Peanut shell biochar in acidic soil increases nitrogen absorption and photosynthesis characteristics of maize under different nitrogen levels

Acid red soils are widely widespread in south China. The strong acidity and aluminum toxicity inhibit plant growth by decreasing soil fertility. Herein, we studied the potential effects of biochar on nitrogen absorption, photosynthesis, and plant-related enzyme activities in maize under different nitrogen fertilizer levels. We carried out a pot experiment with different peanut shell biochar levels (0, 0.5, 1, 2, and 3%) and two nitrogen fertilizer levels (0, 0.2 g kg(-1)) in the acid red soil. The results indicated that the application of biochar significantly improved the soil environment (pH, soil organic matter) and increased crop growth. Moreover, N accumulation was increased by 98-166% with biochar treatments. The application of 3% biochar to the soil under different N levels significantly increased nitrogen use efficiency (NUE) and physiological nitrogen use efficiency (PNUE). In addition, the functional components (amino acid, cellulose, and protein content) were significantly changed under nitrogen fertilizer treatment according to the results of Fourier transform infrared spectroscopy (FTIR). In particular, the treatments of 0.2 g kg(-1) and 3% biochar had the highest photosynthesis parameters of maize. From the results of path analysis, maize growth and development were closely related to the physical and chemical properties of the soil. The study results revealed that biochar could be a green development way to reduce the input of chemical N fertilizer and effective use of resources.