The study looked at how adding crop residues back to salty soil affects the levels of humus, fulvic acid, and humic acid. After the straw decomposed, the humus, fulvic acid, and humic acid levels in the soil increased significantly. The fulvic acid content was much higher than humic acid. The ratio of humic acid to fulvic acid initially increased and then decreased. Adding urea to the soil led to fluctuations in humus and fulvic acid levels. Overall, humus and fulvic acid increased, while humic acid decreased slightly.