Does it Pay to Fertilize Your Pasture

By Shannon Sand

Given the increased moisture that parts of Nebraska have experienced, some producers may be asking themselves, "Should I fertilize my pasture?".

Before answering this pasture fertility question, some things to consider:

• What type of forage do I have?
• What sort of increase in forage can I expect if I fertilize?
• How much fertilizer will I need?
• How much will it cost?

Then, consider some common reasons for fertilizing pasture:

• Increased nutrient density of the forage.
• Increased production.
• To support more grazing livestock.

The last couple of years have seen quite a high level of volatility in the fertilizer market with prices dropping about 10% just the past month, while prairie/grass hays have maintained values around $200 per ton.

According to university research on sub-irrigated grazed hay meadows, a suggested fertilizer application of 70 lbs. of N, 25 lbs. of P and 20 lbs. of S per acre resulted in an average grass increase of about three quarters of a ton per acre. So, a $150 potential hay value increase only requires $56 per acre of fertilizer investment plus application costs. Thus, this would be a 3:1 ROI ratio (return on investment).

Nebraska grazing research shows one pound of additional calf or yearling gain for every pound of nitrogen fertilizer applied. However, this fertilization rule-of-thumb assumes that the amount applied is within general recommendations, which are based on the potential amount of extra grass growth expected. This is affected mostly by moisture.

Some things to look at before deciding:

• Cost of fertilizer for your pasture.
• Pasture production and how much it can support.
• Expected cattle prices.
• Your own historical margins.

Knowing these things can help producers to make an informed decision on whether fertilizing is worth it. In some parts of the state where they have received a fair amount of moisture and given the current futures market and basis, as well as the other factors previously mentioned, it might be a very effective strategy to invest in and help producers capture some additional gains. For others, it just may not be feasible for their current situation.

Fertilizing Brome Pastures

By Todd Whitney

Now is the time to fertilize cool-season grasses such as bromegrass for optimum production. Generally, recommended fertilizer rates for hayed or rotationally grazed brome or cool-season pastures is 60 to 70 pounds of nitrogen per acre. For conventionally grazed brome, the nitrogen rate is 50 to 60 pounds of nitrogen per acre based on grazing efficiency likely being lower.

However, if drier weather is a limiting factor for brome production, then nitrogen fertilizer rates might need adjusted downward. For full production, bromegrass requires at least 16 inches of moisture per acre between winter soil stored and growing season rainfall and/or irrigation.

In UNL bromegrass fertility studies (without moisture stress), unfertilized check pastures yielded 1.35 tons of hay per acre, whereas 60 pounds per acre of nitrogen applications increased hay yields to 2.52 tons per acre. The other benefit of higher fertility was increased protein content being raised 4-6 percentage points in fertilized plots.

The bottom line is that economics will likely favor fertilizing brome if moisture is not limiting. Ideally, fertilizer rates will be based on field soil samples lab analyzed last July. Although water and nitrogen are nutrients needed in the highest amounts by brome, other nutrients like phosphorous, potassium and sulfur availability might also need balanced, and brome yields are directly linked to the first limiting nutrient level for total production.

For example, if accumulated moisture soil profiles and projected rainfall totals are only half of the 16 inches per acre minimum, then either supplemental irrigation will be needed and/or recommended nitrogen fertilizer rates will need reduced to 30 to 35 lbs. of nitrogen per acre.

More information is available on our UNL Extension website, such as NebGuide G1977, “Fertilizing Grass Pastures and Hayland”, and on CropWatch.

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