EFFECW (3F VMLEGU-gr THEEES CUWW 9&3'53 0N SUSSEQUfiNT FREQUCYEGN ANS CARBQHYDRAW. EESERVES' GP ALFALFA “Matias“ 969W; 3.17} ”am. 37mm {:09 “t0 Dag-.999 or? Ms S. MICHEGM STATE EJNEEIEKSWY James E... Yager 1968 3 1293 00670 2520 L I B R A R Y H I m. WWW)UHWWIUWWWWHI ! 1, METEZ‘ESJS‘; -. ‘45 .111 ME ill‘ ...-IIA.'.I\¢|1CRvN L... Alva—Fun fl _. 2 -_‘fl . . _ ABSTRACT EFFECTS OF VARIOUS THIRD CUTTING DATES ON SUBSEQUENT PRODUCTION AND CARBOHYDRATE RESERVES OF ALFALFA (Medicago sativa L.) By James L. Yager The residual effect of cutting Vernal, a hardy alfalfa, for a third time on September 1, September 15, October 1, October 15, November 1, or November 15 was determined in 1966 and 1967 from the first two of three cuttings in the year following cutting treatments at several fertility levels at East Lansing in southern Michigan. In one of the experiments, the cutting treatments were imposed on the same plots for two consecutive years. In another experiment, Cayuga, a hardy alfalfa, and DuPuits, a medium hardy alfalfa, were given similar cutting treatments, and the total available carbohy- drates (TAC) in the roots were determined after each cutting treat- ment and on December 13, April 22, and June 9 on Vernal and DuPuits alfalfa. Alfalfa cut for the third time on September 15 or October 1 yielded as much the next year as when out September 1. James L. Yager Yields of alfalfa did not show a cumulative effect of two consecutive years of cutting treatments made on September 1 or 15 or October 1. The TAC in roots of DuPuits or Vernal alfalfa cut Septem- ber 1 or 15 or October 1 increased to a maximum by November 1, then decreased to similar levels by December 13; these levels were lower than in plants out twice or for a third time on October 15, November 1 or 15; TAC levels were higher on each sampling date in Vernal than in DuPuits. K and PK fertilizer did not affect levels of TAC. The results suggest that the strict recommendations of not cutting alfalfa in September or early October now in effect in southern Michigan and other northern states Should be re-examined. Liberal- izing such recommendations would permit "fall cutting" of alfalfa stands for greater flexibility of management. EFFECTS OF VARIOUS THIRD CUTTING DATES ON SUBSEQUENT PRODUCTION AND CARBOHYDRATE RESERVES OF ALFALFA (Medicago sativa L.) By 1"- C \‘ .- Y\ Q James LQ’Yager A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop Science 1968 ACKNOWLEDGMENTS The author wishes to express his gratitude to Dr. M. B. Tesar for his guidance both in the study and in the preparation of this manuscript. The author also wishes to thank Dr. C. M. Har- rison, Professor 1. F. Schneider, Dr. C. E. Cress, Nelly Galuzzi, and Wesley Edington for having helped in conducting different as- pects of this study. Finally the author wishes to thank the Michigan Agricultural Experiment Station for the financial assistance that made this study possible. ii TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION LITERATURE REVIEW . MATERIALS AND METHODS Experiment I--Three alfalfa varieties, seven cutting treatments, and three fertility levels for one year--1966 . Experiment II--Vernal alfalfa, seven cutting treatments, and five fertility treatments for two consecutive years--1965 and 1966 Experiment III--Three-year old Vernal alfalfa, seven cutting treatments, and five fertilizer treatments for one year-- 1966 RESULTS Experiment I--Three alfalfa varieties, seven cutting treatments, and three fertility levels for one year-—1966 . Experiment 11- -Vernal alfalfa, seven cutting treatments, and five fertility treatments for two consecutive years--1965 and 1966 . Experiment III--Three-year old Vernal alfalfa, seven cutting treatments, and five fertilizer treatments for one year-- 1966 . Summary of Experiments I, II, and III with Vernal alfalfa iii Page vii 11 11 13 14 16 16 27 33 36 Page DISCUSSION. . . . . . . . . . . . . . . . . . . . . . . 38 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . 46 BIBLIOGRAPHY.....................49 iv Table LIST OF TABLE S Residual effects of 7 third cutting treatments and 3 fertilizer treatments on the total yields of the first and second cuttings of 3 alfalfa varieties the year following treatments . Alfalfa yields of a third cutting taken at 7 different dates in the fall Height of fall regrowth of alfalfa on Novem- ber 8, 1966, after fall cutting and topdressing . Alfalfa growth ratings in the spring following treatment Trends of total available carbohydrates in DuPuits and Vernal alfalfa roots after 7 cutting treatments and 3 fertilizer treat- ments Residual effects of 2 consecutive years of treatment with 7 third cutting treatments and 5 fertilizer treatments on the total yields of the first and second cuttings of Vernal alfalfa the following year Vernal alfalfa yields of third cuttings taken 2 consecutive years at 7 different dates . The total yields of 3 cuttings of Vernal alfalfa the year following 7 third cutting treat- ments and 5 fertilizer treatments Page 18 21 22 23 24 30 32 34 Table Page 9. Third cutting yields in tons per acre on 7 different dates of 3-year old Vernal alfalfa.................. 36 10. Summary of the residual effects of 7 third cutting treatments and 3 fertilizer treat- ments on the total yield of first and second cuttings of Vernal alfalfa the first year following treatments in 3 experiments................ 37 11. Comparison of 1938 alfalfa yields with recent yields of Vernal alfalfa fertilized annually with PK under identical cutting treat- ments.................. 40 vi . ___M Figure LIST OF FIGU RES The residual effects of 7 third cutting treatments on 3 varieties of alfalfa as measured by the yields of the first 2 of 3 cuttings the next year . The residual effects of 7 third cutting treatments and K and PK fertilization as measured by average yield of 3 alfalfa varieties in the first 2 of 3 cuttings the next year Trends of average TAC in roots of DuPuits and Vernal alfalfa with 4 third cutting treatments Average trends of TAC in roots of DuPuits and Vernal alfalfa during the fall and winter . . . . The residual effects of 2 consecutive years of 7 third cutting treatments on Vernal alfalfa as measured by the yields of the first 2 of 3 cuttings the following years . . . The residual effects of 7 third cutting treat- ments and K and PK fertilization as measured by the yields of Vernal alfalfa in 3 cuttings the next year . vii Page 17 20 26 28 29 35 INT RODUC TION The detrimental effects of harvesting alfalfa for a third time in September or early October in northern states have been recognized because of more winterkilling and reduced yields in sub- sequent years than when the alfalfa was cut only twice between one- tenth and one-half bloom (about mid-June and mid-August). In contrast, third harvests in mid-October or later have been consid- ered a safe practice without danger of increasing winter injury or materially reducing yields in subsequent years (Silkett _e_t__al. , 1937; Rather and Harrison, 1938; Armstrong _e_t_a_l_. , 1948; and Smith, 1960). The 3-cut system (cutting in early June, mid-July, and late August) has been recommended for about a decade for alfalfa in southern Michigan because the use of winterhardy varieties and increased fertilizer have made the 3-cut system superior in yield and quality to the 2-cut system (Michigan State University Coopera- tive Extension Service, 1967, and Fuess and Tesar, 1968). Similar results favoring the 3-cut system have been obtained in other north- ern states or northern latitudes (Parsons and Davis, 1960; Folkins e_t_a_1. , 1960; Smith, 1960; Chance 333:1. , 1961; Kust and Smith, 1961; and Carter, 1964). There are several conditions, however, when a third cutting may not be made on time, i. e. , by the first week in September, but might be made later in September or early October. First, in some years a drouth after the second cutting in mid-July retards re- growth. Consequently, the third cutting may have very little forage to harvest by September 1. Later in September or early October, there may be good growth of forage because of late summer rains. Second, with the advent of mechanized forage chopping equipment and the practice of feeding green-chopped forage daily to livestock, the fall growth is chopped daily. Frequently a period of one month elapses from the time a field is first used for green chopping until chopping is complete. Third, alfalfa can be harvested mechanically and used as grass silage or haylage without the hindrance of adverse weather that restricts hay curing. This feasibility of a third cutting in September and early October, therefore, is recognized by farmers. The practice, if recommended, would be readily accepted by farmers because they would rather harvest in September than wait until after mid-October, the generally accepted time after which carbohydrate reserves in the roots would not be reduced appreciably and next year' 5 yield would not be lowered materially. The objectives of this study were to determine: (1) if the reported adverse effects of a third cutting of alfalfa in a 3-cut system in September or early October could be wholly or partly overcome by topdressing with potassium or potassium and phospho- rus on established stands of alfalfa, (2) the cumulative effects of a third late summer or fall cutting on alfalfa yields over several con- secutive years, and (3) the trend of carbohydrate reserves following Septemberand early October cuttings in a 3-cut system. LITERATURE REVIEW A third cutting made in- September or early October has been generally regarded as injurious to the yield and permanence of alfalfa in northern states where serious winterkilling may occur. Recommendations have stressed that cutting or grazing of alfalfa during this critical period should be avoided based on research by Graber _et_al. (1927), Willard (1930), Grandfield (1935), Silkett, Megee, and Rather (1937), Graber and Sprag'ue (1938), Rather and Harrison (1938), and, more recently, by Folkins, Greenshields, and Nowosad (1960). Such a cutting in September or early October has, at times, resulted in a reduction of the stand due to Winterkilling, a decrease in vigor and yield the following year, or a combination of both (Silkett 9111. , 1937, and Rather and Harrison, 1938). Graber fl. (1927) compared a 2-cut system of alfalfa (Kansas Common, Turkestan, and Grimm) with a 3-cut system (third cutting Septem- ber 12) in southern Wisconsin and found the three cuttings gave significantly lower average annual yields over a five-year period. They attributed the lower yields to (1) cumulative effects of more rapid exhaustion of the organic food reserves in the roots and (2) more serious degree of winter injury with increased mortality rate. It was shown that alfalfa plants not cut in September were not only higher in storage reserves but had more vegetation to collect snow providing protection against cold weather. Silkett 3131. (1937) working with Hardigan alfalfa in southern Michigan, compared theveffects of five third-cutting dates (Septem- ber 1, September 15, October 1, October 15, and October 31) with two cuttings on the subsequent year' 3 yield at East Lansing. They obtained similar 2-year average yields of 2. 75, 2. 56, and 2. 60 tons per acre for plots cut for the third time the previous fall on Septem- ber 1, September 15, and October 1, reSpectively. The average subsequent year' 3 yield of plots out only twice (second cutting in early August) the previous year was 3. 04 tons per acre, about one- half ton higher than when cut on September 15 or October 1. Rather and Harrison (1938) used the same cutting treatments at three dif- ferent geographic locations in southern Michigan including the East Lansing location reported on by Silkett gt__a_l. , (1937). They obtained acre yields which were likewise similar--3. 15, 3. 01, and 3. 11 tons-- for the year following cutting treatments made the previous fall on September 1, September 15, and October 1, respectively, as com- pared to a greater‘acre yield of 3. 52 tons when cut only twice the previous year. The data support their conclusion made in 1938 that "two cuttings are safest in Michigan" since a third cutting resulted in yields about one-half ton lowerthe next year. Furthermore, in the previous year they obtained yields of only 0. 39, 0. 52, and O. 50 tons on September 1, September 15, and October 1, reSpectively, after the second cutting was made in the one-tenth to one-half bloom stage (probably mid-August). Since these yields were only about one-half ton, they concluded the most practical procedure would be to save the alfalfa for fall or early winter pasture. Recently, Smith (unpublished data) in Wisconsin confirmed what Graber et_al. reported from the same state and what Rather and Harrison reported in Michigan, i. e. , a third cutting in September or October results in lowered yield the next year when compared to a 2-cut system. Relative to yields of alfalfa cut twice, Smith reported that alfalfa cut for the third time on September 1, September 15, Octo- ber 1, October 15, and November 1, yielded 90, 69, 83, 92, and 97% as much for the first cutting the following year. This indicated that, in Wisconsin, in contrast to the reports of Rather and Harrison in Michigan, a third cutting on September 15, and to a lesser extent on October 1, was much more harmful to the next year' 3 yield than a September 1 cutting. The colder winter temperatures and shorter fall growth period in southern Wisconsin, in contrast to southern Michigan, may explain this different reaction from fall cutting. In an attempt to understand the physiological effects of late summer or fall cutting treatments, several workers have studied the levels of carbohydrate reserves in alfalfa roots in order to explain some of the injurious effects of fall cutting (Nelson, 1925; Graber gt_a_1. , 1927; Grandfield, 1935; Rather‘and Harrison, 1938; and recently, Smith, 1960). Graber _e_t_al. (1927) were the first to recognize the impor- tance of carbohydrate reserves in their effect on the production and winter survival of alfalfa. Their hypothesis was that new tOp growth is initiated and developed largely at the-expense of previously- accumulated organic reserves (carbohydrates and nitrogen compounds) in the roots of alfalfa; that the accumulation occurs, principally during the maturation of top growth; that the organic reserves are essential for normal top and root development; that the quantity, quality, and availability sharply limit the amount of plant deveIOpment; and that progressive depletion of such reserves by early, frequent, and complete top removal results in death of the plant. Work by Grandfield (1935) in Kansas also supports the Graber hypothesis. Grandfield found that the amount of growth which takes place'after the last regular cutting influences appreciably the organic reserves stored in the roots before winter. If the growing time between the last cutting and freezing weather is short, the reserves are depleted and there is little opportunity to restore them. As a result, many plants do not survive the winter. From his observa- tion, Grandfield indicated that there must be at least 8 to 10 inches of growth to permit maximum storage. Grandfield also showed that in the fall dormant period (late November), there were very small differences in total carbohydrates of roots due to different previous cutting practices, except for severe treatments such as clipping at 10-day intervals after the third cutting or taking five cuttings during the season. Included in the cutting treatments were 3-cut systems in which the third cuttings were taken on September 1, September 15, and October 1. They reported good agreement between stand and root reserves. Rather and Harrison (1938) examined roots of alfalfa in January for starch content as an indication of carbohydrate reserves. They found that roots from plants not cut for a third time and from plants cut for a third time on October 31 were about equal in starch. Roots from plants cut for a third time on September 1 or October 15 showed depletion of starch, while roots from plants cut on Septem- ber 15 or October 1 had no starch. The September 15 cutting treat- ments produced much more freezing injury than any of the others as indicated by the cracking in the roots. Roots in this condition heaved badly during the spring thawing and freezing. Several researchers have attempted to overcome the adverse effects of fall cutting treatments by fertilization. Two of the early workers who attempted to improve yields and stands by fertilizing during establishment were Graber and Sprague (1938) in Wisconsin. They subjected Canadian variegated alfalfa to two cutting treatments and two fertility levels. The total of three-years' yields for alfalfa at an optimum PK fertility level (14 lbs P + 125 lbs K/acre) cut (1) twice near full bloom and (2) cut twice near full bloom plus one early fall cutting (late September) and one late cutting (about Novem- ber 1) were 10. 4 and 11. 15etons, respectively. The same cutting treatments with no fertilizer applied during establishment gave yields of 7. 61 and 6. 92 tons for cutting treatments 1 and 2. These data indicate that alfalfa grown at a higher fertility level (14 lbs P + 125 lbs K/acre) will maintain productivity even under adverse fall cutting treatments. Wang stil. (1953) working in Wisconsin showed that applica- tions of phosphate in addition to lime or in addition to lime and potash produced increased amounts of starch and non—reducing sugars in the roots and crowns of alfalfa. This increase appeared to promote resistance to winterkilling. 10 A greenhouse study by Jung and Smith (1959) indicated that the ratio of K to P played an important role in plant survival and top- growth production following exposure to freezing temperatures. Gross gt_a_l. (1950) in Iowa reported a significant interaction between alfalfa varieties and phosphorus fertilization. Atlantic, Ladak, and Ranger showed little or no response to P while Buffalo and Grimm responded markedly to P fertilizer. However, under frequent clip- pings, 4-5 per season, Atlantic, Narragansett, Ranger, and Vernal yielded less with P fertilization than when no P was applied. Buffalo responded well to P when clipped frequently while in contrast, Vernal yielded more when no P was used. Parsons and Davis (1960) showed phosphorus at 50 lbs per acre helped overcome detrimental effects of severe cutting schedules in Ohio. For one year the increases of dry matter of phosphorus fertilized plots over unfertilized in 5-, 4-, and 3-cut systems were 84, 48, and 38%. Additional work by Twamley (1960) confirms the work by Gross showing interactions between variety and phosphorus. Twamley showed that phosphorus helped the winterhardy varieties (Vernal and Grimm) more than the less hardy (Ranger and DuPuits); potash was of greater benefit to winter-susceptible varieties. Ill' I .W» ~\~ a: n.‘ MATERIALS AND METHODS Three experiments were conducted at the Michigan State University Crop Science Experimental Farm, East Lansing, Michi- gan, on tiled and untiled Conover loam soil, well suited to the pro— duction of alfalfa. Experiment I--Three alfalfa varieties, seven cuttinitreatments, and three fertility levels for one year--1966 Three alfalfa (Medicago m L.) varieties, DuPuits (medium hardy), Vernal (hardy), and Cayuga (hardy), were band seeded in plots 7 ft wide with a commercial grain drill at 8 lbs per acre with 35 lbs P and 66 lbs K/acre in early August 1964 on a well tiled and well drained soil. The alfalfa was cut in early June, mid- July, and early September in 1965 as recommended in a 3-cut system (Michigan State University Cooperative Extension Service, 1967). In 1966, the first two cuttings were taken as in 1965. In the late summer of 1966, plots 7 X 18 ft in size were established on a Split- plot, randomized complete block design replicated four times. The cutting treatments were as follows: 11 12 None (2-cut system) September 1 (3-cut system) September 15 (3-cut system) October 1 (3-cut system) October 15 (3-cut system) November 1 (3-cut system) November 15 (3-cut system) 4030153}me Three rates of fertilizer--no fertilizer, 166 lbs K, and 22 lbs P + 166 lbs K/acre--were applied after the respective cutting treatments. Yields were determined by mowing an area 2. 9 X 15. 1 ft from the center of the plots. A moisture sample weighing approxi- mately 2 lbs was obtained for moisture determination, dried at 79 C, yields calculated and reported in tons per acre of hay at 12% moisture. The residual effect of the seven cutting treatments was determined by measuring the yields from the first and second harvests taken June 9 and July 14, 1967, respectively. Growth ratings were taken on November 8, 1966, and June 1, 1967. Roots of DuPuits and Vernal alfalfas were sampled for analysis for total available carbohydrates (TAC) from two replica- tions on each fall cutting date of 1966 and on December 13, 1966, April 22, and June 9, 1967. Fifteen to twenty roots were dug from the row adjacent to the outside seeded row in the previously-cut plots, washed free of soil, trimmed of top growth to the crown, and cut to 6 inches. The roots were then dried at 65 C for 12 hours, ground in a Wiley mill to pass through a 40-mesh sieve, and stored in 13 stoppered glass bottles. Before chemical analysis, the samples were dried to constant weight in a forced-air oven at 70 C. To determine TAC (starch and sugars), 500 mg samples were refluxed with 0. 2 _N_ H2804 for 1 hour (Smith, Paulsen, and Raguse, 1964). The carbohydrate content was determined by analyz— ing for total reducing sugars using 3, 5 dinitrosalicylic acid reagent (Bernfeld, 1951). Duplicate determinations were made with 2 m1 of sample (S) and 2 ml of reagent in test tubes. Test tubes were shaken, heated 5 minutes in a vigorously-boiling water bath, cooled in an ice water bath, diluted with 10 ml of distilled water, mixed thoroughly, and absorbance (A) determined on a Hitachi Perkins- Elmer 139 UV-VIS Spectrophotometer at a wavelength of 540 m/..L. A 0. 5 mg/ml glucose standard (Std) was used. The percentage of total available carbohydrates was calculated with the equation: mg/ml of Std X 100 AS X d1lution X 100 WOTAC : X ' AStd Wts in mg Experiment II--Vernal alfalfa, seven cutting treatments, and five fertilizer treatments for two consecutive years--1965 and 1966 Vernal alfalfa was band seeded on untiled soil with good surface drainage in the spring of 1963 at 8 lbs per acre with 35 lbs P and 66 lbs K/acre. The alfalfa was cut in early June and mid-July, 14 1964, for thefirst and second cuttings of a 3-cut system. No top— dressing was applied prior to experimental treatments. Plots were 6 X 19 ft in size with four replications in a split—plot, randomized complete block design. The cutting treatments of 1965 were the same as Experiment I. The fertilizer treatments in pounds per acre were: No fertilizer Fall K - 166 Spring K - 166 Fall PK - 22 P + 166 K Spring PK - 22 P + 166 K 01.11-me The fall-fertilized K and PK treatments were applied November 6 in 1965 and after the respective cutting treatments in 1966. The Spring fertilizer treatments were applied in early April following the previous fall cutting treatments. The residual effects of experimental treatments were deter- mined from yields of the first and second cuttings made June 17 and July 26, 1966, and June 13 and July 19, 1967, according to tech- niques described in Experiment I. Experiment III--Three-year old Vernal alfalfa, seven cutting treatments, and five fertilizer treatments for one year--1966 The alfalfa was seeded, treated, and harvested the same as Experiment II, except that the plots were 6 X 20 ft in size and the 15 experimental treatments were started in 1966 instead of 1965. Prior to treating, the area was harvested in early June, mid—July, and early September in 1964 and 1965. The second cutting in 1966 was in the first week of August. No topdressing was used before cutting treatments began in 1966. The residual effect of the cutting treat— ments was determined from three harvests--June 13, July 18, and September 8, 1967. RESULTS Experiment I--Three alfalfa varieties, seven cutting treatments, and three fertility levels for one year--1966 Yield. -- If fertilized with K or PK, alfalfa cut for the third time on September 15 or October 1 yielded as much (no significant difference at the 1% level) in the first and second cuttings the'next year (third harvest year) as when cut on September 1, the recom- mended date of a third cutting of alfalfa, Figure 1 and Table 1. This is shown in the fertilized alfalfa which when out on September 15 or October 1 yielded from -0. 02 to 0. 25 tons peracre more the follow— ing year than when cut September 1. When not fertilized, the yield was from 0. 14 to 0.22 lower than the September 1 cutting treatment, Table 1. In general, the three varieties (DuPuits, Vernal, and Cayuga) reacted similarly to the cutting treatments. DuPuits alfalfa topdressed with PK showed a significant lack of response to P. 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HoNHHHHHom HGoEHmmHH mHHHHHFU X .fioHmew H H to a, H .aem a. 2 .38 E H .aem H .80 v H .38 H .80 use H .58 3 H seem ”288365 mfifisu HH mmanU m> Hw§o> we mwamu m> mHHHHnHHHQ * Hmspo> m> mHHHHannH hpoHpmxw mocmonHHHmHm msomHHmnHSoU HooHHHHmHm HowsHHHHHHoO nu . H Mdmdfl. 20 Ham» H38: 2: mwsHHHso m Ho m HmHHH 9.3 :H mmHHmHHg «HHMHHw m .Ho 3lo 09398 .3 UoHSmme mm soHHwNHHHHHmH anH paw M was mHGoEHmoLH wast—H6 HZHHHH. H. Ho 303mm. HHSHHHHmm.H 03H 2. .m mmDUHnH Hsofiammah. mHHHfiHHO 2 .82 H .82 2 .80 H .80 H .38 H .38 £5 02 Mm m M VI. .6qu s eeNHHHtem 9.1012 Jed suoi ‘pISIA 21 Alfalfa cut in late fall (October 15, November 1, and November 15) yielded an average of 0. 45 tons per acre more (sig- nificant at 1%) the following year than alfalfa cut on September 1, Table 1 . The actual yield of alfalfa obtained from the fall cuttings taken after October 15 decreased until by November 15, there was little harvestable topgrowth, Table 2. These later fall cuttings were very low in quality since most of the leaves had dropped off, leaving mostly stems to be harvested. TABLE 2. -- Alfalfa yields of a third cutting taken at 7 different dates in the fall Yield, tons per acre 10 0) Variety *5 H H H 2 H :2 go 0 *5, *5; .5 H >’ >’ 33 O O O O O > z :93 8 o o z 2 <1 DuPuits 0 0. 97 1.05 0. 99 0.84 0.76 J - 0. 92 Vernal 0 0. 92 1.05 0. 95 0.77 0. 65 - 0.87 Cayuga 0 0.88 0.98 0.82 0.76 0.59 - 0.81 Average 0 0. 92 1.03 0. 92 0.79 0.66 - 0.87 - Yield not obtained Alfalfa regrowth in the fall was greatest for DuPuits cut September 1. DuPuits alfalfa cut September 15 and October 1 was 22 comparable in regrowth to Vernal and Cayuga cut September 1 and September 15, Table 3. The two hardy varieties, Vernal and Cayuga, were about equal in amount of fall regrowth. TABLE 3. -- Height of fall regrowth of alfalfa on November 8, 1966, after fall cutting and topdressing Height, inches Date, third DuPuits Vernal Cayuga cutting K PK 0 K PK 0 K PK 3-cut system Sept. 1 5.5 5.5 2.4 2.7 4.2 .5 3.0 2 7 Sept. 15 2.0 2.0 1.3 1.0 1.0 .0 1.0 1.0 Oct. 1 1.1 1.8 1.0 0.8 0.9 .0 0.9 1 0 Oct. 15 + + + + + + + + Nov. 1 + + Nov. 15 - - - - — - - - - Plants were not cut when data were collected. + New growth had visibly started. Spring growth in the year following treatment, Table 4, was generally greater for the alfalfa cut twice or for the later fall cutting Fertilized treatments-~October 15, November 1, and November 15. alfalfa had more growth than unfertilized alfalfa. 23 TABLE 4. --Alfalfa growth ratings* in the spring following treatment Growth rating Date, third DuPuits Vernal Cayuga cutting 0 K PK 0 K PK 0 K PK 2-cut system No cut 9 10 10 9 10 10 8 9 9 3-cut system Sept. 1 9 9 9 8 9 9 7 8 9 Sept. 15 8 9 9 8 9 9 7 8 8 Oct. 1 8 10 9 8 9 9 7 8 8 Oct. 15 9 10 10 9 10 9 8 9 9 Nov. 1 9 10 10 9 10 9 8 10 9 Nov. 15 9 10 10 9 10 10 9 9 9 *Rating scale, June 1, 1967 10 = 22 inches or more 9 = 20-22 inches 8 -= 18-20 inches 7 = 16-18 inches Carbohydrates. -- By November 1, the maximum level of TAC in the roots of alfalfa was attained, Table 5 and Figure 3. On December 13, roots of plants cut October 15, November 1, and November 15 were significantly higher in average TAC (27. 86, 27. 83, and 28. 12%, respectively) than plants cut September 1, September 15, and October 1 (27.29, 26. 96, and 26.44%, reSpectively). Table 5. 24 TABLE 5. -- Trends of total available carbohydrates in DuPuits and Vernal alfalfa roots after 7 cutting treatments and 3 fertilizer treatments ‘7- Total Available Carbohydrates 3.. DuPuits Vernal Date, E third :1: Sampling date cutting E k. w 2 -t 3 "‘ 2 2 S a: 'a 2 H '2 8. ‘8. H .3 g 3' <5 '3 3 EL 2i. .J .; O O 8 8 o o z z 5' 2 5; 8 8 8 8 2-cut system No cut 0 24. 81 25. 13 28. 15 27. 12 30.73 28.31 28. 94 18.22 19.77 28.42 28. 82 27. 87 29. 39 K - - - 29.30 28.52 29.22 27.03 18.83 20.75 - - - 30.84 PK - - - 29.12 29.88 29.53 25.98 15.89 19.75 - - - 31.12 Avg 24.81 25. 13 28. 15 28.51 29.71 29.02 28.84 18.25 20.09 28.42 28. 82 27. 87 30.45 3-cut system Sept. 1 0 24.81 - 24.20 27.35 29 88 29 32 28.22 15.08 20.45 28.42 - 27.05 29.03 K - - 28.08 28.72 29 91 28 79 27.82 17.31 19.74 - - 27.18 30.05 PK - - 25.09 28.80 30 92 29 22 28.80 17.59 18.70 - - 28.04 30.74 Avg 24.81 - 25.12 28.22 30 17 29 11 28.81 18.85 19.83 28.42 - 27 42 29.94 Sept. 15 0 25.13 22.13 25.03 30 85 28 89 25.95 13.85 19.58 28.82 25.32 28.58 K - 22.22 24.35 29 83 28 81 27 13 13.48 20.72 - 28.00 28.98 PK Avg 25. 13 22.52 24.75 29.84 28 05 28.85 13.48 19.89 28.82 25.43 27.85 Oct. 1 0 28.15 25.99 29 03 27 11 25.29 13.49 20.91 27.87 28.07 K - 27.83 29 90 27 83 28.50 13.44 18.94 - 28.32 PK - 28.25 29 49 27 73 24.85 14.18 20.33 - 21 58 Avg 28.15 28.82 29 47 27 58 25 55 13.70 20.08 27.87 27 32 Oct. 15 0 27.12 30 34 29 89 25.82 13.99 20.84 29.39 K - 29 17 28 34 27.74 13.97 21.89 — PK - 28 75 27 92 28.28 13.72 17.55 - Avg 27.12 29 42 28 72 27.27 13.89 20.02 29.39 Nov. 1 0 30 73 28.85 28.87 18.79 19.39 K - 27.77 27.03 15.52 20.97 PK - 29.15 27 54 15.32 18.25 Avg 30.73 28 59 27 15 15.88 19.54 Nov. 15 0 28.31 29.02 17.87 18.50 K - 28.88 14.84 18.80 PK - 27.80 14.37 18.29 Avg 28. 31 28.12 18.34 20.25 - No roots sampled 25 TABLE 5. -- Continued “In Total Available Carbohydrates Vernal Average Sampling date 0 s s 2: g ‘ ' . I s I o 2: v is 8 8 a 5 ‘5 r 8 8 8 8 a = z z c: < 5 :53 t3 8 o z z o <: 3. 2-cut system 32.39 30.94 28.78 17.34 22.31 25.82 28. 88 27.01 28. 88 21.58 29.83 27.84 18.78 21.04 32.89 29.48 29.09 17. 14 20.97 - - - 80.07 20.81 29.34 28. 08 18.89 20. 88 30.84 29.47 28.48 18.52 21.87 - - - 80. 12 30.38 29.50 27.21 18.21 20.71 81.97 29.98 28.78 17.00 21.85 25.82 28.88 29.01 29.48 80.84 29.49 27.70 18.82 20.87 8-cut system 32.48 30.12 29.11 17.80 23.37 25.82 - 25.83 28.19 31.08 29.72 27.87 18.35 21.91 31.85 30.07 28.51 18.08 22.45 - - 28.82 29.39 30. 88 29.48 27.07 17.70 21.10 81. 73 30. 59 27. 87 20. 21 22.21 - - 28. 57 29. 87 81. 88 29. 91 27. 14 18. 90 20. 48 82.00 80.28 27.78 18.88 22.88 25.82 - 28.27 29.08 81.09 29.89 27.29 17.85 21 15 80. 59 29. 48 28. 23 18. 25 21. 48 28. 88 23. 73 28. 81 80. 72 28. 18 28. 09 15. 05 20. 53 29.95 28.91 27.88 15.90 21.01 - 24.08 28.87 29.89 28.88 27.51 14.88 20. 87 30.97 29.28 27.88 18.84 22.19 - 24. 14 28.12 29.81 28.88 27.28 14.88 20.78 30.50 29.20 27.28 18.28 21.58 28.88 23.98 28.20 30.07 28.83 28.98 14.88 20. 73 29.74 28. 88 27.84 17.28 20.88 27.01 27.08 29.89 27.99 28.57 15.39 20. 80 29.80 30.09 28.50 18. 15 20.15 - 28. 98 29.85 28.98 28.50 14.80 19.55 81.21 29.23 27.84 15.77 22.25 - 28. 98 80.35 28.48 28.25 17.97 21.29 30.25 29.39 27.33 18.40 21.03 27.01 28.97 29. 88 28.48 28. 44 15.05 20. 54 31.83 30.75 29.85 17.80 28.09 28.28 81.09 30.32 27.84 15.90 21.97 32.71 30.87 27.55 17.92 21.88 28.28 30.97 29.81 27.85 15.95 21.51 80.82 80.88 27.91 15. 98 21.53 28.28 29.89 29.14 28.09 14.84 19. 54 81.74 30.88 28.44 17.23 21.98 28.28 30.58 29.89 27.88 15.58 21.01 32.39 29.47 28.14 17.88 22.48 81.58 29.18 27.51 17.24 20.98 - 29.35 29.33 18.34 21.79 81.58 28.58 28.18 18.93 21.38 - 80.14 28.08 18.80 21.80 31.58 29.85 27.80 18.08 19.93 32.39 29.85 28.51 17.81 21.95 31.58 29.12 27.83 18.74 20.74 30 94 28.11 17.34 21.83 29.88 28.57 17.51 20.17 - 28.58 18. 15 21.79 29.83 27.82 18.40 20.20 - 28.75 15.84 22.47 29.83 28. 18 15.11 20. 38 30.94 27.81 17.11 22.03 29.83 28. 12 18.34 20.25 26 858883 mafia Eu: 5 5E, mflmmdm Hmcpo> tam 9;anan mo Soon 5 moumavhnonumo 3933.5 133 ommnokm mo 38:88 u: .m mmDUHb mama wGSQEwm m 83. .82 mm .93. .82 .85 82. 2 .85 .85 2 <67: .822 .52 .80 3 883.3% r % _ r P — P P . p 5 — - _ wfi :2 i L: / IS \/ I3 \ / M x\ \ / . . \ / , [mm x. \ x I§% s ’4 L A X 1mm W x // X \ [mm . X . 2 .38 If}: xx x / x x \ :3 H .Eom III 5 “:0 02 ll / \ 1mm / 4‘ Fom mats EBB / /\ IS 27 The percentage of TAC in roots from plants cut during the critical period, September 15 and October 1, was not significantly different from the September 1 cutting treatment, Table 5 and Figure 3. On April 22 the percentage of TAC in roots from September 15 and October 1 cutting treatments was significantly lower (at 1% level) than roots of the September 1 treatment, Figure 3. Topdressing with fertilizers did not produce any significant difference in TAC in roots of either fertilized or unfertilized alfalfa cut in late summer or fall, Table 5. The average percentage of TAC in Vernal alfalfa roots was significantly higher (26. 20 vs 24.41%) than in DuPuits for all cutting treatments and sampling dates, Figure 4 and Table 5. Experiment II--Verna1 alfalfa, seven cutting treatments, and five fertilizer treatments for two consecutive years-4965 and 1966 The average yields of the first and second cuttings of Vernal alfalfa cut the previous season on September 15 and October 1 in two consecutive years were not significantly different at the 1% level from the September 1 cutting treatment in each year, Figure 5. In both years following the cutting treatments made the previous year, the yield of the first and Second cuttings of each of the September 1, September 15, and October 1 cutting treatments was less (significant coasts new 23 2: mafia“. mfimhm 1253/ paw mfismsm .3 300a 5 UOZH (57:: .uoOH .900 ma .mem m .ummm _ — _ _ p _ P _ _ P _ b b r I 4: lmH 10H Ira 28 \ 33mg / .\ amsno> / / hpoimxw / \\ 1mm [om [Hm 29 Year 1966 g 1967 i ( 00 Yield, tons per acre N No cut Oct. 1 Oct. 15 Nov. 1 Nov. 15 in 1-4 H «a +9 Q4 {-1. 0) (D (I) U) Cutting Treatment FIGURE 5. -- The residual effects of 2 consecutive years of 7 third cutting treatments on Vernal alfalfa as measured by the yields of the first 2 of 3 cuttings the following years 30 anmmm wm6 mp6 3.6 $6 $6 36 $6 $6 2.6 $6 36 :6 $6 $6 2.6 $6 $6 $6 30$ .ommuoia 36 be m mod rod :6. $6 26 and 6H...“ an 36 2.6 $6 36 mod 36 36 3.6 2 $02 36 S m 2...“ E. 6 no.6 $6 86 and mod 86 36 $66 $6 cad $6 36 mp6 2.6 fl .>oz mp6 :6 mod 36 3.6 26 :6 36 mp6 wm6 mp6 :6 2.6 $6 mug.“ 3.6 3.6 m66 3 .80 6.6 m66 $6 O66 36 «c6 mm6 $6 $6 86 «66 and 666 36 No.6 p66 36 om6 g .30 36 $6 mm6 cm6 86 cm...” :6 666 m~6 :6 36 6o.m 36 3.6 6m6 S6 6w.m 35 mg .Eom 36 No.6 36 wN6 66 wad $6 3.6 m66 26 H66 and $6 3.6 mm6 S6 966 36 fl .uaow Eon—who “so-m $6 mad 3.6 86 .36 $6 36 and 36 wad 36 $6 $6 3.6 86 $6 $6 mm6 «:0 oz 839? uaoum S S S S wagamumwauamumwewxwum au.uu.uuau.ua.nuaa.nat J U u I. m u m .l. W m m. T. W cm 8 M 8 H m B 3 M B X m. 3 3 m B X H a d H a d H a d X z x m X m x m 95:: v.35. and?» N .owmbo>< $3 $2 3mm— ouom non mcou .33? cam; 98:620.“ 2: madam 3925 .«o mwfifiso vacuum. and amp: 23 mo @3on ~33 on“ so mucofiumofi sonata“ m 28 35:53.5 man—So 6.35 p 52> «cofiumob mo memo.» ozusoomcoo N «0 308mm 3383mm n- .m H1533. 31 82.30800 gonowofiho :5 «02 u- n 20.85:. 55:82:33 «02 n- mz 283838.. .8882 so 28 H 2: 8 288258 -- 1.... r. mz .285 x 888888 9.880 x 88:88.2 mz Lao» X 505305 93330 a. sonata.“ 28 o X 53 m> agate“ v.8 pouatou o X mom— mz Mm new M X 52 m> Mm new M X mom“ wz .m X bcmfi m> .m X mama 58> x 88:88.2 mz 308303 mad—«PU X houfifihom m2 m2 m2 2 .80 v 2 .82 m2 m2 m2 a .50 van 3 .«90m m> H .aaom m2 m2 m2 * 2 .80 m> a .Eom m2 m2 wz * ma .«Qom m> a .Eom i. .1. 3. 2 .82 28 .2 :62 .2 .80 v2 .80 v.8 .2 .58 .2 .886 «cos—adage 9:390 m2 m2 m Z .8383??? 92.25 m> nouflwtom 8029? 2am .w .3. *2 * Mk V honfiwtou o .1. .1. .w * M v gonna—pom c 8. m2 .0. Mum v v— .1. I. a... bonito.“ v nonnmtom o r: 8858.: 88:88 95. $2 $2 mcomtmnfiou 353nm cocaowncmwm 0055500 u: .m Mai—Mama. 32 at 1% level) than each of the October 15, November 1, and Novem- ber 15 cutting treatments, Table 6. Topdressing with K or PK produced average annual yields of 0. 39 and 0. 53 tons per acre more, reSpectively, (significant at 1%) than unfertilized alfalfa, Table 6. The yields of alfalfa top- 5 dressed with PK were significantly higher (0. 14 tons per acre) than alfalfa topdressed with K alone. The yields of third cuttings taken in the late summer or fall were similar to Experiment I, Table 7. TABLE 7. -— Vernal alfalfa yields of third cuttings taken 2 consecu- tive years at 7 different dates Yield, tons per acre Cutting date Year *5 H 2 1—1 53 "‘ If") . 31750 U H . +3 . . > >- :4) 0 9* 9* 1'3 *5 0 0 :> 2 c2 2 0 . 0 z z <: 1966 ' 0.85 1.24 1.32 1.12 0.94 0.25 0.95 1967 0.96 1.12 1.03 0.91 0.39 - 0.883:< Average 0 0.90 1.18 1.17 1.01 0.66 0.25 0.92 - Yield not obtained * Nov. 15 not included 33 Experiment III-—Three—year old Vernal alfalfa, seven cutting treatments, and five fertilizer treatments for one year--1966 Alfalfa cut on September 15 and October 1 yielded signifi- cantly more at the 1% level the next year than plants cut September 1 (3. 52 and 3. 94 vs 3. 36 tons per acre, respectively), Table 8, in a 3-year old stand of Vernal alfalfa. Topdressing the alfalfa with PK gave an average increase in yield of 0. 5 tons per acre more than unfertilized alfalfa and 0. 38 tons per acre more than alfalfa topdressed with K alone (significant at 1%), Table 8 and Figure 6. Topdressing with K alone did not give a significant yield increase. Topdressing with PK in the fall gave higher yields (signifi- cant at 1%) the next year than when fertilized in the spring. Yield differences between plants fertilized with PK in the spring and fall, Table 8, were greatest for the earlier fall cutting treatments, September 1, September 15, and October 1. Alfalfa cut later in the fall--Oct0ber 15, November 1, and November 15--yie1ded significantly more (average of O. 92 tons per acre) at the 1% level the next year than alfalfa cut on September 1, September 15, and October 1. The actual fall hay yield from the two later fall cuttings, November 1 and November 15, was not determined 34 TABLE 8. -- The total yields of 3 cuttings of Vernal alfalfa the year following 7 third cutting treatments and 5 fertilizer treatments Yield, tons per acre Date, third cutting +_; an 2:0 7“ s. :1 ',_, 2:: '5 no no no 0 0 :8 o. as M QM > > M :> Z in In M m M In 0.. m 0.. <1 M <1 Ch <1 2 - cut system No Cut 4.37 4.41 4.76 4.32 5.27 4.59 4.80 4.62 3-cut system Sept. 1 3.09 3.27 3.07 3.90 3.45 3.17 3.67 3.36 Sept. 15 3.34 3.48 3.31 4.14 3.31 3.40 3.73 3.52 Oct. 1 3.80 3.82 3.70 4.43 3.97 3.76 4.20 3.94 Oct. 15 4.10 4.15 4.18 4.88 4.47 4.17 4.67 4.35 Nov. 1 4.32 4.46 4.21 4.82 4.90 4.34 4.86 4.54 Nov. 15 4.20 4.90 4.69 4.75 4.80 4.80 4.78 4.67 Average, 3-cut 3.81 4.01 3.86 4.49 4.15 3.94 4.32 4.06 system Planned comparisons ' Significance Fertilizer treatments 0 fertilizer < fertilizer ** O < K # _ ** K < PK ** Fall applications > spring applications ** Cutting treatments Sept. 1, Sept. 15, and Oct. 1 < Oct. 15, ** Nov. 1, and Nov. 15 Sept. 1 < Sept. 15 and Oct. 1 ** Sept. 15 < Oct. 1 ** *, ** -— Significant at the 1 and 5% levels, respectively # -- Not an orthogonal comparison 9‘ -- Average for the 5 fertilizer treatments 35 Fertilizer E None VA K 5 PK 0 V1 m N H 8.108 Jed suoi ‘ptatg IIHIHl ‘H‘ 111 III: III: 11 H mun \‘3 :3 > 56:. .2 Egg “‘3: UIIIJ‘IIII‘JHIII‘ Lu mu “‘1 NHL nnuny; SE 8 2‘3 31%" w LlJlIIHIIlLHIIIH‘flll II n Illllllllllll‘fi «2’5; \ 8 3: /O 45 f3; Illlllllll‘ n IlJllll‘ n nmun II II .. ‘57.“ - *6 H '22 ° 2” a: Ullwlll III u llllllllJlllllllll ‘3," 38 ~\\\\\\\\.\\\\\\\\\\\\\\\\\\\ “5. +5 .2.» ////////////////////////// A as a”; Llllll nu Ill n‘mnnm II m ”1111qu g; .93 2% ‘7‘8 11 II II III‘JUHHIHHHHHHH IIII‘II‘JH *5 .2.- 2 g in Fertilizer S None 35 : flK E EPK J llIIIIll ‘1‘ 111: ill II n mun: mun n: llllll‘ ‘ll Hm IL lllllll‘ Hnn ll\ [um I H 11‘ Ill! LN 11 II n: [LII II In um um 11 um I‘ Hum-II 1 H u\ LLH Hill! 1] IHIIIIIHHHH I I t\\\\\\\\\\ \\\\\\\ \\\\\\\\ \ '///////////////////////// mm nu Ill ILIIIIII III II m m un flll H II III: mu HHHHLHIHIH llll‘ll‘ Ill 9.1312 Jed suo; ‘PIQIA Nov. 15 Sept. 15 Oct. 1 Oct. 15 Nov. 1 Sept . 1 No cut Cutting Treatment FIGURE 6. - The residual effects of 7 third cutting treatments and K and PK fertilization as measured by the yields of Vernal alfalfa in 3 cuttings the next year 36 since climatic factors were such that little harvestable hay could be removed, Table 9. TABLE 9. —- Third cutting yields in tons per acre on 7 different dates of 3-year old Vernal alfalfa No cut Sept. 1 Sept. 15 Oct. 1 Oct. 15 Nov. 1 Nov. 15 0 0.94 1.01 0.90 0.72 - - - Yield not obtained ' Summary of Experiments 1, II, and III with Vernal alfalfa The residual effect of the late summer and fall cutting treatments as reflected by the yield of the first two cuttings in Experiments I and II and three cuttings in Experiment III is shown in Table 10 as a summary. Vernal alfalfa cut on September 15 or October 1 yielded the same (average of 3. 96 and 4. 18 tons) as when cut September 1 (3. 93 tons). In each experiment, the next year' s yields of Vernal alfalfa cut September 1, September 15, and October 1 were less than alfalfa not cut or out October 15, November 1, and November 15, Table 10. For the average of the three experiments, subsequent year' 8 yields of alfalfa cut September 1 or September 15 or October 1 were increased by PK and, to a lesser extent, by K. 37 5:: .w Manamamm 28 .3 b3. .2 257M: Emfizoaxm $2 .3 .33. es... 2 33.--: Evacuaxm gmH 6H fish can a BETH HQoEHhomxm "no 358 mwfifisuvw 839$ Hm6 .36 £6 36 86 mm6 6m.m Hw.m mm6 mp6 36 mm6 mm6 6m6 Hm6 mo6 Bonn .owwanw :6 $6 3.6 6m6 $6 3.6 86 om6 $6 $6 3.6 H66 $6 $6 36 3.6 mH .>o7H 86 $6 m66 666 6m6 £6 6m6 $6 $6 oH.m $6 2.6 N66 36 mm6 Hm6 H .>oZ om6 mp6 $66 £6 36 $6 :6 36 5.6 606 86 H66 H66 m66 $6 :6 mH .HoO wH6 M66 mH6 Hm.m 6m.m om6 22m and 666 om6 m66 cm6 mH6 mm6 mH6 65m H .50 mm.m mH6 wage. 22m mm.m 22m O6.m 6m.m mH6 mm6 :6 bad wH6 H66 0H6 56 mH .Eom mm.m mo6 mm.m EZm mm.m $6 :6 mo.m mm6 6m6 wm6 mH6 HH6 £6 36 no.6 H .Eom EonMm Scum 56 mp6 mp6 56,36 om6 $6 56 $6 $6 wm6 $6 3.6 3.6 mod $6 30 oz 839nm “scum w>¢MnH M o w> .Ho *mwfifiso Honooom Ham Hmpa .Ho 3on H3305. so mHGoEHMonHMo m 5 manoaummfi madman—won» MmNHHHu—Mom m cam mHGmSHmoAH 95336 6.35 H. m0 300%.... Hangman on”. .3 Emagm nu .3 H1332. DISCUSSION Data obtained in two years in the three experiments reported show that well fertilized alfalfa can be cut for the third time in the vicinity of East Lansing, Michigan, (and probably else- where under similar conditions) on September 15 or October 1 and yield as much the following year as alfalfa cut for the third time on September 1. In contrast to this work in Michigan, Graber 313.1. (1927), and Smith ( 1960) in southern Wisconsin showed that third-cutting treatments on September 15 or October 1 decreased the following year's yields when compared to September 1 cuttings. These yield decreases are understandable since southern Wisconsin has a shorter fall growing season to replenish root reserves and yet has more serious hazards attributed to lower temperatures which fre- quently result in more winterkilling and decreased yields the next year. The work reported in these experiments is in good agree- ment, however, with that of Rather and Harrison (1938), working in Michigan. They showed that the September 1, September 15, and 38 39 October 1 cutting treatments yielded the same the next year. They compared the total yields of two cuttings of a 2-cut and a 3-cut system the year following late summer or fall cutting treatments. By taking this approach, they determined that alfalfa cut for a third time in late summer or fall yielded less in the two cuttings the fol- lowing year than alfalfa cut twice the previous year. They logically recommended the 2-cut system as the safest practice. It should be noted that their second cutting was harvested in the "1/10 to 1/2 bloom" stage, probably in mid-August, later than the first and second cuttings harvested in early bloom in this experiment (early June and July 15 to early August). As a result, their third cutting was considerably lower yielding than third cuttings harvested in this experiment and there was less time for replenishment of carbo- hydrate reserves. To make a valid comparison of a 2-cut and a 3-cut system, one must consider some other factors in addition to the total yield of the two cuttings the next year. First, the yield of the first two cuttings of a 2-cut system is the total yield for a 2-cut system while the total yield for a 3-cut system must have a third cutting added to the first two cuttings. This is shown in Table 11 for Vernal alfalfa topdressed with PK and for the data of Rather and Harrison (1938) using Hardigan alfalfa with no topdressing. By comparing these 40 totals of 2-cut and 3-cut systems, it can be seen that Rather and Harrison were right in concluding that the 2-cut system was "safest in Michigan" since the total yield of the 2-cut system was similar to the total yields of a 3-cut system which lowered the carbohydrate reserves and made the plants susceptible to winter injury and bacte- rial wilt . TABLE 11. -- Comparison of 1938 alfalfa yields with recent yields of Vernal alfalfa fertilized annually with PK under identical cutting treatments Rather and Harrison Avg * . Date, Summary Experiments I, II, and IE €33: First and Third First and Third g second cut tin Total second cutting Total . cutting 3 cutting** *** 2-cut system No cut 3.51 0 3.51 4.73 0 4.73 3-cut system Sept. 1 3. 15 0.30 3.45 4.09 0.90 4. 69 Sept. 15 3. 01 0. 44 3. 45 4. 18 1. 10 4. 91 Oct. 1 3.11 0.44 3.55 4.43 1.05 5.13 Oct. 15 3.27 0.35 3.62 4.72 0.87 5.30 Nov. 1 3.40 0.26 3.66 4.84 0.79 5.37 Nov. 15 - - - 4.89 0.25 5.06 *Average of eight trials (Rather and Harrison, 1938), second cutting taken in early August, southern Michigan. **From Table 10, Experiments I and II. 3 cuttings . Experiment III had ***Average of Vernal alfalfa in Tables 2, 7, and 9, added to Experiments I and II only. 41 Their recommendation made three decades ago with non- wilt resistant varieties and little, if any, topdressing needs to be re-examined since in these three experiments, the average total yield of Vernal alfalfa cut September 1, September 15, and October 1 was 0. 52 tons per acre more the next year than the yield of alfalfa F cut twice, Table 11. Various reports in northern states and northern latitudes (Armstrong et a1. , 1948; Folkins et a1. , 1960; “ l" I Smith, 1960; Chance et a1. , 1961; Carter, 1964; Michigan State Uni- versity Cooperative Extension Service, 1967; and Fuess and Tesar, 1968) Show that three cuttings yield more than two when the third cutting is harvested in late August or early September. The results of this study, Table 11, show further that the third cutting can be made any time after September 1 until November 1 with a gradual increasehin total yield from 4. 69 to 5. 37 tons in the following year. Quality is a second factor that must be considered when comparing a 2-cut and a 3-cut system. Hay from a 3-cut system is higher in quality sinceit is younger plant tissue with less fiber and also because it has more leaves which are of prime importance because they contain a much higher concentration of nutrients than the stems (Reid e_t_al. , 1959). Fuess and Tesar (1968) reported that two-thirds of the yield difference between 2- and 3-cut systems was due to leaf drop in the 2-cut system. 42 Alfalfa cut September 1, September 15, or October 1 gen- erally yielded less the next yearthan alfalfa cut the previous year on October 15, November 1, or November 15, Table 11. Here one must consider the practicality of harvesting alfalfa after October 1 when average yields of a third harvest are low (average of 0. 64 tons per-acre), Table 11, and quality is lower, especially at the last date when most of the leaves have dropped leaving only stems with a high percentage of dry matter. By November 15, the quality of the forage left standing was so low that yields were not determined. No cumulative effect of fall cutting or fertilizer treatment occurred when Vernal alfalfa was given the same treatments for two consecutive years, which is in contrast to reports of Kust and Smith (1961), who used a somewhat more severe cutting treatment in a state having more severewinters. Since Vernal alfalfa was able to maintain the same yield level the next year for plants cut the pre- vious September 1, September 15, and October 1, it would be unreasonable to expect a major cumulative effect of cutting treatments onthe yield of Vernal alfalfa. Apparently Vernal alfalfa cut on September 1 had adequate time to replenish most of the root reserves before cold weather‘stopped or severely reduced storage of carbo- hydrates. Even though plants cut September 15 or October 1 regrew only one inch, this regrowth apparently replenished carbohydrate 43 reserves to the extent that they were as high on December 13 as in plants cut on September 1; therefore, next year' 3 yields were similar. In contrast, DuPuits alfalfa, a medium hardy and non—wilt resistant variety, may not maintain the same level of production as did Vernal when cut two consecutive years during the critical period. Table 1 shows a tendency for the average yield of DuPuits to decrease the following year when cut the previous September 15. The fall regrowth of DuPuits, Table 3, indicates that the regrowth of DuPuits was somewhat greater than that of Vernal. With its greater growth, it should be able to replenish carbohydrate reserves to a higher level than Vernal. Therefore, its inherent lower poten- tial winterhardiness may be the primary reason it is less resistant to severe fall cuttings even though it regrows more rapidly as noted above. In Table 8, Experiment III, the following year' s yield of Vernal alfalfa cut the previous September 1 was lowest. In this experiment, the second cutting of the treatment year was made in early August. It is probable that the interval between the Septem- ber 1 cutting and the previous second cutting in early August was insufficient for adequate regrowth. As a result, root reserves were not replenished between the second and third cutting. Thus, the 44 September 1 cutting treatment caused a decrease in yield the follow- ing year, similar in effect to the data of Kust and Smith (1961), who found that when cut on June 28, August 30 and October 1, the second year' 5 yields of Vernal alfalfa were severely reduced. In Experiment III, PK fertilizer applied in the fall gave greater yields than when applied in the spring. Since the stand was I two years old and had not previously been topdressed, the additional amount of PK fertilizer becoming available to the plants by the I earlier application may have made a significant difference. The fertility level was likely low since no fertilizer was applied after seeding. The failure of K alone to give a significant yield increase was probably due to P being more limiting than K in this experiment. The fact that topdressing alfalfa after cutting treatments did not show any difference in TAC of roots indicates that PK and K alone do not affect the level of carbohydrates but must react in some other way in the plant to increase winterhardiness. The following year' 8 yields of all cutting treatments were increased by fertilizer, particularly by PK for Vernal and Cayuga. Vernal alfalfa, a hardy variety, was higher in TAC in the roots than DuPuits, a medium hardy variety, indicating that the higher TAC levels may have contributed to the greater winterhardi- ness of Vernal and the generally higher yields of Vernal cut 45 September 1, September 15, and October 1 the previous year. DuPuits having lower TAC levels and little or no wilt resistance would be expected to show lower yields the next year when a third cutting was taken September 15 and October 1. On December 13, the TAC in roots of plants cut on Septem- ber 1 appeared to be slightly higher than when cut September 15 or October 1 but the difference was not significant. However on April 22, the TAC in roots of plants cut September 15 and October 1 were significantly lower than September 1 cut plants, Figure 3. By June 9, there was no difference in TAC levels apparently since the spring growth had replenished carbohydrate reserves. This research indicates that greater flexibility in fall management of alfalfa is likely in southern Michigan. Farmers can cut hardy, wilt resistant varieties of alfalfa such as Vernal (and probably less hardy wilt resistant varieties) for the third time after harvesting a second cutting mid- to late July and not materially reduce yields of alfalfa the next year. From two years' data, there appears to be no cumulative effect of cutting September 15 or October 1 when compared to a September 1 cutting. SUMMARY AND CONCLUSIONS The residual effect of cutting Vernal, a hardy alfalfa, for a third time on September 1, September 15, October 1, October 15, November 1, and November 15 was determined in 1966 and 1967 p from the first two of three cuttings in the year following cutting treatments at several fertility levels in each of three separate experiments at East Lansing in southern Michigan. In one of the experiments, the cutting treatments were imposed for two consecu- tive years in the same experiment. In another experiment, Cayuga, . a hardy alfalfa, and DuPuits, a medium hardy alfalfa, were given similar cutting treatments. The TAC in the roots were determined after each cutting treatment and on December 13, April 22, and June 9 on Vernal and DuPuits alfalfa. The results show that: 1. In each of the three experiments, alfalfa cut for the third time on September 15 or October 1 yielded as much in the first two of three cuttings the next year as when out September 1. Alfalfa cut on October 15, November 1, or November 15 yielded more than when out September 1, September 15, or October 1. 46 47 In one of the three experiments, fertilizing with K or PK in contrast to no fertilizer gave relatively higher yields the next year after cutting on September 15 or October 1 than when out on the previous September 1. Yields of alfalfa did not show a cumulative effect of two consecutive years of September 1, September 15, or October 1 cutting treatments and fertilizer treatments. The roots of alfalfa cut twice and those cut for a third time on September 1, September 15, October 1, and October 15 attained their maximum TAC level by November 1, then decreased. On December 13, no significant difference occurred in levels of TAC in roots of alfalfa cut September 1, September 15, and October 1. The level of TAC in roots of plants cut September 1, September 15, and October 1 was generally lower on December 13 than in roots of plants out twice or a third time on October 15, November 1, and November 15. Topdressing with K and PK after late summer and fall cutting treatments did not affect the level of TAC in the roots of alfalfa during the fall and winter. The level of TAC in Vernal alfalfa was higher than DuPuits alfalfa during the late summer, fall, and winter. 48 9. PK applied in the fall gave a higher yield the following year than when applied in the spring. 10. Topdressing with PK gave a higher yield than K alone. BIBLIOGRAPHY BIBLIOGRAPHY Armstrong, J. M., Nowosad, F. S., Ripley, P. O., and Kalbfleisch, W. 1948. Alfalfa for hay, silage and pasture. Publ. 735. Can. Dept. Agr., Ottawa. Bernfeld, P. 1951. Enzymes of starch degradation and synthesis. Adv. Enzymology XII: p. 379-395. Interscience. New York. Carter, Jack F. 1964. Alfalfa production in North Dakota. North Dakota Agr. Exp. Sta. Bull. 448. Chance, C. M., Griffeth, W. L., Loomis, C. W., Johnson, A. A., and Winkelblech, C. S. 1961. Forages: production, harvesting, utilization. New York State College of Agr. , Cornell Misc. Bull. 39 (Extension). Folkins, L. P., Greenshields, J. E. R., and Nowosad, F. S. 1960. Effect of date and frequency of defoliation on yield and quality of alfalfa. Can. J. P1. Sci. 41:188-194. Fuess, F. W., and Tesar, M. B. 1968. 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Influence of harvest management on level of carbohydrate reserves, longevity of stands, and yield of hay and protein from Vernal alfalfa. Crop Sci. 1:267-269. Michigan State University Cooperative Extension Service. 1967. Intensified improved certified alfalfa. Michigan State Univ. Ext. Bull. 423. Nelson, N. T. 1925. The effects of frequent cutting on the produc- tion, root reserves, and behavior of alfalfa. J. Amer. Soc. Agron. 17:100-113. Parsons, J. L., and Davis, R. R. 1960. Forage production of Vernal alfalfa under differential cutting and phosphorus fertilization. Agron. J. 52:441-443. Rather, H. C., and Harrison, C. M. 1938. Alfalfa management with special reference to fall treatment. Michigan Agr. Exp. Sta. Spec. Bull. 292. Reid, J. T., Kennedy, W. K., Turk, K. L., Slack, S. T., Trim- berger, G. W., and Murphy, R. P. 1959. Effect of growth stage, chemical composition, and physical properties upon the nutritive value of forages. J. Dairy Sci. 42:567-571. Silkett, V. W., Megee, C. R., and Rather, H. C. 1937. The effect of late summer and early fall cutting on crown bud formation and winterhardiness of alfalfa. J. Amer. Soc. Agron. 29:53-62. Smith, Dale. 1960. The establishment and management of alfalfa. Wisconsin Agr. Exp. Sta. Bull. 542. Unpublished data. Wisconsin Agr. Exp. Sta. 51 , Paulsen, G. M., and Raguse, C. A. 1964. Extraction of total available carbohydrates from grass and legume tissue. P1. Physiol. 39:960-962. Twamley, B. E. 1960. Variety, fertilizer, management inter- actions in alfalfa. Can. J. P1. Sci. 40:130-138. Wang, L. C., Attoe, C. J., and Truog, E. 1953. Effect of lime and fertility levels on the chemical composition and winter survival of alfalfa. Agron. J. 45:381-384. Willard, C. J. 1930. Root reserves of alfalfa with special reference to time of cutting and yield. J. Amer. Soc. Agron. 22:595- 602. ill||||||||NlllllllINNIWIIHIHIIIUlllllltlllllllillHl 31293006702