M I N O R E L E M E N T S T U D I E S ON P O T A T O E S IN MAINE 1

.A_RTHUR HAWKINS ~, J. A. CHUCKA 3, AND B. E. BROWN 4 Maine Agricultural Experiment Station Aroostook, Me.

INTROD UCTION

The study presented in this paper was made to determine what effect the addition of certain of the so-called minor or secondary ele. ments might have on the growth and yield of potatoes when grown on Caribou loam in Aroostook County, Maine. The study was an outgrowth of the serious magnesmm deficiency that developed about IO to 12 years ago in Caribou loam, the leading potato soil in Aroos- took County. Insofar as the magnesium deficiency was concerned remedial measures from a practical standpoint proved to be fairly simple. These consisted in (a) the addition of an available magnesium compound, such as calcined magnesium sulphate, to the potato fertilizer; (b) the application of finely ground dolomitic limestone directly to the soil as a means of counteracting excessive soil acidity and supply- ing magnesium; and (c) a combination of both (6) .

Boron, copper, iron, manganese, and zinc are recognized as elements necessary for the proper functioning of green plants (IO). Increased crop yields have resulted under certain conditions with the application of salts of these elements (I , 2, 4, 5, 7, 8, II , 12, I3) .

For these reasons it seemed advisable to determine whether these elements are furnished in satisfactory quantities by the soil or whether the addition of these elements would increase the yield of potatoes on Caribou loam.

OUTLINE OF EXPERIMENTAL STUDY

Field experiments were conducted to compare a common fertilizer mixture with the same mixture plus a minor element. The sulphate salt of the elements copper, iron, manganese, nickel, and zinc was used

XConducted cooperatively in Aroostook County, Maine, by the Maine Agricul- tural Experiment Station and the Bureau of Plant Industry, U. S. Department of ~griculture.

2Assistant Agronomist, Maine Agricultural Experiment Station. ~lqead of Agronomy Department, Maine Agricultural Experiment Station. 4Senior Biochemist, Fruit and Vegetable Crops and Diseases (Potato Project),

Bureau of Plant Industry, U. S. Department of Agriculture The cooperation of the following growers is gratefully acknowledged: Fred

Ashby, Stanley Beckwith, Earl Blackstone, Leo Daigle, Merle Duncan, H. W. Kitchen, and Burns Long.

1941] HAWKINS, et al: MINOR ELEMENT STUDIES 235

at the rate of IOO pounds per acre in 1932; 25 and 50 pounds per acre 1933 to 1936; and 12. 5 and 25 pounds per acre in 1937 . From 1932 to 1936 inclusive ten plots consisting of single 5o-foot rows of each treatment were used and arranged in the randomization method. The treatments were hand-spread in furrows on either side of a ridge, made by opening discs, in such a way as to simulate two bands when the potato planter split the ridge.

Some mixing of the fertilizer with the soil occurred so that some of the fertilizer or fertilizer-plus-element mixture may have come in contact with the seed pieces. To prevent possible contact of the mix- tures with the seed pieces in the 1937 experiment and to simulate commercial practice the treatments were applied by machine in the conventional side placement band method. Six randomized plots of single 2oo-foot rows were used per treatment in this year. Two leading varieties, Irish Cobbler and Green Mountain, were grown, the latter variety in all tests except on Farm E in 1935 and Farm F in 1937. Ten tests were made during the five-year period (Table I ) .

The results of the boron tests are given in table 2. The 1936 boron experiment consisted of ten 5o-foot single-row plots of each treatment. The fertilizer and fertilizer-borax treatments were hand-spread as men- tioned previously. Injury definitely occurred with an application of 5 pounds of borax per acre when the fertilizer-borax mixture was hand- spread and planting was done immediately. In this method of applying treatments, the borax may have come in contact with, or was very close to, the seed piece. To avoid possible contact of the borax with the seed piece the treatments were applied with a potato planter in the conventional 2-band side-placement method in 1937 to 1939 in- clusive. Six randomized 2oo-foot single-row plots of each treatment were used.

In all these experiments the plots were arranged so that the Analysis of Variance Method could be applied to the data to determine their significance.

DISCUSSION OF RESULTS

Copper, zinc, and particularly nickel had a very depressing effect upon the yield of potatoes when the sulphate salt of these elements was applied at the rate of xoo pounds per acre. But the yield was not significantly affected by an application of xoo pounds of manganese sulphate.

Not a single case of significant variation from the check plots occurred

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TABLE 2.--The influence of boron upon yield of potatoes

Treatment

Check (a)

Plus Borax(b) 2.5 Ibs. 5.0

I0.0 2 0 . 0

I936@)

Fai3n A B

554

544 38I(C)

I937

A C

345 58I 337

333 579 375 280 59I 376

I938

C D E

336 346 382

342 356 379 333 342 400 332 353 34I

I939

C E

213 388

I98 39I Ig6 375 I86 356

(a) 4-8-7 at i ton per acre in 1936, I937 and Farm E. I938. 8-I6-2o at iooo pounds per acre at other farms in I938 and I939.

(b) Pounds per acre rates. Source of boron----ordinary borax. (c) Fertilizer hand-spread in 1936. Possible contact of fertilizer-borax mixture

with seed piece. Apparent toxicity of 5-pound rate. 1937-1939 treatments applied by machine, two-band side placement method.

with hand-spread applications of 2 5 and 5 ~ pounds per acre rates or the machine applications of I2. 5 and 25-pound rates of copper, iron, manganese and zinc sulphates.

The application of these particular elements has influenced plant growth under certain conditions, chief among which is a neutral or alkaline soil reaction, particularly true with respect to iron and man- ganese, and on peat soils inherently low in these minor elements. In view of the fact that the p H of the Caribou loam on which these tests were conducted averaged about 5.0 the occurrence of a deficiency of iron or of manganese appears unlikely. Apparently the copper present in the soil either naturally or from spray residues is ample to meet the requirements of the potato plant for this element.

Nickel sulphate reduced the yields of potatoes at all the rates used. Even the lowest rate, I2I/~ pounds per acre, produced a significantly lower yield on one of the two farms upon which it was used. Larger amounts resulted in serious reductions in yield, indicating that nickel is quite toxic to potato plants. Since all the elements were added in the form of sulphates, it is apparent that the injury is caused by the specific action of the nickel ion itself. That nickel proved to be de- cidedly injurious during germination and later growth was quite obvious from the retarded emergence and subsequent stunted growth particularly where higher amounts of nickel sulphate were applied.

In I936, when the fertilizer-borax mixtures were applied so that the mixture had a chance to come in contact with or was near the

238 THE AMERICAN POTATO JOURNAL [Vol. I8,

seed piece, the addition of borax at the rate of 5 pounds per acre caused a significant decrease in the yield of potatoes of 18 per cent on one farm and 34 per cent on the other. The 2.5-pound rate of borax treatment decreased the yield but not significantly.

In I937 when the fertilizer-borax mixtures were applied by machine in the two-band side-placement method, a significant increase in yield was produced on one of two farms with both the 2. 5 and 5.o-pound per acre borax treatments. This did not follow in I938 since no significant variation from the check plot was found on three farms for 2.5, 5 and Io-pound rates.

In I939, the 5-pound borax treatment produced a significantly lower yield on farm C but no significant variation from the check on the other farm. The Io-pound application caused a reduction in yield on both farms, again a significant decrease on farm C. The 2o-pound application significantly depressed yields on both farms.

SUMMARY AND CONCLUSIONS

In I929, potato growers in Aroostook County, Maine, were con- fronted with a shortage of available magnesium in the soil which proved to be a serious detriment to growth and subsequent yields of potatoes. The remedy which was simple and easily applied was to include an available magnesium compound in the potato fertilizer mixture and to supplement with light applications of dolomitic lime- stone to reduce the acidity of the soil as well as to increase the mag- nesium supply. Soon after the remedy came into use it was practically impossible to locate a field of potatoes suffering from magnesium-hunger in Aroostook County.

The question then arose as to what effect the addition of other so-called minor elements to the fertilizer m, ixture would have on yield of potatoes. Comparative field studies were conducted on Caribou loam. Copper, iron, manganese, nickel, and zinc sulphates were added to a potato fertilizer in the years I932 to I937 inclusive; and boron, as borax, was added to a fertilzer mixture, I936 to I93 ~ inclusive.

The results obtained indicate that comparatively small amounts of boron and nickel added to fertilizer may be toxic to potatoes. The addition of small amounts of zinc indicated a tendency, though not sig- nificant, to increase potato yields. Manganese, iron, and copper, added to the fertilizer in the amounts used, had little or no effect on potato yields. In general it is concluded that at the present time there is no need for the addition of any of the above elements to fertilizer used for growing potatoes under Aroostook County conditions.

I941 ] HAWKINS, et al: MINOR ELEMENT STUDIES 239

LITERATURE CI'TED

1. Allison, R. V. et ctl. 1927. The stimulation of plant response on raw peat soils of the Florida everglades through the use of copper sulfate and other chemicals. Fla. Agr. Exp. Sta. Bul. 19o.

2. Barnette, R. M. et al. 1936. The use of zinc sulfate under corn and other field crops. Fla. Agr. Exp. Sta. Bul. 292.

3. Bertrand, Gabriel. 1926. The importance of minute chemical constituents (Infiniments petits chimiques) o1 biological products: Nickel, cobalt and insulin. Science 64:629-630.

4. Bibliography of references to the literature on the minor elements and their relation to the science of plant nutrition. Second Edition 1936.

5- Boiret, H. and Paturel, G. 1892. The use of sulphate of iron in agriculture. Ann. Agron. 18 (1892):417-44o.

6. Chucka, J. A., and Brown, B. E. 1938. Magnesium studies with the potato. Amer. Pot. Jour. 15:3Ol-312.

7. Churchman, W. L., et al. I936. Copper sulfate as a plant nutrient and soil amendment. Crop Protection Digest. Bul. Series 55-

8. Gilbert, B. E. I934. Normal crops and the supply of available soil man- ganese. R. I. Agr. Exp. Sta. Bul. 246.

9. Hendrick, I. and Carpiauz, E. 19o8. The action of manganese on the potato and the beet. Bul. Inst. Chim. et Bact. Gembloux 75:66-72.

IO. Miller, E. C. 1938. Plant Physiology, McGraw-Hill Co., N. Y. II. Russel, R., and Manns, T. F. 1933. The value of copper sulfate as a plant

nutrient. Trans. Penin. Hort. Soc. 23:51-57. 12. Skinner, J. J. and Ruprecht, R . W . 193o. Fertilizer experiments with truck

crops Fla. Agr. Exp. Sta. Bul. 218, 13. Townsend, G. R., and Wedgeworth, H. H. 1936. A manganese deficiency

affecting beans. Fla. Agr. Exp. Sta. Bul. 30.

I N F E C T I O N O F F I R S T - Y E A R P O T A T O S E E D L I N G S W I T H F U S A R I U M S O L A N I V A R . E U M A R T I I a

j. H. JENSEN AND R. W . Goss

Nebraska Agricultural Experiment Station, Lincoln, Nebr.

T h e tes t ing of pota to p lants g rown f rom seed tubers for resis tance to fusa r ium wilt, e i ther in the field or in the greenhouse, has m a n y d isadvantages in a b reed ing p rog ram. I n the field the percentage of infection wi th Fusarium solani "car. eumartii is usual ly so low tha t a large number of escapes occur when g rowing single seedl ing p lants and this ser iously in terferes wi th a b reed ing p rogram. I n the greenhouse a much h igher percentage of infection can be obta ined but the number of p lants which can be g rown to m a t u r i t y is l imited, owing to the space requ i rement and cost. T h e tes t ing of f i rs t -year seedlings in the green- house would pe rmi t the use of large numbers of p lants and a h igh degree of e l iminat ion of susceptibles, if the typical disease could be p roduced

1Published with the approval of the Director as Paper No. 283, Journal Series, Nebraska Agricultural Experiment Station.