Study on Enteromorpha Polysaccharide/Konjac Glucomannan Mulch Films with Biochar as a Fertilizer Carrier

In order to protect the ecosystem from the impact of plastic film pollution, it is necessary to explore biodegradable materials for producing a plastic film. In this study, mulch film was prepared using biochar as the fertilizer carrier, Enteromorpha polysaccharide (EP), and konjac glucomannan (KGM) as the film’s matrix. The result of Fourier transform infrared (FTIR) showed that the Enteromorpha polysaccharide extracted from Enteromorpha prolifera (E. prolifera) was rich in hydroxyl, carboxyl, and sulfonic groups. The result of FTIR, scanning electron microscopy (SEM), and energy-dispersive spectroscopy of biochar proved that urea was successfully loaded in biochar, and the urea loading capacity of biochar reached 17.8%. The transmittance of EP/KGM/urea-loaded biochar film (urea-BCF) was less than 3%, which meets the requirements of the black mulch film. The degradation rate of the mulch in the soil can reach 68.3% after 80 days of burial, indicating an excellent degradation performance. The SEM results showed that the biochar particles were distributed uniformly in the membrane matrix. In addition, the leaching experiments showed that the release of urea achieved an equilibrium after 20 h, with a cumulative of almost 76.9%. This method not only achieves the high value utilization of E. prolifera but also provides a simple strategy for preparing mulch film.