- Production -

Consider Litter

Chicken litter in fertility programs increases with
high fertilizer prices.

By Leo Espinoza

The high price of fertilizers has resulted in an increase in the use of chicken litter as part of a farmer’s fertility program. Extension publication “The Use of Chicken Litter in Row Crops” can be found at the following link: www.uaex.edu/Other_Areas/publications/PDF/FSA-2147.pdf.

Perhaps the most important recommendation is to obtain an analysis of the litter as close to the time of application as possible. Below is a table with the statistics of 100 samples of broiler litter analyzed by the University of Arkansas Agricultural Diagnostic Laboratory during 2008. The wide range of litter moisture and nutrient contents listed in Table 1 underscores the importance of having the litter analyzed.

Table 1. Statistics of 100 samples received by the Diagnostic Lab during 2008 and classified as “broiler” litter. Nutrient levels are reported on “as is” basis.
  Moisture N P2O5 K2O
  % lb./ton lb./ton lb./ton
Average
34 55 60 63
Median 31 57 60 63
Mode*
25 60 61 58
Range 15-64 24-88 30-115 25-91
*Mode equals the most common value observed.


Nitrogen In Chicken Litter

The amount of nitrogen (N) shown in the report represents the amount of N that can potentially become plant available. The nitrogen in the chicken litter is mostly in the organic form that needs to be mineralized. Published studies report varying degrees of mineralization (conversion to a form plants can use). For practical purposes, assume that 50 to 60 percent of the N will become plant available during the first year, and no additional benefit should be expected in following years, especially if litter is applied at rates of 1 to 2 tons/acre.

The rate at which the nitrogen becomes plant available is particularly affected by temperature and moisture. The optimum temperature for mineralization to proceed is reported to be 75 degrees F and higher. This is important to know as wheat farmers may consider applying litter in February and March to meet the nitrogen requirements of the crop.

What Researchers Have Reported
Researchers in Georgia concluded that the rate of mineralization was significantly slower in clay soils than on sandy soils as clay soils tend to remain wetter for longer time periods. They also noted higher denitrification rates for the same reasons, as compared to chemical fertilizer. Recent studies in Arkansas concluded that poultry litter is not a good alternative to urea-nitrogen in rice produced with delayed irrigation, as the potential for denitrification is higher than in other cropping systems, such as corn and cotton.

Other researchers have reported that when temperature and moisture conditions are near optimum levels, a large portion of the nitrogen is mineralized (becomes plant available) in four to six weeks.

It appears that there is no difference between fresh and pelletized chicken litter in the supply of major nutrients. However, the pelletized formulation is significantly higher in price than fresh litter. There are some sources of pelletized litter that may show higher nitrogen analysis resulting from supplementation with chemical fertilizer, typically ammonium sulfate.

Phosphorus/Potassium In Chicken Litter
Many farmers find chicken litter a good alternative to supply phosphorus (P) and potassium (K), particularly in soils with low levels of such nutrients. It has been reported that 2/3 of the phosphorus in chicken litter exists in the inorganic form, particularly as orthophosphate, which is the form plant roots use. The remaining 1/3 exists as organic P that, as in the case with nitrogen, needs to be converted into a form plants can use.

For fertility purposes, assume that 90 percent of the phosphorus and potassium can become plant available during the first year. The phosphorus applied with the chicken litter, just like commercial P fertilizers, can be tied up or fixed.

The position of the University of Arkansas Division of Agriculture is to recommend chicken litter based on phosphorus requirements. Applying chicken litter to meet the nitrogen requirements of a crop may result in phosphorus application rates that exceed the amount a crop may need to achieve optimum plant growth.

Other Benefits
The beneficial effects of chicken litter applications to restore the productivity of recently leveled fields is well known. In addition to supplying major nutrients, chicken litter can also provide <0.1 lb. boron/ton and 0.5 to 1.0 lb. zinc/ton.

A study conducted in Alabama to assess the effects of long-term applications of broiler litter and ammonium nitrate showed that surface soil pH levels of plots receiving ammonium nitrate had decreased by 0.1 to 1.0 units (depending on N rate), while soil pH of plots receiving broiler litter remained unchanged or showed higher than initial levels (especially for high litter application rates). The soil at this location was fairly sandy and had a low CEC.

Such a dramatic change would not be expected to occur as fast in soils with higher buffering capacity (high CEC).

Application Of Chicken Litter
If chicken litter is going to be used as a source of nutrients, it is important that the application equipment be properly calibrated. The two factors to consider are application uniformity and application rate.

Please refer to fact sheet FSA 1040 “Calibrating Chicken Litter Spreading Trucks” www.uaex.edu/Other_Areas/publications/PDF/FSA-1040.pdf for information on calibrating application equipment.

Failing to properly calibrate application equipment can result in areas over- or under- fertilized, resulting in streaking.

Results from a study in Colorado, using 10 litter spreader trucks, showed that seven out of 10 spreaders had patterns that were off-center. Another one of the spreaders had one side with 7.5 times the amount of manure on it than the other side. Some of the trucks did not seem to be loaded evenly (trucks were loaded according to common procedure). They also reported swath widths ranging from 7.5 feet to 16.1 feet, with an average of 11.1 feet.

Value Of Chicken Litter As Fertilizer

Estimating the value of chicken litter is always tricky. We can look at different scenarios:

• For purposes of this exercise, assume the price of urea is $500/ton ($0.54/lb N) and P and K are $800/ton ($0.67/lb K2O; $0.87/ lb P2O5).

• Assume a litter analysis of 60-50-60 (content per ton).

• For nitrogen, about 60 percent of the total N will be plant available, which is equivalent to 36 lb N/ton.

• For P2O5 and K2O, assuming 90 percent of the total P and K content is plant available, is equivalent to 54 lb K2O and 45 lb P2O5.

• Then 36 x $0.54 = $19.44; 54 x $0.67 = $36.18; 45 x $0.87 = $39.15

• 19.44+36.18+39.15 = $94.77 per ton of this material.

Now, what if a farmer does not need any P? Then one may argue that the value to that farmer could be reduced by $34.15 to $55.62, or to $58.59 if no K is needed.

One also could argue that when chicken litter is used on cut ground, the value should be the equivalent to the yield gain over a check area that received no litter application.

Results of a calibration workshop in Arkansas, using 10 litter trucks, showed that the litter loads contained in such trucks varied in density from 27.9 to 38.2 cubic feet.

Things To Remember
Chicken litter is known to be a good source of nutrients, but the concentration of such nutrients can be highly variable. A representative sample prior to application is recommended to calculate actual nutrient input. Spreader trucks must be properly calibrated to achieve the highest spreading uniformity.

The University of Arkansas recommends applying chicken litter based on phosphorus requirements of the intended crop.

Leo Espinoza is a soil scientist with the University of Arkansas, Department of Crop, Soil and Environmental Sciences. Contact Espinoza at (501) 671-2168 or email lespinoza@uaex.edu.