Abstract:

To explore the effect of deep rotary tillage combined with organic materials on improving acidic characteristics of rhizosphere soil and growth, yield and quality of flue-cured tobacco, a field experiment with flue-cured tobacco cultivar ‘NC102’ was conducted in acidic red soil in Shilin County, Yunnan Province. Based on two-factor split zone design, deep vertical rotary tillage and traditional tillage, as well as application of organic soil ameliorative materials (no ameliorative material, acidic organic fertilizer, alkaline organic fertilizer and biochar) were set to study tillage methods, organic materials and their interactions on physic-chemical properties of rhizosphere soil, root system, growth morphology, yield and quality of flue-cured tobacco. The results showed that physicochemical properties of tobacco-growing soil were mainly affected by tillage methods, ameliorative materials and their interaction. Deep vertical rotary tillage combined with organic fertilizer could significantly reduce soil bulk density, and increase soil porosity, hydrolytic nitrogen, available phosphorus, available potassium and water-soluble chlorine content. In particular, the application of alkaline organic fertilizer and biochar was more beneficial to increase soil available potassium content. The total amount of soil exchangeable acid, hydrogen ion (H⁺) and aluminum ion (Al³⁺) were significantly reduced. The soil silica-aluminum ratio, cation exchange capacity and base saturation were increased, and effect of acidic soil improvement was enhanced. The root crown morphology, yield and output value of flue-cured tobacco were mainly affected by deep rotary tillage and alkaline ameliorative materials. Tillage methods, organic modified material and their interaction had a great effect on chemical components usability index of flue-cured tobacco. The application of basic organic fertilizer and biochar mainly affected total sugar, reducing sugar, potassium and water-soluble chlorine. Deep vertical rotary tillage significantly affected six conventional chemical indexes of tobacco leaves. Therefore, in mountainous tobacco-growing areas of acidic soil in Yunnan Province, deep vertical rotation tillage combined with application of alkaline organic fertilizer and biochar can coordinately improve soil acidity and fertility, and simultaneously promote growth of above-ground and underground parts of tobacco, form a good root-shoot relationship, which can increase yield, output value, and harmonious chemical composition of flue-cured tobacco.

Key words: flue-cured tobacco, organic material, deep vertical rotation tillage, soil acidification, quality