From year to year, the cost of fertilizer can fluctuate, and occasionally, a certain analysis or brand of fertilizer may not even be available. Why all the changes? When you consider the raw materials that make up a typical fertilizer blend, where these materials originate and how they are processed, it becomes quite apparent. The cost and supply of fertilizers designed for greenhouse and nursery use are intertwined with a number of variables, including geography, global markets, politics, transportation logistics and energy costs.
If you look at the guaranteed analysis “derived from” statement on a bag of blended fertilizer, you will see that fertilizers (especially complete blends containing N-P-K, Ca, Mg, S and micronutrients) can easily contain a dozen or more components (see photo above). Even if your fertilizer source is a blender, there may be other components in the product that are not listed on the label. The complexity of ingredients in fertilizer blends is particularly apparent when you look at a blended granular product (Figure 1, page 36).
The raw materials that go into fertilizer are also incorporated into a number of other products unrelated to ornamental horticulture. Unfortunately, the supply and demand issues related to these other products sometimes conflict with the needs of our industry. For example, a few years ago, fertilizer raw material prices skyrocketed due to a number of converging factors:
The combination of these factors resulted in greatly increased demand for a smaller supply of raw materials. When you consider the fact that these same raw materials are used in other industries, it’s no wonder that their prices went through the roof. But what exactly are these raw materials and where do they come from?
Most fertilizer blends consist largely of nitrogen (N), phosphorus (P) and potassium (K). These three elements make up the largest bulk and cost of most blends. Nitrogen, phosphorous and potassium (N-P-K) are also present in plant tissue on a percentage scale on a dry weight basis. The Fertilizer Institute has an abundance of online resources available that detail the origin and use of fertilizer components. Here are a few facts from their website.
Nitrogen (N). Available worldwide, nitrogen gas is a major component of the atmosphere (78 percent). Based on this fact, one would expect that nitrogen itself would be almost free for plants, much like the hydrogen, oxygen and carbon that plants take directly from the air or water. The process of manufacturing nitrogen-based fertilizer combines naturally occurring nitrogen from the atmosphere with natural gas to form anhydrous ammonia. This substance can then be applied directly to crops as a nitrogen fertilizer or used to make other fertilizer products including: urea and ammonium nitrate. While it may sound simple, this process requires a significant amount of energy that not everyone can produce or afford.
Phosphorus (P). Phosphorous is found in slightly less than 1 percent of the earth’s crust. Phosphorous-based fertilizer comes from the phosphates originating in rock deposits as fossilized remains of ancient marine life or from volcanic activity. Mined rock phosphate from these natural geological deposits is combined with other chemicals to produce triple super-phosphate or mono-ammonium phosphate (MAP). China, the United States, India, Canada and Brazil have the greatest phosphorous resources. Although many countries have found reserves of phosphate rock, the energy-intensive extraction and processing steps make it feasible for only a few countries to supply phosphate-based fertilizer.
Potassium (K). Potassium is the seventh most common element in the earth’s crust comprising approximately 2.5 percent. Potassium-based fertilizer is derived from naturally-occurring ore deposits that were formed when seas and oceans evaporated. Mined potassium or potash is unearthed, purified and granulated with other nutrients. Typical potassium fertilizer sources are potassium nitrate, potassium sulfate, potassium chloride or mono-potassium phosphate.Significant potassium reserves exist around the world, but most production is done in Canada, Germany, Russia, Belarus and Israel.
Secondary elements. Calcium (Ca) makes up 3.6 percent of the earth’s crust, magnesium (Mg) makes up 2.1 percent and sulfur (S) is less than 1 percent. Calcium sources include limestone and gypsum rock, although lime and gypsum may be derived from industrial processes. Fortunately for greenhouse and nursery growers, some irrigation waters can supply significant sources of calcium, magnesium and/or sulfate. Sphagnum peat moss can mineralize in a container and supply a significant supply of sulfur to ornamental crops.
Micronutrients. Plants require boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) in very small quantities on a parts per million (ppm) scale in plant tissue on a dry weight basis. These nutrients are derived from mineral ores whose presences in the earth’s crust range from common to very rare. Copper, iron, manganese and zinc fertilizers are usually available in sulfated form or chelated to make them more available to plants over a wider range of root zone pH levels. Boron and molybdenum are available in a couple of forms of borates or molybdates.
The majority of fertilizer raw materials are primarily used in field production agriculture worldwide. The process of making these raw materials useful as fertilizers in greenhouse and nursery production costs money. These materials may have to be purified to remove components that could be injurious to ornamental container production or modified to fit production systems (e.g. be more soluble). They must then be transported to the blender plant, mixed together, packaged and shipped to the customer or distributor. Fertilizers are heavy, and as a result, transportation can be a major expense. Availability of shipping containers and trucks also has an impact on the ability to ship raw materials and finished goods in a timely fashion.
When you consider all the components that go into blended fertilizers, the origin of these materials, their limited worldwide supply and alternative uses, it’s easy to see the inherent volatility of fertilizer pricing and availability. Although fertilizer is a fairly low percentage of a plant’s total direct production costs, fertilizer prices will likely continue to rise with mounting oil prices and increasing demand for fertilizers in the global market.
Although fertilizers may only represent less than 5 percent of the total direct cost of producing a plant, a growing operation’s annual fertilizer bill can add up to a significant sum. Since it’s clear that fertilizer prices are unlikely to decrease any time soon, what can growers do to reduce the potentially negative impact on their operations?
Switch to a lower-cost fertilizer. Upon first glance, switching to less expensive products may seem to be an easy choice. Yet, if these lower-grade fertilizers are made with poor-quality raw materials or offer inconsistent and unpredictable results, crop performance may suffer significantly.
Change formulations in order to use less fertilizer. Instead of only considering a fertilizer’s cost per bag, it’s better to compare the unit cost per crop when using different products. One strategy currently popular with growers is to choose products containing a higher percentage of nitrogen (N). Since water soluble fertilizers (WSF) are applied in concentration units of parts per million (ppm) of nitrogen, growers will need less product per gallon when they start with a formulation that contains a higher percentage of nitrogen.
However, other nutrients besides nitrogen are also important. It’s possible to equalize nitrogen, but switching formulations might easily lead to a shortfall of another nutrient. Before making a change, study product labels carefully.
Use less of your current fertilizer. Some growers are successfully choosing to use the same fertilizer product while cutting their rates and concentrations dramatically. Current fertilizer programs may be providing more than adequate nutrition, so any extra is being wasted or leached out of the root zone.
However, reducing fertilizer rates may limit some nutrients such as micronutrients. One possible compromise is to reduce N-P-K, but supplement with micronutrients. This can be a cost-effective way to maintain crop quality.
Consider controlled-release fertilizers (CRF). Some industry professionals have suggested migrating away from CRFs to WSFs as a way to save money. However, a simple cost analysis demonstrates otherwise. While CRFs certainly are more expensive per pound compared to WSFs, they work more efficiently, can be applied at lower doses per pot and can result in less leaching of nutrients. Controlled-release fertilizers can easily be incorporated into the growing media before planting so the fertilizer is in close proximity to the roots where it is needed. Nutrient release from CRF is temperature-based, as is plant growth, so its use can be tied to plant demand. Plus, CRFs that are fully coated are not subject to huge nutrient losses caused by leaching. CRFs feed continuously as crops are watered, so root zones have a more uniform nutritional supply.
CRF rates for greenhouse use should be conservative. CRFs are much easier to adapt for crop types as compared to WSF, and their rates can be increased for heavy feeders without having to zone plants nutritionally. Longer-term CRFs can provide valuable post-production feeding both in the garden center and at the consumer’s home, leading to better plant quality and customer satisfaction.
The best solution for dealing with fertilizer costs lies within the proper selection and use of the fertilizers you purchase. Fertilizer applications should provide the correct amounts and ratios of all essential nutrients at the right time to meet crop plant requirements. Any practice that doesn’t achieve this basic goal will result in lower plant quality and, most likely, reduced revenues. The key is balancing fertilizer use with plant needs, which involves regular program assessment and an emphasis on best management practices. After all, you can use the best fertilizer in the world, but if it’s not being used wisely or correctly, crop quality and your bottom line will suffer.