To provide a scientific basis for fertilizer application, a field experiment was conducted to study the effect of chemical N fertilizer reduction combined with biochar application on soil nutrient content,quality and yield of tobacco. Four treatments were set as: CK(conventional N fertilization), B(biochar+100% conventional N fertilization), BN1(biochar+85% conventional N fertilization), BN2(biochar+70% conventional N fertilization). The results showed that the contents of organic carbon, dissolved organic carbon, total nitrogen, nitrate and available potassium significantly increased under the combined application of biochar and N fertilizer. Compared with the control, the highest organic carbon and dissolved organic carbon contents were observed under the BN2 treatment, the increment was 31.90% and 39.84%, respectively; the contents of total nitrogen, nitrate and available potassium under the B treatment reached the largest value, and increased by 15.28%、56.40% and 22.24%, respectively; under the three treatments with biochar addition, the contents of total nitrogen, nitrate and available potassium decreased with the decrease of N fertilizer application rates. Soil microbial biomass carbon and nitrogen under different fertilization treatments significantly increased by 38.76%~55.34% and 78.92%~158.58% compared to the control, respectively. The treatments of biochar addition combined with 15%~30% reducing nitrogen application rate significantly increased total sugar, reducing sugar content in cured tobacco leaf, decreased the total nitrogen and nicotine content, and improved the harmony of intrinsic chemical components of tobacco leaf. In addition, the treatment with 15% reducing nitrogen application rate did not make much difference on economic characters of tobacco compared with CK. While, the yield and output of tobacco in BN2 was much lower than CK. Overall, considering soil conservation and quality and yield of tobacco, it is feasible to reduce nitrogen application rate with biochar addition in tobacco-growing area of central Henan , and the optimum treatment was BN1(1 500 kg/hm2 biochar+44.6 kg/hm2 chemical N fertilizer). |