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ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Publications at this Location » Publication #342383
Title: Initial substrate moisture content and storage temperature affects chemical properties of bagged substrates containing controlled release fertilizer at two different temperatures

Author
item Altland, James
item JEONG, KA - The Ohio State University

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2017
Publication Date: 11/8/2017
Publication URL: http://handle.nal.usda.gov/10113/5883117
Citation: Altland, J.E., Jeong, K.Y. 2017. Initial substrate moisture content and storage temperature affects chemical properties of bagged substrates containing controlled release fertilizer at two different temperatures. HortScience. 52(10):1429-1434. doi:10.21273/HORTSCI12216-17.

Interpretive Summary: Bagged potting mixes can be sold with controlled release fertilizers premixed into the substrate. Controlled release fertilizers are coated with a resin or plastic, and designed to release nutrients slowly over time to provide nutrients for plants as they grow. When controlled release fertilizers are premixed into bagged potting mixes, nutrients might release while the potting mix is stored in the bag. The objective of this research was to determine how moisture content of the potting mix and storage temperature affect nutrient release from the fertilizer into the substrate while being stored in the bag. Substrate pH increased with increasing moisture content due to greater lime reactivity. Approximately 25% of N was immobilized between 2 and 14 days of storage. Low moisture content reduced the rate of N release from the controlled release fertilizer. Phosphorus was rapidly immobilized by microbial activity in the bagged substrate. Moisture content had more direct effect on nutrient release from the controlled release fertilizer than temperature.

Technical Abstract: 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. Moisture content had more direct effect on nutrient release from CRF than temperature, as well as lime dissolution and pH.