Synergistic effects of bio-organic fertilizer and different soil amendments on salt reduction, soil fertility, and yield enhancement in salt-affected coastal soils

Abstract

Soil salinization is associated with soil productivity and food stocks, and hazards to the sustainable development of agriculture economics and the ecological environment. Hence, to evaluate the improvement and underlying mechanisms of agricultural amelioration practices on salinity alleviation, soil fertility improvement and crop growth, the organic fertilizer and soil amendments were applied to the rice field in coastal saline soil over one year. In this study, five treatments replicated three times were conducted in 15 experimental plots including CK (no amendments addition), OF (bio-organic fertilizer addition), OH (bio-organic fertilizer combined with hydrolytic polymaleic anhydride addition), OQ (bio-organic fertilizer combined with carbon nano sol addition), OB (bio-organic fertilizer combined with potassium fulvic acid addition). Co-application of organic fertilizer and soil amendment significantly reduced soil pH and EC by 1.3 % - 3.7 % and 14 % - 20 %, respectively. Organic treatments OH has the highest content of SOC (10.46 g kg⁻¹) and available nitrogen (AN, 76 mg kg⁻¹). OB treatment has the highest content of available potassium (AK, 294 mg kg⁻¹), and the activity of soil urease (S-UE) and alkaline phosphatase (S-AKP). Organic treatments have significantly increased the plant height, leaf area, 1000-grain weight (4 %-7 %), and yield of rice (4 %-15 %) compared to CK. Organic fertilizer and amendments added explained 81 % and 68 % of the variation in SQI and rice yield, respectively. RDA analysis indicated that S-UE activity and nitrogen were the most factors that contributed to SQI and rice yield. Our results suggested that the organic fertilizer combined with soil amendments improved soil quality comprehensively, and enhanced rice growth and yield by reducing soil salt and salinity, and increasing soil biochemical properties (S-UE and N content) in coastal saline soil.