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III. Recent Developments in Fertilizer Use
RANDALL J . J O N E S A N D HOWARD T. ROGERS
It is apparent that no substantial progress was made in increasing
corn yields in this area from 1909 to 1945. Cotton and tobacco yields,
however, began an upward trend during the thirties and for the 1941-1945
period were 171 and 134 per cent, respectively, of the 1909-1913 yields.
Increased per acre applications of fertilizer to cotton and tobacco has
been an important factor in increasing the yields of these crops. It would
be expected that in this region of favorable climatic conditions for corn
production higher rates of fertilization should also result in increased
corn yields. The importance of increased corn yields in the Southeast is
emphasized.by the fact that approximately one-third of the crop acreage
is devoted to corn, which is not greatly different from the proportion
of land planted to this crop in the Corn Belt.
Volk (1942) estimated that 65 per cent of the land in Alabama
planted to corn would produce about 11 bushels per acre without applying
nitrogen, and that only 12 per cent of the acreage would produce 30
bushels or more without adding this plant nutrient. Jones (1942), summarizing 12 years’ results from seven experiment fields in Alabama,
showed that the increase in yield due to increments of nitrogen was nearly
a linear response up to 36 lbs. of nitrogen per acre. At that time, very
few experiments in which high rates of nitrogen were used had been conducted, and most of the tests employed open-pollinated varieties of corn
with relatively wide spacing of plants. Generally, the genetic 1imitat.ion
of open-pollinated varieties combined with a low number of plants per
acre had concealed the possibilities of fertilization in the few cases where
high rates had been used.
Volk (1944), however, reported results from 15 tests in Alabama conducted cooperatively with farmers, which showed substantial increases in
corn yields for each 15-lb. increment of nitrogen from 0 to 75 lbs. per
acre. The potential for high yields was pointed up when Krantz (1945)
reported an increase from 19 bushels per acre without nitrogen to 107
bushels of corn with 120 lbs. of nitrogen added to Norfolk sandy loam.
Cummings (1947), summarizing 3 years’ results of 38 fertilizer tests in
North Carolina with corn, reported average yields of 28, 50, 68, and 78
bushels per acre from plots receiving 0 , 40, 80, and 120 lbs. of nitrogen,
respectively. All plots received adequate phosphate and potash and were
planted to adapted hybrids with 9,000 to 10,000 plants per acre.
Investigators in Georgia, Mississippi, and North Carolina (Brooks,
1948; Jordan, 1947; Krantz, 1947) demonstrated the need for an adequate
number of plants per acre with high levels of fertilization for maximum
yields. Krantz (1947), using spacings of 4,000, 9,000, and 12,000 plants
per acre in one experiment, obtained per acre yields of 53, 82, and 93
bushels, respectively. Brooks (1948) found that there was no yield
NEW FERTILIZERS AND FERTILIZER PRACTICES
increase for spacings above about 10,000 plants per acre, even when
fertilized with adequate phosphate and potash and rates of nitrogen up
to 150 lbs. per acre.
In the Georgia tests, maximum yields ranged from 78 to 117 bushels
per acre at different locations, and increases were obtained for rates of
nitrogen up to 90 lbs. per acre. I n the North Carolina tests, nearly linear
response was obtained to rates of nitrogen up to 120 lbs. per acre when
fair to good moisture condiTions prevailed. Similarly, Jordan (1947)
showed increases in yields of corn from rates of nitrogen up to 120
pounds per acre a t several locations in Mississippi. In most of the experiment,al work on high rates of fertilization for corn, nitrogen has been
the nutrient producing most of the spectacular increases. The results
from Georgia, however, show that either phosphate or potash may be as
limiting as nitrogen on some soils. At one location, a 40-bushel increase
was obtained for the application of 60 Ibs. of PzOs per acre. Likewise,
a t one location, a 32-bushel increase was attributed to the application of
60 lbs. of K 2 0 per acre. While only one experiment out of seven, in
1947, gave less than 30 bushels per acre increase for 90 Ibs. of nitrogen,
in most cases the increase duc to either phosphate or potash was less
than 10 bushels per acre.
Krantz (1947) pointed out the need for nutrient balance, although in
most tests nitrogen was the key to high yields. For example, Dunbar
sandy loam produced a 24-bushel increase for potash when high rates
of nitrogen wc3re applied, but no response to potash without nitrogen.
Conversely, a striking response to nitrogen was obtained when potash
was supplied, but no nitrogen response occurred without potash.
Striking crop response to high rates of fertilization is not restricted
to the southeastern states. Scarseth et al. (1943) showed that during
1939 yields of corn on Clermont silt loam in Indiana were increased from
11 bushels per acre without nitrogen to 71 bushels where 120 lbs. of
nitrogen per acre were applied. Likewise, yields on Vigo silt loam were
increased from 26 bushels without nitrogen to 91 bushels wit.h 120 Ibs. of
nitrogen. This is indicative of the response that may be expected under
some conditions in the Midwest. Results obtained by various investigators (Jones, 1942; Krantz, 1945; Ohlrogge et al., 1944) show that,
within the range in which nitrogen is a limiting factor, about one bushel
of corn is produced for every 2 Ibs. of commercial nitrogen applied.
Widespread interest in these experimental results and in corn fertilizer
demonstrations has been evident, but, the supply of nitrogen fertilizer
has been inadequate to meet the demand in recent years. Statistics are
not available to show to what extent the recent increased consumption
of fertilizers in the southeastern states is due to heavier fertilization of
RANDALL J . J O N E S A N D H O V A R D T. ROGERS
the corn crop. From 1946 to 1948, however, the average corn yield for
the 7 southeastern stat,es previously mentioned was 129 per cent of the
yield during the 1909-1913 base period. This was the first significant
increase in corn yields in this area for over 30 years.
6. Use of Anhydrous Ammonia as a Fertilizer
Some of the advantages that have been suggested for using anhydrous
ammonia as a fertilizer, as compared with solid nitrogen materials, include (a) a cost approximately 50 per cent less than solid forms of
nitrogen, (b) immediate absorption by the soil, even at low moisture
content, (c) more uniform distribution, and (d) less expense in application under certain conditions.
Anhydrous ammonia is a gas at ordinary temperatures and pressure
and contains 82 per cent nitrogen. Thirty per cent aqueous ammonia has
also been used to some extent. At 100°F. the pressure over anhydrous
ammonia in a closed vessel is about 200 lbs. per square inch. It is in
liquid form under high pressures and changes to a gas as it is released
from the container.
Waynick (1934) claim the first attempt to apply anhydrous ammonia as a fertilizer material in surface irrigation water. The use of
anhydrous ammonia in irrigation water for citrus began in California
about 1934 and appears to have steadily increased until it is now a
widespread practice and is being used on a variety of crops in that state.
Chapman (1944) stated that anhydrous ammonia was being used in
California on practically every type of irrigated crop which requires
nitrogen fertilizat,ion. The field crops thus treated include cotton, corn,
barley, oats, wheat, flax, sugarcane, sugar beets, hops, and rice, as reported by various investigators. Among the fruit crops are citrus, nearly
all varieties of deciduous tree crops, and cane berries. Anhydrous ammonia has also been used on melons, carrots, onions, artichokes, tomatoes,
beets, and other vegetables.
Merrill (1948) estimated that 18,000 to 20,000 tons of anhydrous
ammonia were used in California during the 1947-1948 crop year. Anhydrous ammonia constituted about one-third of the total sales of
nitrogen for fertilizer in Arizona during t.he past crop season.
Since about 1944, the practice of direct application of anhydrous
ammonia to the soil has developed rapidly in California and in the
Mississippi Delta area. I n Mississippi, Louisiana, and Arkansas approximately 15,500 tons of anhydrous ammonia were used during the
1947-1948 crop year. Moat of this nitrogen was applied to cotton on
more than 600,000 acres of land a t an average rate of about 40 lbs. per
acre (Andrews et al., 1948; Garman, 1948,* Louisiana Dept. Agr. and
NEW FERTILIZERS AND FERTILIZER PRACTICES
Immigration, 1948"). The indications are that a limited supply of
ammonia was hhe major factor in restrirting the wider use of this material
Waynick (1934) studied the behavior of anhydrous ammonia in
alkaline soils and found that the rate of nitrification was more rapid
than t.hat of ammonium sulfate.
The Arizona Agricultural Experiment Station (1945) reported that
the applicatior, of anhydrous ammonia to some soils raised the pH t o as
high as 9.5 immediately after treatment. I n these desert soils the pH
soon dropped to about 7.7, where it remained for a period, and nitrification proceeded a t a satisfactory rate. Anhydrous ammonia was nitrified
as readily as urea or ammonium sulfate in highly buffered soils. Ammonia applied in irrigation water was retained in the surface inch of
soil where it was readily nitrified.
Jackson and Chang (1947) studied the factors affecting absorption
of NH3 by soil by releasing ammonia gas into a beaker of soil which
was placed in a vacuum desiccator with suitable connections for aspiration, These investigators concluded that (a) soil of intermediate texture,
moisture content, and p H value will absorb 60 lbs. of nitrogen per acre
from NH, released a t a depth of only 1 to 2 inches, (b) a soil containing
only 6 per cent clay provided adequate sorption capacity for NH3,
(c) soils of high pH value with free calcium carbonate will retain 600 lbs.
of nitrogen per acre from NH3 released 2 to 4 inches below the surface,
and (d) air-dry soil absorbed instantly almost three times its own bulk
volume of NH3.
Chapman (1944) concluded that the major factors affecting the
evaporational loss of ammonia from irrigation water were soil permeability, temperature, and degree of agitation of the water. His results indicated that under most conditions losses would be under 10 per cent by
furrow irrigation. With high water temperahre and low soil permeability, however, losses may be of the order of 25 per cent. Dyke (1948)
pointed out that rather high losses of ammonia may occur by floodirrigation methods such as those used on rice fields. Kennedy (1944)"
studied the effects of concentrat,ion and drop size on losses of ammonia
applied in sprinkler irrigation water. He reported losses of the order
of 20 per cent.
Although few data are available on the efficiency of anhydrous ammonia in comparison with other sources of nitrogen in California and
adjoining states, there have been rather sat,isfactory yield increases from
this material. Rhoades (1948) " reported increases from the application
of anhydrous ammonia to wheat equivalent to those obtained from the
use of ammonium nitrate. When 30 lbs. of nitrogen were applied, the
RANDALL J . J O N E S A N D HOWARD T. ROGERS
average yield increases a t two locations were 9.9 bushels per acre for
ammonium nitrate and 13.4 bushels for anhydrous ammonia. According
to Garman (1948)*, a rice experiment in Arkansas showed a yield of
76.9 bushels from use of anhydrous ammonia and 72.7 bushels from
ammonium nitrate when each was applied a t t,he rate of 50 lbs. of nitrogen per acre.
Rather extensive field studies have been made by Andrews et al.
(1948) in Mississippi. These investigators reported that when 32 lbs. of
nitrogen were applied 4 inches deep as a side dressing anhydrous ammonia gave an average yield of 44.3 bushels per acre and ammonium
nitrate produced 42.8 bushels in 13 tests on corn. In similar tests with
cotton a t 18 different locations, anhydrous ammonia gave an average
increase in yiela of 296 lbs. of seed cotton per acre, as compared with
313 Ibs. for ammonium nitrate. Anhydrous ammonia was used successfully for preplanting application on oats, but some difficulty was experienced in making top dressings in the spring due to excessive soil moisture.
Leavitt (1948) * described the development of equipment for the introduction of anhydrous ammonia into irrigation water and for direct application to the soil in California. Approximately 15,000 steel cylinders of
150-lb. capacity are being used in that area to transport ammonia from
filling depots to the farm where the ammonia is metered into the irrigation water. A machine built especially for injection of anhydrous ammonia directly into the soil was adapted from a Killifer cultivator.
This machine has self-sealing injection shanks. I n the latest model, a
trailer with a 4,500-lb. capacity tank is attached behind the applicator.
In California the rate of application ranges from about 60 to 120 lbs.
of nitrogen per acre on the various crops.
Andrews et al. (1948) listed the specifications of equipment for storage
of ammonia, transportation to farms, and application to the soil in the
Mississippi Delta area. Anhydrous ammonia is transported from the
railhead or from storage tanks in 1,000-gallon field transport trucks from
which it is transferred to smaller tractor tanks of 80- to 110-gallon
capacity. These invest.igators point out that anhydrous ammonia has
been satisfactorily applied in the Delta area under the following conditions: (a) to prepared level land before planting, (b) to bedded land
before planting, (c) during the process of bedding before planting, (d)
during the planting operation, and (e) as a side dressing. Machines
have been designed to apply the ammonia in the soil 4 to 6 inches deep.
Applicators are specially designed knife-type openers with flat suctiontype points equipped with disc hillers or other apparatus for sealing in
the ammonia vapor.
The use of ammonia as a fertilizer will probably continue to expand
NEW FERTILIZERS AND FERTILIZER PRACTICES
since it is a low cost source of nitrogen, and there appear to be no serious
mechanical difficulties in the application of either the anhydrous or
aqueous form to the soil.
3. Methods of Application
a. Furrow-Bottowh or “Plow-Sole” Placement of Fertilizers. Generally accepted principles which might be considered the basis for determining best methods of fertilizer placement have been described by the
National Joint Committee on Fertilizer Application (1948). Some of
the important factors affecting placement are (1) nutrient balance within
the root zone, (2) early stimulation of seedlings, (3) fixat,ion of added
nutrients by the soil, (4) suitable crop rotations to utilize available plant
nutrients to a maximum, (5) adaptation of methods to fit soil and plant
requirements, and (6) avoidance of high salt concentration in contact
with seed or roots.
Various advantages have been suggested for deep placement of fertilizer. It was t,heorized that (a) the fertilizer would be kept in a moist
zone of soil throughout the growing season, (b) band placement on the
furrow-bottom should reduce fixation of phosphate by the soil, (c) reduced nitrification of ammonia nitrogen by deep placement would decrease leaching losses during wet years and prevent upward movement
of the nitrogen during dry seasons, (d) possible injury by high salt concentration from larger amounts of fertilizer would be avoided, and (e)
the application of fertilizer before the rush season would give better
Scarseth et al. (1943) proposed plow-sole application of fertilizer in
Indiana as a possible means of insuring ample plant nutrient supply,
particularly nitrogen, during dry seasons. They reported that up until
about 1939 response to small amounts of nitrogen applied in the row
or as side dressing to corn was uncertain. These investigators used
higher rates of fertilizer than were generally used in the fertilization of
corn in the Corn Belt a t that time and showed significant increases in
corn yields by supplementing row applications with furrow-bottom placement of additional nitrogen. These tests were not designed to compare
equal amounts of plant nutrients supplied by different methods. Essentially, these experiments showed that high rates of fertilizer would greatly
increase the yields of corn, particularly on the less fertile soils of the
Corn Belt. Furthermore, they showed t.hat good response to corn fertilization was possible during years of low rainfall. These investigation3
stimulated interest in deep placement of fertilizers throughout the Corn
Yoder (1945), reporting results on Wooster-Canfield silt loam in
JONES AND HOWARD T. ROGERS
Ohio, compared plow-sole application with row application and concluded
that plow-down fertilization was no more effective for corn than other
methods, even under extreme drouth conditions. I n these tests equal
amounts of plant nutrients were used by several methods of placement,
including combinations of row and plow-sole fertilization. Millar (1944)
reported ll-year averages of corn yields on Hillsdale sandy loam, showing that equivalent amounts of R complete fertilizer were more effective
when applied in the row at planting than when placed on the furrow
bottom or broadcast and plowed under. Caldwell et al. (1946) concluded from 3 years of tests on deep placement that this method was not
effective in Minnesota even during dry periods.
Rich and Odland (1947) concluded after one dry season and two
normal years that the usual band application was fully as effective for
silage corn in Rhode Island as plow-sole or other deep placement of all
or part of the fertilizer. These investigators pointed out that the rapid
early growth obtained by row placement lessened weed competition. In
placement tests in Nebraska with nitrogen on corn, Fitts et al. (1946)
showed that nitrogen applied a t planting time or last cultivation was
equally as good as furrow-bottom placement.
Volk (1946) pointed out that deep placement of fertilizer has been
long practiced in the southeastern United States, since farmers in the
Cotton Belt placed fertilizer in the “middle burster” bottom by hand
and bedded on it, many years before mechanical distributors were developed. Tests in the southern states, however, have failed to show that
deep placement of fertilizers for corn has any marked advantage over
row placement. Bartholomew (1948) reported that there was no consistent benefit from plow-sole application in 37 tests a t various locations
in Arkansas. Krantz (1948) found no difference between side-dressed
and plow-sole applications of nitrogen on corn in experiments in North
A limited number of tests has been conducted with small grain and
other crops. Smith (1947) failed to obtain response to nitrogen and
phosphate on winter wheat in Kansas from furrow-bottom placement,
although significant increases in yields were obtained when these fertilizers
were placed with the seed or when the nitrate was top-dressed in the
spring. Yoder (1945) concluded that all of the fertilizers for small grain
should be applied with the drill a t time of seeding, and Weidemann
(1943) reported that placing the fertilizer deep in the soil by plow-under
methods or deep drilling was not as effective on wheat yields as broadcasting and discing the fertilizer materials into the surface soil.
Experiments with soybeans on Miami loam in Michigan failed t o give
favorable increases for plowed-under applications of fertilizer, according
NEW FERTILIZERS AND FERTILIZER PRACTICES
to Millar (1944). Karraker and Freeman (1944) failed to obtain any
benefit to yield or quality of burley tobacco from placing part of the
fertilizer on the furrow hottom as compared with row-side band placement.
Merrill (1948) pointed out that the best method of application of
fertilizers has been such a controversial matter that it has been very
difficult for the equipment manufacturer to develop new machines for
distributing fertilizers. Widespread interest in plow-sole placement encouraged farm equipment manufacturers to develop special fertilizer
distributors. It is estimated that a total of approximately 30,000 attachments for plow-sole application has been sold, principally in the Corn
Belt. The practice was most widely used in Wisconsin, Illinois, and
Indiana, but recent reports from the Corn Belt states reveal that many
of the fertilizer distributors developed for plow-sole applications. have
been discarded by the farmers. Interest in this method of placement is
apparently decreasing, as evidenced by the following record of sales of
one manufacturer of plow-sole fertilizer distributors:
Some of the disadvantages of furrow-bottom placement which have
been mentioned in various reports include (a) fertilizer is placed too
far below roots of small plants, (b) in cool, wet seasons conversion of
ammonia nitrogen to nitrate is too slow, (c) plowing operations are
interfered with, (d) distributors on the market have insufficient hopper
capacity and are adapted only to two-bottom plows, and (e) restricted
aeration in the fertilizer zone in some soils results in poor response to
Experimental findings to date show little or no advantage of deep
placement over conventional methods for most crops on which it has
been tested, when equivalent amounts of fertilizer are used.
b. Subsurface Placement of Fertilizers for Sod Crops. Agronomists
have been interested for a t least 20 years in the idea of subsurface placement of fertilizers and liming materials for sod crops. Rogers (1942)
found that appreciable losses of surface-applied fertilizer may occur
through runoff from pasture lands under certain conditions. It has been
commonly observed that poor growth is obtained from permanent pasture
sods during dry seasons. Furthermore, experimental data show that
RANDALL J . J O N E S A N D HOWARD T. ROGERS
phosphate fertilizer moves down in the soil very slowly. These observations suggest that there might be some benefit from subsurface placement
of this material as contrasted with the conventional method of surface
Before the development of suitable machines for subsurface placement
of fertilizers in grasslands, Midgley (1931) placed superphosphate in
knife grooves 4 inches apart and 6 inches deep in small plots of bluegrass
sod. He reported a 57 per cent increase in growth of the bluegrass over
surface application. An experimental fertilizer placement machine which
will place the fertilizer in sod crops in bands a t any desired depth from
about 2 to 9 inches and a t any spacing from about 6 to 32 inches was
described by Schroeder (1947).
Placement tests were conducted a t two locations by the Kentucky
Agricultural Experiment Station (1947)" in which phosphate from four
different sources was placed in bands 12 inches apart and 4 inches below
the surface. There were no beneficial effects the first year from placing
all of the phosphate below the surface. These tests did not include a
combination of surface and subsurface placement. More recently tests
have been initiated in Virginia, Kentucky, and Georgia which have included a split spplication with part of the phosphate on the surface
and part below the surface a t various depths and spacings, but results
are not yet available. Studies are under way in New York state using
the tracer technique with radioactive phosphorus to compare subsurface
placement of phosphate fertilizer with surface applications on permanent
Drake (1948)" failed to find any benefit on alfalfa from subsoil
placement of part of the phosphate in bands 12 inches apart and 8 inches
deep over 'standard placement in Cecil clay loam during a dry season.
Caldwell et al. (1946) reported that broadcast surface applications of
fertilizer for alfelfa were as effective as plow-sole placement on Clarion
soil in tests in Minnesota. Reports from the North Carolina Agricultural
Experiment Station (1947)" did not show any benefit to alfalfa or to
a lespedeza-Dallis grass mixture from subsurface localized applications
of phosphate or potash fertilizers over mixing in the upper 4 inches of
soil or broadcasting on the surface. I n this test the subsurface treatment
was the application of 90 per cent of the fertilizer a t a depth of 4 inches,
with the remaining 10 per cent applied to the surface. Parberry (1946),
however, reported that a 400-lb. per acre application of superphosphate
placed 1 inch below the surface of a brown iateritic soil in Australia was
definitely superior to surface applications in stimulating ryegrass yields.
Placement a t the l-inch depth was as good as 2- or 3-inch placements.
Brown and Munsell (1938) found that limestone applied on the sur-
NEW FERTILIZERS AND FERTILIZER PRACTICES
face a t the rate of 2 tons per acre to a fine sandy loam had penetrated
to a depth of 6 inches in a pasture sod after 10 years. They concluded,
however, that the rate of penetration was sufficient to make surface
application to grassland an effective and efficient method of liming.
Pohlman (1946), using glazed tile cylinders, showed that liming the
16-24 inch layer of Gilpin silt loam tripled the yield of alfalfa when
the surface 0-8 inches had a pH of 5.6. Maximum yields were obtained
when the entire 0-16 inch layer was limed to neutrality. A 50-per cent
increase in root growth in the 16-24 inch zone was obtained by liming
I n tests conducted by the North Carolina Agricultural Experiment
Station (1947) ,+'either eubsurface placement of limestone or mixing the
liming material with the surface 4 inches of soil was superior to surface
placement on alfalfa.
Experimental findings thus far on subsurface placement of fertilizers
for sod crops do not consistently show an advantage for this method.
Possibly, Volk's (1946) observation that plants appear t o be able to
take plant nutrients from a soil zone the moisture content of which is
below wilting point, if some of the plant roots are in a moist medium,
may be related to this problem. The need for more fundamental studies
on root distribution and plant nutrient feeding a t various moisture levels
c. Application of Fertilizers in Irrigation Water. Various liquid fertilizer materials have been applied through irrigation waters, including
both anhydrous and aqueous ammonia, phosphoric acid, sulfuric acid,
sulfur dioxide, ond water solutions of various carriers of nitrogen and
phosphate, as well as mixed fertilizers.
The application of fertilizer in surface irrigation wat,er, according to
Proebsting (1948),* started in California about 30 years ago; and McGeorge (1948)* reported that it began in Arizona about 1933. The practice, however, has become reasonably widespread only within the last 5
years, as indicated by statistics on liquid fertilizers compiled by the
California State Department of Agriculture (1947). The combined
amount of liquid mixed fertilizer and phosphoric acid used in California
increased from about 2,000 tons in 1943 to over 13,000 tons in 1947. I n
addition, a large tonnage of anhydrous ammonia was used in that state
during the 1947-1948 crop year, most of which was applied in irrigation
water. During the first quarter of 1948, approximately $750,000 was
spent in California for liquid mixed fertilizer, although plant nutrients
in this form cost approximately 4 times as much per unit as in solid
materials. This represented about one-sixth of the total expenditure for
JONES AND HOWARD T. ROGERS
mixed fertilizer during these 3 months, according to the California State
Department of Agriculture (1948).
McCollam and Fullmer (1948) reviewed the history of the use of
fertilizer solutions in California from 1923, when the first liquid fertilizer
plant was built, to 1948 when 30 companies were distributing fertilizers
in “liquid” form. They pointed out the following developments in the
compounding of liquid mixed fertilizers: (a) nitrogen is generally added
in the forms of ammonium nitrate, nitrogen liquors, urea, and potassium
nitrate; (b) phosphorus is added almost exclusively as phosphoric acid,
with some ammonium phosphate being used; and (c) muriate of potash
and potassium nitrate are used as sources of potash.
One manufacturer sold for agricultural use 5,500 tons of 53-per cent
phosphoric acid during 1947 and approximately 6,000 tons in 1948. The
largest tonnage was applied in California and most, of the remainder in
Arizona, Utah, and Colorado.
Records of the Arizona Fertilizer Control Office (1948) show that 11
registrants listed 36 products for sale as liquid fertilizer in that state
during 1947. -4side-dressing service by which any desired fertilizer mixture can be applied t,hrough irrigation waters is the latest development
in Arizona (McGeorge, 1948)*. These mixtures are usually made from
“simples” which are mixed a t the time of application in the water a t the
The Washington State Department of Agriculture (1948)* reported
statistics showing that 23 per cent of the nitrogen sold as straight nitrogen
materials in that state during the 1946-1947 crop year was in the form
of liquid ammonia which is assumed to have been used in irrigation water.
Although Jones and Green (1946) did not report supporting data,
they stated that, phosphorus added as phosphoric acid in irrigation water
penetrated the root zone of such crops as citrus, sugar beets, and alfalfa
and tended to convert native soil phosphates to more available forms.
Chapman et al. (1945) concluded that experimental findings did not
show a sound basis for the use of sulfur, sulfur dioxide, sulfuric acid, and
other acidifying agents in California citrus groves. Surveys by Smith
(1946) and Turnell (1948), however, indicated widespread interest in
this practice and rather extensive use of sulfur for acidifying soils in some
of the western states.
Fertilizers are applied through sprinkler irrigation in the Willamette
Valley, according to Powers (1947). He has stated also that the fertilization of mint in Oregon through irrigation water is a general practice.
The addition of fertilizer to pastures through irrigation in the coastal
area of Oregon and Washington is becoming increasingly important.
King et al. (1943) in Oregon, Nissley (1946) in New Jersey, and Davis