Walker Lake bulletin. (Hawthorne, Nev.) 1883-1926, 1923-01-06
MANURING PRACTICE
GOOD FOR POTATOES
q, Geo. Stewart, In Charge Of Flels
Crops, Experiment Station,
Utah Agricultural College.

Mauuring practices vary consider
ably. In the East commercial ferti-
lizers are in general use, especially
In the trucking sections. Phosphorus.
potash, and nitnogen are frequently
applied. This form of manurins has
not yet become general In the West
Potato growers OF Utah and adjacent
states depend on farm manure, and
sod-matter and for the fertilizins
elements. Occasionally late fall OF
early spring growth of alfalfa Is
turned under. but the usual practice
Is to make hay of this and return
to the land the manure made by the
animals to which the hay Is fed.
With 50 many cattle on the summer
ranges this is probably the most prof.
table system of fertilizing the land.
The functions of organic matter OF
farm manure and sod is principally to
supply organic matter. In the end,
amplete decomposition results and
the fertilizing elements are added to
the soil in a readily available form.
Important, however, as the fertilizing
elements may be. the indirect effect
Is still more important. Coarse man.
ure and large roots are hlndrances to
cultivation and irrigation, but under
favorable conditions, these are soon
reduced to fine particles which are
stu undergoing active decay and
which mix readily with the soil par
tieles. Organic matter in such con-
dition is valuable in two distinct
ways: ID by increasing the water
holding capacity. and t2) by creating
condition Of medium poroslty in the
soil.
Increases water-hoIdino capacity
Decaying organic matter absorbs
water much as does sponge. Be-
cause many of the particles are hol-
low, the surface to which films OF
water can cling IS much greater than
on solid soil particles of the same
volume. In addition organic matter
c,atains a substance called humic
acid which has the power of hold
ing many times its own weight OF
water in q loose chemical combina-
ton
Controls perosity and aeration:-
Besides. organic matter loosens clay
soils and renders them porous. 1t has
the opposite effect on coarse sands
and otherwise extremely porus soils,
In which it serves as sort OF binder as
well as a retainer OF water.
It IL common knowledge that wet
sand. even n nearly pure and very
coarse, win hold together with great
er tenacisy than the same sand when
deprived Of tts moisture. Organic
matter, therefore. consolidates loose
soils both by supplying a binding
agent and by furnishing q retainer OF
water A high degree of looseness
In ciays and high degree OF consoli-
dalton In sands increase the water
holding powers OF such soils. These
conditions also encourage more de-
sirable aeration and uniformity of
emperature.
Compact clays have too little pore
space to hold much water to permit
the easy exchange Of gasses between
the soil and the atmosphere. Roots
and bacteria both need air oxygen also
helps In rendering mineral plant-foods
soluble Sandy soils are likely to De
too hot and clayey soils too cold. rhe
extra moisture and the consolidation
In sandy soils moderate the tempera-
ture OF these soils and thereby de-
cresses evaporation. In heavy soils
the increase of pore space encourages
more through ventilation. As the wa
ter content increases to about med
rum the pore space increases. II
more water Is added the volume de-
creases and consequently the air
space. II is at this point OF greatest
volume that soils aerate most readily
and consequently warm up most rap
idly. Roots can penetrate more easily
and more dee ply because air is avail
able al greater depths aad because
there Is less resistance. In all re-
spects the soil is then in the most
favorable condition for plant growth.
On this account this condition In soil
Is known as the optinum uLatin word
meaning the best) water content. Ac-
lively decayinS organic matter tends
to bring al soils to this desirable