This afternoon I took a walk in the cover-plot to see if I can find another shed or two. The deer have really been eating on the turnip bulbs and there seems to be a manure pile about every couple square feet out there. This isn’t surprising since lately I’ve been seeing around 12 to 15 deer of an evening. Since I will be growing a crop on this site come spring/summer, this got me thinking.
Nutrients from Whitetail Deer ?
I wonder, in addition to the nutrient value and organic matter I will be getting from the plants themselves this spring, how much nutrient value could I be looking at with all this deer manure?
I did a little research, did some inferring, and got out the calculator to do some basic math:
The USDA calculates something called an animal unit (AU) to determine the amount of forage an animal eats in a day. A cow is more or less the standard for the AU measurement assuming a 1000 lb. cow eating 26 lbs. of dry matter a day.
According to this bulletin a cow/AU produces about 59.1 lbs of manure per day which equates to 0.31 pounds of Nitrogen and 0.11 pounds of Phosphorus per day. Well, what does that equate into deer droppings? This is where a little bit of inferring happens.
According to Global Rangelands a whitetail deer has an AU of 0.17, and according to a USDA document from Texas, a whitetail deer AU is 0.13 assuming an average 100 lb. deer including adults and yearlings. The Texas source suggests 7 head of deer per animal unit. Lets use this number from Texas as a conservative approach to calculate numbers for deer in Missouri.
You got your calculator handy? Lets look at a few numbers:
Lets assume 2 animal units, (14) deer in the field at night (very conservative since I know more show up after dark).
Lets use the USDA nutrient numbers (assuming cow and deer values are close) and calculate nutrients for the month of January (31 days).
2 animal units = (0.31 lbs. N) X 2 = (0.62 lbs. N) X 31 days = 19.22 lbs. Nitrogen/ acre/ month
2 animal units = (0.11 lbs. P) X 2 = (0.22 lbs. P) X 31 days = 6.82 lbs. Phosphorus/ acre/ month
Soil Health
The benefit of claiming these kind of nutrients is the ability for manure to build organic matter in the soil, something commercial/chemical fertilizers cant do. Increased organic matter increases water holding capacity, which is a must in these Ozarks soils. This is a food plot now, but I will be growing a crop on this site, so soil health is important to me. Good soil health should be important to all agriculture producers, because its good for the environment and boosts your bottom line. If you’re growing a food plot, thinking soil health will ultimately give your food plots an edge, therefore giving you the edge come deer season.
only problem I see with your calculations is that typically the cows are in the pasture area 24/7 whereas the deer don’t spend near that time in the food plot! But we are happy for all the nutrients they deposit in ours!
That’s a good observation. Yes, there certainly are some holes in the calculations/observations. But I will say, that when stockmen are following a management intensive grazing program, they are moving the cows on a regular basis, hitting a particular paddock hard, and then resting it for quite some time before re-entry. I kind of assume this process as one of the variables for comparison. Typically the deer are not in the cover plot all day, but spend a good part of the evening in it and it does have a similar effect to a continuously grazed pasture in my estimation.
If a stockman is managing his pastures well in an intensive rotational program, forage regrowth can actually be managed more carefully at times, and ultimately be more productive. That’s the benefit of the system. Better cattle performance because of better forage performance and production.
Another thought: If food plots are done well, their “artificial” presence is often highly preferred over other forages in the area, and in theory used at a higher rate.
I cleared 4 acres for an orchard in the middle of a hardwood forest. Clay and shale ground. Clover and chicory ground cover with chestnut and apple trees. I’m about six years into the project. The first few years, limited amount of deer traffic came. With liming the site, seeding and mowing, it keeps getting better. The ground there now is loaded with deer droppings. Hard to find a 2’ circle without droppings in it in much of it. I found this information after searching for nutritional values… thanks for the info!!!
So glad you are finding success in your project. It is very rewarding when results are realized! Keep up the good work.