Comparing Various Rates and Application Methods of Liquid Swine Manure in Grain Sorghum Production

Final Report for FNC92-003

Project Type: Farmer/Rancher
Funds awarded in 1992: $2,700.00
Projected End Date: 12/31/1994
Matching Non-Federal Funds: $4,300.00
Region: North Central
State: Kansas
Project Coordinator:
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Project Information


Our family farm operation consists of 400 acres of mostly Kansas River bottom. We farrow out about 100 sows per year. Part of the resulting pigs are sold as feeder pigs, and part finished to slaughter weight. I have been working to better utilize farm produced manure and cover crops as well as a crop rotation and management system that will allow me to virtually eliminate purchased fertilizer, herbicide, and insecticide. I am presently working towards organic certification of my milo, wheat, and soybean production. Sustainable practices that I have adopted after some experimenting include: a crop rotation on part of my acres that can, hopefully, sustain itself long term with almost no added fertilizer, a crop rotation that, with added manure applications, can sustain itself, strip cropping, and a planting, hoeing and cultivating scheme that will eliminate the use of herbicides most years. I am also in the process of switching from dry lot sow gestation and semi-confined barn farrowing to alfalfa pasture gestation and fescue pasture farrowing to supplement my farrowing house farrowing.

I used the assistance of my local county extension agent Mike Christian, the Rural Center’s Jerry Jost, as well as agronomy specialists Dan Devlin and Dave Whitney in designing this trial. It was also reviewed by my local conservation district. Mike sent soil tests to the KSU lab and helped weigh and compute harvest results with the county weigh wagon.

Even though billions of gallons of liquid manure are collected and spread on land throughout the United States each year, we are a long way from the point where we should be of matching soil and crop needs with available manure nutrients. My goal is a manure management plan tailored to my operation that is reasonable and sustainable, and will allow me to make the best use of the manure captured and stored. Ultimately I’m working on a management and resource use scheme where animals spread much of the manure themselves. Then crops and grass can quickly cycle those nutrients, thereby reducing holding and spreading costs and minimizing water contamination.

In order to make better use of captured manure I need to know soil and crop needs; have reasonably priced application equipment, that can apply manure to minimize losses while being reasonably trouble free; and do manure analysis rates and trials to determine an application rate that optimizes crop yields without leaving carryover nutrients out in the field. I was lucky and found a good used honey wagon with injection capabilities at a farm sale at a very reasonable price.

To run the trial I first had to measure the acreage that the tank would cover using the studies I made two application methods. Then I picked a uniform site that had been farmed the same way several years. Soil tests on the site had the following results:
pH 5.7
Phosphorus 41 Lbs/A
Potassium 690 Lbs/A
Organic matter 2.0%
Surface, subsoil, and profile nitrogen: 9, 5, and 6 respectively

I examined a broad cast and disk method versus and injection application method. This was done at 1x, 2x, 3x rates. The 1x rate equaled 2,695 gallons per acre with a manure analysis of 36 Lbs N/1000 gallons and 23 Lbs P2O5 per 1000 gallons. This gives the application amounts shown in Table 1.

Table 1
Rate,Total N/Acre, Available N/Acre,P2O5/ Acre
1x 98 49 61
2x 196 98 122

3x 294 147 183

Table 1 also shows the nitrogen and phosphorus supplied by the manure in total and during the growing year, it assumes 50% of the total nitrogen is available during the first growing season. The broadcast applications were disked in 24 hours after application. A Department of Soil Science Table at the University of Wisconsin uses a 20% loss when manure is not incorporated. By their definition both of my procedures, would be considered incorporated. My results would suggest an 8% loss in yield in the broadcast disk as compared to the injected application. Table 2 shows the harvested yield at each rate and under each application method. Table 2 shows the test layout and the carryover profile nitrogen in each plot.

There didn’t seem to be a lot to be gained by going to the tripe application rate, only in one inject replication did the 3x rate beat the 2x rate, and in the other inject replication the 2x rate beat the 3x rate by a large margin.

Table 2 Test Plot Layout and Results

Rate,Method,Yield/Acre,Available N/Acre,Carryover
1x Inject 95.2 bu 49 1
2x Inject 98.8 bu 98 2
3x Inject 113.5 bu 147 3
Control 80.5 bu 0 1
1x Broad. 87.8 bu 49 1
2x Broad. 98.8 bu 98 1
3x Broad. 98.8 bu 147 1
Control 87.8 bu 0 1
1x Inject 98.8 bu 49 0
2x Inject 139 bu 98 0
3x Inject 120.8 bu 147 0
Control 76.9 bu 0 0
1x Broad. 91.5 bu 49 1
2x Broad. 117.1 bu 98 1
3x Broad. 117.1 bu 147 1
Control 72 bu 0 1

*The layout I used for the plots was sequential instead of side by side making it more convenient to apply the various rates of manure. It also made it much easier to harvest as we didn’t have to turn over the rows to harvest each plot. All plots were on the same set of 30” rows running one quarter mile through the field. Each plot measured 85’ and 5 rows were harvested at moisture of 15.4%.

A factor that could be influencing the variable results in the inject applications could e compaction from applying that much liquid to the soil in a short period of time. If that was the case you might expect the 3x rate broadcast application to shine especially since there would be more opportunity for volatilization under that method but that doesn’t seem to be the result either. Compaction or some unknown factor may be contributing to the lack of yield improvement in the 3x rates. I don’t believe it was lack of rainfall in conjunction with the high manure rate because of the subsoil moisture present and timely rains. From these results anyway, one could conclude that the 2x rate or 98 Lbs of available nitrogen is the optimum rate to apply. The surprising thing was that over the whole plot there was hardly any carryover of nitrogen in the profile even at the 3x rate. So if it wasn’t leached during the growing season it was taken up by the crop even though there wasn’t an apparent yield response. The rest of the field not in the test plot received 83 Lbs of actual nitrogen as anhydrous ammonia costing $15.50 per acre, and yielded 112 bushels per acre.

Having done this study, I have a better idea of the available nutrients in the collected swine manure and have made progress toward determining a proper rate of manure to apply for a milo crop when there aren’t any nitrogen credits from other sources. Of course nutrients in the manure will vary considerably, as will nitrogen credits from cover corps, other crops, and previous application carryovers, so in practice it becomes a little mire complicated, but certainly not impossible to figure. I have proven to myself that the manure if applied properly can save numerous fertilizer dollars. It will be especially valuable as I make the transition to organic production. I’ve found it doesn’t take an extremely large application of manure to get realistic milo yields. In most cases where a good crop rotation is used and where nitrogen credits are available from other sources, a single rate application, especially if it is injected, will be adequate to grow a good milo crop. Trying to provide enough nitrogen from manure for a maximum corn yield might lead to a buildup in phosphorus in the soil and more pollution potential. In that case fertilizing to meet phosphorus needs makes more sense. In my case, producing milo, I think I can fertilize to meet nitrogen needs and not get phosphorus buildup.

The results of this study will be shared during a mini-grant session at a Heartland Cluster Conference held February 18, 1995 at the Union on the Kansas State University campus. Farmers from 9 cluster groups from across the state of Kansas and one in Missouri brought together by a Kellogg Integrated Farming Systems grant will be showcasing their sustainable agriculture initiatives. Numerous KSU faculty and staff will also be attending.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.