Nitrogen fertilizer boosts the vegetative growth of plants, lawns, and gardens. This nutrient is essential for producing chlorophyll, which plants use for photosynthesis, contributing to lush, green foliage and strong stem development. Understanding the different forms of nitrogen and where they are sold will help you make an informed purchasing decision.
Different Forms of Nitrogen Fertilizer
Nitrogen fertilizer is categorized into synthetic and organic sources, each having distinct release characteristics. Synthetic options are manufactured compounds designed to deliver nitrogen rapidly for a quick green-up response. Urea is a common synthetic choice, often containing around 46% nitrogen, making it concentrated and cost-effective.
Ammonium sulfate provides about 21% nitrogen and contains sulfur, which can help slightly lower soil pH. Ammonium nitrate is a highly soluble synthetic source, though its purchase may be subject to specific regulations due to its chemical properties. These synthetic forms are quick-release, meaning the nitrogen is immediately available to the plant, ideal for correcting deficiencies quickly.
Organic sources are derived from natural materials, such as blood meal, feather meal, or manure. These are slow-release because soil microbes must break down the organic molecules before the nitrogen becomes available. Organic options tend to have lower nutrient concentrations but improve long-term soil health. Coated synthetic products, like polymer-coated urea, also function as slow-release options, with release controlled by moisture and temperature.
Retail Channels and Purchasing Options
The availability of nitrogen fertilizer varies based on product type and scale of needs. For the average homeowner seeking common blends or smaller quantities, big box stores and home improvement centers are convenient sources, stocking standard nitrogen-rich lawn foods in granular and liquid forms.
Local garden centers and nurseries are excellent resources for specialty fertilizers, including organic and natural-based options. These retailers often employ knowledgeable staff who can provide specific advice tailored to regional soil and plant types.
For larger quantities and high-concentration products, agricultural supply stores, farm co-ops, and wholesale landscape suppliers are the primary options. Stores like Tractor Supply Co. often carry pure forms like urea and ammonium sulfate in 40- to 50-pound bags, which are more economical for large areas. Online retailers also offer a vast selection, providing convenience but requiring attention to shipping costs and regulatory restrictions.
Selecting the Right Concentration and Product
Choosing the right nitrogen fertilizer starts with understanding the three numbers displayed on the packaging, known as the NPK ratio. The first number represents the percentage of nitrogen (N) by weight in the bag. For example, a 50-pound bag of 20-5-10 fertilizer contains 20% nitrogen, meaning ten pounds of actual nitrogen is present.
Interpreting this number allows you to match the concentration to your plant’s specific needs. High-nitrogen formulas, such as 30-0-0 or 16-4-8, promote vigorous vegetative growth and are typically used for lawns or leafy vegetables. Conversely, a more balanced formula like 10-10-10 may be more suitable for general garden use or when focusing on flower or fruit production.
The decision between liquid and granular products depends on the desired absorption rate and application method. Granular fertilizers are spread onto the soil and offer a slower, more sustained release of nutrients. Liquid fertilizers, which are mixed with water, provide an immediate dose of nitrogen quickly absorbed through the roots or foliage. Liquid forms are advantageous for rapidly correcting a visible nitrogen deficiency, but require more frequent applications.
Concentration also plays a role in the true cost of the fertilizer. A bag of 46-0-0 urea may cost more than a bag of 10-10-10, but the cost per pound of actual nitrogen is significantly lower in the higher-concentration product. Calculating the nitrogen percentage helps determine the most economical option. High-concentration products require precise application rates to avoid potential plant damage from over-fertilization.
Safe Handling and Storage
Proper handling and storage of nitrogen fertilizer are necessary for safety and maintaining product quality. When handling fertilizer, wear gloves and avoid inhaling the dust. Always wash your hands thoroughly after use and refrain from smoking, eating, or drinking near the product to prevent accidental ingestion.
To maintain quality, proper storage is essential. Granular nitrogen fertilizers are highly susceptible to moisture, which can cause the material to cake or clump, making it impossible to spread evenly. Store all products in their original, clearly labeled containers in a dry, sealed condition to prevent moisture infiltration. The storage area should be cool, dry, and well-ventilated, out of direct sunlight, and ideally kept below 89.6°F (32°C).
For security, all fertilizer, especially high-concentration products, must be stored out of the reach of children and pets. The storage area should be locked to prevent unauthorized access. Additionally, store nitrogen fertilizer away from combustible materials, such as gasoline or oil, as some nitrogen compounds can act as oxidizing agents that accelerate combustion.