How to Know What Fertilizer to Use on Your Farm

By Emily Folk

Finding the right fertilizer might require you to think outside the bag. With all the products available today, it can prove frustrating to find the best for your budget and operation, but with some testing and research, you can make an informed decision moving forward. It starts with an overview of your options.

We'll detail three commercial fertilizers and two organic alternatives for your fields. Whether you choose diammonium phosphate or manure, you have solutions.

Diammonium Phosphate

Among common agricultural fertilizers, diammonium phosphate provides a substantial amount of phosphorous at around 46 percent. If you perform a test on your soil and find it lacking in phosphorous, you should consider this fertilizer to balance your levels. It has more use than its high phosphorous content, however.

Diammonium phosphate also has an ammonia component which delivers about 18 percent nitrogen. Often applied in liquid form because of its high water solubility, this fertilizer is a good choice for a farmer who needs to make considerable adjustments to the health of their fields. If you find that farmer is you, look into it.

Ammonium Nitrate

If your operation involves specialty crops like citrus and pasture lands, you should consider using ammonium nitrate as a fertilizer. It's an effective source of nutrients for nitrogen-deficient fields, with a typical product in this category providing 33 percent nitrogen. Consult your test results to see if purchase is necessary.

To balance the soil levels of your field, stock up on ammonium nitrate or a similar fertilizer with a high nitrogen content. Urea fertilizers deliver some of the highest amounts of nitrogen, so browse your options to decide on the ideal solution for your property. You'll find something which perfectly suits your requirements.

Potassium Nitrate

You might recognize this fertilizer by its alternative designation, "nitrate of potash." It has a nitrate component similar to the previous commercial options but excels in providing potassium to crops in need of the nutrient. With a standard potassium nitrate fertilizer, you can usually expect it to offer around 44 percent potassium.

Most professionals in agriculture who employ potassium nitrate use it for their vegetable crops. If you raise leafy green vegetables, tomatoes, celery or potatoes, this fertilizer will work well in maintaining your operation. Even certain kinds of fruit crops benefit from potassium nitrate, so it has a broad spectrum of applications.


Over the course of a year, you can accumulate a sizable pile of compost to use around your farm. It's a cost-saving measure that'll cut down on your waste, making what some have termed "black gold" from your discarded organic materials. But it's a little more complicated than that, and there are some points to remember.

After you're confident the compost has completely broken down and is ready for use, layer it on an area you'd like to fertilize. It improves the general properties of the soil, ideal for a slow nutrient release and water retention. If you'd benefit from these properties and need something you can make yourself, compost is best.


Evidence of fertilizer use dates back 8,000 years, reflecting the importance of the practice. The ancestral farmers who once worked the land used manure and its qualities make it an excellent option for today's professionals. There's a reason for its longevity, and with the correct application, that reason's easy to understand.

More than repurposing the waste of cows, chickens, goats and other animals, a farmer who uses manure enjoys additional advantages. After it's aged six months or so, manure will reduce the risk of erosion and decrease both ammonium and mineral losses. You also won't have to worry about a toxic buildup of chemicals.

Making Your Choice

So how do you know what fertilizer to use on your farm? You should test the soil and inspect its levels, and from the information you glean, you can make an educated decision. Maybe you'd benefit from a commercial fertilizer designed to address imbalances, or you might prefer a natural alternative.

It comes down to a few different factors like your budget, the nature of the problem and what you already have available. You should review some of the options in this article and see if any of them have the potential to help, and if you find one that might work, do a little more research. It certainly can't hurt.

You have a unique farm, and it requires a unique approach. We can't tell you what form it'll take, but seeking out an answer is the right first step.

About the author: Emily is a sustainability writer and avid gardener. You can read more of her work on her site, Conservation Folks, where she writes about helping tomorrow’s planet today.