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W AN ABSTRACT Submitted to the Sdhool of Graduate Studies or _ Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Farm Crops 19 Approved ' Thomas C. Graham ABSTRACT THE INFLUENCE OF SEEDING RATES ON GRASS SEEDS MIXTURES UNDER DIFFERENT CUTTING TREATMENTS The balance of species in a pasture is determined mainly by the proportion of each species in the seeds mixture and by the rate of seeding. The cutting and grazing management and the application of fertilizers also play an important part. Because of a lack of concrete information on the com- petitiveness of various species in a complex mixture, a greenhouse experiment was set up to study their behaviour under the contrasting conditions of seeding rates and cutting treat- ments. Soil fertility remained constant for all cultures. Rates of seeding were varied from 5 to 40 pounds per acre in two complex grass seeds mixtures, one of which was predominantly ryegrass and in the other cocksfoot was dominant. Half of the cultures were cut at two week intervals, and the other half harvested at the hay stage. The yield of the ryegrass mixture was not affected by seed rate, and in the final cut, the five pound rate of seed- ing was equal to the 40 pound rate. In the cocksfoot mixture, the yields increased slightly with seed rate increments. The heavy seed rates gave ryegrass complete dominance in both mixtures, while cocksfoot and timothy developed better under low rates of seeding. At the 40 pound rate, both mixtures Thomas C. Graham were very similar in botanical composition. Plants in the low seed rate were roughly three times the size of those in the highest seed rate. The total yield in both mixtures from the hay cutting treatment was double the total yield from five cuttings. Frequent cutting caused considerable injury to the root system of the complex mixtures, whereas the roots of the single species were not affected over the duration of this experiment. THE INFLUENCE OF SEEDING RATES ON GRASS SEEDS MIXTURES UNDER DIFFERENT CUTTING TREATMENTS BY THOMAS C. GRAHAM A THESIS Submitted to the School of Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Farm Crops 1956 ACKNOWLEDGEMENTS The author wishes to express his very sincere thanks to his major professor, Dr. C. M. Harrison, for his guidance during the course of the experiment, and for valuable assistance in the preparation of the manuscript. Also to Mr. William.F. Hueg, whose cooperation in.the greenhouse and advice in writing the manuscript were much appreciated. Acknowledgement is also made to the‘W. K. Kellogg Foundation, who generously provided facilities for this study. INTRODUCTION ................................... REVIEW OF LITERATURE ........................... EXPERIMENTAL PROCEDURE ......................... EXPERIMENTAL RESULTS 1. 2. 3. 4. 5. Comparison of yields of mixtures ....... EffeCt Of seeding rate on yields eeeeeee Effect of seeding rate on botanical analysis ..................... Effect of seeding rate on CStBbliShment eeeeeeeeeeeeeeeeeeeeeeeeee Effect of seeding rate on root grO'th 00......OOOOOOOOOOOOOOOOOO0.0.... DISCUSSION 0.00000000000000000000QOOOOOOOOOOO... SWY AND CONCLUSIONS OOCCCOOOOCOOOOOCOOOOOOOO LITERATURE CITED ............................... Page 1 4 11 15 22 3O 33 36 41 44 45 C O .. . e e 0 I O Q emomeemmmlee I... I, I a. — CO. I 0.0.0.1.“. deOeOeseoeeeee seeeeeee THE INFLUENCE OF SEEDING RATES ON GRASS SEEDS MIXTURES UNDER DIFFERENT CUTTING TREATMENTS 1. INTRODUCTIQN "'Twas expected that the thickness of the plants should help to kill the weeds; yet upon due observation 'tis found that when their excessive numbers have brought a famine amongst them, they are forced to prey one upon the other and 'tho the stronger survive, yet even those are weakened by hunger, that they become the less able to contend with the weeds. This I am certain of, that the least competent number of plants will bring the greatest crop." . These are the words of Jethro Tull, a noted English farmer, who wrote a series of essays on tillage and vegetation in 1733. He had remarkable powers of observation and strongly criticised the traditional husbandry of his day, supporting his theories by a number of simple but very effective experiments. His observations above referred to the seeding of alfalfa, and he proved his point by producing record yields of hay from as low as two pounds of seed per acre. Tradition rather than knowledge continues to dominate many of our agricultural practices, and this has been par- ticularly evident in the use of grass seeds mixtures. The traditional rate of sowing in most parts of Britain, indeed in most European countries, has been until recently thirty or more pounds of seed per acre. This has usually been Justified by the argument that a generous seeding is required for better 2 weed control and to compensate for adverse soil conditions. Moreover, the use of complex mixtures involving a large number of different species, tended to encourage heavy seed rates, while the farmer himself has always been rather guilty of sowing that little extra seed, "Just to be on the safe side." ‘With better quality seed and improved techniques in sowing and cultivation, the farmer is now using much lower seed rates. This trend has been influenced by the increased use of simpler mixtures, which the plant breeder has made possible by providing a much greater variety of grasses and legumes to suit a wide range of farming conditions. Now, instead of mixing different species together, various strains of one grass and legume are blended together and sown at low rates. Competition between species is reduced to a minimum and grazing management is greatly simplified. There has always been considerable interest in seed-rate experiments with particular emphasis on simple mixtures, but little attention has been given to the effect of seed-rate on the more complex multi-purpose mixtures which are still in general use. When a large number of species are grown together in a mixture, strong competition in the early stages is inevitable and as the density of plants increases, such competition is greatly intensified. The balance of species in a mixture is influenced mainly by the rate of seeding and proportion of each species; the soil conditions and fertilizers applied; and finally, the 3 cutting or grazing management. Because of a lack of con- crete information on the competitiveness of various species in mixtures, a greenhouse experiment was set up to study the behaviour of the various components of complex mixtures under the contrasting conditions of seed rates and cutting treat- ments. Soil fertility remained constant for all cultures. 2. mg! 01“ LITERATURE There is a wealth of literature on grass seed mixtures, dating back to the late 19th century, when complex mixtures were first used by Robert Elliot, a farmer in the Southern Uplands of Scotland. The subject has been a most controver- sial one ever since, and even today, there is still some divergence of Opinion, both in Britain and the United States, on the relative merit of simple and complex mixtures, and how much seed should be used under various conditions. The trend towards simple mixtures began in the present century, when Gilchrist, of Cockle Park, and Findlay, of Aberdeen, introduced relatively simple prescriptions with special emphasis on the use of adapted strains of grass and clover. Stapledon and Davies followed with some excellent work at Aberystwyth,‘Wales by simplifying mixtures even further and blending different grass strains to give more level production throughout the season. Since the last war, advances in grassland research have been so rapid that most of the reference material quoted comes primarily from that period. The review can be divided into three sections, - seeds mixtures, rate of seeding, and cutting treatments. §gggg Migtureg. The physiological factors involved in compounding seeds mixtures have been thoroughly examined by Blaser, et al (3), particularly those affecting seedling competition. All the common grasses and legumes have been classified according to their aggressiveness by weighing the 5 seedlings of each species. Ryegrass was considered very aggressive, orchard grass aggressive, and timothy non- aggressive, while among the clovers, red clover was much more aggressive than white clover. Competition between the species was influenced greatly by the time of seeding and the addition of nitrogen. As seeding in the spring favored the dominance of grass over legumes, they recommended that the ratio of grass and legumes should be adjusted for spring and summer seedings. In comp pounding mixtures, they suggest that several simple mixtures of different maturity should be used and manipulated during the season according to growth, rather than a general purpose mixture which will not give such a uniform distribution of grazing. Simple and complex mixtures were compared by Hanson and Hein (9). at Beltsville, over a period of four years. They found that complex mixtures gave superior yields only in the spring of the first year, losing this advantage in July and August. After four years in pasture, Kentucky bluegrass com- prised over 90 percent of the grass population of all the mixtures in which it was included. Hughes (11) obtained similar results in England when he compared the yields and livestock output of simple and complex mixtures. Over a period of three years, the total production of the simple and complex mixtures was very similar, but the simple mixtures gave more uniform production over drought periods. Liveweight gains per acre, however, did not produce 6 any significant difference over the whole period, but the grazing management of the simple mixtures was much easier. Aberg, at al, (1) conducted both field and greenhouse studies at Iowa, on grass and legume associations, and found that the results were sometimes reversed on account of wide differences in environmental conditions. In the greenhouse, the yields of forage and roots from orchard grass and timothy were higher in association with alfalfa and brome grass than when grown alone. Timothy and orchard grass, however, were antagonistic as orchard grass reduced the timothy yield when they were grown together. £332 9; Seeding. Heddle and Herriott (8), working under Scottish conditions, compared simple mixtures of ryegrass and cocksfoot at rates of 10, 20 and 30 pounds per acre, with a common seeding of 3 pounds per acre of S 100 white clover. In the first year, ryegrass gave much better ground cover than cocksfoot at the low seed rate, thus preventing the ingress of weeds. In the early stages, more seed gave higher yields, but after the first harvest, the three seed rates gradually equalized. In order to insure quick ground cover, the 20 pound rate was recommended, the 10 pound rate being quite adequate under favorable conditions. A greenhouse experiment by Erdmann and Harrison (5), studied the effect of ryegrass and redtop used as nurse grasses in lawn and turf mixtures containing Kentucky bluegrass and red fescue at seed rates of 10 to 40 pounds per acre. Ryegrass produced the highest yields and was just as aggressive at the 7 low seed rates as at the high seed rate. In areas where fast growing nurse grasses are not essential for quick ground cover, they recommend a pure seeding of one turf grass. This view is supported by Juska (14) who found that ryegrass and redtop did more harm than good, due to their aggressive competition in newly established lawn mixtures. A comprehensive field study by Hunt (13), of 27 grass strains used in Scottish seeds mixtures gave wide variations in percentage establishment. The average for ryegrass was 30 percent, while cocksfoot was 20 percent, and timothy 15 ‘ percent. The seed was broadcast at normal rates under a nurse crop of cats on good land. This poor rate of establishment accounts for the farmer's reluctance to risk a low rate seed- ing unless he is able to drill it. Parry (16) at Aberystwyth, also found that ryegrass yielded equally well at rates of 24 down to 6 pounds per acre, although the low seeding rate encouraged more weeds in the first year. To counteract this, the proportion of white clover was increased from 1 to 4 pounds, as the amount of ryegrass was decreased. He suggested that the 15 pound rate was quite adequate for a simple mixture, and this could be reduced to 10 pounds when drilled. MacDonald (15) at Cornell, working with timothy as a pure species found that the yield of hay actually began to decline beyond a seeding rate of 4 pounds per acre. He recommended that seed rates of aggressive species should be reduced to a minimum to give slower grasses a chance to establish. Buller (4) 8 also obtained similar results at Pennsylvania State University, where seed yields of orchard grass andtimothy were slightly reduced by broadcasting double the amount of seed. There was no significant difference, however, with drilling at low and high seed rates. The broadcast seed rates were 3 and 6 pounds per acre, both for orchard grass and timothy. This rate was halved for drilling. Cutting Tregtmegtg. Under greenhouse conditions, Harrison and Hedgson (7), showed that the total yields of grasses cut weekly for eight weeks was less than the final yield from one cutting at the end of the experiment. This applies both to top and-root growth and the injury was more severe when the clippings were reduced from 3" to l" in height. Orchard grass gave nearly double the yield of timothy under the 3" cutting treatment, but they were both almost killed out by the 1" cutting. Wagner(18), conducted a similar experiment with grass and legumes at Beltsville, varying the interval between clip- ping and keeping the height of cutting constant at 2". The greatest reduction in growth occurred when the grass was clipped during the later stages of develOpment, and brome grass was more sensitive in this respect than orchard grass. The data suggests that moderate clipping in the early stages should help the legumes and less aggressive grasses to compete against weeds and give quicker establishment. Under intensive production for grass-drying in Scotland, Holmes and Maclusky (10), observed that heavy nitrogen and 9 frequent cutting quickly eliminated clover in the mixture, but did not reduce the yield of grass. Grass however, can be gradually killed out by frequent defoliation and applications of nitrogen, as demonstrated by Harrison (6), when he grew Kentucky bluegrass under high temperatures in the greenhouse. The rapid growth exhausts root reserves, and with no leaves to replenish the supply, the plait eventually dies out. Root growth of grasses grown in mixtures also seems to be affected by interaction between species. This has been con- firmed by Ahlgren and Aamodt (2) in the greenhouse, using bluegrass, timothy and redtop. They found that the weight of roots per plant was greater when grown in pure culture than in mixtures, indicating some antagonism between the species. A field experiment carried out in England by Hughes and Davis (12), correlated fairly closely with the results obtdhed in this experimmnt. A ryegrass mixture and a cocksfoot mixture seeded at 6 and 18 pounds per acre were compared under grazing and cutting treatments for a period of three years. The low seed rate gave just as good results as the high seed rate, while yields from the hay and aftermath treatment in the first year almost doubled that from rotational grazing. The plots were grazed by sheep and rested for two week intervals. Half the plots received nitrogen, and in the third year pasture, those plots only contained about 5 percent white clover, while the plots without nitrogen had almost 20 percent. There was even further reduction of white clover by the hay treatment along with nitrogen. The seed rates had no 10 significant effect on the clover content, but in the absence of nitrogen, it was observed that more clover had colonized the cocksfoot plots at the low rate of seeding. 11 mW The experiment was started in the greenhouse at Michigan State University, East Lansing, Michigan, in January 1956, and completed at the end of May. The seedings were made in 10" clay pots using quartz sand and a standard nutrient solution. The three principal grasses used in compounding mixtures - ryegrass, cocksfoot and timothy were grown as single species and in two complex mixtures, with the clover standard throughout all the mixtures. The single species were Domestic ryegrass (Lolium multiflorum), Perennial ryegrass (Lolium perenne), Orchard grass (Dactylis glomerata), two pedigree strains of cocksfoot, S 37 and S 143,* and timothy (Phleum pretense), Two complex mixtures were used - one in which ryegrass predominated, and in the other cocksfoot was predominant. The proportion of timothy and clover was constant in both. Details of the mixtures are as follows: - Single Grggg Mixtuggg. 1. 18 lbs/ac Domestic ryegrass 12 " Commercial Perennial ryegrass 2. 6 " S 23 Perennial ryegrass (Pasture type) 3. l4 " Orchard grass (Danish cocksfoot) 7 " S 37 cocksfoot (hay type) 4. " S 143 cocksfoot (pasture type) 5. 8 " Timothy * Orchard grass is known as Danish cocksfoot in Britain. 8 37 and S 143 are British strains of cocksfoot. 12 Each mixture contained a standard clover seeding as follows: - 1 lb. Red clover f lb. New Zealand white clover i lb. S 100 white clover i lb. Kent wild white clover QQmELg; Mixtgrgg. The ryegrass - dominant mixture contained 50 percent rye- grass and 25 percent cocksfoot, while in the cocksfoot - dominant mixture the proportions were reversed. For convenience, these mixtures will be referred to as Ryegrass mixture and Cocksfoot mixture. _ LWWZ-WW 4 lbs Domestic ryegrass 2 lbs Domestic ryegrass 6 " S 23 Per. ” 3 " S 23 Per. " 10 " Commercial " 5 " Commercial " 4 “ Orchard grass 8 “ Orchard grass 3 " S 37 cocksfoot 6 “ S 37 cocksfoot 3 " S 143 " 6 " S 143 ” 6 ' Timothy 6 ” Timothy 2 " Red clover 2 " Red clover l " N. Z. white clover l " N. Z. white clover t " S 100 ” ” f " S 100 S ' i " ‘lild ” " f " ‘Wild " " Four seeding rates, 5, 10, 20 and 40 pounds per acre were used. The 20 lb. per acre rate in the greenhouse was regarded as equivalent to a normal seeding rate in the field and used as a check. 13 To insure the accuracy of seeding rates, the seeds in each species were counted and the proportions used were as follows: - Ryegrass l lb/ac equiv. to 3 seeds per pot Orchard 1 n I n 6 n n n Cocksfoot l " " u 8 n n n Timothy 1 N n n 12 n n n Red clover 1 " " n 4 n n N White clover l " " N 12 n n w Germination in all the samples was over 90 percent, and no fungicide was used. The mixtures were sown on the 29th of January, and replicated six times. The experiment was set up in a split plot design, so that one half could be clipped regularly at two week intervals to represent grazing treatment, while the other half was allowed to go to the hay stage before cutting. An aftermath cutting was taken so that both treatments were completed at the end of may, after four months growth. The greenhouse temperature fluctuated between 65° and 70° F. for the first three months, but was much more irregular in May, when it sometimes reached 90° F. The cultures were watered as required, and after emergence, received a three salt nutrient solution once a week. The pH remained fairly constant at 7.2, and to prevent excessive accumulation of salts, the pots were flushed out regularly with water. There was considerable variation in the water requirements of each pot, some drying out much more quickly than others, and causing irregular growth. Individual watering I. . o . . m . O . . H L t , . . . a‘. s x . . . . . u s . D . ' , . -‘ O . e: l4 compensated to some extent. All the seedlings had emerged by two weeks with ryegrass first, followed by orchard, red clover, cocksfoot, white clover and timothy in that order. Seedling counts were made before clipping was started on the 27th of March. The single grass species were further advanced than the mixtures, being about eight inches tall before the first cutting, while the complex mixtures averaged only five inches, but this evened out before the second cutting. The clippings were taken two inches above the sand level. The species were hand separated at the time of cutting for botanical analysis, and the green weight and oven dry weight recorded. Cultures at the hay stage were harvested on the 15th of May, and the aftermath was cut two weeks later. Chemical analyses were made for a comparison of crude protein. (Table 3.) After the final harvest, the root systems were examined \ by selecting an average culture from each treatment. (The sand was carefully washed away from the roots and individual plants were counted before green and oven-dry weights were taken. As clover had almost been eliminated from most of the cultures, separate counts were not taken. The few which had survived were very poorly developed. 15 4. EXPERIMENTAL RESUBTS 1. Compariggg of Yielgg 9f Mixturgg. ‘ Yields were compared at a normal rate of seeding equival- ent to 20 pounds per acre. Rates for cocksfoot and timothy were reduced to 14 and 8 pounds respectively in the simple mixture, in order to obtain a comparable number of plants in each seeding. Plant counts taken before the first cutting revealed that there was little difference between.the various mixtures. Sggdling gountg 2e; ggltuggx - Ryegrass Cocksfoot Timothy Ryegrass mixt. Cocksfoot mixt. 64 70 75 69 81 Table 1 gives the dry weight yields under the five clipping treatments. Orchard grass made good initial growth, but did not stand up as well as ryegrass to continuous cutting. The ryegrass mixture was slightly superior to the cocksfoot mixture, which did not maintain its yield in the last two cuttings. The hay and aftermath yields are given in Table 2, and with.the exception of ryegrass, were almost double the total yield from 5 cuttings. Perennial ryegrass and orchard grass gave the lowest yields, while domestic ryegrass gave the highest yield of hay. The cocksfoot mixture under this treatment was superior to the ryegrass mixture. An analysis of the percentage clover in the aftermath showed that domestic ryegrass almost eliminated the clover, while timothy and perennial ryegrass gave the best clover counts. Grggg neight yield: are given in.Table 3 and show that 16 orchard grass was the lowest producer in both cutting treat- ments, while domestic ryegrass was the highest. There was a considerable variation in the percentage dry matter between the species, with domestic ryegrass lowest, and timothy highest in both cases. When a crude protein analysis was taken at the time of the third clipping and at the hay stage, the cultures which were regularly clipped gave an average protein of 36 percent, which dropped to 24 percent in the hay. There were only slight differences in analysis between the different mixtures, and considering that there was less than 5 percent clover in.the average mixtures, the protein content was very high. ‘When the average protein yield from both cutting treatments were compared, the hay and aftermath cuttings were still superior to the clipping treatment. Fig. 1, illustrates the difference in growth between the single species and the complex mixtures, and Fig. 2 gives a comparison between the ryegrass and cocksfoot mixtures before cutting commenced. Ryegrass was dominant in both mixtures and crowded out cocksfoot and timothy particularly at the heavy rates of seeding. COMPARISON OF YIELDS OF MIXTURES TABLE 1 Dry weight yield in grams (Average of three cultures) FIZQ CLIPPINGS 17 MIXTURES March April April May May TOTAL 27 10 24 8 22 Domestic ryegrass 1.8 4.4 12.0 15.4 19.1 52.7 Perennial . ryegrass 2.5 3.8 7.6 10.3 13.3 37.5 Orchard grass 2.9 4.5 8.0 7.3 7.4 30.1 COCKSfOOt 200 4e0 803 Bel 8.5 30.9 Timothy 1.6 4.2 8.0 8.8 10.6 33.2 Ryegrass Mixtura 203 401 809 11.0 1103 3706 Cocksfoot ' mixture 1.? 5.1 8.5 7.6 7.1 30.0 18 TABLE 2 COMPARISON OF YIELDS OF MIXTURES Dry weight yield in grams (Average of three cultures) TWI - H ta and a to th MIXTURES May Hay Total Percent clover 15 29 yield in aftermath Domestic ryegrass 65.5 10.5 76.0 0.3 Perennial ryegrass 34.6 14.9 49.5 6.2 Orchard ‘ grass 42.0 7.5 49.5 4.1 Cocksfoot 54.0 8.6 62.6 4.4 Timothy 55o]. 10.2 65.3 6.6 Ryegrass mixture 57.3 15.1 72.4 2.9 Cocksfoot . mixture 61.7 17.1 78.8 4.2 TABLE 3 TOTAL GREEN WEIGHT AND PROTEIN ANALYSIS OF MIXTURES CUT FIVE TIMES CUT TWICE 19 MIXTURES green percent percent green percent percdnt weight D.M. protein weight D.M. protein Domestic ryegrass 415 12.7 - 644 11.8 23.0 Perennial ryegrass 282 13.3 35.8 383 12.9 29.0 Orchard grass 201 15.0 35.0 361 13.8 22.6 Cocksfoot 213 14.5 - 481 13.0 23.1 Timothy 214 15.5 33.5 438 14.9 22.2 Hyegrass mixture 287 13.1 37.7 517 14.0 25.5 Cocksfoot mixture 222 13.5 36.7 532 14.8 24.2 20 A . {I‘- fife-1'43 .‘ -ht' . ‘ .- . . .-_‘-r. ‘b-k; 4‘15. -_ Domestic Perennial Orchard Cocksfoot Timothy ryegrass ryegrass grass Fig. l. Mixtures ready for the first cutting. Above - Single grass mixtures. Below - Complex mixtures at 4 rates of seeding. 5 lbs. - 10 lbs. - 20 lbs. - 40 lbs. per acre. 21 Fig. 2. Comparison of complex mixtures before the first cutting under different rates of seeding. Above - Ryegrass mixture. Below - Cocksfoot mixture. Rates of seeding - 5 - lO - 20 - 40 pounds per acre. 22 2. EFFECT OF SEEDING RATE ON YIELD OF MIXTURES Table 4 gives the dry weight yields of the two complex mixtures under two cutting treatments. On account of their different behaviour, each mixture will be considered individually. R e r t . For the first two cuttings, the yields increased as the seed rate increased, so that there was about twice the yield from the 40 when compared with the 5 pound rate. Q the third cutting, yields began to equalize until in the final cutting, the 40 pound rate actually gave a lower yield than the 5 pound rate. OVer the whole period, there was little difference in total yield, although the 20 pound rate had a slight advantage over the others. Differences in total yield in the hay treatment were not significant, but still showed the same general trend as the seed rate increased. The Coefficient of Variance was below 5 percent in both cases. Qggggggg§_g;;§g;g.l For the first three cuttings, this mixture responded in very much the same way as the ryegrass mixture, except that the 40 pound rate gave a slightly higher yield. The yields began to diminish for the next cutting and this continued in the final cutting, showing that cocksfoot did not withstand severe clipping as well as ryegrass. Over the whole period, there was a wider gap in total yield between each seed rate. Analysis of the data shows that the difference in yields was significant for the clipping treatment, but in the hay treatment, only the 40 pound rate gave a significant increase over the 5 and 10 pound rates. TABLE 4 23 EFFECT OF SEEDING RATE ON YIELD OF COMPLEX MIXTURES Dry weight in grams. (Average of three cultures) RYEGRASS M URE iv 1 Seed rate March April April May May TOTAL per acre 28 11 25 9 23 5 lbs. ' 0.9 2.5 8.2 10.3 10.4 32.3 10 " 1.2 2.9 8.5 10.7 10.5 33.8 20 " 2.3 4.0 8.9 11.0 11.3 37.6 40 " 2.2 4.7 9.2 10.6 9.5 36.2 L.SeDe (5%) = 2.2 m3. cocxssoor MIXTURE (Five clippings) Seed rate March April April Mmy May TOTAL per acre 28 11 25 9 23 5 1b,. 103 3.5 7e? 609 5e]- 2‘05 10 n 1.3 4.2 8.4 7.3 6.5 27.7 20 " 1.7 5.1 8.5 7.6 7.1 30.0 40 " 2.1 6.1 11.3 10.0 8.4 37.9 L.S.D. (5%) = 2.4 gms. 24 TABLE 4 (cont.) EFFECT OF SEEDING RATE 0N YIELD OF COMPLEX MIXTURES Dry weight in grams. (Average of three cultures) WO NGS HAY STAGE AND AFTERMATH R e re s mixtu e Cocksfoot mixture Seed rate gay May TotaI May May Total 30 17 31 5 lbs. 56.0 15.2 71.1 49.7 12.8 62.5 10 n 56.6 15.4 72.0 51.1 12.9 64.0 20 n 57.3 15.1 72.4 61.7 17.1 78.8 40 n 58.9 14.9 73.8 73.7 19.9 93.6 L.S.D. (5%) - 6.6 gms. L.S.D. (5%) - 16 gms. Fig. 3 shows the growth patterns of the two mixtures under the clipping treatment. The mixtures were fairly similar in growth up to the third cutting when the cocksfoot mixture began to decline. Fig. 4 brings out the striking difference between the two cutting treatments, the total yields from the hay and aftermath being about double the yield from five cuttings. Fig. 5 shows pictures of the single grass species under the two cutting treatments. Figs. 6 and 7 give comparisons between the two complex mixtures at the third and fifth cuttings. Growth tended to be coarser and more straggling at the low seed rates while the 40 pound rate produced a finer more erect growth. D. W. Yield in grams. lot H O 5 r 25 Rolba (O " Hyegrass mixture Cocksfoot mixture w r boat... \ 20 m 10 .. 5n Marc}; 28 April 11 Apt-1'1 25 Ma; 9 m; 23 Fig. 3. The effect of seeding rate on the growth pattern of complex mixtures, cut five times. 26 Ryegrass mixture ._ _ O 8 b — 1 e -5)... m C .1 W t 3 .u. m. C N a“ a u nor D t fl 1 e .u p s m m e O t m t a .1 o r t .m 5 8 M t .w an i m o be ...tr1.1.....mtttu is... , Jim.” . saga... ..,r...... .3 0 .ww.}x...£..admiawflun _.....rw.un......_ my 5... “Vansuwflw Ext}... 1 Q C S b 1 .. 5 7'5. 53 25, 5 7 3.5 5 Hon" 23.: use H33. 0 5 254 The effect of seeding rate and cutting treatment Fig. 4. on the yields of complex mixtures. 27 A ‘7. °* 2*" Domestic Perennial Orchard Cocksfoot Timothy ryegrass ryegrass grass Perennial -Domestic Orchard Cocksfoot Timothy ryegrass ryegrass grass Fig. 5. Single grass mixtures at normal seeding rate. Above - before the fifth clipping. Below - before cutting at the hay stage. I» I. 28 yer-- ,.....-- ¢1lgmer o). , T "eff Fig. 6. Comparison of complex mixtures before the third cutting at different rates of seeding. Above - Ryegrass mixture. Below - Cocksfoot mixture. Rates of seeding - 5 - 10 - 20 - 40 pounds per acre. 29 .Eig. 7. Comparison of complex mixtures before the fifth cutting at different rates of seeding. Above - Ryegrass mixture. Below - Cocksfoot mixture. Rates of seeding - 5 - lO - 20 - 40 pounds per acre. 3O 3. E CT OF SEED RATE AND CUTTING TREATME ON BOTANICAL ANALYSIS OF MIXTURES The percentage analysis by weight of each species in the mixture has been averaged in Table 5. To find the effect of rate of seeding on the composition of the mixtures, only the data for the extreme rates of seeding have been used. In all cases, the 10 and 20 pound rates were intermediate in effect. Where the cultures were clipped frequently, the pro- portion of ryegrass in both mixtures increased slightly in the high seed rate at the expense of cocksfoot. The changes in botanical composition, however, were much more marked in the hay cutting treatment. Ryegrass maintained complete dominance in both mixtures at the high seed rates at the expense of both cocksfoot and timothy, but at the low seed rate, cocksfoot was dominant. Clover was not affected by seeding rate under either cutting treatment. Fig. 8 shows the ryegrass/cocksfoot ratio in the fifth cutting and the aftermath of both mixtures. This presents a more realistic picture of how the mixtures looked at the end of the experiment. Again, it shows that seed rates exerted only a slight influence on the balance of the mixture after five cuttings, but in the aftermath cutting, there was a dis- tinct bias toward cocksfoot at the low seed rates. TABLE 5 31 EFFECT OF SEED RATE AND CUTTING TREATMENTS __q_rg BOTANICAL ANALYSIS OF MIXTURES Percentage analysis based on average dry weight of all cuttings. Comparison of mixtures at 5 1b. and 40 1b. rate. RYEGRASS MIXTURE Percent Ryegrass Cocksfoot Timothy Clover Analysis 5# 40# 5# 40# 5# 40# 5# 40# 5 cuttings 51 58 3O 21 17 18 2 3 2 cuttings 38 59 44 27 15 10 3 4 COCKSFOOT MIXTURE Percent Ryegrass Cocksfoot Timothy Clover Analysis 5# 40# 5# 40# 5# 40# 5# 40# 5 cuttings 35 43 46 36 l6 l9 2 cuttings 25 51 55 34 17 10 3 75 50 N U" Cf. Rg. Ryegrass mixture 01.. . u in .\.-e . >9~g~ fl 0, ,. . 3 I'. '- 29331». .' .- '1; - rumilLJ . .' . — ‘._. . ~ <. ' " .1 . . ' - _'.. ‘ - 4‘ ..‘ b"mp¢..-_ex: .‘3 'fi. . ‘ e A .,. - .‘L, % . W" . 1. '0, 7a.? - 32 \) V" \J‘ 0 Percentage Analysis Based on Dry Weight Yields [0 V1 Cf. Rg. Five cuttings Cocksfoot mixture a ’ 4 v... 'A a . ¢ 5 . . I A V fr: ' "'2‘ i " ‘f A ’E . r I e 3. : ' ' , h'!‘ r- ' .‘ 7 I" ‘I. '\ I" .' {w I..." :5" Two cuttings . \—,~ ‘. — e .'- -.:"“_'\:.'l 4‘ _ _. +1.4 V“ J -| a" If... . '.‘ 1.. : W I! :~ 1&1. ,.' '- : -". f ». r. -- ~ xx, 0 .,"‘_r:, -*:-J ’ -' F": ‘ <21 '. .' 1,15.“ f .’ . . --. t ' . e, \.L .‘ V" ‘ __u .5 "1 ' Q ‘1. '-_L ' E' .c .4 . s" . 1‘ 3' 5 10 20 40 Rates of seeding in pounds per acre ”5 10 2o 40 Fig. 8. The effect of seeding rate and cutting treatment on ryegrass - cocksfoot ratio in mixture. 33 4. EFFEC1:OF SEED RATE_ON ESTABLISHMENT Plant counts were taken after emergence, on March 10th and again at the end of the experiment on June 2nd. The results are reported in Table 6. .At the seedling stage, the number of plants increased with the seed rate, but not in pro- portion. About 75 percent of the seeds sown at the 5 pound rate produced seedlings, while only 54 percent emerged in the 40 pound rate. There was no difference in emergence between the mixtures as the photographs in Fig. 9 will show. The plants were again counted after removal from the pots at the close of the experiment, and the green weight was taken to give a measure of the average size of the plants. It was noted that frequent cutting had eliminated a considerable number of plants, especially at the high seed rates, whereas cutting twice was much less severe. In the 5 pound rate of seeding, the number of plants was actually the same as the original seedling count. The average stand for both mixtures was 68 percent in the lowest rate of seeding and 37 percent in the highest rate of seeding. A comparison in the size of each plant is equally significant. Comparing the two extreme seeding rates, the average size of plants in the low rate was three times that of the plants in the high rate. They were also more vigorous and had a well developed root system. This is illustrated in Fig. 12, where four typical plants of each group were photographed side by side. TABLE 6 EFFECT OF SEED RATE ON ESTABLISHMENT Plant counts average of three cultures SEEDLING STAGE - March lOth 34 RYEGRASS MIXTURE COCKSFOOT MIXTURE 5# 10# 20# 40# . 5# 10# 20# 40# No. of seeds sown per pot 30 60 120 240 32 64 128 256 AV e Noo Of seedlings 22 43 69 128 25 46 81 141 Percentage emergence 73 71 '58 53 78 72 63 55 PLANT COUNTS AFTER RQOT SEPARATION - Jung and RYEGRASS MIXTURE COCKSFOOT MIXTURE 5# 10# 20# 4o# 5# 10# 20# 40# Five cuttings 18 3O 54 75 18 24 50 82 Two cuttings 25 3O 52 105 23 35 58 110 AVe Wt. 01 each plant 1.3 1.0 0.6 0.4 1.3 1.1 0.6 0.4 Final .Cut5x 6O 5O 45 31 56 38 4O 32 percent. stand .OutZX 83 5O 43 44 72 55 45 43 ’\ ‘- 35 Ryegrass Orchard Cocksfoot Timothy Fig. 9. Seedling emergence of mixtures. Above - Single Grass mixtures at normal rate of seeding. Below - Complex mixture at different rates of seeding. Rates - 40 lbs. - 20 lbs. - 10 lbs. - 5 lbs. per acre. 36 5. EFFECT OF SEED RATE AND CUTTING TREATMENT 0N ROOT GROWTH After the final cutting, the root system of each mixture was examined, using one culture from each treatment as an example. The weight of oven-dry roots is given in Table 7. The results from the single grass mixtures indicate that ryegrass produced the strongest root system, while orchard grass had the weakest. This was in accordance with the pro- duction of top growth which demonstrated that orchard grass did not resist continuous defoliation as well as ryegrass. Comparing the two cutting treatments, no difference in root growth was observed, and the roots were not adversely affected by frequent cutting over the duration of the experiment. In the complex mixtures, frequent cutting distinctly re- duced the amount of roots, particularly in the ryegrass mixture. In the heavier seed rates, the roots from the after- math were almost double those from the fifth cutting, and this correlated very closely with the corresponding forage yields. It appears that the toot/top ratio remained constant at both cutting treatments, and as forage yields dropped, the root system diminished. Seeding rate had the same general effect on root growth as it had on top growth. There was a gradual increase in roots as the rate of seeding went up, and this was more apparent in the hay cutting treatment. Photographs in Figs. 10, 11, and 12 show the effect of seed rate and cutting treatment on root growth. 37 TABLE 7 EFFECT OF CUTTING TREATMENTS ON ROOT GROVE}; Dry weight in gms. of washed roots in each culture SINGLE GRASS MIXTURES 4*— Cutting Domestic Perennial Orchard Cocksfoot Timothy treatment ryegrass ryegrass grass 5 cuttings 11.8 10.8 8.1 9.5 9.8 2 cuttings 12.2 11.1 8.4 10.0 10.1 Percent diff. between cuttings 3 3 4 5 3 COMPLEX MIXTURES Ryegrass mixture Cocksfoot mixture Cutting treatment 5# 10# 20# 40# 5# 10# 20# 40# 5 cuttings 6.1 6.5 7.2 7.8 6.8 7.0 7.1 7.2 2 Onttings 1005 11.6 14.8 1501 902 10e0 1301 1302 Percent diff. between cuttings 72 78 105 94 35 43 85 83 38 Rates - 5 - 10 - 20 - 40 pounds per acre. Complex mixture before and after root separation. Fig. 10. Above - Cultures after final cuttings. Below -‘Washed roots of cultures. Rear - After 2 cuttings. Front - After 5 cuttings; 39 Fig. 11. Boot growth of complex mixture after different rates of seeding and cutting treatments. 5 lb. rate 40 lb. rate 2 cuttings 5 cuttings 2 cuttings 5 cuttings 4O Fig. 12. Root growth of complex mixture at different seed rates. Above - Cultures from 5 1b. and 40 1b. seed rate. Below - Comparison of size of four individual plants. Left - 5 1b. rate Right - 40 1b. rate 41 5. D SCUSSION This experiment was conducted under controlled conditions in the greenhouse where there was a plentiful supply of moisture and nutrients, and a favourable temperature for rapid growth of grass. Moreover, the seedings were made under ideal cultural conditions without a nurse crop and with complete freedom from weeds and volunteer grasses. Nevertheless, it can be used to illustrate the basic principles of competition between species in a complex mixture and how this is affected by the rate of seeding and subsequent management. The injuri- ous effect of persistent cutting on the root system of grasses has also been demonstrated very effectively. The first object of the experiment was to find out how reduced rates of seeding affected the yield and competition between the species in a complex mixture. A wide range of seed rates was used, so that the growth pattern could be observed under extreme conditions. The main competition in a general mixture comes from ryegrass and cocksfoot, and in order to study their behaviour, two complex mixtures were made up with the prOportion of each actually reversed. This gave ryegrass initial dominance in one mixture and cocksfoot dominance in the other. The only way to interpret these results is to compare yields of dry matter between the rates of seeding, and in both cutting treatments, the two mixtures gave remarkably consistent results. The standard ryegrass mixture, whether it was cut twice or five times, gave very similar yields at all rates of 42 seeding, while in the cocksfoot mixture, the rates equalized at the third cutting, but in the last two cuttings, yields dropped considerably. The 40 pound rate had a distinct advantage in the early stages of growth, but by the third clipping the low rates had tillered out so well, that the yields were almost equal. This would indicate, therefore, that the traditional rate of seeding for general purpose mixtures is excessive, and could be reduced considerably without affecting its performance. Quite apart from the economy in seed, a moderate seed rate with a small proportion of ryegrass gives a better balanced mixture of species, allowing more room for the less aggres- sive grasses to develop. A quick growing nurse grass, such as ryegrass, can be of real value in giving rapid ground cover against weeds, but it also competes with the slower growing species in the mixture. There is still a tendency to use too much ryegrass in mixtures mainly because it is cheap and adds bulk to the mixture. Botanical analysis illustrated this point very well in the cocksfoot mixture at the heavy rate of seeding. In the initial seeding, there was 50 percent cocksfoot and 25 percent ryegrass, but in the final cutting at the high rates of seeding, the situation was reversed as ryegrass occupied 50 percent of the stand, leaving cocksfoot with about 35 percent. In fact, after the hay cutting treatment, both mixtures were almost identical in composition at the 40 pound rate. This shows that ryegrass can exert a strong influence in the mixture even at the moderate proportion of 25 percent. 43 Summarizing the combined effects of seed rate and cutting treatment, it appears that a high rate of seeding plus frequent cutting, both favour the more aggressive ryegrass, while cocksfoot and timothy have a better chance of survival at low seed rates under a moderate cutting treatment. It was observed that cutting down to 2 inches was more severe on cocksfoot and timothy, which were more erect in growth than ryegrass, and as a result, did not make such quick recovery. Examination of the root system substantiated the results obtained from the top growth. An increase in seed-rate produced overcrowding, and as a result, the roots of grasses seeded at the 40 pound rate were very small and poorly developed. This was particularly evident in the ryegrass mixture, when the yield in the final cutting dropped con- siderably partly due to excessive competition for moisture and nutrients. The effect of the two cutting treatments on root growth was most apparent and definitely proved that too frequent cutting causes coneiderable injury to the roots, as well as reducing the yields of forage. The yields of top and root growth of the single grass mixtures were not adversely affected by cutting five times, which might indicate that single species can.withstand frequent cutting better than complex mixtures. However, the clipping treatment would have to be extended for several more weeks before this could be confirmed. 1. 2. 3. 4. 5. 7. 44 SUMMARY AND CONCLUSIONS Rates of seeding were varied from 5 to 40 pounds per acre in two complex grass seeds mixtures, half of which was cut at two week intervals, and the other half harvested at the hay stage. Single grass mixtures at a standard rate of seeding were used for checking results. The species used were ryegrass, orchard grass, cocksfoot and timothy, and the proportion of clover in each mixture was constant. The yield of the ryegrass mixture was not affected by seed rate, and in the final cut, the five pound rate of seed- ing was equal to the 40 pound rate. In the cocksfoot mixture, the yields increased slightly with seed rate increments. The heavy seed rates gave ryegrass complete dominance in both mixtures, while cocksfoot and timothy developed better under low rates of seeding. At the 40 pound rate both mixtures were very similar in botanical composition. Plants in the low seed rate were roughly three times the size of those in the highest seed rate. The total yield in both mixtures from the hay cutting treatment was double the total yield from five cuttings. Frequent cutting caused considerable injury to the root system of the complex mixtures, whereas the roots of the single species were not affected over the duration of this experiment. 1. 2. 3. 4. 5. 9. 10. 11. 12. 45 LITE TURE ED Aberg, E., Johnson I. J. & Wilsie, C. P. "Associations between grasses and legumes." Agronomy Journal. Vol. 35, pp. 357‘3690 1943e Ahlgren, H. L. & Aamodt, 0. S. "Harmful Root Interactions as a possible explanation for effects noted between various species of grasses and legumes." Agronomy Journal. Vol. 31, p. 982e 1939e Blaser, R. E., Skrdla, W. &:Taylor T. "Factors in com- pounding Forage Seeds Mixtures." Advances in Agronomy. V01. 4, ppe 179-216e 19520 ‘ Buller, R. E. Bubar J. S., Fortmann H. R. & Carnahan, H. L. "Effects of Nitrogen Fertilisation and Rate and method of Seeding on Grass Seed Yields in Pennsylvania." Agronomy Journal. Vol. 47, pp. 559-563. 1955. Erdmann, M. H., & Harrison, C. M. "The Influence of Domestic Ryegrass and Redtop upon the Growth of Kentucky Bluegrass and Chewings Fescue in Lawn and Turf Mixtures." Agronomy Journale VOle 39’ Pp. 682-6890 1947. ' Harrison, C. M. "Responses of Kentucky Bluegrass to Variations in Temperature, Light Cutting and Fertilizing." Plant Physiology. Vol. 9, pp. 83-106. 1934. Harrison C. M., & Hedgson, C. W. "Response of Certain Perennial grasses to Cutting Treatments." Agronomy Journal. Vol. 31, Pp. 418-430. 19390 Heddle, R. G., & Herriott, J. B. D. "The establishment, growth and yield of ultra-simple grass seeds mixtures in the South East of Scotland. Effects of varying seed rates.“ Journal of the British Grassland Society. Vol. 10, pp. 157- 167. 1955. Henson, P. H., & Hein, M. A. "A Botanical Yield Study of Pasture Mixtures at Beltsville, Maryville. Agronomy Journale v01e 33, PP. 700-708e 1941. Holmes, W. & Maclusky, D. S. "The effect of continued massive applications of Nitrogen on the yield of grassland" Journal of Agric. Science. Vol, 45, pp. 129-140. 1954. Hughes, G. P. "Comparative Seasonal Output of Ultra Simple and General Purpose Seeds Mixtures." Journal of Agric. Science. Vol. 43, pp. 413-421. 1952. Hughes G. P., & Davis, A. G. ”The Development of Swards sown with Simple Mixtures at Different Rates of Seeding under varying systems of manuring and management." Journal of British Grassland Society. Vol. 6, pp. 167-177. 1951. 13. 14. 15. 16. 17. 18. 46 Hunt, I. V. "Seed Establishment in the West of Scotland." Journal of Brit. Grassland Soc. Vol. 9, pp. 85-91. 1954. Juska F. V., Tyson J. & Harrison, C. M. "Competitive Relationship of Marion Bluegrass as influenced by various mixtures, cutting heights and levels of nitrogen." Agronomy Journal. Vol. 47, pp. 513-518. 1955. MacDonald, H. A. "Simple Seeds Mixtures are best." Farm Research. Vol. 21, p. 7. (Cornell Univ. Agron. Dept.) Parry, D. W. "Reduced Rates for Seeding to Grass at the College Farm, Aberystwyth." Journal of Brit. Grass. Soc. Vol. 8, 1953. Stapledon R. G. & Davies ‘W. "Seed Mixture Problems." Welsh P. a. Station Bulletin. Series H, pp. 5-38. Wagner, R. E. "Effects of Differential Clipping on Growth and Development of Seedling Grasses and Legumes." Agronomy Journale VOle 44’ Pp. 578-584. ." 4: L “ ~ " e" '1 ‘.‘:.fl ‘3': 3 (I . f ‘1 ~ ROOM USE 63‘:qu " Date if“ Demco-293 HICHIGRN STRTE UNIV. 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