| In this paper,a field plot experiment was conducted to investigate the effect of five treatments on nutrient supply,the microbial biomass,enzyme activity as well as flue-cured tobacco growth,yield and quality for tobacco-planted soil in Xichou County,Yunnan Province,The five treatments included no fertilizer(T1),single chemical fertilizer(T2),chemical fertilizer+cow dung in dosage 1(T3)with 1500 kg/hm~2,chemical fertilizer+cow dung in dosage 2(T4)with 4500kg/hm~2,and chemical fertilizer+cow dung in dosage 3(T5)with 6500kg/hm~2.The primary results were as follows:1.Based on single chemical fertilizer,adding the cow dung was favorable to improve the soil organic matter,which was positively related to the amount of cow dung.During the three periods,the contents of soil organic matter were in the order of T5>T4>T3>T2>T1.The contents of soil organic matter in T5,T4 and T3 treatments were 6.25-29.70 g/kg,25.67-27.44g/kg and 23.40-25.25 g/kg,which increased by 16.54%-27.02%,11.11%-24.24%and 5.14%-16.11%compared with T2 treatment,respectively.Nutr:ient supply of cow dung was higher than chemical fertilizer because available nutrients were less released in rosette stage but more in later stage.2.The cow dung could promote the accumulation of MBC,MBN and MBP,which were positively related to the amount of cow dung.Their contents were in the order of T5>T4>T3>T2>T1 at three stages.The MBC content in T5,T4 and T3 treatments improved by 150.45%-207.29%,48.12%-161.03%and 19.77%-93.31%compared with T2,respectively.Meanwhile,the MBN content in T5,T4 and T3 treatments improved by 94.61%-97.04%,57.88%-68.23%and 10.85%-37.01%compared with the T2,respectively.As to MBP,the contents in T5,T4 and T3 treatments improved by 94.61%-97.04%,57.88%-68.23%and 10.85%-37.01%compared with the treatment T2,respectively.It showed that the combined application of adding cow and chemical fertilizer could promote the microbial growth and soil activity.3.Compared with no fertilizer(T1)and single chemical fertilizer(T2),adding cow dung significantly promoted enzyme activity,with emphasis on T5 treatment;The enzyme activities were higher in T2 at the rosette stage,while they were higher(especially urease,sucrose and acid phosphatase)in organic matter treatment at vigorous growing stage and the mature stage.The amount of cow dung had little effect on catalase activity.4.Combined application of cow dung and chemical fertilizer was favorable to promote the flue-cured tobacco growth,which was positively related to amount of the cow dung.At later stages,the flue-cured tobacco growth was obviously promoted by the manure compared with the rosette stage,especially the T4 and T5 treatments.5.The tobacco yield was increased by adding cow dung,which was positively related to the amount of cow dung.Compared with T2 treatment,the tobacco yield in T5,T4 and T3 treatments increased by 7.01%,6.59%and 4.20%,respectively.The tobacco quality in T4 treatment was optimized,and the proportion of first-class tobacco and smoking quality were in the order of T4>T5>T3>T2>Tl.The chemical composition of the flue-cured tobacco was more harmonious by applying the manure.In general,the high proportion of first-class tobacco proportion was favorable to the increase of overall quality and average price.The output value was in the order of T4>T5>T3,which were increased by 8.47%,7.01%and 4.20%compared with T2 treatment,respectively.Taken together,combined application of cow dung and chemical fertilizer could enhance soil nutrient supply,and increase the tobacco quality.Adding cow dung with 4500 kg/hm~2 on the basis of single chemical fertilizer is advisable for tobacco-planted soil in Yunnan region. |
