Reductive soil disinfestation enhances melon yield over two consecutive cropping seasons by improving soil fertility and rhizosphere biota

Intensive year-round multiple-cropping systems in tropical regions often lead to severe soil degradation and yield decline. Reductive soil disinfestation (RSD) offers an eco-friendly solution, yet its effectiveness and persistence under tropical continuous cropping systems remain unclear. We first evaluated the effects of a single RSD treatment using four organic amendments (fermented chicken manure, fermented sheep manure, wheat bran and commercial organic fertilizer) on melon-cultivated soil. The persistence of these effects was then assessed over two consecutive seasons. The results demonstrated that RSD significantly improved soil fertility, with RSD-wheat bran showing the most persistent effects, sustaining increases of 51.5%, 68.3%, and 60.2% in AN, AP, and AK compared with controls after two consecutive growing seasons. Reductive soil disinfestation also restructured microbial communities by enriching beneficial taxa (Bacillus) and suppressing pathogens (Fusarium), while markedly reducing pathogenic nematodes (Meloidogyne, Rotylenchulus). These changes collectively enhanced melon growth and sustained yield increases across both seasons. Correlation analysis further revealed positive associations among soil fertility, beneficial microbes, and plant traits, whereas pathogenic fungi were negatively correlated. Overall, RSD restored soil health and maintained higher melon yields across successive cropping cycles, highlighting its potential as a sustainable strategy for intensive production in tropical regions.