NORTHERN GREAT PLAINS FIELD STATION, 1913—1922 
of obtaining a good stand of fruit trees and the tendency of a large 
number of trees to die during the first few years of the experiment. 
This interferes with the uniformity of the plats and increases the 
probable error of results. Replacements are not satisfactory, as 
they can not be compared accurately with the older trees. 
CLEAN CULTIVATION, COVER CROPS, MULCHING, AND MANURING 
A detailed cultural test involving 44 field plats was started in 
1916 to study the effects of clean cultivation, cover crops, mulching 
with straw, and manuring on the hardiness of different kinds of 
plants. Clean-cultivated plats are worked often enough to keep 
them free from weeds. Plats growing a cover crop are given clean 
cultivation until about July 1, when oats are sown. Frequently the 
oats have been killed by frost before making a very good growth. 
Mulched plats are given clean cultivation throughout the summer 
and covered with straw to a depth of about 1 foot late in November. 
The mulch is allowed to remain until spring. Manured plats receive 
an application of well-rotted manure as a top-dressing every two years, 
each application being at the rate of about 20 tons to the acre. 
Five classes of plants were included in this experiment: Plums, 
deciduous shelter-belt or forest trees, apples, ornamental shrubs, and 
herbaceous perennial flowering plants. The different treatments 
were duplicated for each class of plants. Owing to poor stands and 
other reasons, all have been discarded except the eight plats of plums. 
Results with apples and plums only will be reported here. 
The work ah apples included 16 plats. In eight plats they were 
on hardy Siberian crab roots, and in the other eight plats they were 
worked on the common French crab roots. The varieties used were 
Virginia, Hibernal, Oldenburg (Duchess), Patten, Longfield, North- 
western Greening, Malinda, Grimes Golden, McIntosh, Winesap, 
and Northern Spy. But few apples on the French crab roots 
remained alive in 1918, so these eight plats were discarded in that year. 
TaBLE 13.—Survival of apples on tender and on hardy roots at the Northern Great 
Plains Field Station under different cultural treatments 
| On French crab On Siberian crab 
| root 
roots roots 
Treatment | | | 
| Planted Alive | Planted Alive 
| in 1916 in 1918 | in 1916 in 1920 
GEAMECHIGRV ALON ee eets ee eee eo 48 2 48 28 
OLS sh see ee eee EE ae ne en. Sno 48 16 | 48 35 
(COW GIP GIOVE a es ans ee Se ea eI oe =e 48 2 48 31 
MUSWATTINO OE ee ee IS Se ie gn we A ee a 48 4 48 24 
More satisfactory results were obtained in the blocks with apples 
on hardy roots, but even here stands became so poor that these 
blocks were discarded in 1920. The number of trees planted and 
the number remaining under each treatment when the experiment 
closed are given in Table 13. 
The best survival was on the mulched plats. The difference was 
especially marked in the apples on the tender French crab roots. 
