If the applicator supplies the double crop requirement for both small grain and the subsequent corn or
soybeans crop in one fall application, N overloading of small grain crops can result in lodging. Lodging
can also occur if the farmer over applies commercial fertilizer to add supplemental nutrients. This
problem can be avoided by split applications of nutrients, by soil testing, by the quick nitrate test, and by
tissue analysis of the standing crop.
Biosolids should be applied to forages and hay crops in the early spring (March-April) or late summer
(August-September). Applications during these time periods make the nutrients available just before
periods of maximum cool season grass nutrient uptake. Early spring and late summer applications also
help minimize disruption of cool season forage growth from smothering effects. Summer applications,
depending on weather conditions at the time, can result in some nutrient burning of hay or pasture
because the drier conditions and higher temperatures have already stressed cool season grasses. Prior
to application, pasture fields must be grazed to 4 inches and hay cut to 6 inches. No application may be
made to warm season grasses and alfalfa between September 15 and March 15 because these species
are not actively growing during this time and do not utilize nutrients.
Federal and state biosolids regulations forbid the grazing of beef cattle within 30 days of application and
within 60 days for lactating dairy cows. Since most pathogens die from exposure to sunlight and changes
in temperature, moisture, and soil conditions, these regulations are intended to help assure that grazing
livestock have minimal exposure to pathogens contained in the biosolids. Therefore, any grazing operation
receiving biosolids must either have sufficient additional acreage that does not receive biosolids or have
sufficient hay or other feed to maintain herd condition until the waiting period has passed.
ECONOMICS
Biosolids are supplied free to the cooperating farmer. Because biosolids provide nutrients, the amount of
commercial fertilizer applied can be reduced, resulting in a cost savings. The amount of that cost savings
is dependent on the nutrient content of the biosolids. Case studies show the first year economic value of
nutrients derived from biosolids in the Coastal Plains and Piedmont regions of Virginia range from $25 to
$50 per acre on pasture land and $50 to $70 per acre on corn, small grains, and soybean land.2 Additional
savings, up to $12 per acre, can be realized when the biosolids supplier disks fields to incorporate the
biosolids into the soil—assuming the timing of application and incorporation reduces the farmer’s land
preparation requirements.
If lime-stabilized biosolids are applied, farmers reduce the cost of lime application, which typically ranges
from $9 to $18 per acre and can last up to three years. Soil structure is improved through the addition of
organic matter contained in biosolids. Measuring the benefits and putting a dollar value on the micro- and
secondary nutrients and soil structure improvement are very difficult. In many cases, these benefits
accrue over a long period. No attempt was made to measure the residual nutrient value for subsequent
crops.
Biosolids application regulations require that the supplier routinely soil test fields. Thus, for farmers who
do not test as much or as frequently as is generally recommended, the soil test results associated with
biosolids applications provide them with more information for management decisions than they would
otherwise have available. In addition to the information, a minor cost savings accrues to the farmer.
2 These estimates were based on $0.23 per pound for N, $0.30 per pound for P, and $0.14 per pound for K. The
quantities of biosolids and nutrient analysis information are based on case studies for the L. C. Davis farm in New
Kent County, the J. R. Smith farm in Louisa County, and the J. B. Cocke farm in Hanover County.