Application of carbon-based nutrient fertilizer improved soil fertility and seed yield of Paeonia ostii ‘Feng Dan’

Oil tree peony is an emerging woody oilseed crop in China. There is a lack of research on dedicated ecological fertilization methods in its production, however relevant technologies play a crucial role in improving seed yield. In this study, a 2-year field trial on Paeonia ostii ‘Feng Dan’ was conducted to focus on carbon-based nutrient fertilization. Seven treatments were established, including different combinations of chemical and carbon-based nutrient fertilizers: CK (CalvinKlein), CF (50 kg chemical fertilizer), CNF1 (50 kg chemical fertilizer＋ 30 kg carbon-based nutrient fertilizer), CNF2 (50 kg chemical fertilizer＋ 60 kg carbon-based nutrient fertilizer), CNF3 (50 kg chemical fertilizer＋ 90 kg carbon-based nutrient fertilizer), CNF4 (50 kg chemical fertilizer＋ 120 kg carbon-based nutrient fertilizer), BF (50 kg chemical fertilizer＋ 150 kg bio-organic fertilizer. We evaluated the effects on tree peony growth, seed yield, quality, soil fertility, and microbial community. After two growing seasons, the CNF3 treatment significantly increased seed yield by 45.95% and oil content by 26.60% compared to the CK treatment. CNF3 also improved soil fertility, with a notable increase in total nitrogen (20.00%), organic matter (18.95%), cation exchange capacity (51.98%), available nitrogen (234.56%), phosphorus (20.09%), and potassium (67.65%). Microbial populations and community structure were enhanced under CNF3 treatment, promoting beneficial bacteria like Proteobacteria and reducing harmful fungi like Ascomycota. Redundancy analysis highlighted available phosphorus as a key driver for bacterial communities and organic matter for fungal communities. Through this study, we identified the positive effects of carbon-based nutrient fertilizers on seed yield and soil fertility in tree peony, aiming to provide a sustainable and efficient fertilizer option for agricultural production.