogen fertilizers on physiological characteristics of flue-cured tobacco during the growth process.(1)Effects of combined application of biochar and nitrogen fertilizers on dry matter,nitrogen accumulation in different organs of flue-cured tobacco,and nitrogen use efficiency.The results of Experiment II showed that,on the basis of conventional fertilization increased biochar could promote dry matter and nitrogen accumulation in different organs of tobacco,and promote the growth of flue-cured tobacco.The treatment of conventional fertilization reducing nitrogen 15% increasing biochar had a certain positive effect on dry matter and nitrogen accumulation.The treatment of conventional fertilization reducing nitrogen fertilizer 30% and application of biochar inhibited the organs and nitrogen accumulation,and the growth of flue-cured tobacco.On the basis of conventional fertilization,the application of biochar had a significant effect on the nitrogen use efficiency,which could be improved by 12.99%.Conventional fertilization enhanced biochar reduction of nitrogen fertilizer 15%treatment could improve the nitrogen use efficiency of 6.66%.However,the utilization rate of nitrogen fertilizer decreased significantly when the 30% nitrogen fertilizer was reduced.(2)Effects of combined application of biochar and nitrogen fertilizers on conventional chemical components of tobacco leafs during the growth of flue-cured tobacco.The results of Experiment II were as follows,the conventional fertilization adding biochar could reduce the reducing sugar,total sugar,chlorine content of middle leaves and improve the nicotine content,and showed inhibitory effect on the nicotine content in the late growth stage of tobacco plant;the potassium content in tobacco leaves was no obvious role in promoting.With the decrease of nitrogen levels,reducing and total sugar contents increased,but there was no significant effect on chlorine content.3 Effects of combined application of biochar and nitrogen fertilizers on conventional chemical components of flue-cured tobacco.Take C3 F as an example(the same below).In Experiment I,the nicotine content increased with the increase of the amount of nitrogen;under low nitrogen level,combined application of bichar(medium and high amounts)could reduce the chlorine content in middle leaves of flue-cured tobacco,improve tobacco moisture absorption,and the other chemical constituents also had significant influence,but not consistent;medium nitrogen level,combined application of biochar to improve the potassium content in tobacco leaves at the same time also increased the chlorine content of tobacco leaf,and improved the tobacco sugar ratio;under high nitrogen level,combined application of biochar could improve tobacco reducing sugar,total sugar,nicotine,potassium and chlorine content,reduce the total nitrogen of tobacco and sugar ratio.In Experiment II,potassium content in tobacco leaves of five treatments were low,the rest of the routine chemical components were in suitable range of high quality tobacco.On the basis of conventional fertilization increasing biochar decreased the contents of reducing and total sugar in middle leaves of tobacco;in addition to the external control,the treatments of reducing 15% nitrogen + biochar and reducing 30%nitrogen + biochar had high ratio of sugar to nicotine,carbon and nitrogen compounds were coordination.4 Effects of combined application of biochar and nitrogen fertilizer on mineral elements in tobacco leaves.Experiment I results showed that middle leaves Ca content were high each treatment,not conducive to the formation of high-quality tobacco.Low level of nitrogen fertilizer,adding biochar can reduce the Mg content in middle leaves;medium and high nitrogen levels,adding biochar could increase Mg content of tobacco leaves,but generally were in the appropriate range.The content of P was in low level,biochar and nitrogen fertilizer could significantly increase the P content of tobacco leaves,thus to improve the P content of tobacco leaves by applying biochar in the soil,and improve the quality of tobacco leaves.The low and middle nitrogen levels,application of biochar could increase B content of tobacco leaves,but the overall tobacco leaves had high B content.Under the middle nitrogen level,the Cu content of tobacco leaf was significantly increased,and the middle amount of biochar in the high nitrogen level could significantly increase the Cu content of tobacco leaves.Under three nitrogen levels,the combined application of biochar could significantly increase the contents of Fe、Mn、Zn in tobacco leaves(other than Zn in middle nitrogen and high biochar,Mn in high nitrogen and middle biochar).5 Effects of combined application of biochar and nitrogen fertilizer on neutral aroma components of flue-cured tobacco.In Experiment I,under low nitrogen level,combined application of high amount of biochar,aromatic amino acid degradation products,Maillard reaction products,carrot pigment degradation products,Solanone and neophytadiene content were increased.In the middle nitrogen level,adding middle amount of biochar could increase other types of aroma components content except for Solanone.Under high nitrogen level,combined application of biochar did not significantly improved the neutral aroma components content.For different amount of nitrogen treatments,the overall performance was that carotenoid degradation products,Solanone and neoplytadiene contents of middle nitrogen level were the highest.6 Effects of combined application of biochar and nitrogen fertilizer on the sensory quality of flue-cured tobacco.Experiment I.Under low nitrogen level,the combined application of biochar could enhance tobacco aroma,improve the aftertaste,combustion,partial white ash,and the highest total score.But at the same time,it also increased the offensive odor and irritation of tobacco leaf.Middle nitrogen level,the combined application of middle amount biochar could increase the aroma quality,improve the aftertaste,and achieve higher score,meanwhile increased the tobacco odor and irritation.Under high nitrogen level,the overall quality of tobacco smoking was low.The total score of smoking decreased with the increase of N application rate.In summary,combined application of biochar(2.4 t·hm-2)and nitrogen fertilizer(conventional nitrogen reducing nitrogen 15%)could increase the soil urease,dehydrogenase activity,improve MBC and organic carbon content,soil bulk density decreased,play a role in improving soil,also could increase soil alkali hydrolyzable nitrogen content,reduce nitrogen leaching,and increase the utilization rate of nitrogen fertilizer.Combined application of biochar and nitrogen fertilizer could promote the accumulations of nitrogen and tobacco plant,reduce the absorption of chlorine, improve the coordination of chemical components in tobacco leaf,increase the content of neutral aroma substances,and improve the quality of tobacco leaf.