As we enter September, fall is quickly approaching. Now is a good time to start thinking about doing a soil test.
It is recommended to sample in the fall or spring, both before planting. If soil nutrient levels are low and crops and forages are planted without making necessary corrections, yield may decrease. Fields should be tested every three to four years, and it is best to stay consistent on the time frame of when samples are collected.
A standard soil test generally provides information on soil pH, phosphorus and potassium levels, along with recommendations for lime and fertilizer applications to achieve desired production goals.
In my experience working with producers, many focus on pH and lime application. Maintaining proper pH is important; nitrogen (N), phosphorus (P) and potassium (K) are also important. Nutrient-deficient pastures and fields can lead to reduced forage quality, lower yields and increased weed pressure. Conversely, excessive soil nutrient levels may lead to livestock health concerns, plant health issues and nutrient runoff into surrounding waterways.
Soil pH measures how acidic or alkaline the soil is. This is important because it can affect the availability of nutrients the plant can uptake and utilize. Meaning that if soil pH is too high or too low then the plant cannot take up other minerals in the soil even if those nutrients are present. Typically, the pH level for optimum growth in forages is between 6.0-7.0, with the exception of legumes. Some legume species have different requirements.
Nitrogen plays a critical role in plant growth and development. It is a major component of proteins, enzymes and chlorophyll, which is essential for photosynthesis. Adequate nitrogen promotes vigorous plant growth, healthy leaf development and efficient uptake of water and nutrients.
Legumes have the ability to fix atmospheric nitrogen. They have a symbiotic relationship with Rhizobium bacteria found in root nodules. Legumes can convert the atmospheric N into a form that is usable by the plant. Those who have legumes in their forage stand may be able apply less nitrogen, depending on the legume inclusion rates.
Nitrogen is highly mobile in the soil and can be used up quickly. Some producers apply a small amount of N to pastures in March to allow for early grazing. Another time it can be applied is after first cutting to provide a boost in growth after the lush spring growth has occurred. It could also be applied in the early to late summer to increase production during the summer slump and can help carry forward the fall growing season.
Phosphorus is another vital macronutrient required for plant growth. It has a crucial role in energy transfer, photosynthesis, DNA and RNA synthesis, plant development, root growth and overall plant vigor. Phosphorus deficiency often results in slow or stunted plant growth.
Potassium is important to regulate growth and plant reproduction, and can assist in the plant’s availability have a higher tolerance for drought and pests. During the spring lush, there are higher levels of potassium in pastures. For this reason, avoid applying potassium to pasture fields during this time to help prevent the cause of grass tetany in livestock. This occurs when there is an overabundance of potassium and interferes with magnesium absorption, which causes an Mg deficiency. It is recommended to feed a high-mag mineral supplement during the spring lush.
Fall is an excellent time to apply phosphorus and potassium because these can help improve overall forage productivity for the following season. These nutrients can be applied in a single application or split-applied between spring and fall. Best application practices are based on soil test recommendations, plant needs and management goals.
Best practice when applying fertilizer is to record the following information within 24 hours: name of who applied the fertilizer, date, location and method of application, number of acres applied to, total amount of fertilizer applied, fertilizer analysis, soil conditions at time of application, weather conditions at time of application and surface conditions at time of application. Ohio law requires certified applicators to keep these records for three years.
In Ohio, those who apply fertilizer to more than 50 acres of agricultural production grown primarily for sale are required by the Ohio Department of Agriculture to hold a fertilizer applicator certificate.
