Fishwaste compost effects on rhododendron growth and nitrogen leaching and transformation

• Published in: Journal of environmental quality 1997-05, Vol.26 (3), p.733-739
• Main Authors: Kuo, S. (Washington State Univ. Res. and Ext. Center, Puyallup, WA.), Hummel, R.L, Jellum, E.J, Privett, D
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; AZOTE; Biological and medical sciences; CRECIMIENTO; CROISSANCE; DECHET DE POISSON; DESECHOS DEL PESCADO; Freshwater; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Leaching; LESSIVAGE DU SOL; LIXIVIACION; NITROGENO; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; RHODODENDRON; Rhododendron fortunei; Soil-plant relationships. Soil fertility. Fertilization. Amendments
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq1997.00472425002600030019x

Availability and leachability of N in fishwaste compost should be considered before it is used as growing media for nursery stock. This study examined N availability and leaching, and transformation of organic N constituents in fishwaste compost (HGF) as well as the effect of the compost on growth of rhododendron (Rhododendron fortunei 'Scintillation'). With an initially high inorganic N concentration, the compost enhanced growth of rhododendron during its first flush of growth. Because of extensive N leaching, this beneficial effect was short-lived. Periodic additions of N fertilizer at 150 mg N kg-1 were required to improve growth of rhododendron. Approximately 45% of inorganic N present initially in the HGF was leached regardless of the proportions of HGF in the mixtures. With N uptake by the plants representing a small fraction of inorganic N added, the inorganic N loss not accounted for probably was lost by denitrification and/or ammonia volatilization. Most N fertilizer applied as NH4NO3 to 100% bark was also leached. Concentrations of labile amino acids changed significantly in 4 mo, from 53.6% to 5% of total organic N in the HGF. Similar reduction also occurred for amino sugars. Even with such a magnitude of change in the two labile N fractions, there was no marked increase in inorganic N in the leachate 2 wk after transplanting and in growth of rhododendron. A large proportion of amino acids and amino sugars present in the compost initially were probably transformed to a more stabilized organic N form