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Forage & Grains
Poultry Litter on Pastures - Trash or Treasure?

By Dave Johnson, NODPA Vice President, Organic Producer

Added February 11, 2014. Graze just what grows or fertilize for more? It’s a question that goes through the minds of graziers, especially when it seems like the pasture quality is marginal, drought patterns persist, and the land base is pretty tight. While Kiwi grass farmers regularly time applications of synthetic Nitrogen (N) to manage the feed wedge, I would venture to guess that most organic grass farmers in the states seldom apply fertilizer to pastures, maybe because a shot of organic N is not as easy to come by.

Some of us live in areas where poultry litter is available, albeit via a few hour truck ride, for the cost of material plus hauling. So how does it work, and what are the benefits and drawbacks of using this on pastures? That is the gist of a recent Odairy thread initiated by NRCS animal scientist and grazier, Karen Hoffman. She specifically asked for experiences with chicken litter regarding timing/time of year and amounts of applications; interval between application and grazing; effects on palatability and quality of the grass; cool season vs. warm season grasses; and any other practical advice. What follows reflects comments from my experience, from former dairyman and consultant Rodney Martin, and from the sage of organic farming in the finger lakes, Klaas Martens.

“Colloidal Soup: Favorite Soil Mineral Recipes”

Klass Martens went on to explain how Ca and K behave in soil: “Neal Kinsey does a good job explaining the chemical interaction of Potassium (K) with Calcium (Ca) in his book ‘Hands on Agronomy’. K has an atomic mass of 39 and Ca has a mass of 40 but Ca combines with a charge of +2 while K is only +1 so the calcium attaches twice as tightly to the soil colloid. Putting large amounts of mined K fertilizers on soils with a pH over 6.8 results in little or no increase in soil test levels of K. It either leaches out or ends up in the crop. The K in manure, on the other hand can load over to the soil more effectively. This is partially because the N in manure can leach K even more easily than it does with Ca.”

Along with his comments on Ca in litter, Klaas adds; “The Ca in gypsum reacts much faster than that in lime, and gypsum also has a lot of sulphur. Sulphate reacts more strongly than nitrate and can easily combine with Ca, Mg, or K. Jerry Brunetti often recommends using small but regular applications of gypsum on pasture and hay fields to provide readily available Ca for forages and to keep sulphur levels in feed higher for animal health. Sulphur is needed to make methionine and cystine, amino acids that cows need for immune function. In sulphur-deficient soils, adding gypsum can often lower somatic cell count.”

As with any soil amendment, balance and moderation are critical issues that, if neglected, can lead to unforeseen troubles down the road. Again, Klaas adds; “I’ve found that excessively high Ca levels tie up copper and iron often leading to increased parasite pressure in cattle. Andre Viosin, the author of several important books on grazing , wrote a small book titled ‘The Law of the Maximum’ that says whenever a mineral is in excess, it can cause a shortage in one or more other minerals.”

Excess use of poultry litter can push Phosphorous (P) levels up too high (some intensive operations already max out in this nutrient), and Rodney Martin’s comments confirm potential problems; “I also used poultry litter and mushroom compost for quite a few years, and in my experience, excess P in the soil often leads to excess K in forages, which is detrimental to animal health.” He continues and gives some great advise; “I would suggest a 2 ton/ Acre limit for poultry litter coupled with 1 ton of high calcium limestone. The calcium will help to offset the P in the soil and bring up the calcium in the plant to offset the K. This is a very simplistic suggestion. Soil and Forage tests on a regular basis and listening to your cows will ultimately give you a sense of direction on your particular farm.”

Living at the headwaters of a watershed (the Chesapeake) with major nutrient management problems downstream (too many CAFOs), and beginning with a very depleted run down farm, I found chicken litter readily available and found it to be a a real boon to quickly bringing our farm back to good productivity; trucking that manure 160 miles to our upland pastures where nutrients were needed. Most of the native fertility in our area was long gone, sitting in the harbors and bays of New York and Philadelphia from years of hay exported to feed horses.

Nutrient Values to Expect in Poultry Manure

First, what is in poultry litter as fertilizer, and how does it differ from synthetic fertilizers? Manure analysis can yield a wide range, so I have typically estimated 40-60# of Nitrogen (N), Phosphorous (P), and Potassium (K) per ton, plus 100-200# of Calcium (Ca) from layer litter (3-3-3-5). But as with any organic source, it is not all available immediately. Broiler or turkey litter will test differently, and any of it can vary based on the type of housing and how the manure is managed before and after it arrives at your farm.

Of course there is much more to NPK, and we can thank Klaas Martens for giving us the LONG and the short of it:

“We found that when manure is used as the primary nitrogen source, yields can be increased by using excessive amounts of poultry manure up to about 3 tons per acre, but weed pressure goes up and soils rapidly become overloaded with P and K. This may work well short term, but it is an expensive way to supply nitrogen and it leads to huge overloads of P and K as well as imbalances that can be hard to correct afterwards. Legumes should be part of the fertility program on all farms. It’s very important to be aware of the differences between layer manure, broiler manure, and turkey manure and to monitor calcium levels especially when using them at high rates. Soil testing and rotating between the different kinds of poultry manure may be necessary to avoid driving calcium either up or down too far and lime applications definitely need to be adjusted to reflect the calcium from other sources and the basic difference that is needed in general recommendations between conventionally farmed soils and organic. Wood ash, gypsum, layer manure, leaf compost, and quarry dust are all organically approved fertilizers that contain significant amounts of Calcium in addition to their other components.”

“Layer manure” he continues, “ contains around 10% calcium which is a lot more than it looks like at first glance. Most limestone only contains between 20 and 25%. The Ca in limestone takes a lot longer to become active than the Ca in layer manure. In the first year, a ton of layer manure can offset almost a ton of lime in its effect on the soil. Broiler manure and turkey manure will actually leach out calcium if applied in excess of immediate crop uptake and soil tie up. Synthetic nitrogen leaches out much more calcium. Each pound of synthetic N over what it takes to bring the C/N ratio to 10 can leach out about 3 pounds of Ca. That’s why standard lime recommendations don’t work right for organic farms.”

Application Rates and Soil Testing

At our farm in Liberty, PA, we have used poultry litter, preferably layer manure, usually “raw” (2-4 weeks old) or aged in a pile for a few months, on cool season pastures and hay ground. To avoid the noxious odor (and bad PR), and get the best bang for the buck, we have found it is best applied before or during a rain event, early spring (Ap 1) thru fall (Oct1) on vegetative swards. Consider an outdoor shower after spreading; your family will appreciate it. A typical rate would be 2 tons per acre per year, but we have used up to 4 tons per acre on a nitrogen hungry crop like thick ryegrass swards over the season in 1/2 to 2 tons per acre applications. This is on a farm that has historically had soil test levels of N, P, K, Ca on the lower end of low for crop requirements. On cropland at the Martens farm in the finger lakes of New York, Klass shared: “In a 5-year experiment done with Thomas Bjorkman at Cornell, we found that in soils with low to medium P and K levels, maximum corn yield response was reached at 3500# per acre of poultry litter. With higher rates, weed biomass continued to go up with no further gain in corn yield. I think 2 tons per acre is a good general rule of thumb maximum rate but that would lead to trouble if continued for very many years without regular monitoring with soil tests. This experiment was done with a good legume cover crop plowed down.”

The wisdom of soil testing cannot be overemphasized when importing soil amendments. Admittedly, the use of litter has introduced a few weeds not previously seen on our farm and concurring with Klaas, a higher weed pressure on fields with heavier doses of litter.

Will the cows graze well after use? Palatability issues seem minimal if followed by a decent (1/4”+) rainfall and some time (7 days min), and if spread fine and even using a litter spreader or similar (like a side slinger). We tried using an old NH box spreader once and created a streak the cows would not touch the rest of the year. Klaas’ experience, mostly on cropland, has been to use a litter spreader or lime spreader to apply poultry litter. He finds that they spread evenly and are pretty accurate in rate when set correctly. It is important that the operator has a good handle on spreader delivery rates, headland shutoff, and field speeds to achieve a controlled, accurate spread.

Expected Yield Response

So what kind of production can poultry litter provide on pastures, and does it pencil out? We have found 5-6 tons of dry matter per acre in most years to be a reasonable target. It is no secret that N fertilization increases both the protein and energy of grasses. This surprised us one year when we applied litter to an old neglected grass-only hayfield and found 3rd cutting Protein levels of 19% and RFQ over 170. But one of the best uses we discovered was season extension. Soil N is less active or available at cold temps, but N from fertilizer provides a quicker start in the spring, and late applications extend fall grazing by stockpiling, often adding 4-6 weeks of grazing. Another benefit we found litter can provide when applied after grazing or 1st cutting hay, is we can gain about twice the growth during summer dry spells for a given amount of precipitation. Does it pay? I have heard litter costing anywhere from $10 to $100 per ton delivered. Two tons/acre should provide another ton of forage. What is the cost of a ton of dry matter worth to your farm?

Timing of Application Depends upon the Crop

As with any use of manure, the timing and the overall fit into crop rotations needs to be considered to make the best use of the amendment without creating problems. Heavy applications year after year on the same crops (even a diverse, polyculture pasture) is a recipe for a trainwreck. On our farm, after years of permanent pasture and hay, we have seen a benefit with a diversified rotation including corn, legumes, oilseeds, covercrops, and various small grains. Litter applications are now limited more to preplant before a heavy feeder like corn.

The research Klaas Martens cited sheds more light on timing:

“The Cornell systems trials showed that timing of manure applications was important and dependent on which crop was grown. Winter grains responded well to fall applications while a lot of spring crops had no response at all to spring applied manure. The biggest negative effect of spring applications was increased weeds.”

He goes on to mention; “My observation is that fertilizer for a heavy feeder like corn is best applied to the cover crop that precedes it. Pasture is the exception. It seems to respond as Dave indicated in his post. It does the most good when applied just before a rain in early spring or fall. Rye grass gives the best response and at the highest rates. If winter grains are seeded for grazing, they should be fertilized at seeding or slightly before. Warm season grasses and summer annuals respond well to high rates (2+ tons/acre) just before planting. Summer seeded brassicas and small grains for fall grazing should be treated like summer annuals.”

A crop like sudex can also benefit from the N in litter with an application after 1st cutting, again timed with rainfall. An early spring application on a limited acreage may provide earlier turnout, but if you have more pasture in spring than you can manage, you may not want to cover the whole farm.

There is always a downside to most of our best intentions, and poultry litter is no exception. The upper limit pushes grass at the expense of clovers, but clovers do like it in moderation. Another negative repercussion if you spread and get no rain for 4 weeks, is that you and the neighbors get to live with the odor, not to mention all the lost volatized N you paid for.
Given our collective lack of insight, the current farm model is not a very long term sustainable plan: growing soybeans and corn in the Midwest with fossil fuel and chemicals, hauling it to the eastern seaboard to raise millions of birds and then hauling the poultry manure a few hundred miles more. As organic producers, we also need to consider the risk of importing undesirable substances like arsenic (mostly eliminated from poultry feed now), antibiotics, hostile bacteria, or GMOs to our farms, an area largely unknown that needs more serious research.

So how’s that for a simple answer?

Dave Johnson farms in Liberty, Pennsylvania and has been involved with NODPA since 2003. David’s farm has been certified organic since 2001. He recently sold his dairy herd, but used to milk a seasonal herd of 50-90 cows and shipped his milk to Organic Valley. Current farm operations include a rotation of Corn, soybeans, oilseeds, small grains, cover corps, and forages and permanent pastures. Email:, Phone: 570-324-2285.