Take advantage of the dry fall

Many parts of Ohio have or will soon complete harvest. It has turned noticeably drier recently, with much of Ohio in the “abnormally dry” and “moderate drought” categories. 

The dry conditions are not ideal for forage or cover crops that have been planted but do provide an opportunity to take soil samples — assuming you can get a probe in the ground — and apply lime where needed. 

Were there fields you harvested this year that didn’t perform as well as expected and may suffer from nutrient deficiencies? What is your soil pH? Has it been a few years (more than three) since nutrient levels were measured? 

If you find yourself in the situation of needing to soil sample, take samples soon. 

Soil pH and lime

Why is lime such a critical component of crop production? According to the Ohio Agronomy Guide, correct soil pH is essential to maximize nutrient uptake and promote high crop yields. 

The target soil pH for most crops is between 6.2 and 6.8. At this range, nutrient uptake and plant growth are maximized. 

Soil pH measures the soil acidity or alkalinity, and the lime requirement is determined using the buffer pH, or lime test index, which measures soil acidity. The lower the buffer pH is below 6.8, the greater the lime requirement. 

The table on Page A11 shows the tons of ag lime needed to raise soil pH to the desired level.   

Lime and liming materials provide the following benefits: 

• Provides calcium and magnesium to the soil 
• Increases soil pH and nutrient availability 
• Reduces harmful concentrations of aluminum, magnesium and molybdenum 
• Promotes favorable microbial activity 

Materials advertised as liming products are labeled based on their Effective Neutralizing Power. The ENP considers the equivalence, purity, fineness, percentage of moisture (Ohio Agronomy Guide, 2017). 

The base for agricultural lime is an ENP of 2,000 pounds per ton. This is an important item to remember. Let’s assume a lime recommendation of four tons of lime per acre. If using agricultural lime with an ENP of 2,000, simply apply four tons per acre.

What if the ENP is less than 2,000 pounds per ton? Let’s assume the product you are going to use as lime has an ENP of 1,500 pounds per ton. If this is the case, you will need to apply more of the product. 

Following is the calculation: 4 tons per acre x (2,000 pounds per ton/1,500 pounds per ton) = 5.3 tons per acre. 

Should the material you choose have an ENP greater than 2,000, less material will be required to meet the laboratory recommendation. 

In addition to the ENP, the Ohio Agronomy Guide (2017) provides these additional considerations:

• Depth of tillage: Tri-State recommendations are based on an 8″ sample depth. 
• No-till: consider two samples: shallow (0″ – 4″) and deep (0″ – 8″). 
• Acidic subsoil: consider sampling separately. 
•  Forage crops: a minimum of two tons per acre is recommended if soil pH is 6.2 or less. 

Soil sampling

Now is an excellent time of year to collect soil samples. There are a variety of sampling techniques that can be used to take samples. 

The pros and cons of three of these methods are highlighted in the table on page A10. 

Summary

Soil sampling to determine lime and fertilizer requirements has always been the foundation of crop production. I encourage you to talk with your agronomist or extension professional about soil sampling, submitting samples and interpreting recommendations. Rising input costs make soil sampling an even more important investment.