Study on Productivity Improvement of Saline-Acid Degraded Paddy Soil by Special Organic Fertilizer Based on Earthworm Manure
Affected by seawater intrusion and acid-sulfate parent material, coastal paddy fields in Guangxi suffer from salt accumulation, soil acidification, active-aluminum toxicity and nutrient deficiency, which restrict rice production. Field experiments were carried out in saline-acid degraded paddy soils in Beihai, Guangxi. Suitable rice cultivars were screened, and the amelioration effect of lime-based acid-reducing fertilizer was evaluated. Furthermore, the effects of earthworm-manure-based organic fertilizer combined with earthworm manure, Bacillus and arbuscular mycorrhizal fungi on soil improvement and rice productivity were investigated. The results showed that rice cultivar Wuyou 308 was the optimal variety. Lime-based acid-reducing fertilizer increased soil pH and available phosphorus and achieved remarkable yield increase. The special earthworm-manure organic fertilizer raised soil pH, reduced exchangeable aluminum and soil salinity, improved soil organic matter, available phosphorus, available potassium and soil enzyme activities, and reshaped soil microbial communities. Beneficial taxa including Pseudomonas, Bacillus, Trichoderma and Penicillium were enriched, whereas harmful groups were suppressed. Under this treatment, rice grain yield reached 445 kg/mu, with a 117% increase compared with the control, and rice milling quality was significantly improved. In conclusion, the earthworm-manure-based organic fertilizer alleviates aluminum toxicity, activates soil nutrients and optimizes microbial communities, and achieves simultaneous improvement of soil health, rice yield and quality. It provides a technical solution for ecological restoration of coastal degraded paddy fields.