B. E. Brown

Minor element studies on potatoes in Maine

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 Aroostook 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 supplying 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.

Further studies on the placement of fertilizer for potatoes

SummaryThe efficiency of a potato fertilizer depends not only upon its composition, the rate at which it is applied, but also upon where in the furrow there was only a slight difference in yield as compared with complete fertilizer applied at each side of the seed piece.The main implication suggested by the results is that potato fertilizer may be rendered more efficient by applying it not as a complete fertilizer but by what might be termed a differential placement. In view of the fact that superphosphate is believed to promote root development the placement of this constituent in contact with the seed piece, especially as it exerts no appreciable injurious action when applied at normal rates, would appear desirable. As certain nitrogen materials when in contact with the seed piece cause the most injury it would seem desirable that they be placed on each side of the seed piece in combination with the potash materials not only to avoid injurious effects but to promote the efficiency of the potato fertilizer as much as possible. From a yield standpoint the divided placement, over the two-year period, (Treatment 6), gave a yield that was 27.5 bushels greater than that obtained when the complete fertilizer was applied in a band on each side of the seed piece (Treatment 2).The results presented herein, although obtained over a two-year period on one soil type, suggest strongly that all the ingredients of a potato fertilizer do not necessarily render their greatest efficiency when applied as a complete fertilizer even though the method of application, side placement, is known to be favorable to emergence, stand and yield.Finally, it should be considered that the only phosphati material used in the present study was ordinary superphosphate, containing 18 per cent P2O5. Just how other phosphates, such as ammonium phosphate, would have behaved, if similarly applied, was not determined.

Fertilizer placement for potatoes: A comparison of level-band and hi-lo methods

SummaryIn recent years much interest has been taken in the placement of fertilizers for the potato crop. The results of several years’ field work, 1931–35, showed that of the 6 or 7 methods of placement compared, the most profitable method was the one which placed the fertilizer in a band on each side of the seed piece, two inches therefrom and on a level with or slightly below the lower plane of the seed piece. Accordingly this particular method was officially recommended by the National Joint Committee on Fertilizer Application and it is the one that has been generally adopted by potato growers and machinery manufacturers alike. Since the general adoption of this method, other methods have been suggested for the potato crop. One of them, the so-called Hi-Lo method, is reputed to have an advantage from placing one of the fertilizer bands two to three inches below the seed piece level into presumably more moist soil in order to better maintain its nutrient availability to the potato plants should dry weather prevail. Another suggested change involved placing more of the fertilizer in the lower band than in the upper one, such as the 25–75 per cent fertilizer distribution considered in the, present tests.

Field comparisons of colloidal phosphate and superphosphate as sources of phosphorus in potato fertilizers

SummarySuperphosphate, triple superphosphate, and mono-ammonium phosphate (Ammo-Phos) are the main sources used to supply phosphorus in potato fertilizers. As is generally recognized, growing potato plants require relatively large amounts of readily available plant nutrients. Although the amount of phosphorus absorbed is only about one-eighth to one-fourth of the amount of nitrogen and potash absorbed, the source of phosphorus must also be readily available to meet the needs of the potato plant for this essential plant nutrient. For a number of years a material designated Colloidal or Waste-pond Phosphate has been on the fertilizer market; at least it has been offered for sale to farmers who use fertilizer for crop production purposes. Potato farmers have been solicited to purchase the material on the strength of statements that its phosphorus is available and that, moreover, it has additional merit because of its content of certain so-called minor or secondary nutrient elements.Field studies have been made in Maine, New Jersey, Pennsylvania, and Virginia to compare Colloidal Phosphate and superphosphate as sources of phosphorus in potato fertilizers, the results of which have shown:1.In all field comparisons,—a total of 13 having been made,—potato plants receiving fertilizer mixture formulated with superphosphate produced greater yields than those receiving the fertilizer mixtures which had Colloidal Phosphate as the source of phosphorus. In Maine, the average increase for 8 tests was 68 bushels per acre in favor of superphosphate; in New Jersey, 1 test, 27 bushels per acre; in Pennsylvania, average of 2 tests, 24.5 bushels per acre; and in Virginia, average of 2 tests, 64 bushels per acre.2.The more favorable influence of the superphosphate fertilizers on earlier emergence, vine development, tuber set, and number of marketable tubers produced was pronounced.3.The results reported herein afford a pattern showing (1) that the use of Colloidal Phosphate as a source of phosphorus in potato fertilizers is not justifiable, and (2) that the maintenance of normal vine growth and maximum potato yields requires the use of a material high in available phosphorus as the source of phosphorus in potato fertilizers.

The influence of magnesium on different potato soil types

SummaryObservations made over a period of several years have disclosed well defined growth disturbances of potato plants in a number of important potato producing sections. The sections under observation have been chiefly along the Atlantic seaboard, including certain potato producing sections in Maine, New York, New Jersey and Virginia, although reports of similar plant disturbances have been reported elsewhere.Wherever the trouble prevailed the chief symptom has been a chlorotic condition of the foliage, the lowest leaves being most seriously affected. In severe cases these leaves finally turn brown, thicken, become hard and eventually die. The change of color from normal green to yellowish green to yellow starts at the margin of the leaf and gradually involves the entire leaf until in advanced stages brown necrotic areas develop.The plants were stunted in growth and while frequently the later growth possessed a more nearly normal color there would be enough of an upset in the life of the plants to cause marked reductions in yield.In practically every case examined, the main exceptions occurring in Virginia, the affected plants were found to be growing on very acid soil, pH 4.2 to 5.0, probably too acid for normal potato development. Coupled with this was the use of fertilizer containing a high proportion of ammonia nitrogen which tended to aggravate the acidity prevailing near the growing plants. With this high acidity factor prevailing it would be reasonable to assume that leaching of basic compounds would be active, particularly lime and magnesia. Where the pH reading went much above 5.2 very little, if any, trouble was in evidence, nor was it found where considerable quantities of manure were used or green cover crops turned under.As there were no recognizable pathological symptoms it was believed that the chief trouble was an improper nutrition of the plants, due to some deficiency of an essential element or possibly to the presence of some poisonous compound in the fertilizer. However, analytical work on samples of fertilizer which were applied for the potato crop showed no toxic material present and in every respect the fertilizer was normal so far as plant food content was concerned. About the only special feature brought out by the work was the large proportion of ammonia nitrogen in the fertilizer.

Soil fertility and fertilizer problems facing the potato industry

3. Leach, J. G. The nature of seed piece transmission of potato blackleg. Phytopath. 17: 155-160. 1927. 4. Leach, J .G. Potato blackleg: The survival of the pathogene in the soil and some factors influencing infection. Phytopath. 20: 1930. 5. Patel, M. K. Viability of certain plant pathogenes in soils. Phytopath 19: 295-300. 1929. 6. Ramsey, G. B. Studies on the viability of the potato blackleg organism. Phytopath. 9: 285-288. 1919. 7. Rosenbaum, J. and G. B. Ramsey. Influence of temperature and precipitation on the blackleg of potato. Jour. Agr. Res. 13: 507-513. 1918.