3. Nutrient Management Strategies for the Best Return on Investment
Updated: Apr 19
(start at 56:45 to listen about effluent and SDI)
Another area we have been working in is hog and dairy effluent. We take deep pit or dairy manure that has been scraped out of a dairy. It goes through a solid separator that squeezes out the big particles in the manure. The byproducts of the screw press has the texture and consistency of corn silage, so you can stack, haul and spread it.
The second step involves a microfilter. It has a drum inside that is spinning about 1500 rpms and throws the liquid through the screen. The manure is then clean enough to blend with water and run through SDI.
To my knowledge, this is the first site where we can take a concentrated manure that has 10-12% solids, run it through two pieces of equipment, and get it clean enough to go through irrigation. Our goal is to have two to three of these units on a trailer and move them to different livestock operations. We can do about 50,000 gallons per day through this machine. What is the ratio and how thick are we blending this? That depends on the moisture in the soil and how fast we want to get it out. We usually do a 1:1 or 1:5 part ratio. If the manure is really wet, you don’t need much water. For example, we could take 100 gallons a minute of irrigation water, and 100 gallons a minut of manure, blend those together and send that out. That would probably be the most concentrated. If we were irrigating, we would probably do closer to a 1:5 or 1:10 ratio. How many gallons per acre you put out is going to be determined by the nutrient concentration. For hog manure, we are putting out 2000-5000 gallons an acre; dairy manure is going to be 10,000-20,000 gallons per acre. Cost wise, each unit will be about $100,000-150,000. Ideally, these units will be available to rent out for 1/10 cent per gallon.
Todd Rokey has been putting manure through his drip system for 4 years. Here is a video about it. He has put on 2.1 million gallons of effluent over the past 4 years. He has an outdoor lagoon; the solids settle out, and we pump liquid off the top. One challenge we have is the lagoon is too dirty early in the season to go straight through our drip system. This year we are hoping to have a new pump set up in place so we can pump manure earlier. In the past, it has only been pumped through late July and early August.
The dairy in Minnesota and South Dakota we have been working with have a product called feed pad runoff. It has a lot of water in it. We have applied 168,000,000 gallons of that through SDI. They used to apply it with a dragline, so the application savings have paid for the drip systems very quickly.
We are continuing to do more work with drainage. A few years ago, we installed a drip field, then it rained quite a bit. We started trenching through the end of the field to put our pipe in, and water started dripping out of the drip lines. That made us start exploring using a drip system to remove excess water during the growing season. We have several fields in Illinois and Missouri that we installed just for that purpose, so we are hoping to get some good data to quantify how much water we can remove from a field and what is the benefit to that.