More Food from Soil Science Audiobook Ch. 3 - Some Crops Are MORE Sensitive to Calcium Needs

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C H A P T E R 3
Some Crops Are More Sensitive
to Calcium Needs

CALCIUM IN RELATION TO TOXICITY OF SPRAYS AND
FUMIGANTS IN CONTACT WITH THE FOLIAGE

THE importance of calcium in building up protoplasm resistance
to the toxicity associated with certain sprays and fumigants,
and its relation to the killing effects of herbicides, are too often
overlooked. The following story emphasizes the importance of
people with different training working together.
The importance of pulverized limestone in the soil to the
general welfare of cucumbers, as previously mentioned, was of
much concern to the owners of a cucumber-producing greenhouse
plant in Barberton, Ohio, who prompted me to initiate several
pot experiments. The soil was known to have a high pH of 8.4,
with a very low reading of available calcium. (I want to give
much credit to Dr. Barnes and Dr. Bradfield, who were with Ohio
State University at the time-1932-1934-for their stimulating
ideas and discussions helped me greatly in formulating these experiments.)
The high pH of the soil, along with a very low available
calcium reading, were difficult to understand in terms of our
ideas on the reliability of the soil acidity test in determining lime
needs of the soil. (Since the publication of the 1957 U.S.D.A.
Yearbook, we have a better understanding of this.)
The potassium content of the greenhouse soils was very high,
due to excessive applications of muriate of potash, a ton to the
acre having been applied every year. This undoubtedly had
much to do with upsetting the soil nutrient level. Much of the
calcium leached away as calcium chloride.
To set up the experiment ten quart tubs were filled with soil
and were separately treated with different amounts of pulverized
limestone. Successive tubs except the check received the equivalent
of 400, 800, 1,200, 1,600, 2,000, 2,400, 2,800, 3,200 and 3,600
pounds of calcium per acre. Each tub treatment was repeated
four times. Individual cucumber plants were grown in each tub
and supported on strings hanging from a wire 8 feet above the
tubs. There were differences in rate of growth, from the check
plants, which grew slowly, to those receiving 2,800 pounds of
calcium, which grew more rapidly. Beyond that, there was little
difference in the rate of growth.
When the first plants reached the overhead wire, some of the
margins of the older leaves on all plants which received less than
1,600 pounds of calcium per acre began to turn yellow and die.
This marginal burning is often mistaken for potassium deficiency.
When the plants had cucumbers ready to pick, sulphur dioxide,
from sulphur which had accumulated on a six-inch main line
steam pipe which was used once a year to carry steam for soil
sterilization to a greenhouse beyond, was accidentally released
in the compartment.
The next day many of the plants were entirely dead; whereas
those receiving 2,800 pounds or more of calcium showed no noticeable
injury. When the damage was evaluated, all the plants
receiving 1,600 pounds of calcium per acre or less were dead.
Those in the tubs having between 1,600 and 3,200 pounds exhibited
considerable damage to the older leaves. The results are
shown in the accompanying figures. Apparently, the injury was
indirectly correlated with the amount of available calcium in the
soil. Several years later, I was discussing this with Mr. Fuller,
who marketed the Fuller method of greenhouse fumigation to kill
mites on flowering plants. He said he could not understand why
his method seemed perfectly safe in some houses while in others
it did considerable damage. As he thought about it, he said he
had no difficulty in well-managed houses. Injury occurred in
badly managed greenhouses. I related my experience with cucumbers
and told him to check on the available calcium in the soil.
Perhaps he could find the answer. Several years later he told me
he had restricted his fumigation to greenhouses that were well
managed and where applications of pulverized limestone had
been made.
In 1934, after I returned to New Jersey and started a research
program on soil fertility problems, I reported results on
a pH-available calcium problem in Soil Science. We were finding
many similar cases in sandy loam soils due to excessive uses of
nitrate of soda in the production of vegetable crops. During the
next twenty years I ran into this same problem in many different
areas east of the Mississippi River.
Some six years after I had had the experience with the cucumbers,
I was asked to work on a co-operative project where
arsenic injury was being studied on fruit trees in New Jersey.
The leaves on these apple trees had turned yellow and dropped
off at about the time the fruit was half grown wherever arsenate
of lead had been used for the control of worms in the fruit.
Eventually the trees showed many naked branches with only two
or three leaves on the tip. This condition was not unlike the
symptoms of magnesium deficiency on apple trees. In the following
year or two, the trees did not set fruit, and some of them
died. Since arsenate of lead was a common spray ingredient, and
since the foliage turned yellow at about the time arsenate of
lead was used in the spray, this ingredient was viewed with suspicion,
and chemical studies were started to find out how the
arsenate of lead was causing the injury. It seemed that the injury
occurred a week or two after the spray was applied. It followed
the pattern of a systemic disease: no burning or immediate
injury, but a gradual fading of the green color and abscission
of the leaf.
After six years of study, trying to find out how arsenate of
lead was doing the damage, we felt we were up against a stone
wall. Nothing definite had been learned. At this time it was decided
that the assistant extension specialist in horticulture, Mr.
Harold Robertson, and I were to make a survey of the orchards
and find out how widespread this damage really was and whether
we could find some correlations in the field.
From my previous experience, I was prompted to take a
portable acidity tester with me. After visiting at random ten
orchards, all of which were being sprayed with arsenate of lead,
we found orchards ranging in injury from those in which trees
were in poor growth with some trees dying, to orchards which
were in perfect condition and yielding heavy crops of fruit. It
was also noticeable that where the trees were badly damaged,
cover crops would not grow very well under the trees. It was
evident that arsenate of lead was not the real cause, although it
did not eliminate the possibility of some indirect effect, since
we found no orchards where arsenate of lead had not been used.
We decided to investigate one of the most badly damaged orchards,
which happened to belong to Paul Burke, on Rancocos
Creek in Camden County, New Jersey. We found him very
co-operative and anxious to work with us.
I must digress for a moment to give some background information,
because sociological factors are sometimes tied in with
cultural practices. To my way of thinking, Paul Burke was a
gentleman fruit grower. He worked very closely with experiment
station people, read, in addition to other things, everything
he could find on fruit culture, and tried to do the right thing.
He and his wife lived in one of the beautiful old homes in New
Jersey, surrounded by antique furnishings which would do credit
to many museums. Their family consisted of three sons, two in
college and the third getting ready to attend Cornell University.
The eldest son had attended the University of Pennsylvania and
was the current Olympic sculling champion. Everyone worked,
and it was very discouraging to see acres and acres of orchards
gradually dying, apparently in spite of following recommended
practices. As we walked through the orchards and saw the poor
crops, our conversation revolved around the idea that a good
crop of apples on such a fruit farm should pay the expenses necessary
to assure three boys a college education; whereas a poor
crop could actually just be an additional expense.
I resolved that I was going to solve Mr. Burke's problem if it
was the last thing I ever did. I asked Paul what the lime condition
in his soil was, and he said the pH was satisfactory, 6.4
to 6.8. The soil was a loamy sand and had produced exceptionally
fine fruit in past years. As we walked through the orchard,
we found spots near trees where some sweet clover plants were
growing two feet tall. I grabbed a plant and was surprised that
it could be pulled up with very little effort. When I examined
the roots, I found that the tap root had grown one inch and had
then divided so that it resembled an inverted Y, with the branch
roots all growing parallel to the surface of the soil at the one-inch
depth. Mr. Burke told us he had applied 2 tons of limestone per
acre before the sweet clover was sown. He had disced the limestone
into the ground. I got my acidity tester and checked the pH
and found the soil tested 4.7. Paul said my soil tester was wrong,
that he had tested the soil with his tester and it was 6.4. Then I
took a sample of the surface inch of soil and we both got a 6.4
reading. The limestone was all in the surface. When he told me
that he had run the disc harrow eight inches deep to mix the
limestone with the soil, I told him he used the wrong tool to do
the job.
We secured a shovel and started digging holes around the
trees. All the older roots had sent feeder roots up to the surface
inch of soil. Every time he disced the soil, he cut off all the
feeding roots. We realized that the trees were starving. He used
sulphate of ammonia as his nitrogen fertilizer. This was making
the soil more acid.
When we realized that the problem seemed to be associated
with a lime deficiency in the subsoil, we suggested that he apply
limestone, 2 tons to the acre, plow it under, and put 2 tons on
after the ground was plowed. Up close to the trees where he
could not plow we suggested that he spread six to eight shovels
of limestone. He was worried about cutting off the roots when
he plowed the ground. I told him it would not be any worse than
cutting them off with the disc harrow. Several months after he
applied the limestone we dug holes around the trees again and
found the soil full of feeding roots. That late summer I left
Rutgers University and I did not see this orchard for three years.
When I did see the orchard again, it was producing a fine crop
of fruit. I could hardly believe that this was the same orchard,
and Mr. Burke informed me that he was still using arsenate of
lead.
A number of years later I had occasion to work with a peach
grower in one of the southern states along the Atlantic seacoast.
This grower had 60 acres of fruit. When I first visited this orchard,
the grower was alarmed about the growth condition of
his trees, particularly since he had been told that he was not in
a peach-growing area and that weather conditions and spray
materials were responsible for the sickly appearance of some of
his trees just when they were beginning to produce fruit. As we
walked through the orchard, he pointed out trees that were showing
signs of injury. When I asked him whether he had used
limestone on the soils, he informed me that he had been warned
by his college advisers that he should not use it as it might ruin
the orchard. When I told him that he would lose a number of his
trees if he did not put on limestone, he started an argument. I
told him I wasn't interested in arguing, but that if he was willing
to put on 3 to 4 tons of limestone per acre around some of his
sick trees, I was sure the trees would be revived.
When he saw how much good the limestone did for these
trees, he put limestone on all the trees. After that he had vigorously
growing trees that yielded quantities of high-quality fruit.
The college advisor still warns him against using limestone on
peaches. The grower, for some reason, did not tell him about his
putting on the limestone. The human equation is hard to understand
at times.
It seems as though every time I mention limestone to a grower
he tells me that he has been warned by his county agriculture
agent not to use limestone. A number of years ago I told a
spinach grower that his problems were due to insufficient lime
in his soil, and he told me that his county agent had told him to
be careful not to overlime. I set up some plots applying 2, 4, 6,
and 8 tons of limestone per acre. I found out later that several
people from the experiment station had taken pictures of the plots
because they were sure that I would "overlime" the soil. The
grower told me that when the spinach on the 8-ton plots began
to grow better than on the other plots, they stopped taking pictures.
The plot outyielded the others. I couldn't understand why
they weren't interested in growing better spinach, and why they
didn't take pictures up to harvest. Their attitude seemed to be to
try to prevent growers from growing better crops rather than to
help the farmer to do a better job. It was a case where the book
could not be wrong.
We have too much of a negative approach to our fertility
problems. A lot of research people—I should label them testersseem
to try to disprove anything that is new. They make up their
minds that the new idea is wrong and won't work, and then they
try to prove it. And if they can't prove it is wrong, they blame
the weather. They would do the farmer much more good if they
would approach a problem humbly and open-mindedly, and
reserve their final opinions until all the evidence was in.
I have heard agricultural research people criticize people engaged
in fundamental research in other fields as being long-haired
and too impractical or so technical that nobody could understand
them. I immediately classify such a person as ignorant or too
lazy to try to understand. It is my candid opinion that our
agricultural problem, if there is one, can only be solved by men
who are steeped in fundamental research. There is no place for
the politician in this picture. A farmer, to maintain a satisfactory
standard of living, must look to the fundamental research man
for guidance. Superficial thinking is responsible for low average
yields, which can only lead to a low standard of living. The picture
is not a pretty one; and our extension service set-up must
assume a lot of the responsibility for making the picture as dark
as it is.
Agriculture is complicated business. It is 100 per cent a chemical
phenomenon and it takes chemical knowledge to understand
it. We find farmers who are doing an exceptionally good job
who have no chemical training, but for every one like that there
are ten or more who are barely existing. To them, chemistry is
bunk. I knew a college professor who, when confronted by some
statement he could not understand, turned it aside by saying,
"It's the bunk." He even wrote a book which was a repetition of
what others had written before him in other books. People with
such points of view should not be in a position where they can
teach others. They are responsible for much of the agricultural
misinformation that is disseminated for the farmer's use. It will
be corrected eventually, but in the meantime many farmers will
lose their farms.

THE AMOUNT OF CALCIUM IN THE SOIL AND
THE GROWTH OF CUCUMBERS, TOMATOES AND
CELERY IN A GREENHOUSE, AND CELERY AND
HORSE-RADISH IN THE FIELD

During the early 30's I was employed by a large greenhouse
grower in the Akron area to help him find out why cucumbers
and tomatoes were growing so poorly with what seemed like
ample fertilizer. The cucumbers grew to the wires 6 feet above
the ground with much yellowing of the older foliage, which soon
caused premature drying of the old leaves and much malformation
of the fruit. Diseases seemed to be prevalent in abundance.
There were many "nubbins," mature cucumbers not over 3 inches
long. By this time the growing tips showed symptoms of mosaic.
The tomato plants seemed to grow freely enough, but they
did not set fruit readily and much of the fruit that did set developed
into rough, misshapen specimens. The leaves showed
many chlorotic areas and premature drying of the older leaves.
An examination of the foliage with tests applied while examining
leaves under the microscope showed a large amount of
potassium but no available calcium crystals. When we examined
the soil there was no available calcium. However, the pH of the
soil was above 8.0. The potassium was very high and the phosphorus
was low. A situation existed here which was contrary
to general knowledge—a pH above the neutral point but a negative
test for calcium.
The soil indicated a highly dispersed physical condition—very
slippery and slimy when it was wet, and baking as hard as a
brick when it was dry. The soil between the rows, where there
was much traffic, was as hard and smooth as an asphalt highway.
When it was worked between crops, it was hard and lumpy. It
was very difficult to steam-sterilize the soil because of this lumpy
condition.
It happened that a Dr. Doolittle, from the U.S.D.A. Department
of Plant Pathology, stopped by about this time, so I had
a chance to discuss our mosaic problem with him. When he
looked at the plants, he asked, "Why are you applying so much
potash?" I told him that I was unaware of any heavy applications
of potash having been made. However, this agreed with the
microscopic examination I had made previously. When we inquired
about this from the grower, he said he had applied a ton
of muriate of potash per acre before each crop of cucumbers,
because he had been advised that if you wanted to grow highquality
cucumbers, you needed an abundance of potassium.
He further informed us that the first time they used it the cucumbers
were definitely better than the previous crop, but that after
that succeeding crops were not of high quality. I assumed from
this that the potash had made available, through displacement,
liberal quantities of calcium the first few times it was used, and
that succeeding applications released less and less calcium, which
was not sufficient to balance the liberal quantities of potassium
in the soil. This also could account for the high pH, because of
the greater activity of the potassium ion. In other words, with no
available calcium in the soil, the plants absorbed potassium in
large quantities. There apparently was so little calcium and so
much potash that the plants looked as though they had a disease.
The soil (normally a good silt loam) was hard. Limestone could
soften this soil; but the pH was above 8.0. (I later found that
by adding magnesium limestone, the pH of 8.0 dropped to 6.8.)
I immediately got some of this soil into the laboratory, mixed
it thoroughly, divided it into four lots, and filled eight-inch pots
with it. One lot I put in pots with no additional treatment, for
a check. To the second lot I liberally added pulverized limestone.
To the third lot I added calcium sulphate, or gypsum, and to the
fourth lot I added potassium nitrate. I planted cucumber seed
and grew the plants on strings until the largest were 6 feet tall.
Without any treatment, the plants grew slowly, and resembled
the plants in the greenhouse. The gypsum and limestone plants
were beautiful by comparison. They looked like well-grown cucumber
plants. If there was any difference, it was in favor of the
limestone. But the potassium nitrate plants were a sorry sight.
They grew slowly and resembled the greenhouse plants, except
that they were not as good.
When I took the plants out of the pots, I found that the roots
on those receiving limestone were all through the soil, so that
the soil fell apart when I removed it from the pots. The soil in
the gypsum-treated lot was not as loose. The soil in the other
two lots was hard. The roots had grown between the pot and
soil and the soil held together firmly in a hard ball. When I tested
the soil, I found it to be 6.8 in the limestone series, 7.3 in the
gypsum series, and over 8.0 in both the check and the potassium
nitrate-treated soil. I must point out here that I did not apply
equivalent amounts of calcium as limestone or gypsum.
I decided you could have a high pH soil and still have calcium
deficiency. I immediately ordered two carloads of dolomitic,
pulverized limestone and spread 80 tons on the eleven acres of
greenhouse beds. We used a rototiller to mix it with the soil.
It was the end of our troubles. The so-called mosaic on the
cucumbers disappeared, the spotty condition on the tomato
leaves disappeared, and the soil became mellow instead of turning
up in large, hard lumps.
I was asked to come back to the New Jersey Experiment Station
after this, and the first problem I got involved in was a high
pH, calcium deficient celery soil. When I told my colleagues what
I had concluded, they said, "You can't have such a condition out
here. You can only have that in the alkali soils." But when a
grower brought me half-grown celery plants with the heart leaves
rotting, I immediately said it was calcium deficiency. He said
that it couldn't be because the pH was neutral. When I checked
the plants and soil for calcium, I found none. There certainly
was no calcium available to the plant. It was too late to do anything
in the field, so we got enough of his soil to set up an experiment
in the greenhouse. We compared the untreated soil with
the same soil to which we had added limestone, and set in some
of his sick plants. Without limestone, the plants made no further
growth. With limestone, the plants started to grow and finally
outgrew the calcium deficiency injury. When I tested the soil in
the two lots, that with the limestone had a pH of 6.4 while the
check lot tested 6.9. The pH had actually been lowered by the
lime treatment.
I have seen this happen on numerous occasions. I have recommended
3 to 8 tons of limestone per acre on soils that had a
neutral pH but very little available calcium, and have had the
growers call me and ask me why their pH dropped to 6.2. They
were always ready to condemn the limestone, but when we
checked the soil for calcium we found it adequate for the soil
type. I must warn anyone who conducts these tests that the pH
will vary from 6.0 to 7.0 during a twelve-month period.
Soluble salts tend to move up and down in the soil, depending
on its moisture content. During the summer, except after
very heavy rains, soluble salts may be very high in the surface
inch of soil. During the winter these salts are very low, accompanied
by some leaching. During the summer, loss of nutrients
occurs mostly from surface runoff. The soluble salts in the surface
usually have very little calcium, unless the soil is saturated
with calcium. Most of the calcium probably is lost by leaching.
Water running out of drain tiles where large amounts of mixed
fertilizer had been applied has been known to carry 40 p.p.m.
of calcium, in the form of calcium chloride.
When I asked the celery grower how his soil had reached this
low calcium condition, he told me that the farm had originally
been a potato farm where the pH was maintained at 5.5 or less
to control scab. However, the owner had found too much scab
and had sold the farm. The present owner had grown a fairly
good crop of celery with 150 pounds of nitrate of soda the first
year. During the following years, he had found that he had to
use more and more, until for the present season he applied 1,500
pounds of nitrate of soda, and his celery developed calcium deficiency.
My explanation to him was that the soda probably was
kicking calcium out of the exchange complex until most of
it was replaced by sodium. The nitrate nitrogen probably did
not help the celery much. The problem, therefore, was to replace
this sodium with calcium. Since the calcium requirement of this
Collington sandy loam should not be over 2 tons of pulverized
limestone per acre-foot, it should have been a simple matter to
correct. However, when we went to the field with the problem,
we found a plow sole 2 to 4 inches thick under the plowed
layer. In some cases this was as hard as concrete. So, we plowed
under a ton of limestone and applied another ton on the surface
and mixed it as well as we could. We worked on this problem
for seven years, during which time we had applied 6 tons of
pulverized limestone per acre; and our celery still suffered from
what seemed like calcium deficiency. I finally asked Dr. Joffee
from the Soils Department at Rutgers to work with me on this
problem. He very carefully examined the soil profile to a depth
of four feet, tested various layers and, after some calculations,
told the grower he probably would need another 6 tons of limestone.
He found later that the irrigation water, which came from
a 300-foot, ten-inch well, contained an appreciable amount of
sodium chloride. A new well was drilled 100 feet deep to give
salt-free water. Nevertheless, applications of limestone gave a
definite boost to the celery for several years after this. During this
trial period, a smaller field where he grew plants developed calcium
deficiency. When the plants were four inches tall, the hearts
died out, very much as they would do with boron deficiency. A
heavy application of pulverized limestone was applied broadcast
over the plants. Four rows of plants were left without limestone
for a check. The hearts of these plants and the older leaves made
no further growth. Those that received the limestone recovered
and made a normal growth. The grower told me he could see an improvement twenty-four hours after the limestone was applied.
I have used this same treatment on spinach with equally
good results. Even though this grower did grow some very good
celery during the years we worked with him, it was necessary to
apply some limestone every year to maintain a healthy growing
crop. It seemed very difficult to kick the sodium out of the colloidal
complex. My experience in later years convinced me that
if we had applied 4 to 6 tons of calcium limestone per acre along
with some gypsum, and had mixed it with the soil through the
use of a rototiller set deep enough to break up the plow sole,
we might have seen a permanent correction in two years. As it
is, after some twenty years the grower is still having a problem,
but it is easily corrected with a ton of limestone.