The high-nitrogen fertilizer labeled 46-0-0 is a powerful tool for lawn care, offering a highly concentrated source of nitrogen that promotes rapid growth and deep color. This product is a form of urea, which provides the highest percentage of nitrogen found in any common granular fertilizer. Used correctly, it is an excellent way to address nitrogen deficiencies and achieve a deep green turf. However, its extreme concentration demands careful and precise application to prevent damage.
Decoding 46-0-0 and Nitrogen’s Function
The numbers on any fertilizer bag represent the NPK ratio, indicating the percentage by weight of Nitrogen (N), Phosphate (P₂O₅), and Potash (K₂O). In the case of 46-0-0, the product is 46% nitrogen, with zero percent phosphorus or potassium. This formulation is urea, a synthetic organic compound and the most concentrated solid nitrogen fertilizer available for turfgrass.
Nitrogen is the nutrient turfgrass requires in the greatest quantity, acting as a primary component of chlorophyll, amino acids, and proteins. Chlorophyll is the pigment responsible for the grass’s green color and its ability to convert sunlight into energy through photosynthesis. A high-nitrogen source like urea promotes the rapid vegetative growth that results in a dense, lush lawn with vibrant green foliage.
When applied to the lawn, urea is highly water-soluble and quickly enters the soil solution. It must be converted to ammonium and then nitrate before the grass can absorb it. This quick availability makes it highly effective for correcting nitrogen deficiencies and providing a fast boost to the turf. For this reason, 46-0-0 is often referred to as a “quick-release” nitrogen source.
Application: How to Use High-Nitrogen Fertilizer Safely
The intense concentration of 46-0-0 makes it highly effective but also carries a significant risk of chemical burn, known as “fertilizer burn,” if applied improperly. To avoid this scorching, application rates must be calculated based on the actual nitrogen content, not just the product weight. A general maximum application target is 1 pound of actual nitrogen per 1,000 square feet of turf.
To achieve this target, you would spread approximately 2.17 pounds of the 46-0-0 product per 1,000 square feet. For most homeowners, a safer, lighter feeding rate of 0.5 pounds of nitrogen (about 1 pound of product per 1,000 square feet) is recommended to minimize risk. Using a calibrated broadcast or rotary spreader is necessary to ensure the granules are distributed evenly across the lawn, preventing concentrated patches that cause burn marks.
The most important safety step is to water the lawn immediately after spreading the fertilizer. This action dissolves the urea granules, washing the concentrated nitrogen off the grass blades and into the soil where it can be utilized by the roots. Failure to water in the product promptly can lead to ammonia volatilization, which is the loss of nitrogen as a gas, reducing its effectiveness and increasing the likelihood of foliar burn.
When to Use 46-0-0 vs. Balanced Blends
The decision to use a single-nutrient fertilizer like 46-0-0 should be informed by a soil test, which provides a detailed analysis of existing nutrient levels. Since 46-0-0 contains no phosphorus or potassium, it is best utilized only when a soil test confirms that these other two macronutrients are already present in sufficient amounts. Applying this product when P and K are low will fail to provide the comprehensive nutritional support your turf needs for overall health.
This concentrated nitrogen source is most appropriate when the primary goal is a rapid green-up or to quickly correct a clear nitrogen deficiency in established turf. It acts as a targeted supplement, providing a quick flush of growth during the active growing seasons of spring and fall. Avoid applying any high-nitrogen fertilizer during periods of extreme heat or drought stress, as this can severely damage the struggling grass.
Conversely, a balanced or complete fertilizer, such as a 10-10-10 or a formulation with a ratio like 20-5-10, is better for general maintenance or for new lawns. New turf requires phosphorus to support the development of a strong, deep root system, which 46-0-0 cannot provide. While 46-0-0 is highly effective for a specific nitrogen boost, a more balanced blend is needed for comprehensive nutritional support across the entire growing season.