Combination of organic fertilizer and slow-release fertilizer increases pineapple yields, agronomic efficiency and reduces greenhouse gas emissions under reduced fertilization conditions in tropical areas

Abstract

To ensure pineapple productivity, large amounts of chemical fertilizer are used in the tropics of China. However, the high temperatures, rainfall and low fertilizer utilization efficiencies lead to fertilizer leaching loss and greenhouse gas emissions, which are very unfavourable to the sustainable production of pineapple. The purpose of this study was to determine whether reducing fertilizer applications could increase pineapple yield, quality and agronomic efficiency and reduce the global warming potential. A 4-year field experiment with five fertilization pattern treatments (e.g., CK: no fertilization; NPK: traditional fertilization; INF: reduced nitrogen (N), phosphorus and potassium fertilizers; INF + M: based on INF, 20% N was replaced by organic fertilizer; INF + M + S: based on INF, 20% and 15% N were replaced by organic and slow-release fertilizers, respectively) was established to ascertain the potential role of reduced fertilization levels in increasing pineapple yield, quality and agronomic efficiency and reducing greenhouse gas emissions. The results revealed that compared with the NPK treatment, the INF, INF + M and INF + M + S treatments increased pineapple yields by 8.1%, 13.0% and 27.1% averaged over the two seasons, respectively, and significantly improved the agronomic efficiency and reduced the global warming potential and greenhouse gas emission intensity without compromising quality. In addition, when compared with INF treatment, the INF + M and INF + M + S treatments could significantly reduce the nitrous oxide and carbon dioxide emissions and thus decrease the global warming potential by 21.2% and 29.2%, respectively, and greenhouse gas emission intensity by 32.0% and 32.5%, respectively, averaged over two seasons. However, the INF + M and INF + M + S treatments showed no significant differences. The INF + M + S treatment provided the highest yields, agronomic efficiency and soil methane uptakes among all treatments (p < 0.05). The nitrous oxide and methane emissions showed significant positive correlations with soil moistures and temperatures, respectively. Meanwhile, both nitrous oxide and carbon dioxide showed significant positive correlations with the soil ammonium and nitrate contents. We highly recommend the INF + M + S treatment as an environmentally friendly fertilization strategy for pineapple in tropical regions with high yields, high efficiencies, and low greenhouse gas emissions.