Primary and Residual Effects of a Bio-based Composite Fertilizer in a Wheat-Barley-Maize Cropping Sequence
摘要
Conventional fertilizer efficiency is generally low, while global fertilizer resources, particularly phosphate reserves, are rapidly being depleted. Rice husk (RH) is an abundant, silicon-rich agricultural by-product with significant potential as a sustainable fertilizer precursor. In this study, a bio-based composite fertilizer (RH-NPK) enriched with nitrogen, phosphorus, potassium, and silicon was developed through alkaline hydrolysis of rice husk, subsequent acidification with phosphoric acid, and nitrogen enrichment using ammonium nitrate.
MethodsA greenhouse experiment was conducted to evaluate the primary and residual effects of RH-NPK in comparison with a conventional 15–15-15 fertilizer. Wheat was grown as the first crop, followed by barley and maize cultivated sequentially in the same soil without additional fertilizer input.
ResultsThe chemical and mineralogical properties of RH-NPK were characterized by FTIR and XRD analyses, which confirmed the presence of silicate, phosphate, and nitrate functional groups and a mixture of amorphous and crystalline mineral phases. The fertilizer contained 9.82% N, 7.66% P, 13.6% K and 2.94% Si, with a near-neutral pH (6.15). RH-NPK produced plant dry weights comparable to or higher than those obtained with 15–15-15 in wheat, even at a 25% reduced application rate. The residual effect was pronounced in maize, where biomass exceeded the conventional fertilizer. Moreover, RH-NPK significantly increased plant nitrogen, phosphorus, potassium, and silicon concentrations, especially in the second and third crops.
ConclusionThe results demonstrate that RH-NPK is an effective Si-enriched bio-based fertilizer capable of improving nutrient use efficiency and sustaining crop productivity while reducing reliance on conventional mineral fertilizers.