TREES AND SHRUBS FOR THE NORTHERN PLAINS 3 



SOIL TYPE 



Tree and shrub species at the Mandan station were tested on 

 Cheyenne fine sandy loam soil. Fine gravel, encountered in the 

 fourth to fifth foot, grades into fine sand in the seventh to beyond the 

 tenth foot. Water penetrates the soil readily, but the holding capacity 

 of the soil is low from the fourth foot through at least the tenth foot. 

 A high percentage of the water held was available to plants. Most 

 of the tree roots fed from the surface 3 or 4 feet. On farms testing 

 was on a wide range of soils that varied from sand to clay. Only in 

 rare cases were farm plantings made on sites that had a water table 

 sufficiently close to the surface that it could be penetrated by tree or 

 shrub roots. 



METHODS OF TESTING 



Species tested were received either as seed or seedlings from the 

 following sources: Division of Plant Exploration and Introduction of 

 the United States Department of Agriculture, commercial nurseries, 

 or local collection. Testing to determine hardiness, usefulness, and 

 general adaptability of the various species for windbreak purposes 

 was done in one or more of the following ways: (1) In nursery rows; 

 (2) in arboretum plantings of 1 to 10 plants; (3) in block plantings of 

 pure stand of approximately 100 plants each, spaced 4 by 4 feet, or of 

 49 plants each, spaced 6 by 6 feet; and (4) in cooperative farm wind- 

 break plantings where the species were planted in rows, usually be- 

 tween or adjacent to other species. Small numbers of plants were 

 always tested in the nursery or arboretum rather than in the block 

 plantings. Some species were tested in the arboretum, in blocks of 

 pure stand, and in the farm windbreak plantings. 



A few seedlings of some species were planted on the station grounds 

 as ornamentals at the same time that the test-block or arboretum 

 plantings were set out. The ornamentals received a limited amount 

 of irrigation after 1920. Their growth and survival was compared 

 with that of trees or shrubs of the same species growing under dry- 

 land conditions. 



All species at the Mandan station received clean cultivation each 

 year to control weed growth and to keep the soil in suitable condition 

 for absorbing rainfall. Annual notes on growth, survival, winter and 

 other types of injury, and setting of terminal buds were taken at the 

 end of each growing season for all station plantings except the orna- 

 mental ones, and every 5 years for the cooperative farm windbreaks. 



The scientific and common names and the origin of all species that 

 were tested during the 1913-50 period to determine their suitability 

 for windbreak purposes are given in table 3. Those species which 

 carry a Plant Introduction (P. I.) number were introduced from foreign 

 countries by the Division of Plant Exploration and Introduction of 

 the United States Department of Agriculture. Nearly all lots of seed 

 and seedlings were given an accession number for identification when 

 they were received at the Mandan station. 



