280 SEEDING AND PLANTING 



or other cover after seeding. The looser and coarser the covering 

 soil, the greater the depth can be without injury. Overdeep cov- 

 ering is a common defect in nursery practice particularly when the 

 soil is likely to become compact on the surface. 



18. Quantity of Seed per Given Area of Seedbed. The 

 quantity of seed to sow on a given area of seedbed depends 

 upon a number of factors, of which the following are the more 

 important: 



a. The species. 



b. The tree per cent value of the seed. 



c. The length of time that the seedlings remain in the seedbeds. 



d. The quality of stock required. 



e. The method of seeding. 



Overdense seeding causes the resulting seedlings to be tall, 

 slender, and weak. The tendency in many forest nurseries in the 

 United States in recent years has been toward the overcrowding of 

 the seedbeds. As a result, much of the 2- and 3-year seedling 

 coniferous stock has been ill-suited for transplanting or field 

 planting. On the other hand, when the stand is too thin it 

 unnecessarily increases the cost. Quantity should be secondary to 

 quality. 



Insofar as the species is the greatest factor in determining the 

 size of the seed, it is of the highest importance in determining the 

 quantity that should be sown on a given area. The number of 

 seed per pound is a rough index of the quantity that should be 

 sown. In species that have seed of approximately the same size, 

 those which grow most rapidly should ordinarily be less densely 

 crowded, and consequently a less amount of viable seed should be 

 sown. Thus, rapidly-growing species like larch should have 2 or 

 3 times the space in the seedbed during the first and second years 

 as slow-growing species like hemlock and spruce. 



The utilization value of the seed determined from germination 

 tests, or better yet the tree per cent or the percentage of seedlings 

 to be expected under the particular nursery practice, should 

 always be taken into consideration in determining the most ac- 

 ceptable amount of seed for a given area. Thus, white pine seed 

 that has been stored in the open for a year after collecting should 

 ordinarily be sown twice as dense as fresh seed, due to its 

 diminished utilization value and the much smaller number of 

 plants to be expected from a given quantity. Most species can 



