Monday, March 30, 2015

Finishing up does better nutrient conservation pay? The incorporation part of the story

The recent post on nutrient conservation was supposed to be an evaluation of why we often inject or incorporate our manure, but I only really got injection covered. So I thought this week I’d try to do a part two, where I focused on incorporation of some solid manures (since we don’t have commercial options for injection of solid manures available quite yet – at least not many, though I have seen one or two homemade systems as well as some research systems).

Example of the USDA-ARS developed by Dr. Pote. Manure is ground up prior to injection to facilitate the actual injection.

So here, I am going to use examples for two types of manure, beef solid manure and poultry layer manure. Based on the ISU publication, using manure nutrients for crop production it looks like we’d expect between 15-30% of our applied nitrogen to be lost to volatilization if we broadcast a solid manure and don’t incorporate it. Alternatively, if we broadcast apply it and leave it on the surface for a while before we incorporate it, such as if we were applying manure in the winter but could not incorporate until spring.

There are a few ways to approach this topic. The first is, were you going to do some tillage anyway? If so, then we would have paid for the tillage operation anyway, so the cost may be close to $0/acre. However, though this may in principle be true there may be a time cost associated with having to conduct the tillage operation at a time close to when the manure was applied. That is, what might need to purchase new or larger application equipment to adjust when we are playing manure or we might need to pay for additional labor to make sure these operations get accomplished at roughly the same time. The other option was that no tillage was going to be performed, so adding that tillage operation represents are real cost. In either case I’m going to treat these cases the same, and use data from the 2015 Iowa Farm Custom Rate Survey, to estimate the cost of incorporation. Based on my look through the document it looks like it would cost somewhere around $15 per acre to get an incorporation operation performed.

Beef feedlot manure

To perform an economic comparison, we need to know what manure application rate we are planning to use. Often times solid manures are applied based on phosphorus management decisions. This often makes about 10 tons per acre a reasonable application rate for beef manures; though it will depend based on your crop rotation, the current soil phosphorus levels in your soil, anticipated crop yields, and the nutrient content of your farm’s manure so considerable variation about this number could exist based on your production system and management objectives.

If you made me guess, I’d expect about 20 lbs N/ton of manure from a feedlot. This means that if we are applying 10 tons per acre we’d be putting on 200 lbs of nitrogen (this may sound like a lot as a typical recommendation for corn following soybean is around 150 lbs/acre), though only about 70 lbs/acre would be available in the first year. This means we were probably thinking about side-dressing some nitrogen to supply our crop with the rest of its nitrogen need. Anyway, our question becomes would hiring someone to get our manure incorporated at the time of application pay for itself in terms of nitrogen savings? In this case we are anticipating losing 15-30% of our applied N if we don’t incorporate quickly, so this would amount to about 30 – 60 lbs of N per acre, or about $13 to $26 worth of nitrogen value being conserved. So in this case it looks like it would justify the $15 per acre cost of incorporation.

Layer manure

In the case of layer manure I’m going to assume an application rate of about 4 tons per acre. In this case I’m estimating the manure has about 37 lbs N/ton (and about 24 lbs N per ton that would be available in the first year). At this application rate, I’d be applying almost 150 lbs N/acre (of which about 100 lbs N/acre would be expected to be available in the first year). In this case if we lost between 15-30% of the applied N to volatilization, we’d be losing 20 to 45 lbs of N per acre, which amounts to about $10-20 an acre worth of value. This again would put us right in the range were incorporation would just about pay for itself, especially if we were doing the tillage anyway and just need to adjust when it is performed.

Other thoughts

So this is just a little wrap-up with a few concluding thoughts. It may seem like I’m promoting incorporation pretty vigorously in this post, and I am, but I certainly understand there are instances when incorporation may not make sense. One good reason for doing this might be erosion. Limiting erosion is often about leaving residue on the surface of the soil to help protect it, any time we perform a tillage pass some of the residue will be lost. I have seen numerous studies that have shown manure application without incorporation may reduce erosion, at least in some situations. Thus, as with most things it is about weighing the benefits and costs and figuring out what best works in your farm. Is nitrogen conservation most important or is it potential erosion and soil loss? In either case are there additional changes you could make to protect against that concern or is this approach the best option.

Percent of initial residue cover remaining after manure application/incorporation

(Fragile Residue)
(Non-fragile residue)

% of Residue
% Residue
% of Residue
Disk incorporate

Thursday, March 12, 2015

Preparing your barns for spring and summer

Spring is one of my favorite times of year; I enjoy seeing the world turn green with signs of new life, crops in the field, young livestock out on pasture, and the hope a new growing season provides. However, in the livestock business spring also offers some new challenges for our barn’s ventilation systems. As summer and winter ventilation changes are drastically different it’s important to check over your ventilation systems start prepping your barn for the heat stress challenges summer is sure to bring.

The objective of any ventilation system is to replace the stale air in the buildings with fresh air from outside. We do this to remove excess heat and moisture from the barn, minimize dust, limit the build-up of potentially harmful gases like ammonia or hydrogen sulfide, and to provide oxygen for respiration. In addition to doing all this, often times we also are trying to conserve energy while trying to create this optimum environment to raise our pigs. Over the winter, you probably made some changes to your barn ventilation system to focus on being energy efficient while not chilling pits and parts of your ventilation system have been sitting, collecting dust all winter.

With that in mind, here is a list of a few key components of your ventilation system to think about as warmer weather approaches:
  • Fans – In some systems, such as tunnel ventilated facilities, many of the fans were winterized with plastic or at the very least were idle for many months. In barns with natural ventilation you also probably had some fans you weren't using for winter ventilation. Fans should be cleaned, have their belts tightened and shutters adjusted to open freely. Fans with dirty blades, shutters, or loose belts can move as little as 25% of their rated capacity, costing you money by having to run longer to achieve the same air exchanges and not effectively cooling your animals.
  • Curtains/Curtain operation – Curtains should operate freely without hang-ups. It is important that pulleys and cords move; a curtain that gets hung-up isn’t providing the ventilation you need. Don’t forget to check the drops/emergency measures – summer thunderstorms and power outages can be a real danger to animals, so check the drops on a regular basis.
  • Soffits – All soffit openings should be open, not only to provide for mid-range ventilation but also to allow the attic to vent and avoid extreme building heat
  •  Inlets – Inlets are generally adjusted to direct air across the ceiling in the winter but may point slightly downward in the summer to promote cooling. Try to make your inlet opening consistent throughout the barn.
  • Water lines – Water consumption is critical in hot weather. Check all your nipple and cup waterers and filters to be sure that flow rates meet the basic needs of the pig.
  • Stir fans – Stirring fans should be cleaned and checked for proper operation.  Tilt them slightly downward for cooling.
  •  Cooling Nozzles – Nozzles used for sprinkling animals may have sediment built up in the line or the orifices may be plugged.   Check controller settings.  These should be cycled on an off in a manner that allows animals to become dry before wetting them again. 
  •   Evaporative Pads – Evaporative pads are used most typically in gestation and breeding facilities.  Remove winterizing material and inspect for rodent damage and bird nests.  Be sure the pump is working properly and that drip holes on the inlet tube are free-flowing. 
With those tips in mind, pick yourself a nice day in the next couple weeks and get your barn ready for spring,  so that when the summer heat arrives, your cooling breeze keeps on flowing. A big thanks to Dr. Jay Harmon for providing a few tips to help me out in writing this post.

P.S. - You may be wondering what this has to do with manure... well it just felt seasonal and next week I'm planning to touch on a the topic of hydrogen sulfide concentrations during manure agitation (since spring application season appears to be fast approaching).

Tuesday, March 3, 2015

Does better nutrient conservation pay? The story of injection and incorporation

A common question we ask is how much should be willing to pay for conservation, but every now and then the stars align and initiating a conservation practice at your farm makes you money. One example I discussed earlier was the case of manure sampling, which by helping you use your manure resources better saves you money (you can check out this old post here - by helping better manage your manure as a fertilizer resource.

Let’s take the time to talk about another practice – injection and incorporation. So the approach of this little write up will be to explore how the costs of manure management change with the surface application as opposed to injection/incorporation and how the benefit we get from our manure changes.

Swine Manure
Let’s start with swine manure. In working these calculations, I’m going to be working with what I consider to be an average swine manure from a finishing operation with a deep pit, something like a 60-30-25 (N-P2O5-K2O) pounds per 1000 gallons.

In this case we are working with a liquid manure and it makes some sense to perform some sort of injection/immediate incorporation rather than just surface applying. One of the reasons to do this is because it places the phosphorus below the ground surface, which helps protect it from surface runoff and keeps it there when we need it. However, the primary reason for injection/immediate incorporation is for nitrogen management. Getting the manure in the ground, mixed with soil, and covered reduces the amount of nitrogen we lose through volatilization.

So let’s work some examples to see how these practices compare. In the case of direct injection of the manure we do a good job of limiting ammonia volatilization, reducing it so it is typically between 0-2% of the total amount of nitrogen we applied. If we had just surface applied this liquid manure we’d expect that between 10-25% of our nitrogen would be lost. So what value does this have at our farm?

Alright, so let’s assume we are working in a corn-soybean rotation and we plan to apply our manure at the maximum return to nitrogen suggested rate. In Iowa this would mean our ideal rate (based on current corn and nitrogen prices) would be 134 lbs N per acre that we want to supply to our crop. In the case of the swine manure we proposed that would mean we’d want to apply about

In the injection system to do this we’d need to apply about 2400 gallons per acre, because we are getting about 56 lbs of available N per 1000 gallons of manure. To calculate this I adjusted the total amount of N in the manure times and availability factor and a loss factor. I used 95% available in this case, based on ISU PM 1003 which suggests swine manure will be 90-100% available, and correct for nitrogen losses during application by multiplying by 0.99, which assumes 1% of the applied N will be lost to volatilization.

134 lbs N/acre / (0.99 * .95 * 60 lbs N/1000 gallons) = 2400 gallons per acre

If we had surface applied without incorporation how would have this changed? Well, we’d still have the same manure and I’d assume the same N availability, but my correction for ammonia volatilization would be different. In this case, I’d assume that between 10 and 25% of the applied N would be lost. We’d have to apply closer to 2900 gallons per acre.

134 lbs N/acre / (0.75 * .95 * 60 lbs N/1000 gallons) = 3150 gallons per acre

So what does this mean? We’ll I had to apply an extra 750 gallons of manure per acre to get the same crop production, reducing the number of acres we cover with our manure. This means we are applying, and wasting, about $18.50 worth of extra nitrogen value.

The second part of this question is how did my costs change? To estimate this I need to do some quick estimating about how this would affect my manure application expenses. It’s not perfect, and every situation is different, but to get a rough cause of the cost I use the figure below.

So, how do you use this graph? Well the blue diamond graph represents injection while the red squares represent broadcast (we could talk about why the graphs have different shapes, but not today). So in the case of injection we said we wanted 2400 gallons per acre, and using the top line I’d estimate an application cost of about $0.02 per gallon, which would give an application cost of about $48.50 per acre. In the case of surface application, we wanted about3150, which has an application cost of around $0.01 per gallon, or about $30 per acre. So, that means injecting cost us about $18 more an acre, while we only saved an extra $18.50 worth of nitrogen value. In this case the value of the conserved nitrogen covered our additional application expenses.

Dairy manure
So, what about dairy manure? In this case I estimate dairy slurry will have about 25 lbs N/1000 gallons, which will be about 35% available.

Using the same assumptions as before I’d calculate a manure application rate of 15,000 gallons per area to supply 134 lbs N to our corn crop, while for surface application it would be 20,000 gallons per acre. In this case, I’d estimate an application cost of about $0.011 for injection (total cost of $169 and acre where as in the case of surface application the cost was about $0.0078 per gallon (total cost of $159 an acre).

The extra 5,000 gallons would contain about $19 worth of fertilizer value, once again making injection a great choice to increase the value of your manure and to help protect the environment.