208 FARM GRASSES OF THE UNITED STATES 
weight of blue-grass and redtop has been 14 lbs. in 
most States. ‘This standard was established when it 
was impossible to clean grass-seed. Ordinary grades 
are now quoted at from 14 to 20 Ibs., and fancy or extra 
fancy seed at 20 to 36 and even 4o Ibs. per bushel. 
These differences are due almost entirely to variations 
in the amount of chaff present. 
The most important factors affecting the rate of seed- 
ing of lawn grasses are the quality of the seed, the time 
of year, the condition of the soil, and the purpose for 
which sown. From two to four bushels of seed are 
commonly recommended. Three or four bushels of 
good seed, weighing at least 25 Ibs. to the bushel, is 
the proper amount tosow. Four bushels per acre is 
at the rate of four-fifths of a quart per square rod, or 
one quart to 340 square feet of surface, which equals 
an area 17 by 20 feet. By weight it is 10 ounces per 
square rod, or one pound to 436 square feet, which 
equals approximately an area 20 by 22 feet. If 20 
lbs. to the bushel is taken as an average weight, and 
the seed be sown at the rate of four bushels per acre, 
it requires a half pound per square rod, or one pound 
on 500 square feet of land, which is an area 20 by 25 
feet. Quality of the seed as regards purity and vitality 
must, after all, control the amount sown. Seed con- 
taining much chaff and of low germinating power 
should be sown at the rate of six bushels per acre. 
Where the weight is 30 to 35 Ibs. per bushel, and the 
percentage of germinable seed is high, the amount 
need not be over three bushels. Intermediate grades 
should be sown in proportion. 
In late spring or late fall sow more heavily than in 
