Clover, a member of the Trifolium genus, is a popular choice for forage, cover cropping, and as a resilient lawn alternative. Unlike typical turf grasses, clover fertilizer does not emphasize nitrogen, the primary nutrient in most lawn care products. Understanding these distinct nutritional needs is the first step in providing the proper soil amendments for a healthy and productive clover stand.
Understanding Clover’s Nutritional Demands
Clover belongs to the legume family and forms a symbiotic relationship with Rhizobia bacteria. These bacteria colonize root nodules and perform nitrogen fixation, converting atmospheric nitrogen gas into a usable form. This process effectively eliminates the need for large applications of nitrogen fertilizer.
Clover’s fertilizer requirements shift to other macronutrients, particularly phosphorus (P) and potassium (K). Clover is a heavy feeder of these minerals, which are essential for strong root development, energy transfer, and overall plant health. Clover thrives in a slightly acidic to neutral pH range, ideally between 6.0 and 7.0. If the soil is too acidic, the Rhizobia bacteria become less effective, hindering nitrogen fixation and nutrient uptake.
The Importance of Soil Testing
Before applying any fertilizer, a comprehensive soil test is a necessary diagnostic step. This analysis provides a precise snapshot of the soil’s current condition, including pH level and concentrations of phosphorus, potassium, and various micronutrients. Guessing nutrient requirements without this data often leads to wasted product or potential harm to the clover stand.
The soil test report specifies the exact amount of lime needed to correct any pH imbalance, which is the most important amendment for clover management. The report also includes recommendations for P and K, usually expressed in pounds per acre or per thousand square feet. These specific numbers allow for a targeted and efficient fertilization strategy. Most local agricultural extension offices or private labs offer testing services.
Choosing Specific Fertilizer Types
Since clover requires little supplemental nitrogen, the most appropriate granular fertilizers have a low first number in the N-P-K ratio. Common recommendations include blends such as 0-20-20 or 5-10-30, focusing on phosphorus and potassium. The 0-20-20 blend is often the preferred choice for established plots, providing a maintenance dose of the two most needed nutrients.
NPK Ratios and Establishment
For new clover stands, a small amount of nitrogen, such as that found in a 5-20-20 blend, may support seedlings during the initial establishment phase before root nodules are fully active.
Lime and Micronutrients
The most significant soil amendment is usually lime, such as calcitic or dolomitic lime, which raises the soil pH into the optimal range. Dolomitic lime also provides magnesium, an element required for chlorophyll production. Certain micronutrients, particularly boron and sulfur, are also important. Boron is involved in seed production and cell wall formation, while sulfur is closely linked to the nitrogen fixation process. If a soil test indicates a deficiency, these elements can be applied separately, though boron must be applied carefully as excessive amounts can be toxic.
Application Rates and Timing
The timing of fertilizer application is important for maximizing effectiveness. For established clover stands, the best time to apply granular fertilizer is in the late fall or very early spring, just before the active growth cycle begins. This early application allows nutrients to be absorbed when plant demand is increasing and moisture is typically high.
A secondary application may be beneficial in the late summer or early fall to boost reserves before winter dormancy. Application rates must strictly adhere to soil test recommendations. A general maintenance application of a blend like 0-20-20 is often around 200 to 300 pounds per acre. Lime application is best done in the fall, as it can take several months to fully alter the soil pH.