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Initial substrate moisture content and storage temperature affects chemical properties of bagged substrates containing controlled release fertilizer at two different temperatures
- KA YEON JEONG, JAMES E. ALTLAND
- Hortscience 2017 v.52 no.10 pp. 1429-1434
- Sphagnum, bags, bark, electrical conductivity, microbial communities, pH, peat, perlite, potting mix, slow-release fertilizers, storage temperature, storage time, water content
- Bagged potting mixes can be stored for weeks or months before being used by consumers. Some bagged potting mixes are amended with controlled release fertilizers (CRF). The objective of this research was to observe how initial substrate moisture content and storage temperature affect the chemical properties of bagged potting mix with CRF incorporated and stored for up to 180 days. A substrate composed of 60 sphagnum peat : 30 bark : 10 perlite (by vol.) was either not amended with fertilizer (control), or amended with 0.59 kg m-3 N of a controlled release fertilizer (Osmocote 18N-1.3P-5K) that was either ground (CRF-G) or whole prills (CRF-P). Substrates had initial moisture contents (IMC) of 25%, 45%, or 65% and were stored at temperatures of either 20 or 40 °C. Initial moisture content and storage temperature affected pH, EC, and nutrient release. Substrate pH increased with increasing IMC due to greater lime reactivity. Approximately 25% of N from CRF-G treatments was immobilized between 2 and 14 days of storage. Low moisture content of bags, due to low IMC or storage at 40° C, reduced the rate of N release from CRF-P treatments. Substrate P was rapidly immobilized by microbial communities.