How to Maximize Dairy Manure


My previous column was about the first steps you need to take to deal with and relieve some of the pressure of high fertilizer prices. Now is the time to seize a change that livestock farms, especially those that produce a lot of manure, can make to reduce or completely offset their fertilizer while supporting high crop yields.

The first step is to recognize that manure is your main source of nutrients.

Calculations I did several years ago showed that for many farms, especially in New York State, more fertilizer is coming to the grain truck than the fertilizer truck. This is especially true for farms with low forage diets – less than 60% – which import a lot of feed.

Even with a daily application of manure, there are steps you can take to maximize the reuse of these nutrients.

Break down nutrients

Manure contains 20 to 30 pounds of nitrogen per 1,000 gallons – with half the volatile ammonia and half the organic nitrogen. About 35% of organic nitrogen is available by decomposition the following year. So you potentially have 10 to 15 pounds of ammonia N, plus 3.5 to 5.25 pounds of organic N per 1000 gallons.

If you spread manure daily or on the surface without immediate incorporation, you lose the 10 to 15 pounds of ammonia, but retain the organic nitrogen unless it is physically vented from the field to nearby streams. This is especially true if you are spreading it out on snowy ground.

On an 8,000 gallon per acre manure application, that means you are throwing away $ 80 to $ 120 per acre of ammonia nitrogen by not incorporating or injecting it. Instead of having 108-162 pounds of nitrogen, you only have 26-42 pounds of N. In other words, you’ve thrown away 75% of the nitrogen and now have to buy expensive fertilizer to make up for it.

Spreading without immediate incorporation means you have to apply a lot more manure to meet your nitrogen needs. This dramatically over-fertilizes phosphorus and potassium, wasting this valuable fertilizer.

Phosphorus is 8 to 10 pounds per 1,000 gallons of manure and is not lost through volatilization. Leaving manure on the surface during the winter allows a significant amount to move through streams during spring runoff.

Leaving a bare field without a living cover allows more dissolved phosphorus to move out of the field and into the water as well. Research has shown that this often occurs when manure is applied to bare soil in the fall and winter. All of this will accelerate the uneven phosphorus level on your farm.

Unless you have a sample grid or a variable rate fertilizer applicator on your planter, you’re stuck with fertilizing for the least tested part of your field to minimize yield loss. This is money wasted because the medium and high test areas get fertilizer that has no economic return to pay.

Potassium is also 20 to 30 pounds per 1,000 gallons. At 8,000 gallons per acre, that works out to 240 to 400 pounds per acre of 0-0-60 fertilizer. Potassium will attach itself to particles in the soil, so it is less likely to leave. But spreading on frozen or snow-covered ground can also allow this valuable fertilizer to leave the farm.

Manure has a wide range of fertilizer content and composition. Agitation can also have an effect on this. There is no substitute for manure sampling at the start, middle and end of emptying the storage.

The first step in management is knowing the data you are working with.

If the manure contains fertilizer equivalent to 30-10-30 per 1,000 gallons, this equals $ 59.20 per 1,000 gallons of fertilizer purchased. If you plan to apply 8,000 gallons per acre, then you are applying $ 473 per acre. This is a large number considering the high price of fertilizers.

If your commercial fertilizer applicator would randomly go out and drive across the field and spread fertilizer anywhere, you’d be rightfully angry. Why do this to you?

Think about the injection

The biggest opportunity to compensate for fertilizers is the use of manure injectors. The number and types are increasing every year as more and more farmers realize the economic and environmental benefits of this technology. By simply putting manure in the ground rather than on top, you can dramatically reduce, if not eliminate, winter losses from runoff.

Most importantly, nitrogen doesn’t volatilize with your money. Ammonia interacts with the soil exchange and stays there until the soil is warm in the spring. With the use of an ammonia inhibitor compound, it can be stored for six to eight weeks after the soil warms up before converting to nitrate.

Our research in the Delaware Watershed in New York State found that injecting manure into winter forage or cool-season grasses in November through frost could meet all of this needs. cultivation the following spring. As soon as it warms up, ammonia turns into nitrate and is quickly taken up by the roots of fast growing grasses or winter triticale. With enough manure injected, you can meet all of the crop’s fertilizer needs without it flowing into waterways or into the air.

This environmentally friendly late application leaves more room in your storage in case the spring application is delayed. With these high fertilizer prices, it doesn’t take long to pay for an injection system. The only complaint I have heard is that the farmer runs out of manure too soon.

For grass fields and winter fodder, you can still inject if you don’t have manure storage. Just take your daily spreading tanker with rolling injectors at the back in the field and start injecting. When the tank is empty, stop, lift the injectors and start again the next day with the next load until you have the field covered.

We do not suggest knife injectors due to the higher horsepower and tendency to push more stones. We suggest using a roller after the field is fertilized to push down any grass or stone that has been lifted. Go through the narrowest setting.

Avoid compaction

The downside to daily manure application is on days when the soil is too wet for traffic. Injection or surface application can damage your yields in the long run in this situation.

By keeping axle loads below 8 tonnes per acre, you can avoid deep compaction that decreases yield. Keep the tire pressure at 15 pounds per square inch to distribute the weight over a larger area and prevent surface compaction.

If you inject into patches of grass or well established winter forage, the roots will cushion the impact and distribute the weight more. As the roots grow, they exert tremendous lateral pressure to push back the compaction. Think of the roots of a tree lifting up a concrete sidewalk.

For the spring application, Quirine Ketterings, Nutrient Management Program Manager at Cornell, took the injection further by injecting in 30-inch rows and then planting the no-till or strip corn directly on these. rows. As soon as the corn seed takes root, it immediately enters the manure NPK.

The farmer she worked with was able to get maximum yield from manure alone, and Ketterings found no root burns.

Another obvious advantage is that you can inject right next to non-farm neighbors and there is no residual odor.

Good luck!

Kilcer is a Certified Crop Advisor in Kinderhook, NY


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