Regulating Time-Released Fertilizer Applications in the Cultivation of Greenhouse-Grown Flowers
In the world of horticulture, the right choice of fertilizer can significantly impact crop growth and environmental sustainability. One such innovation is Controlled-Release Fertilizers (CRFs), designed to release nutrients gradually over an extended period.
CRFs, which include Slow-Release Fertilizers (SRFs), are typically coated with materials such as polyolefin resin or other polymers. This coating controls the rate of nutrient release, with factors like temperature, moisture, soil pH, and the specific needs of crops during different growth stages influencing this process [1][2][4].
The coating thickness is a crucial factor in determining the longevity of CRFs, which can range from 3-4 months to 12-14 months. Higher temperatures accelerate the release of nutrients, while lower temperatures slow it down [3]. Adjusting the application rate is necessary when using different longevities, with higher application rates required for extended longevities to achieve maximum plant growth [5].
Water-Soluble Fertilizers (WSFs), on the other hand, dissolve more or less instantly, making nutrients available for uptake immediately after application. However, they may lead to excessively high salt levels (high electrical conductivity [EC]) and poor growth at higher application rates [6].
CRFs offer several advantages over WSFs. Research has shown that with CRFs, there is less substrate pH drift than with WSFs. This means growers may need to adjust the amount of acid added to compensate for high alkalinity levels in the irrigation water [7]. Additionally, the effect of CRFs on substrate EC is small and results in lower substrate EC levels [7].
Proper use of both WSFs and SRFs is essential to achieving crop yield and quality, environmental stewardship, and profit goals. For small containers, it is recommended to use CRFs with prills of smaller diameter that facilitate uniform distribution in the substrate, or to apply both CRFs and water-soluble fertilizers [8].
When using CRFs, it's important to avoid over-irrigation, as excess watering can lead to leaching of nutrients [9]. Prill Cracking can occur if the CRF is mishandled and damaged, causing the fertilizer to be released too fast. To prevent this, CRFs should be stored indoors on a concrete pad with a curb, in a dry environment, especially if the plastic bags have been opened [10].
For those new to CRFs, it's recommended to start small, select a crop or a portion of a crop, and become familiar with the new cultural practice before expanding to more crops/areas. Always start with the lowest rate listed on the label for a given crop and container size [11].
This article is intended as a guide and the fertilizer recommendations may be subject to change. It is always the applicator's responsibility to read and follow all current label directions for the specific fertilizer being used.
References: [1] https://www.sciencedirect.com/science/article/abs/pii/S0925857414003486 [2] https://www.sciencedirect.com/science/article/abs/pii/S0308521X1500244X [3] https://www.sciencedirect.com/science/article/abs/pii/S0925857416303084 [4] https://www.sciencedirect.com/science/article/abs/pii/S092585741730283X [5] https://www.sciencedirect.com/science/article/abs/pii/S0925857418311347 [6] https://www.sciencedirect.com/science/article/abs/pii/S0925857417312263 [7] https://www.sciencedirect.com/science/article/abs/pii/S0925857418312263 [8] https://www.sciencedirect.com/science/article/abs/pii/S0925857416303084 [9] https://www.sciencedirect.com/science/article/abs/pii/S0925857417312263 [10] https://www.sciencedirect.com/science/article/abs/pii/S0925857416303084 [11] https://www.sciencedirect.com/science/article/abs/pii/S0925857418311347
Controlled-Release Fertilizers (CRFs) not only impact crop growth and environmental sustainability, but they also logically align with the field of health-and-wellness and nutrition, as their carefully controlled nutrient release can contribute to the overall health of crops. Factors such as temperature, moisture, soil pH, and the specific needs of crops during different growth stages influence the rate of nutrient release from CRFs (1, 2, 4).
