IO 
The Colorado Experiment Station 
deep. Later cultivations should be as deep or slightly shallower 
than the first cultivation. When the first cultivation is made, the 
roots have not extended very far into the space between rows. The 
stirring of the surface layer at that time by the cultivator makes a 
dry layer on top. If this is maintained the beans will root below 
the dry layer. Cultivation should be aimed primarily to keep 
down weeds and prevent the formation of a crust. Usually all cul¬ 
tivation should cease by the time the first pods commence to set. 
Sometimes the plants have grown enough so that cultivation should 
cease before this time. Care should be taken never to cultivate 
when the young bean plants are wet, as they are easily broken at 
such times, and when so broken are very susceptible to certain bean 
diseases. Under irrigated conditions cultivation should follow ir¬ 
rigation, as soon as the surface moisture and the plants will per¬ 
mit. The aim should be to prevent the loss of water by cultiva¬ 
tion rather than to furnish water by excessive irrigation. 
Irrigating Beans .—A study has been made of bean irrigation 
in eight Colorado counties. This study shows conclusively that it 
is fully as easy to over-irrigate beans as to under-irrigate them. 
As an average of all results obtained, two irrigations give higher 
yields than three or more irrigations. There was some difference 
as to quality of land; very open gravelly lands would stand more 
irrigation than sandy loams, loams and clay loams. 
In irrigated regions beans should be given water when they 
show a need for water, namely, when the plants show a very dark 
green and commence to wilt during hot periods of the day. If 
the plants are light green and growing vigorously, irrigation may 
often be delayed unless it is necessary to irrigate to get the water. 
Beans in irrigated districts will usually be planted in rows 
around 24 or 28 inches apart. The first step in irrigation is to use 
a furrow opener and make furrows between the rows. Water is 
run down these furrows under proper control, until the soil is 
moistened laterally and to a depth of at least 2 feet. This figure 
2 feet is a relative one. Sometimes there is moisture enough in the 
subsoil at less than 2 feet from the surface when the surface needs 
irrigation. In such cases a lighter run of water will suffice. The 
last irrigation should very seldom be given after the blooming 
period; just as the plants are coming into bloom is as late as water 
should be applied in ordinary seasons, and on ordinary soils. Later 
irrigations delay the maturity of the crop and endanger proper 
ripening, because of possible frost injury. Such later irrigations 
do not materially increase the yield of beans. 
