Abstract:

The study explored the effects of rapeseed oil cake organic-inorganic compound fertilizer (OICF) combined with potassium feldspar soil conditioner (PFSC) on soil fertility, and growth, yield, quality and fertilizer use efficiency of flue-cured tobacco, aiming to provide a theoretical basis for tobacco field fertilization. Using flue-cured tobacco variety ‘Honghuadajinyuan’ as material, a field experiment was conducted in red soil in Kunming tobacco planting area, and six fertilization treatments were set up, i.e. T1 (CK, conventional dosage of N, P and K, inorganic compound fertilizer of tobacco), T2 (OICF, equal to T1 in N, P and K rate), T3 (OICF combined with PFSC, equal to T1 in N, P and K rate), T4 (OICF combined with PFSC, 20% less N, P and K than those of T1) and T5 (soil conditioner with neither manure nor fertilizer), T6 (neither manure nor fertilizer). The results showed that compared with CK, T2 and T3 significantly enhanced soil pH by 0.51 and 0.69 units respectively, increased the contents of organic matter, hydrolysable nitrogen, available phosphorus, available potassium and SOC by 13.02%-43.48%; and T2 increased TN content by 10.98%, and T3 and T4 also enhanced C/N level by 16.02% and 13.23% respectively. Compared with CK, T2 and T3 significantly improved the growth of tobacco, and the leaf area and leaf area coefficient of the tobacco plants were increased by 2.11% and 4.50% under T2, and 7.39% and 23.96% under T3, respectively. Compared with those of CK, the proportion of high grade leaf and output value were increased by 7.87% and 17.66% under T2, and 11.75% and 29.37% under T3, respectively. Meanwhile, T3 and T4 increased the yield by 14.92% and 8.80%, respectively. Furthermore, T2 and T3 improved the tobacco filling value and leaf stalk weight, the tobacco under these two treatments had uniform texture, excellent physical properties, and reached the highest comprehensive score. Besides, compared with those of CK, the total sugar and reducing sugar were decreased by 4.37% and 4.43% under T2, and 23.93% and 10.90% under T3, respectively. Meanwhile, the total nitrogen and nicotine were enhanced by 12.64% and 11.11% under T2, and 15.81% and 8.12% under T3, respectively, and the potassium oxide and water soluble chlorine contents were increased by 27.65% and 35.94% under T2, and 4.76% and 14.29% under T3, respectively, so that the chemical composition of tobacco leaves was more harmonious. Compared with CK, T2, T3 and T4 enhanced apparent N use efficiency by 13.40%-24.14%, and T2 and T3 increased physiological N use efficiency by 5.85% and 10.75%, respectively; T2, T3 and T4 increased apparent P use efficiency by 42.49%, 48.99% and 16.26% respectively, and physiological P use efficiency by 22.68%, 34.88% and 13.53% respectively. Similarly, T2, T3 and T4 raised apparent K use efficiency by 11.88%, 20.30% and 7.67% respectively, T2 and T3 increased physiological K use efficiency by 9.45% and 18.87%, respectively. In summary, the application of rapeseed oil cake organic-inorganic compound fertilizer or organic-inorganic compound fertilizer combined with potassium feldspar soil conditioner could improve soil pH and fertility, and promote tobacco plant growth, tobacco yield and quality, and the utilization of nitrogen, phosphorus and potassium fertilizer in flue-cured tobacco.

Key words: flue-cured tobacco, organic-inorganic compound fertilizer, potassium feldspar soil conditioner, quality, fertilizer use efficiency