il l 1 ( W‘Hl‘i IN i IHKIH‘IMI‘EIW 1 \ ‘ 114 158 THS THE EFFECT OF LEVELS OF PHOfiPHATE AND zfiQYIRSH FERTELEZA‘E‘EON 6N WELD; QUALIYY, ARE CGMPOSETEQN OF SEBAGO PCTA?OES GRGWN 0N HOUGHTON MUtK Thesis for file Dogma o; M. 5. MICEEGRN STATE UNE'X’ERSETY Leo Klameth 1959 if???” THE EFFECT OF LEVELS OF PHOSPHATE AND POTASH FERTTLTZATTON ON YIELD, QUALlTY, AND COMPOSITION OF SEBAGO POTATOES GROWN ON HOUGHTON NUCK by Leo Klametn AN ABSTRACT Submitted to the College of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE -Department of Soil Science Year 1959 \ Approved (221:;27/g;;21&3‘-#7 /fi" LEO KLAMETH ABSTRACT In this study several combinations of phosphate and potash fertilizer were evaluated regarding their influence upsn scil test and yieli.©uality, ani campositisn of potatoes grown on organic soil during the growing seasons of 1956 and 1957. The yield, size, specific gravity, and compo- sition of the tubers were determined. From top samples the yield, per cent dry matter and composition were deter- mined. Regression analysis, analysis of variance, and simple correlations were used in evaluating the relation- ships that existed. The yield of tubers was significantly influenced by fertilization. A curvilinear type equation apparently fitted the yield data with a much greater degree of accuracy than did a straight line function used. Also restricting the analysis to data in the response range gave a much better fit than when all the data were used. Specific gravity of the tubers was related inversely to application rates of P205 and K20. The maturity of tops as indicated by the per cent dry matter was affected inversely as additional amounts of P205 and K20 were applied. The tubers and tops were analyzed for nitrogen, calcium, phosphorus, potassium, magnesium, and sodium. In general, there was a marked seasonal variation in the effect of the applied P295 and K20 on the per cent LEO KLAMETH ABSTRACT composition of several of the elements. A straight line equation explained more of the variance than did the curvilinear equation when applied fertilizer was used as the variable to predict their composition. The phosphorus percentages of tops and tuber increased with increased application of P 0:. The potassium percen- 2) tages of tops and tubers increased with increased appli- cation of K20. The K soil test reflected the amount of applied K20 to a greater degree than did the P soil test in predicting the amount of applied P205. THE EFFECT OF LEVELS OF PHOSPHATE AND POTASH FERTILIZATION ON YIELD, QUALITY, AND COMPOSITION OF SEBAGO POTATOES GROWN ON HOUGHTON MUCK by Leo Klameth A THESIS Submitted to the College of Agriculture of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Soil Science Year 1959 ACKNOWLEDGMENT The author wishes to express his sincere gratitude to Dr. J. F. Davis and to Dr. R. L. Cook under whose guidance, supervision, and support this work was conducted. Acknowledgment is given to Lawrence N. Shepherd for assistance in field and laboratory work, to John C. Shickluna for determinations made on the soil samples, to Bernard R. Hoffnar of the Agricultural Economics Department for help obtained in the statistical analysis of the data, and to H. M. Brown of the Farm Crops Department for critically reviewing the thesis. The writer is grateful to Dr. E. J. Benne of Agricul- tural Chemistry Department for furnishing samples of deter- mined composition. He also expresses his gratitude for the opportunity of associating with the graduate students of the Soil Science Department during this work. The financial support given this project by the Agricultural Economics Branch, Division of Agricultural Relations, Tennessee Valley Authority was appreciated. TABLE OF CONTENTS PAGE INTRODUCTION. . . . . . . . . . . . . . 1 REVIEW OF LITERATURE . . . . . . . . . . . 2 METHODS AND MATERIALS. . . . . . . . . . . 6 RESULTS AND DISCUSSION . . . . . . . . . . 10 Yield Relationships . . . . . . . . . . 10 Specific Gravity . . . . . . . . . . . 12 Size . . . . . . . . . . . . . . . 13 Chemical Composition of Tubers . . . . . . 1A Yield and Chemical Composition of Tops. . . . 16 Soil Tests . . . . . . . . . . . . . 18 SUMMARY . . . . . . . . . . . . . . . l9 BIBLIOGRAPHY. . . . . . . . . . . . . . 21 APPENDIX . . . . . . . . . . . . . . . 2A TABLE 10. ll. 12. LIST OF TABLES Plot diagram. Adjustment of the Beckman Spectrophotometer for the determination of calcium and sodium. Soil test and yield, specific gravity and per cent of grade B tubers as affected by levels of Phosphate and potash fertilization Yield as influenced by levels of phosphate and potash fertilization . . . . . . . Analysis of variance of yield of A x A x 3 factorial as influenced by levels of phos- phate and potash fertilization. . Regression relationships between yield, per cent of grade B, and specific gravity of tubers and the levels of phosphate and potash fertilization using 114 observations and determined by the equation y = a + lel + ngg + b3(X1X2) . . . . . . . . . Comparison of regression relationships of the yield of tubers and the levels of phosphate and potash fertilization using variation in observations and type of equation. Soil test and yield, specific gravity, and per cent of grade B tubers as affected by phos- phate fertilization . . . . Soil test and yield, specific gravity, and per cent of grade B tubers as affected by potash fertilization . . . . . . Composition of tubers as affected by levels of phosphate and potash fertilization . . Composition of tubers as affected by phosphate fertilization . . . . . . . . Composition of tubers as affected by potash fertilization . . . . . . PAGE 25 28 29 3A 35 36 37 38 39 MO 42 43 TABLE 13. 14. 15. 16. 17. 18. 19. 20. 21. PAGE Averages of yield, specific gravity, per cent of grade B, and composition of tubers. . . 44 Percentage change of 1957 averages of yield, specific gravity, per cent of grade B, and composition of tubers with respect to 1956 averages . . . . . . . . . . AA Regression relationships between the composition of tubers and the levels of phosphate and potash fertilization using 51 observations and determined by the equation y = a + blxl + b2X2 + b3(X1X2) . . . . . . . . . 45 Yield, per cent dry matter, and composition of tops as affected by levels of phosphate and potash fertilization . . . . . . 47 Soil test and yield, per cent dry matter, and composition of tops as affected by phosphate fertilization. . . . . . . . A8 Soil test and yield, per cent dry matter, and composition of tops as affected by potash fertilization. . . . . . . . . . . 49 Regression relationships between the yield, the per cent dry matter, and the composition of tops and the levels of phosphate and potash fertilization using 21 observations and determined by the equation y = a + blxl + b2x2 + b3(x1x2). . . . . . . . . . 50 Simple correlation coefficients of the per cent K in tubers and tops and the applied P205 fertilizer* at constant K20 fertilizer levels . . . . . . . . . 51 Regression relationships between applied P O fertilizer and active P and between appTied K20 fertilizer and active K using 105 obser- vations and determined by the equation yapplied = a. + bXaCtive o o u o o o o 51 INTRODUCTION High yields of potatoes (Solanum tuberosum) are produced on organic soils. Approximately 17,000,000 acres of organic soils are located in the north central region of the United States. These land resources under proper management represent potential areas suitable for future food production. Proper management includes an understanding of the effect of applied nutrients upon the yield, quality, and chemical composition of the crop, as well as its residual effect upon the soil. In this experiment several combinations of phosphate and potash fertilizer were evaluated regarding their influ- ence upon yield, quality, and composition of Sebago potatoes, and soil tests during the growing seasons of 1956 and 1957. REVIEW OF LITERATURE Work on the fertilization of potatoes grown contin- uously on the same land was done by Lawes and Gilbert. Burton (2) reported results for the first twelve years in the following table: EFFECT OF MANURIAL TREATMENT AVERAGE RESULTS FOR THE YEARS 1876-87 (from Gilbert, 1888) 3’5 Diseased % Dry Specific Treatment Tons/A Tubers Matter Gravity Unmanured 2.0 3.15 28.1 1.118 Dung (avera e of years 1876-81) 5.2 5.51 25.8 1.106 Superphosphate 3.7 3.66 26.8 1.115 Mixed mineral manure 3.8 3.45 26.5 1.114 Ammonium salts alone 2.3 4.06 26.2 1.110 Nitrate of soda alone 2.6 4.93 26.5 1.112 Ammonium salts and mixed mineral manure 6.7 6.26 25.6 1.104 Nitrate of soda and mixed mineral manure 6.7 7.00 25.8 1.108 The data show a maximum reduction in the percentage dry matter from 28.1 to 25.6. This was accompanied by a 235 per cent increase in yield, so that the net result was an increase of 0.56 to 1.72 tons of dry matter per acre. Bigger, gt a1. (1) and Lucas, gt a1. (18) found that the highest average yield of potatoes was produced where 100 pounds per acre of phosphate and 300 pounds per acre 2 of potash was applied. Davis (6) found that potatoes growing in soil to which 600 pounds of 0-9.5-27.5 per acre had been applied produced the highest yield of No. 1 Irish Cobbler per acre. Fitch (13) on 10 Iowa soils obtained highest yields from potatoes growing in soil to which 500 pounds of 0—9-27 fertilizer per acre had been added. Hardenburg (15) stated that old muck is usually deficient in available nitrogen and contains some residual potash while newly developed organic soils seldom need much com— mercial nitrogen and are likely to be deficient in both potash and phosphate. Cobb (5) reported that good cooking quality is closely associated with high dry matter and low nitrogen content of the tuber, with temperature and variety as the more important factors influencing these. Potatoes at the extremes of the density range are unsuited for commercial usage. Low density potatoes are watery and waxy and produce a translucent product of poor reconstitution properties, while potatoes of very high density often result in products which slough badly on cooking or have low cohesive properties (31). Clark, at 31. (4) found specific gravity to be a practical method for making a preliminary selection for mealiness. Shoemaker (24) used specific gravity to express different degrees of mealiness. Potatoes with a specific gravity of greater than 1.080 are bakers, from 1.080 to 1.070 are boilers, and those less than 1.070 are fryers. Terman, 22 a1. (28), (29), (3o); Chucka, at 31. (3); Fineman (11); Dunn and Nylund (9); and Smith and Kelly (25) reported that soils fertilized with muriate of potash as compared to the non-chloride forms produced tubers that had a lower specific gravity and a lower starch percentage. Eastwood and Watts (10) found that specific gravity was affected by a complex of factors including potato variety, potash level, and potash source. Hawkins (16) reported that the proportion of the nutrients absorbed by the plant from the soil that were translocated into the tubers was as follows: 80 per cent of P, 67 per cent of N, 60 per cent of S, 40 per cent of Mg, and 5 per cent of Ca. Terman, at al. (27) noted a decrease in the concen- tration of NO3 and Mg in the plant with an increase in potash fertilization. The nutritional unbalance in plants grown on soils fertilized with excessive amounts of potash may be the reason for the decrease in yield frequently obtained. Gausman and Awn (14) concluded from an experi- ment showing the effects of C1” from CaCl2 on P32 accumu- lation in potatoes that the amount of P32 increased as increments of Cl' from CaCl were increased to 400 ppm. 2 Above 400 ppm. there was an apparent and progressive de— 32 crease in the amount of P accumulating in the potatoes. Hence, the inhibitory effect of the higher amounts of 01' on the uptake of P32 is implied. Metzger (19) found that phosphate fertilized plots produced vines slightly heavier than the check and that they reached their maximum weight and declined in weight one week earlier than the check. Plots fertilized with potash reached maximum weight three weeks later than did those grown on the unfertilized plots. Penston (21) stated in a study of the potato plant that the regions of meristematic division, photosynthesis, and translocation and storage of food materials contain K in considerable quantity. The association of K with protein in nearly all tissues also suggests that it may be necessary for protein metabolism. METHODS AND MATERIALS The potatoes were grown on a Houghton muck (pH 6.0- 6.3) at the Michigan State University Muck Experimental Farm, in Clinton county. An incomplete factorial design was used having four no fertilizer plots and using ten levels of P205 and 18 levels of K20. Included within this incomplete factorial was a 4 x 4 x 3 factorial having 100, 200, 300, and 400 pound per acre rates of P205 and 200, 400, 600, and 800 pounds per acre rates of K20. The plot outline (Table 1) was the same for the years of 1956 and 1957, with 1956 being the first year of crop production on this land. Fertilizers used the first year were muriate of potash (60%-K20) and treblesuperphosphate (45%-P205). The second year sulfate of potash (48%-K20) and treblesuper- phosphate (45%-P205) were used. The fertilizer was broad- cast on the plots and mixed into the soil with a tandem disk harrow in the spring just previous to planting. The 30 foot plots were planted by machine in four rows 32 inches apart. Potatoes from the two inside rows for a length of twenty feet were used for the harvest area. At the time of harvest the tubers were graded as to size, those being considered as grade A to be larger than 1-7/8 inch in diameter and those less as grade B (20). The weights of A's and B‘s were recorded for each plot. A sample of approximately 10 pounds of tubers was saved from each plot. The specific gravity was determined on these tubers by comparing their weight in water to their weight in air. The tubers were then s1iced,dried, ground, and stored in glass Jars for chemical analysis. On forty selected plots in 1957 top samples were taken late in the growing season and yields of tops and per cent dry matter determined. The samples were dried, ground, and saved for chemical analysis. The samples receiving the same treatment in each year were bulked together, with the check plots being the only exceptions. Thus, as can be seen from Tables 10 and 16 determinations were made for N, Ca, K, P, Mg, and Na on 123 different samples. Nitrogen was determined by the KJeldahl process (22). A two-gram sample of the tubers and a one-gram sample of the tops was used. The perchloric acid method of Piper (23) was used in wet ashing the plant samples. A one-gram sample was placed in a 125 ml beaker and 15 mls of concentrated nitric acid was added to it. The sample was digested on an electric hot plate until almost all the organic matter was destroyed and a clear solution was obtained. Six mls of 70 per cent perchloric acid was then added to the solution and the 8 digestion continued until the oxidation was complete and a clear, colorless solution was obtained. The solution was then evaporated almost to dryness, cooled and the volume was made up to 100 mls with 0.1N HCl. The solution was filtered through Whatman No. 42 filter paper and put in bottles as stock solution. The P content was determined by the ammonium molybdate method. One ml of the stock solution was diluted to ten mls and six drops of ammonium molybdate-sulfuric acid reagent was added, followed by the same amount of Fiske- Subbarrow reagent (12). The solution was then shaken thoroughly and allowed to stand for fifteen minutes. Then it was placed in a colorimeter tube and the transmittancy of the solutions was measured using a Lumetron Colorimeter With a PEG filter (650 mu). These readings were compared to those recorded on a previously developed standard curve. Potassium in the stock solution was determined on the Perkin-Elmer Model 52C flame emission spectrophotometer as described by Jackson (17). Calcium and sodium contents of the stock solutions were determined by using the Beckman spectrophotometer Model DU equipped with flame emission source. Adjustment of the Beckman for specific cations are given in Table 2. Magnesium was determined colorimetrically using the thiazole yellow method of Drosdoff and Nearpass (8). One ml of the stock solution was placed in a 50 ml volumetric flask. Approximately 25 mls of 0.1N HCl was added followed by: 1 ml of 5 per cent hydroxylamine hydrochloride, 5 mls of an equal mixture of 2 per cent starch solution and com- pensating solution, 1 ml of thiazole yellow, and 5 mls of 3N sodium hydroxide solution. It was brought to volume, mixed and allowed to stand for ten minutes. The intensity of the color of the solution was then measured by a Coleman Universal Spectrophotometer Model 14, set at a wavelength of 540 mu. The soil samples were taken in the spring of 1957 previous to the application of fertilizer. The samples were extracted with 0.018 N acetic acid, the extractant proposed by Spurway and Lawton (26). The soil extract ratio was 1:4 and the mixture, with one-fourth teaspoon of activated carbon, was shaken for one minute. The extract- able P was determined by a colorimetric method using the ammonium-molybdate-hydrochloric acid solution proposed by Dickman and Bray (7) and Fiske and Subbarrow reducing reagent. The extractable K was determined with a photolometer using a red filter (wave length of 650 mu) and employing a sodium cobaltinitrite procedure involving the use of 95 per cent ethyl alcohol. RESULTS AND DISCUSSION Yield Relationships The average yields of tubers from all plots were 218.8 and 366.5 cwt. per acre for 1956 and 1957, respec- tively. This increase of 67.1 per cent could possibly be attributed to a more favorable growing season in 1957. Analysis of variance of yield of the 4 x 4 x 3 factorial is given in Table 5. The average yield from plots of replication 1 of this factorial was consistently lower than from replication 2 or 3. Replication 1 had an average yield per plot of 216.0 cwt. per acre with replication 2 and 3 at 230.0 and 227.7 cwt. per acre in 1956. For 1957, replication 1 had an average yield per plot of 329.4 cwt. per acre with replication 2 and 3 at 384.4 and 404.1 cwt. per acre. Highly significant yield differences (1% level) were obtained in 1956 between 100 versus 200, 300, and 400 pounds per acre rates of P205 fertilizer. The highest yields were obtained where the lower rate of P205 was used. The levels of K20 application had a significant influence upon the yield. Plots where 400 pounds of K20 per acre were applied in 1956 had a significantly higher yield than plots that received either 600 or 800 pounds per acre. The interaction of fertilizers had a highly significant 10 11 influence upon the yield in 1956. This is indicated by the difference in yields of the plots receiving the dif- ferent K20 levels where P205 levels of fertilization were different. Multiple correlation analyses were conducted using three types of equations: (a) y = a + blxl + b2x2 + b3 (Xlx2)3 (b) log 9 = a + bllog x1 + bglog x2; and (c) log ‘9 = a + bllog x1 + b2xl + b3log x2 + buxg; x1 and x2 refer to the pounds of P205 and K20, respectively. Where type 0 equation was used applied P205 and K20 produced a significant influence upon the yield (Table 6). The interaction of P205 and K20 had a significant negative influence upon the yield but was not of sufficient magni- tude to cause a negative slope to the curve. The adjusted coefficient of multiple determination (R2) showed that the equation used explained 10 per cent of the variation in yield in 1956, and 20 per cent in 1957 as due to fertilizer. The standard errors of estimate indicate a high degree of variation in the data. A curvilinear equation which allows for decreasing yields as well as increasing yields as more fertilizer is applied was fitted to the 1956 and 1957 yield data. The results indicate that 34 per cent of the variance in yield in 1956, and 61 per cent in 1957 was explained by the equation that was used. This type of equation apparently l2 fitted the data to a much greater degree of accuracy than the straight line function used. Thirty-six plots receiving 150 pounds per acre and less of P205 and those receiving 400 pounds per acre and less of K20 were selected to make a further analysis because they were in the "response range" as indicated by Table 3. The response range is defined as the range of fertilizer application over which an additional increment causes an increase in yield. With this group of observa- tions two analyses were made; one using a straight line type equation: ‘9 = a + blxl + b2x2 + b3 (x1x2); and the second using a curvilinear type equation: log y = a + bllog x1 + belog x2. Comparison of the four analyses of yield and applied fertilizer are given in Table 7. Restricting the analysis to data in the response range gave a higher R2 when the straight line and curvilinear type equations were used then when all data were used. This would be expected because there were fewer observations and the data appear to be less heterogenous within this range. It is evident that the curvilinear type equation used with 36 observations explained more variance as indicated by larger R2 values. This might imply that data from plots where fertilizer applications are made beyond where an increase in yield results, is largely of academic interest. Insofar as possiblefertilizer'treatments should be for the most part within the response range. 13 Specific Gravity Highest average specific gravity tubers were produced on plots which received 25 pounds per acre of P205 fertil- izer in 1956 and zero pounds per acre in 1957. The plots receiving 25 and 50 pounds per acre of K20 produced the tubers with the highest specific gravity in 1956. In 1957 those receiving zero and 50 pounds per acre of K20 produced the highest specific gravity tubers. Inverse relationships were indicated between specific gravity and applied P205 and specific gravity and K20 (Tables 6, 8, and 9). These observations were substantiated by linear regression analysis which gave a negative significant relationship between applied P and specific gravity, and 205 applied K20 and specific gravity. The interaction factor had an appreciable influence only at the high rates of fertilization. The adjusted coefficient of multiple deter— mination showed that the equation explains 64 and 38 per cent of the variance for 1956 and 1957, respectively. Size The percentage of grade B tubers tended to be highest on the unfertilized plots (Tables 8 and 9). A small, but significant, correlation was found between the interaction of P205 and K20 applied and the percentage of grade B tubers (Table 6). A significant negative correlation also existed between K20 applied in 1956 and the per cent of grade B tubers. The regression equations explained a 1L1 limited amount of the variance (l6 and l per cent) in the per cent of grade B tubers for 1956 and 1957, respectively. This indicates a minor effect of fertilizer combinations on the number of tubers smaller than 1-7/8 inch in diameter. Chemical Composition of Tubers The tubers were analyzed for nitrogen, calcium, phosphorus, potassium, magnesium, and sodium. These data are reported in Tables 10, ll, 12, and 15. The relation— ships between the composition of tubers and the levels of P205 and K20 fertilizers as expressed by the equation '9 = a + blxl + b2x2 + b3(x1x2) are reported in Table 15. This type of equation was used because higher R2 values and lower S values were obtained than where the curvilinear type equation (log y = a + bllog x1 + belog x2) was calcu- lated to express these relationships for Ca, P, and K. In general, there was a marked seasonal variation in the effect of the applied P205 and K20 on the per cent composition of several of the elements. In 1957 as applied P205 and K20 were increased the per cent N in the tubers decreased. The coefficients of both terms were negative and significantly different from zero. The results in 1956 were so heterogenous that no coefficient of any variable was significantly different from zero. There was a tendency for the per cent of Ca to be reduced as P205 applications increased in 1956. In 1957 15 an increase in Ca percentage was associated with the amount of K20 applied. This is indicated by the significant coef- ficients of the respective terms. The amount of variance explained in the per cent Ca was much higher in 1957 than in 1956, as indicated by the respective higher values of 60 and 22 per cents. As the amount of P205 applied increased, the percen- tage of P in the tubers increased. This relationship was highly significant both years as indicated by the signifi- cance of the coefficients for the applied P205 term (x1) and also by the amount of variance accounted for. In 1956, 65 per cent of the variance was accounted for, and in 1957 approximately 77 per cent. Similarly, as the amount of K20 applied increased, the per cent of K in the tubers increased. There appears to be a significant effect on percentage of K in the tuber with increasing rates of applied P205 in 1957 (Table 15). Simple correlation coefficients of the per cent K were calculated according to the amount of applied phosphate fertilizer, where the K 0 level is held constant (Table 20). 2 In two cases out of four where the amount of applied K20 fertilizer was held constant the applied P205 fertilizer appeared to have a significant effect on the percentage of K in the tubers in 1957. In 1956 the K in the tuber did not appear to be significantly affected by the amounts of P205 fertilizer applied (Table 15). This was also found 16 to be true where simple correlation coefficients were deter- mined to evaluate this relationship (Table 20). In 1957 the per cent of Mg increased as the amount of P205 and K20 applied increased. This is indicated by the large amount of variance (77 per cent) accounted for. This relationship was not apparent in 1956. Under conditions of the experiment, the application of P205 and K20 apparently had little effect on the per cent of Na contained in the tuber. Data in Table 13 and 14 show considerable variation occurred in 1957 and 1956 based on the per cent change of values. It is interesting to note the changes of 67.1 per cent in yield, 0.2 per cent in specific gravity, 8.9 per cent in grade B, 1.2 per cent in per cent N, 21.6 per cent Ca, 7.8 per cent P, 7.4 per cent K, 13.8 per cent in per cent Mg, and 18.0 per cent Na. Yield and Chemical Composition of Tops The effect of P205 and K20 applications on the yield, per cent dry matter and composition of tops are reported in Tables 16, 17, 18, and 19. There was a very small effect from applied P205 and K20 on the yield of tops. None of the coefficients of the equation are significant. As the amount of P205 and K20 applied increased, the per cent dry matter decreased. Seventy-six per cent of the variance was explained as indi— cated by the value of R2, 17 There was a tendency for the per cent of N to decrease with additional applications of P205 and K20, and a tendency for the per cent of Ca to decrease as the amount of P205 applied increased. The per cent of Ca decreased as the K20 applied increased. The percentage of P in the tissue increased as the amount of P205 applied was increased. There appears to be a significant effect on the per- centage of K in the tissue with increasing rates of applied P205. This was also true with tubers in 1957 (Table 15). However, if Simple correlation coefficients of the per cent K in the tops are calculated according to the amount of applied P205 fertilizer where the K20 level is held constant, this over-all relationship apparently fails to hold (Table 20). A negative or positive correlation can be noted de— pending on the level of K20 used. This might suggest that the interpretation of data on an over—all basis may be different than what might be the case if the relationships are considered where the levels of one of the factors is held constant. The per cent K was higher in tissue that was grown on plots where the highest amounts of K 0 were 2 applied. The per cent of Mg decreased as the amount of P205 and K20 used were increased. There appeared to be a ten- dency for the per cent of Na to decrease as P205 and K20 applied to the soil increased. However, no significant coefficients were observed in these relationships. 18 Soil Tests The data in Table 21 show that the K soil test reflected the amount of applied K20 to a greater degree than did the P test in predicting a similar P205 relation- ship. The small range of the determinations of the P soil test were found not to have a significant relationship with the P205 applied. The determinations of the K soil test were found to be significantly influenced by K20 applied. SUMMARY Studies were carried out to determine the effects of levels of phosphate and potash fertilization on yield, quality, and composition of potatoes grown on Houghton Muck. The yield, size, specific gravity, and composition of the tubers were determined. From top samplés the yield, per cent dry matter, and composition were determined. Regres- sion analysis, analysis of variance and simple correlations were used in evaluating the relationships that existed. The results are summarized as follows: 1. The average yields of tubers were 218.8 and 366.5 cwt. per acre for 1956 and 1957, respectively. This difference of 67.1 per cent could be attributed possibly to a more favorable growing season for the production of tubers. 2. Multiple correlation analysis and analysis of variance showed that fertilization had a significant influ- ence upon the yield. 3. The prediction of yield based on applied fertili- zer with a curvilinear type equation using a selected group of plots gave higher R2 values and lower S values than a straight line type equation. 4. Specific gravity of the tubers was related in- versely to application rates of P205 and K20. 19 . .1. . 3|....1.. iil-Vfbvli.’ .. 20 5. Check plots had a higher percentage of size grade B tubers than those receiving fertilizer. 6. The maturity of tops as indicated by the per cent dry matter was affected inversely as additional amounts of P205 and K20 were applied. The interaction of P205 and and K20, however, had a significantly positive effect on the per cent dry matter. 7. In 1957 N percentages of the tubers and the tops decreased as additional amounts of P205 and K20 were applied. 8. Phosphorus percentages of tops and tubers increased with increased application of P205- 9. Potassium percentages of tops and tubers increased with increased application of K20. 10. The straight line equation explained more of the variance than did the curvilinear equation when applied fertilizer was used as the variable to predict composition of tubers. 11. The K of the soil test was significantly influ- enced by K20 fertilization. 12. The P of the soil test was not significantly influenced by P205 fertilization. 10. ll. BIBLIOGRAPHY Bigger, T. C., J. F. Davis, and K. Lawton. The behavior of applied phosphorus and potassium in organic soils as indicated by soil tests and the relationship be- tween soil tests, green tissue tests, and crop yields. Soil Sci. Soc. Amer. Proc. 17:279-282, 1937. Burton, W. G. The Potato. Chapman and Hall Ltd., 37 Essex St. W. C. 2 London, 1948. Chucka, J. A., A. Hawkins, and B. E. Brown. Potato fertilizer-rotation studies on Aroostook Farm 1927-41. Maine Agr. Expt. Sta. Bul. 414, 1943. Clark, C. F., P. M. Lombard, and E. F. Whiteman. Cooking quality of the potato as measured by specific gravity. Amer. Potato Jour. 17:38-45, 1940. Cobb, J. S. A study of culinary quality in white potatoes. Amer. Potato Jour. 12:335-344, 1935. Davis, P. N. Growing and fertilizing potatoes on muck soils. Amer. Potato Jour. 2:486-488, 1925. Dickman, S. R. and R. H. Bray. Colorimetric deter- mination of phosphate. Ind. and Eng. Chem. Anal. Ed. 12:665, 1940. Drosdoff, M. and D. C. Nearpass. Quantitative micro- determination of magnesium in plant tissues and soil extracts. Anal. Chem. 20:673-674, 1948. Dunn, L. E. and R. E. Nylund. The influence of fertili- zers on the specific gravity of potatoes grown in Minnesota. Amer. Potato Jour. 22:275-288, 1945. Eastwood, T. and J. Watts. The effect of potash ferti- lization upon potato shipping quality. Amer.Potato Jour. 33:265-268, 1956. Fineman, Z. M. The influence of fertilizers on yield and specific gravity of potatoes grown in Alaska. Amer. Potato Jour. 24:82—89, 1947. 21 l2. l3. 14. 15. 16. 17. l8. 19. 20. 21. 22. 23. 24. 25. 22 Fiske, C. H. and V. S. Subbarrow. The colorimetric determination of phosphate. Jour. Biol. Chem. 66: 375, 1925- Fitch, C. L. Fertilizer and subsoil studies for potatoes on 10 Iowa peat and muck farms in 1931. Amer. Potato Jour. 9:105-109, 1932. Gausman, H. W. and A. B. Awan. Effects of chloride from calcium chloride on P32 accumulation in potatoes. Agron. Jour. 48:431, 1956. Hardenburg, E. V. Muckland potato production in New York. Amer. Potato Jour. 11:244-246, 1934. Hawkins, A. Rate of absorption and translocation of mineral nutrients by potatoes in Aroostook County Maine, and their relation to fertilizer practices. Jour. Amer. Soc. Agr. 38:667—681, 1946. Jackson, M. L. Soil Chemical Analysis. Prentice-Hall, Inc., Englewood Cliffs, N. J., 1958. Lucas, R. E., E. J. Wheeler, and J. F. Davis. Effects of potassium carriers and phosphate-potash ratios on yield and quality of potatoes grown in organic soils. Amer. Potato Jour. 31:349-352, 1954. Metzger, c, H. A preliminary report on the effects of commercial fertilizers on potatoes in Colorado. Amer. Potato Jour. 14:382-394, 1936. Motts, G. N. Potato Graders Manual. Michigan State University, East Lansing, Michigan, Extension Folder F-186, 1958. Penston, N. L. A study by micro-chemical methods of the distribution of potassium in the potato plant. Ann. Bot. 45:673-692, 1931. Pierce, W. C. and E. L. Haenisch. Quantitative Analysis. John Wiley and Sons, Inc., New York, 1948. Piper, C. S. Soil and Plant Analysis. Interscience Publishers, Inc., NewIYork, 1953. Shoemaker, J. S. Vegetable Growing. John Wiley and Sons, Inc., New Ydrk, 1953. Smith, 0. and W. C. Kelly. Fertilizer studies with potatoes. Amer. Potato Jour. 23:107—135, 1946. 26. 27. 28. 29. 30. 31. 23 Spurway, C. H. and K. Lawton. Soiltesting: a prac- tical system of soil diagnosis. Mich. Agr. Exp. Sta. Tech. Bul. 132, 3rd ed., 1944. Terman, G. L. Effect of rate and source of potash on yield and starch content of potatoes. Maine Agr. Exp. Sta. Bul. 481, 1950. Terman, G. L., P. N. Carpenter, and S. C. Junkins. Nutrient content of potato plants as affected by fertilizer treatment and other factors. Soil Sci. Amer. Proc. 14:137-142, 1949. Terman, G. L., A. Hawkins, C. E. Cunningham, and P. N. Carpenter. Rate, placement, and source of phosphorus fertilizers for potatoes in Maine. Maine Agr. Exp. Sta. Bul. 506, 1952. Terman, G. L., A. Hawkins, and P. L. Johnson. Effect of level of accumulated potash in the soil on potato yiild and quality. Maine Agr. Exp. Sta. Bul. 449, 19 7. Western Regional Research Laboratory Potato Program. Composition of potatoes as related to specific gravity and quality. Amer. Potato Jour. 26 181-182, 19A9. APPENDIX 24 TABLE 1 PLOT DIAGRAM-—SECTION F-2 MUCK EXPERIMENTAL FARM 25 Plot size 30 ft. by 10-2/3 ft. Plot # Treatments Plot # 114 *Pl50 **K450 P200 K700 95 113 P300 K300 P300 K800 94 112 P400 K400 P400 K800 93 111 P300 K900 P50 K400 92 110 P250 K600 P200 K200 91 109 P25 K25 P200 K800 90 108 P300 K600 P400 K200 89 107 P300 K200 P150 K150 88 106 P200 K400 P250 .K250 87 105 P300 K700 P300 K400 86 104 P50 K50 P250 K500 85 103 P0 K200 P200 K100 84 102 P25 K75 P100 K800 83 101 P150 K300 P50 K100 82 100 P100 K400 P100 K300 81 99 P100 K200 P250 K750 80 98 P0 KO P100 K600 79 97 P400 K600 P350 K700 78 96 P100 K0 P200 K600 77 *P as P205 . **K as K20. TABLE 1 (Continued) r :— Plot # 26 Plot # Treatments 76 P150 K600 P0 KO 57 75 P400 K800 P0 K200 56 74 P75 K225 P200 K800 55 73 P50 K150 P200 K200 54 72 P250 K400 P350 K350 53 71 P350 K500 P100 K800 52 70 P0 K0 P100 K600 51 69 P300 K200 P25 K75 50 68 P350 K350 P150 K150 49 67 P200 K400 P200 K500 48 66 P400 K200 P100 K200 47 65 P300 K400 P250 K250 46 64 P200 K500 P350 K400 45 63 P400 K600) P300 K700 44 62 P200 K600 P25 K25 43 61 P300 K600 P300 K800 42 60 P400 K900; P400 K400 41 59 P350 K400 P100 K0 40 58 P100 K100 P100 K400 39 27 TABLE 1 (Continued) Blot # Treatments Plot # 38 P300 K800I P200 K100 19 37 P200 K600 P400 K800 18 36 P100 K400 P300 K400 17 35 P150 K600 P300 K300 16 34 P400 K400 P400 K900 15 33 P250 K500 P200 K800 14 32 P50 K100 P50 K50 13 31 P300 K900 P350 K700 12 30 P100 K600 P250 K600 11 29 P200 K700 P75 K225 10 28 P150 ' K300 P50 K150 9 27 P400 K200 P100 K100 8 26 P250 K750l P100 K200 7 25 P200 K400 P350 K500 6 24 P250 K400 P300 K600 5 23 P100 K800 P100 K300 4 22 P150 K450 P50 K400 3 21 p400 K600 P200 K200 2 20 P300 K200 P0 K0 1 TABLE 2 ADJUSTMENT OF THE BECKMAN SPECTROPHOTOMETER FOR THE DETERMINATION OF CALCIUM AND SODIUM Wave length Photo tube resistor Photo tube filter Selector Photo-multiplier sensitivity Zero suppression Oxygen pressure (a) tank (b) instrument panel Hydrogen pressure (a) tank (b) instrument panel Slit Width 422.7 "2 blue 0.1 full 1.0 40 11 10 5.75 .07 589.3 "2 blue 0.1 2 1.0 40 11 10 5.75 .05 28 .pfiom oaumoo zmao. nufiz pouomnpxm* 29 6.6 6.6 oso.a m6o.H s.66m 6.:6m .66 .6 com 60H 66 m.6 6.: H6o.a m6o.a 6.666 6.0Hm .6A .6 com o 66 H.ma 6.m m6o.a H6o.H :.:om 6.6Hm .H: .: com o 60H 6.: H.: 66o.H 66o.H 6.66m H.6mm .6: .6 06H 66H m: m.6 A.6 m6o.H A6o.a 6.66m m.m6a .66H .6 66H 66H 66 :.A :.m mso.a :Ao.H 6.6Hm H.6Am .wm .oH 66H 06 m m.6 m.m m6o.a m6o.H m.m:m m.smm .. .. 06H 06 ms 6.: 6.6a 66o.a :6o.H 6.6mm H.mma .66 .oH ooa 66m ma H.w 6.6 m6o.H m6o.a A.6mm m.m6a .66 .6 ooH com :6 6.» m.6 mso.a 6eo.H 6.6mm :.wom .66 .A ooH 60H 6 0.: s.: mso.a m6o.H p.666 6.6AH .m6 .6 ooH 00H 66 6.m H.6 oso.a mso.a m.m6m 6.H6m .66 .6 60H 06 mm :.: :.6 :6o.H 66o.H 0.66m 6.66H .. -- 00H 06 mm 6.6 6.6 Heo.a Hso.H 6.6Hm H.06H .6: .6 6» 6m 06 6.6 H.6 66o.H Hso.a 6.:6m 6.:6m .Am .m 6» 6m men 6.6 H.6 meo.a 6eo.a o.m6m 6.H6H .6: .6 66 06 6a 6.s 6.6 oso.H oeo.a 6.6:m o.H6H .H: .6 66 66 :oH s.m m.6 66o.H HAO.H H.mmm 6.6AH, .Am .m 6m 6m 6: 6.A m.s 66o.H 6eo.a 6.66m 6.6:H .66 .6 6m 6m 66H A.A 6.6 A6o.H m6o.a 6.:6m 6.66 .:m .6 o 60H 0: 6.6H 6.:H Heo.a m6o.H 6.66H :.:HH .Am .6 o 60H 66 6.:H 6.6 m60.a :Ao.H H.66H A.mma .6: .6 o o A m.ma m.oH 66o.a m6o.a m.A6H s.mma .Am .6 o 0 A6 m.AH :.mH m6o.a Heo.a 6.6AH 6.omH .:m .6 o o on A.s :.m Heo.a m6o.H 6.6mm 6.60m .66 .6 o o 66 A6aa 666a A6ma 66aa A6aa 666a *9 *a one 6oma .oz m @6696 & mpa>mno camaomdm <\p30 ono< non monsom uon illiHlf' ZOHB6no 0H6H00Qm fi\uzo 0n0< n00 mnsdom uon Ap0schcoov m mqmmpu oHpH00Qm <\wzo 090< s00 mezzom HOHm [I II ‘7 l. l. 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