Extraction and characterization of fulvic acid from corn straw compost by alkali solution acid precipitation

The effective utilization of corn straw is a challenge. Extracting fulvic acid from corn straw compost improves the utilization rate of corn straw, reduces the use of chemical fertilizers, and supports sustainable agricultural development. By the response surface, the best alkali solution acid precipitation extraction conditions were obtained, which involved a KOH concentration of 9.67%, a reaction temperature of 100.32 °C, a reaction time of 9.91 h. Through the Fourier transform infrared spectroscopy (FTIR), it found that BFA contained more oxygen-containing functional groups than MFA, such as those in aliphatic, hydroxyl, ketone and carbonyl groups. Compared to the MFA, the BFA included more types of hydrogen and showed a looser superficial structure. The average molecular model of BFA was constructed with the formula C17H16O7 (M=332). BFA has a lower molecular weight than MFA, which should ensure that BFA is readily absorbed and used by crops. BFA promoted the growth of rice seeds effectively, and the optimal BFA concentration for seed germination was 0.4%. In this study, corn straw composting was used as the main object. The molecular structure of BFA extracted from corn straw compost was established by the alkali solution acid precipitation method. It confirmed that BFA could replace MFA as a biorenewable, environmentally friendly agricultural product.