Combining organic amendments and enhanced efficiency fertilizers to improve the quality and nutrient use efficiency of pineapple

• The application of 4Rplus technology can significantly improve the yield and quality of pineapple and reduce the nutrient surplus;. • Among different organic alternative treatments, 40 M treatment has the best effect;. • Adding biochar on the basis of 40 M treatment further improves the test effect. China's intensive pineapple farming expansion has led to soil degradation, excessive nutrient input and loss, and reduced efficiency. This study addresses these issues with a multi-objective, coordinated soil and nutrient management approach by developing 4Rplus nutrient management technologies.. These technologies combine organic amendments (manure and biochar) with enhanced efficiency fertilizers (controlled-released fertilizers, CRFs) at optimal nitrogen (N) rates to improve yield, quality, nutrient use efficiency, and reduce N loss in pineapples. The finding show that 4Rplus technologies can significantly enhance the agronomic traits, pineapple quality, and N use efficiency (NUE) while reducing N surplus. Yield, dry matter, and NUE showed an initial increase followed by a subsequent decrease as the organic substitution (as N) ratio increases. Among the treatments, 40 % organic substitution combined with CRF (40M+CRF) showed optimal results, achieving yield, dry matter, and NUE increases of 37 %, 24 %, and 51 % compared to conventional practices, respectively. Fruit quality traits, such as soluble solids, sugar-acid ratio, and Vitamin C content, also improved by 7.7 %-11.4 %. Comparatively, the 20M+CRF and 60M+CRF treatments showed similar but less effective improvements in dry matter, NUE, and fruit quality. The addition of biochar to the 40M+CRF treatment (40M-B+CRF) yielded further enhancements. Compared to the 40M+CRF treatment, the 40M-B+CRF treatment resulted in significant increases in aboveground dry matter (10 %), nitrogen and potassium uptake (26 % and 19 %, respectively), and NUE (22 %). It also significantly increased fruit Vitamin C content by 4.7 % and soluble protein by 18.2 %.