烤烟-大豆/红薯套作模式对土壤肥力、烟叶品质及经济效益的影响OA

[Objective]The study aimed to systematically investigate the effects of post-tobacco intercropping pattern on the soil-flue-cured to-bacco complex and their differential mechanisms,and identify efficient synergistic planting models for grain and tobacco production.[Meth-od]Using Yunyan 87 as the test material,three treatments were established in the Honghe tobacco-growing area of Yunnan:tobacco mono-cropping[T0(CK)treatment],tobacco relay intercropping with soybean(T1 treatment),and tobacco relay intercropping with sweet potato(T2 treatment).Soil fertility,upper leaf quality of flue-cured tobacco,and economic benefits were measured,and the action pathways were analyzed using structural equation modeling.[Result]Compared with CK treatment,T1 treatment significantly increased soil total nitrogen and total potassium contents,enhanced urease activity,promoted above-ground dry matter accumulation of flue-cured tobacco,improved single leaf weight and moisture content of upper leaves,and significantly elevated total nitrogen and reducing sugar contents.T2 treatment signifi-cantly enhanced soil enzyme activities,increased single leaf weight and moisture content of upper leaves;however,the potassium-to-chlorine ratio decreased significantly,while soil pH and potassium content declined markedly.Compared with CK treatment,the two intercropping pat-terns had no significant effects on the yield and output value of upper tobacco leaves,yet which increased total economic benefits of tobacco fields by 9.7%and 74.7%,respectively,through additional income from soybean(5381 kg/hm2)or sweet potato(44 683 kg/hm2).Structural e-quation modeling revealed differentiated pathways between the two intercropping systems:intercropping with soybean primarily influenced the system through the'biological activation-nutrient immobilization-slow-release supply'pathway,whereas intercropping with sweet potato oper-ated mainly via the'root activation-microbial synergy-nutrient efficiency enhancement'pathway.[Conclusion]Intercropping soybean or sweet potato after tobacco harvesting could synergistically achieve soil fertility improvement,tobacco leaf quality enhancement and increased income.The soybean model was more conducive to improving the intrinsic quality of tobacco leaves,while the sweet potato model had more significant economic benefits.The study systematically elucidated the differentiated mechanisms of these two grain/oil and economic crop re-lay intercropping systems under identical ecological conditions from the perspective of action pathways.