What a change in the weather we’ve experienced in the last couple of weeks! Although you can still find snow piles in the snow belt, we’ve quickly jumped into spring with warm and relatively dry weather.
The higher angle of the sun, longer and warmer days and drying winds have all combined to rapidly remove excess moisture from the soil.
While planting and widespread fieldwork is still several weeks away, I was able to see distinctive knife marks from anhydrous applicators in drier fields throughout the region.
Nutrient management
When it comes to nutrient management, I’ve heard all sorts of old wives’ tales about nutrient sources and application timing. One that I often hear repeated is that you need to put down phosphorous and potassium this year for next year’s crop. While this may be true if using an organic fertilizer source like compost or manure, synthetic fertilizers are “plant available” almost immediately. MAP, DAP and potash are water soluble and can be taken up by plants in fields once dissolved — with proper soil pH and fertility levels. Plants do not care when or where the nutrients come from, as long as they are available to support crop growth.
There are some circumstances that can influence how much of a nutrient is available to plants. In particular, soil pH can drastically influence the availability of phosphorous and other nutrients. Soils with a pH below 6.0 can create an environment where phosphorus binds to aluminum and iron, which then limits availability to plant roots. Maintaining soil pH between 6.0 and 7.0 maximizes the availability to plants to promote growth.
With acidic subsoils in eastern Ohio, lime is often required to raise or maintain soil pH. However, overapplication of lime causing the pH to rise above 7.5 can cause phosphorous to bind with calcium, which also decreases its availability to plants.
Release of nutrients
The old idea that you must put down fertilizer a year in advance may be referring to the fact that manure and similar organic sources both require a process called mineralization, a process aided by soil microbes, to release all the nutrients into the soil.
All of the nutrients found in your manure will eventually be available in the soil, but bedding type, time of year and temperature can all dictate how fast it will be released. On average, approximately 70% of phosphorous and potassium in manure will be available in the first year of application, with the rest becoming available over the next few years.
Nitrogen availability is a little more complex to determine. Generally, one third of the organic nitrogen will be available in the year of application with the rest becoming available in following years. Obtaining a manure analysis and referring to OSU Extension’s Ohio Livestock Manure Management Guide (Bulletin 604) will help you better incorporate manure into your nutrient management plan.
Soil test
We can’t talk about nutrient management without emphasizing the importance of soil testing. With tight crop margins, a soil test could save you hundreds or thousands of dollars in nutrient inputs. It is recommended to soil test fields every 3 to 4 years to monitor nutrients and soil pH.
If you need assistance interpreting a soil test or developing nutrient recommendations, contact your local extension office. Better yet, call and ask for a farm visit. We’re all suffering from cabin fever and would love an excuse to get out of the office.
