Should I Fertilize My Beef Pastures?

In part 17 of our “What’s Your Beef?” series on raising cattle on small farms, we discuss grazing conditions for beef cattle and other classes of grazing livestock. 

My motivation in writing this article is due to the many atrocious grazing conditions that I find beef cattle and other classes of livestock grazing in throughout the pasture season. Much of what we will be discussing in this article can be applicable to almost any class of grazing animals, such as milking dairy cattle, dry dairy cows, dairy heifers, beef cow calf operations, stocker cattle, horses, sheep, and goats.  

Lush growing grass like this provides almost all of the nutrients that animals need. Rich Taber / CCE Chenango

What happens so often is that animals are let loose to graze in the springtime on already overgrazed, nutrient depleted pastures from which they derive few or no nutrients for growth and production, and there they remain for the season. Just because animals are gnawing away on bare soil doesn’t mean that they are getting many nutrients to add to their dry matter intake. If they’re being fed supplemental hay in one form or another, not much harm will occur but this doesn’t occur all that much. This is what has brought us to the era of management intensive grazing which can also go by a plethora of terms. We need to have growing grass of at least 8-12 inches in height available to the animals for which they can graze for several days and then be moved into another paddock. It certainly is not rocket science by any stretch; you allow the grass to grow to a certain level, you let the animals graze it down to a certain level, and then you move them into another paddock. You then rest the previously grazed paddocks for a certain number of days, depending on rainfall levels, and keep doing this right up until the end of the grazing season in late October.   

However, all of this grazing by animals sooner or later removes a certain amount of nutrients from the soil which will need replacing. I have also heard many times how excited some people get when they see animals depositing manure on the pastures, thinking that this is “free fertilizer”. To a point it is, but if the animals are only recycling whatever there is there to begin with; there is not much of a net gain in the soil’s nutrient status. Certainly, manure has some wonderful properties of a biological nature, but it only recycles what’s there to begin with.     

This brings us to the theme of this article; do we need to fertilize pastures to make up for nutrients that are removed? In a nutshell, yes. However, the devil is in the details. We will focus on already existing, established pastures. We can add nutrients in a variety of forms, manure, compost, granular fertilizer, and of course the ever important lime.   

Compare this to what’s happening in a hayfield. Almost 100% of the plant biomass is removed when removing hay from a hayfield, upwards of 5 tons of forage dry matter per acre per year when all the cuttings are accounted for. In a pasture situation, upwards of 70% or more of the plant matter is recycled so the nutrient removal is much less than in a hayfield. This is good insofar as we don’t need to add nearly as many nutrients on a pasture annually as we do a hayfield. Either in a pasture situation, or a hayfield, if nutrients are never added to replace those lost, yields will suffer and animal performance will do so as well.

Grazing animals on a pasture like this is a form of animal neglect. Rich Taber / CCE Chenango

So where do we begin in figuring out how much fertilizer or manure to add to a pasture? 

As always whenever it comes to managing a crop field, we need to take a soil test. I use and recommend the Dairy One Lab in Ithaca, NY to get soils analyzed. When you submit your samples, there will be a place on the submission form in which you stipulate that you will be topdressing a pasture. When you get your results back, they will tell you how much fertilizer you need to spread, and how much if any lime to add, to counteract acidity. 

An excellent source of information is available from Cornell University Cooperative Extension, the Agronomy Fact Sheet 17 on “Nutrient Management for Pastures” which can be found online. This information sheet will give you a good idea of how many nutrients that you need to add to your pastures, but again, the best method is to have an accurate soil test.  Oftentimes I get calls in my office, and a landowner tells me that he or she tested their soil for pH, and now want to know how much lime and fertilizer to add. Unfortunately, knowing the acid level is not enough, as there is another term we need to contend with, and that is “buffer pH”. Buffer pH refers to your soil’s capacity to react to liming elements and will vary drastically with the texture of your soil, meaning the relative amounts of sand, silt, clay, and organic matter that your soil holds. This is why we need to know the name of our soil, which can be determined from the online Web Soil Survey.  

When to add fertilizer elements to your pastures is another management point to consider. Rather than adding elements in the spring, when the grass is already growing gangbusters due to the spring flush, waiting till mid-summer and the growth rates of the grass has slowed down a bit, and after a few paddock rotations can give a more manageable boost to the plants.       

In summary, from Fact Sheet #17, well managed pastures offer many nutrient management benefits. However, there are still steps that should be taken to improve pasture nutrient management. Remember, soil sampling should be the basis for fertility management in pastures. Sound fertility management, along with good grazing management, will consistently result in healthy, productive pastures. Please don’t make your animals graze barren, nutrient poor pastures!