The synergistic effect of lime, green manure and bio-organic fertilizer on restoration of acid field and improvement of tobacco production efficiency

Objectives Lime, green manure and bio-organic fertilizer are popular amendments and nutrient sources of acid soil. Their combined use effect was studied to form efficient and sustainable remediation technology of acid soil.

Methods Field experiments were conducted in 2017 and 2018, using tobacco cultivar of Yunyan87 as tested materials. Four treatments were included, single application of lime (L), combined application of lime and green manure (LG), combined application of lime, green manure and biological organic fertilizer (LGB), and no above materials added as control (CK). At 30 and 60 d after transplanting, tobacco samples were collected, and the agronomic and economic traits, physical characteristics, chemical composition, and smoking quality of flue-cured tobacco were determined. When the tobacco plants were removed, the 0–20 cm soil samples were collected, and the main nutrient contents and acidity characteristics of the soil were measured.

Results Compared with CK, , the soil alkali-hydrolyzable N in treatment L, LG, LGB was increased by 25.7%, 17.9% and 17.1%, available P was increased by 5.76%, 15.0% and 34.2%, soil pH was increased by 0.22, 0.80 and 1.07, the hydrolytic acid was reduced by 58.0%, 66.7% and 77.0%, exchangeable acid was reduced by 75.8%, 77.8% and 80.8%, exchangeable H⁺ was reduced by 94.6%, 96.6% and 97.7%, exchangeable Al³⁺ was reduced by 64.3%, 65.4% and 69.9%, exchangeable base cations were increased by 15.5%, 16.3% and 16.5%, cation exchange capability was increased by 13.2%, 15.5% and 17.6%, respectively. In treatment LG and LGB, soil bulk density was reduced by 5.73% and 6.56%, soil porosity was increased by 5.72% and 6.72%, and soil organic matter contents were increased by 27.0% and 35.2%, respectively. The three treatments led to slow down early stage growth of flue-cured tobacco, but promoted the mid-term growth of flue-cured tobacco. Compared with CK, the proportion of high-quality tobacco in treatment L, LG and LGB was increased by 20.4%, 23.2% and 28.4%, yields of tobacco leaves were increased by 3.71%, 17.8%, and 21.1%, output values were increased by 0.64%, 2.68%, and 2.71%, the chemical composition availabilities were increased by 0.59%, 11.0% and 14.6%, physical indexes of upper tobacco leaves were increased by 3.89%, 3.95%, and 12.87%, and total score of upper tobacco leaves was increased by 3.46% and 3.47% and 7.48%, respectively.

Conclusions Generally speaking, the combined application of lime, green manure and bio-organic fertilizer has the best effect on remediating acid soil, followed by the combined application of lime and green manure, and the effect of single application of lime is the lowest. The combining application of the three materials could increase soil organic matter content and soil porosity, and stimulate the soil nutrient supply to tobacco growth, so achieve economic returns from both sides of tobacco leaf quality and yield, and the sustainable remediation of acid soil.