The D8 dozer was cranked up and I sat in my truck watching it pluck cedar trees like they were annoying weeds. I hate to admit it, but I am a bit of a “tree hugger.” Not the kind you might be thinking of, but living in farm country in Iowa, there are places where trees are a premium, and in particular the red cedars on this farm’s deer habitat had held many a deer during the harsh winter weather. But the cedars had grown numerous and I determined that there was plenty of thermal and escape cover, and over the years I’d developed a bigger need for food plot acres.
So I watched the dozer clear a healthy sized 4-acre field. As the operator pulled out of the gate with a hefty check in his pocket, he waved and said, “Good luck.” I’m not sure I needed luck, but I was definitely in for some work and a bit more check writing. The ground had been feral for years — taken over by the nutrient sucking red cedars — and was in need of some serious TLC. I had visions of thick plantings of clover and brassica, with quality deer habitat all over. But the reality was that there was a lot of work to be done before those dreams could be realized. First, I needed to build my soil.
For food-plotters, the success of deer habitat is largely dependent on the soil below. The healthier the soil and the more you do to properly manage it, the better your food plots will be. There is simply no other way around that fact. So before you even consider what you’re going to plant, you must first make sure the soil will provide a solid foundation for growth. Here are seven dirty ways to get the job done right:
1. Learn the Lingo
Before we delve into the specifics of how to manage soil, I think it’s important to have a good understanding of just what soil is. Soil is the loose layer between the soil horizon (top of the ground) and the parent rock layer beneath, and is the area where plants grow and receive the vital elements for life. Soil consists of varying levels of organic material, organic matter and rock particles derived from the subsoil rock layer.
Organic material is comprised of once living organisms (plant, animal, insect, microorganisms) in varying stages of decomposition. Organic matter is the stable, fully decomposed fraction of organic material otherwise known as humus. It is this portion that is an indicator of soil quality, with a higher humus content associated with heathier soil. Organic matter is important for several reasons, including microbial activity, nutrient supply and for water retention because organic matter acts like a sponge, increasing the soil’s water holding capacity.
The rock particle portion of the soil is directly influenced by the make-up of the subsoil rock layer because it is the source of those minerals. If the rock layer in the soil is high in calcium, the soil will in turn tend to be high in calcium.
2. Study Your Soil
Plants and forages utilize the minerals found in the soil for growth. In general, the higher the mineral content and the higher the organic matter level in the soil, the more productive the soil. It is of little surprise that national soil maps show the highest mineral and organic matter levels are found within the most productive agricultural areas. Neither is it coincidental that these same areas generally produce the best deer habitat and the most trophy-class bucks, because the nutritional plain in these areas is higher than in areas with poorer-quality soil.
Soil is comprised of three basic components; clay, silt and sand. Sometimes soils can be comprised of only one of these components, but in most cases soil is a combination of two or all three components. Clay consists of the finest particle size of the three basic soil types, which allows for a tight compaction and thus tends to hold moisture better than the other soil component types. Conversely, sand contains the largest particle size and water drains through this soil type. Silt, typically associated with water runoff or creeks and rivers, has a particle size that falls in the middle of clay and sand. When you combine these basic soil types you end up with loam. Loam can be broken down into subcategories such as sandy loam, clay loam or silt loam. If the predominant soil type is sand but also contains some clay and silt, the soil is categorized as sandy loam. The same is true for clay or silt loam, with the type of subcategory loam determined by the predominance of the specific soil type.
In general, loam and its subcategories are considered the most productive soil types due to the fact that it does not have the extreme characteristics of a simple single soil type. For example, a sandy loam might be well drained but not to the degree of sand alone, allowing it to better hold moisture. Clay loam might hold moisture and not be very well drained, but will drain better then pure clay.
3. Insist on Quality Control
In order to improve your soil, you first must figure out what you are dealing with in your deer habitat. A great place to start is with a soil map, which can be found in several different places, including your local FSA (Farm Service Agency) or NRCS (National Resource Conservation Service) office. These maps will show you the specific soil classification found in your food plot. Soil classification is insightful because it can get you a good overview of the soil characteristics you are working with.
For example, one of the farms where I plant food plots has a Macksburg soil type, characterized as a very deep, somewhat poorly drained soil for loess (wind-blown silt) found primarily on ridges and hilltops. Despite being poorly drained, Macksburg consistency is a silty, clay loam and tends to be productive soil. Another soil type I have on the farm is Sharpsburg, which is similar to Macksburg in that it is found on ridges and is mostly a loess formation, but tends to be more well drained than Macksburg.
What does all of this mean? It means that if you identify the soil class on your deer habitat you can work with someone who knows what these soil types mean, such as an NRCS or soil extension agent. They can explain the general characteristics of the soil, including likely organic matter levels, how well it drains, whether it tends to be acid or alkaline in nature, how productive the soil is likely to be and what plants and forages grow best in that type of soil.
4. Test the Limits
Knowing your soil type and classification is helpful, but will provide only general characteristics. In order to determine the specific practices, you will likely need to improve soil quality, and for this a soil test is required. Many people take a soil test by simply going out to a random part of the plot, dig up some dirt and dump it in a Ziploc bag. Indeed, this method will tell you the soil characteristics, but for only that one spot. Unless your plot is perfectly homogeneous across the entire field, the grid method of soil sampling will give you a more accurate result.
Break the field up into a grid, paying particular attention to having different grids as elevation changes. In other words, if your plot has even a slight slope, make sure to have a grid section at the high and low point of the slope. In a half-acre food plot, I typically have a grid network of at least six different areas.
Collect soil from each of the six locations at least 6 inches deep (a soil probe works best, but a spade will also work) and place them all in a bucket. Mix them together and then take a sample of the mixture, which will give you a good overview of the field.
If the plot is bigger, 1 to 2 acres, you might want to have a bigger grid with more samples. In some cases, with big fields that vary greatly in slope, you might decide to analyze two samples, one in the lower grade and one in the higher grade. I realize that this might seem like overkill, but the results you get will affect every step you take later.
One last thing to remember when soil sampling is to be sure to label your samples and write them down somewhere so you can match up the plot with the right test results. I know that sounds simple, but you would be amazed at how many times I have seen people label samples as “1” or “A” and then not remember which field they corresponded with.
5. Learn How to Lime
If you have ever read any article about food plots, you are probably aware of the importance of proper soil pH. That being said, it is still the most likely overlooked aspect of soil building. Soil pH is the level of acidity or alkalinity of the soil. A pH of 7 is neutral, anything below 7 being acidic and anything above 7 being alkaline. Most food plot forages grow best in neutral soil, but most soils are not neutral. While some soils can be alkaline, most tend to be acidic and require a buffering agent, lime, to raise the soil pH. When you get your soil test results back, they should tell you what the pH level of that field is and the amount of lime needed to neutralize your soil.
There are a few things to consider when applying lime to a plot. First, lime neutralizes soil through physical contact. If you spread lime on top of the field and allow it to sift into the soil, it will take some time for that to occur. Don’t expect to spread lime on a field and the next week the soil be neutralized. The process can take up to a few months. Disking the lime into the soil will help speed the process up, but it will still take some time. Also, if you have an extremely acidic soil, it might take two or more applications to bring the pH up to where you want it.
The type of lime used will also affect the rate at which the soil will be neutralized. For example, a liquid lime will neutralize soil much faster than regular ground or ag lime. Also, pelleted lime typically neutralizes soil faster than ag lime. The reason is the particle size. The smaller the particle size the faster the soil will be neutralized, because it has more surface area and therefore can come into physical contact with more soil. Pelletized lime would not seem to have a smaller particle size, but remember, it is very finely ground lime that is made into a pellet. Once the pellet breaks down, the smaller particle size means more overall surface area when compared to ag lime and a more rapid neutralization.
The down side to liquid lime or pelletized lime is that even though it neutralizes soil more quickly, the soil will not maintain the pH for as long as when using ag lime. Also, ag lime is normally the most cost effective.
6. Feed with Fertilzer
A neutral soil pH is critical, even more so than fertilizer. An acidic soil will bind up nutrients and not allow plants to use them, so regardless of how much fertilizer you apply, a good soil pH is needed for plants to effectively use that fertilizer.
Your soil test will also indicate the amount of N (nitrogen), P (phosphorus) and K (potassium) that is needed for the particular type of food plot forage being planted. There are other trace elements that are sometimes used in fertilizer, but N, P and K are the most common. As I mentioned, the soil test will give you a specific NPK recommendation based on what the current level of each is in the soil and also based on the needs of the plants you are using.
For instance, if you are planting a brassica field, the recommendation will likely be for a high level of N. But if you are planting alfalfa, N requirement will be much less if any at all, but the K level needed might be higher. Furthermore, the field might be very high in phosphorus already and be sufficient for what you are planting, so adding more will only cost you money.
It is important to understand that these nutrients are being pulled from the soil and utilized by the plants, so they have to be replenished regularly. If you have sandy soil, you might need to fertilize more often than you would in heavier soil that does not leach as quickly.
7. Count on Compost
As previously mentioned, the amount of organic matter in the soil is a good indicator of how productive the field will be. The subject is complex and beyond the scope of this article, but suffice to say that organic matter is vital for water holding capabilities, nutrient value and microbial activity. If you have a field low in organic matter, such as a rocky field with little fertile top soil, it doesn’t mean you are out of luck completely.
It will take some time, but adding compost to the soil will gradually increase organic matter levels. In many cases, this doesn’t mean you have to put tons of compost on the field either. The amount needed will vary, but it is not the same as applying lime or fertilizer. Again, it can take time, but it is possible to turn a dismal field into productive deer habitat and food plots.
There is simply no way around the fact that if you do not get your soil where it needs to be you will never have productive deer habitat or food plots, or at least not realize the full potential of those plots. It takes time and money, but your food plot foundation must be as strong as possible. Seed is not inexpensive either, and your time is valuable so there is no reason to throw either away over having poor soil. And I would guess that if you are like me, sitting over a poor looking, deerless field is the biggest motivator to do the extra work and get your soil right.
— Matt Harper is an avid whitetail hunter, and food plot and deer habitat expert from Iowa.