Rape residue can be used as green manure to improve soil quality and crop productivity. A study in Korea found that using rape residue along with 70% chemical fertilizer increased rice growth and reduced weed occurrence. The combination of rape residue and 70% chemical fertilizer led to longer panicles and higher rice grain weight compared to using only chemical fertilizer. This treatment also significantly decreased weed density and biomass. Overall, using rape residue as green manure is a sustainable and effective way to enhance crop productivity and reduce the need for chemical fertilizers in rice-rape double cropping systems.