Herbage Production of Short-rotation Ryegrass

New Zealand Journal of Agriculture, Volume 81, Issue 6, 15 December 1950, Page 545

Herbage Production of Short-rotation Ryegrass

Eight Years’ Production Records from a Trial at the Marton Experimental Area

By

P. B. LYNCH,

Crop Experimentalist, Department of

Agriculture, Wellington.

IN producing short-rotation ryegrass the Grasslands Division of the Department of Scientific and Industrial Research made a notable contribution to the farming economy of New Zealand. Since its release to farmers in 1943 short-rotation ryegrass has rapidly grown in popularity so that today some 100,000 bushels of seed are produced each year, of which approximately 75 per cent, is sown within the Dominion. Farmers’ experience with short-rotation ryegrass, together with the results of many years of experimentation, has shown that it can produce at a high level and be fairly persistent under conditions of reasonably high soil fertility, good moisture supply, and satisfactory management, by which is meant more particularly the avoidance of over-grazing, especially in summer and autumn.

THE purpose of this article is to preJL sent results to date from a trial with short-rotation ryegrass which has been in progress at the Marton Experimental Area for the past 8 years. Details of Trial Area The trial area was ploughed out of grass in 1940 for a swede crop in

1940-41. After the swedes it was ploughed in September, 1941, worked down, and sown to grass on October 30, 1941. The soil type (Wanganui loam) is not particularly fertile and is typical of thousands of acres of terrace and gently rolling downs between Wanganui and Palmerston North. Rainfall is not high, the average being about 35in. per annum, and the district is liable

to dry spells in summer, the effects of which are magnified by persistent winds so that the soil dries out and cracks badly. At the same time some type of drainage is essential, for water does not run freely through the soil and the subsoil is a heavy, compact clay loam. The country is ideally suited to mole draining and the Marton area was thoroughly mole drained shortly after the trial began.

The spring sowing to grass used in the trial is not the usual practice, but was adopted in this case to obtain a sward as quickly as possible. Fortunately it proved very successful and a highly productive sward was soon obtained on all treatments. Particularly for short-rotation ryegrass, spring sowing is not advocated today, because the grass enters into a relatively dormant period in summer and autumn and consequently cannot offer strong competition to weeds or other pasture species at this critical time, shortly after sowing. At the time the trial was sown, however, the behaviour of the plant in this respect was not fully appreciated. The strain of short-rotation ryegrass then available for trial is not considered as persistent ■as that being released at present, but as will be shown this fact has not prevented the strain sown persisting as a valuable and productive element of the sward for more than 8 years. The grazing management has at all times been rotational grazing with sheep. All trial fields have carried over the last 7 years on the average about 28,000 sheep days per acre, which works out at approximately 11 dry sheep per acre average daily carrying capacity. This high figure has been possible with the first-class herbage utilisation which can be obtained with small trial fields (J acre each) and probably could not be duplicated on a farming scale. At no time has the grass been allowed to reseed. This policy has been adhered to in an endeavour to establish the persistency of short-rotation ryegrass without reseeding. - ,

Topdressing has been as follows: — At sowing, 3cwt. of superphosphate per acre; 15-5-42, 3cwt. of superphosphate per acre; 23-3-43, 3cwt. of serpentine superphosphate per acre; 20-7-44, lcwt. of superphosphate per acre; 5-4-45, lcwt. of superphosphate per acre; 12-3-46, 2cwt. of superphosphate .per acre; 4-3-47, 3cwt. of superphosphate per acre plus scwt. of lime per acre; 25-6-48, 3cwt. of superphosphate per. acre plus scwt. of lime per acre; 3-5-49, 3cwt. of superphosphate per acre plus scwt. of lime per acre. , Treatments and Technique The trial consists of 3 fields, each of i acre, and . the . following seeds mixtures were sown: — Field 1: Certified Pedigree perennial ryegrass, 401 b. per acre; Certified Pedigree white clover, 31b. per acre. Field 2: Short-rotation ryegrass (exGrasslands Division), 201 b. per acre; Certified Pedigree perennial ryegrass, 201 b. per acre; Certified Pedigree white clover, 31b. per acre. Field 3: Short-rotation ryegrass (exGrasslands Division), 401 b. per acre; Certified Pedigree white clover, 31b. per acre. Complete grazing records are kept and herbage production is measured by 3 movable cages in each field. The technique adopted allows measurement of growth within the cages by mowing, the cages being shifted at random about the field after each mowing and weighing so that no changes in sward composition occur such as might result from constant mowing of the same areas. Cutting is made when the herbage is at sheep grazing height or a

SHORT-ROTATION RYEGRASS

little higher. Herbage samples are secured at each cut for dry-matter determinations and for dissection into pasture species composition at the Rukuhia Soil Research Station (Hamilton) .

Herbage Production: Yearly Totals Table 1 gives the yearly totals for dry-matter production for the 8 years of the trial to date. For the 8-year totals and for the last 4 years of the trial the highest-yield-ing field has been the 50:50 mixture of short-rotation and perennial ryegrasses (field 2). The short-rotation ryegrass field (3) is intermediate between this field and the perennial ryegrass pasture. Table 2, which shows the sheep days per acre of each field for the approximate periods as Table 1. indicates a slight superiority of both the 50:50 mixture and the short-rotation ryegrass fields over the perennial ryegrass field, but very little difference between the mixture and the shortrotation ryegrass swards. The herbage production figures probably give a more accurate comparison among treatments than the sheep grazing days, but both agree that there is little difference in total production among the three fields, although the two fields with short-rotation ryegrass in the sward have been slightly superior to the perennial ryegrass field. As will be shown in a later section ryegrass was the dominant species in all three fields, which were very similar in species composition for pasture plants other than the ryegrass. Production in Seasonal Periods The merit of short-rotation ryegrass is not considered to be greater total production than perennial ryegrass, but greater production in the critical winter and early-spring month®. The

SHORT-ROTATION RYEGRASS . . .

pasture production figures have therefore been considered in seasonal periods in Tables 3A, 38, 3C, and 3D and these tables have been illustrated by Figs. IA, 18, IC, and ID. The seasons taken have been according to the following classification with minor variations resulting from varying dates of cutting:— Winter: June, July, August (Table 3A: Fig. 1A). Spring: September, October, November (Table 3B: Fig. IB). Summer: December, January, February (Table 3C: Fig. 1C). Autumn: March, April, May (Table 3D: Fig. ID). Winter Production The winter production of herbage in each year is given by Table 3A and illustrated by Fig. IA. The superiority in winter months of the fields containing short-rotation ryegrass is very marked, more especially in the first 5 years of the trial, when it is likely that the proportion of this species was greater than in the last 3 years. Unfortunately this cannot be definitely established, as it is impossible to distinguish between the two species when dissecting the mown herbage. In early spring short-rotation ryegrass can be distinguished from perennial ryegrass in the field by a more vigorous growth and frequently a lighter-green colour, and this fact has made it possible to assert that fields 2 and 3 still contain a considerable proportion of short-rotation ryegrass. But it has not been possible to give numerical data to support these statements. The superior winter production of short-rotation ryegrass is without doubt one of its major advantages. To

indicate more clearly the months when this superiority occurs the yields of the short-rotation ryegrass (field 3) relative to those of the perennial ryegrass (field 1) have been examined in monthly periods. Excluding 1942, which gave abnormal results, probably because of the time of sowing of the trial, the following figures are the means for the 7 years since 1942:

January, 97; February, 97; March, 99; April, 106; May, 101; June, 143; July, 167; August, 146; September, 118; October, 94; November, 99; December, 91. From June to. August inclusive the short-rotation ryegrass field ■ has yielded more than 40 per cent, above the perennial ryegrass field. By October, however, it has declined to 6 per cent, less than perennial ryegrass. Spring Production Table 3B and Fig. IB show, apart from the first year, little differences among the three fields. The earlyspring production is relatively small compared with production in October and November and any superiority of short-rotation ryegrass in September is obscured by the later flush. of growth of perennial ryegrass. The relatively poor showing in spring, 1942, is difficult to explain, for it is not seen at other seasons of the year. However, it followed a flush of growth of shortrotation ryegrass in the . previous summer and autumn (following the spring sowing) and this may have suppressed clover growth temporarily in fields containing that species. Summer Production Table 3C and Fig. 1C show a tendency for summer production of the short-rotation ryegrass fields to be lower than that of the perennial ryegrass field except in the first year, which, however, covers the period immediately after sowing. Short-rotation

ryegrass establishes more rapidly and makes more prolific growth in the first few months after sowing than. perennial ryegrass, and this is apparently true both with spring as well as with autumn sowing. Field 2 (50:50 mixture) maintains a slight superiority until 1949. The relatively marked superiority in 1948 occurred in a drought year when the absolute production on all fields was very low.

Autumn Production Table 3D and Fig. ID show, on the whole, a similar picture to that of the summer production. In 1948 the low summer production was followed by exceptionally low autumn growth in one of the worst droughts experienced at Marton. The relative production figures have little meaning in such circumstances. The foregoing data on the trial may be summarised as follows: — 1. The short-rotation, ryegrass field has given markedly greater herbage yields than the perennial ryegrass field in the winter months, June to August, inclusive, but at other seasons of the year it tends to be slightly inferior. 2. The 50:50 mixture field, though giving slightly less growth than the short-rotation ryegrass field in the winter, gave greater production for the rest of the year than either the perennial ryegrass or the shortrotation ryegrass field. Ryegrass Production At each mowing of this trial herbage samples have been secured and these have been dissected so that the percentage of each species present was estimated on a dry-matter basis. Unfortunately it has not been possible to separate short-rotation ryegrass from perennial ryegrass so that a general figure for “ryegrass” is given in Table 4. After the first year all fields show between 65 and 80 per cent, “ryegrass” and the variation among them in the amount of ryegrass is small. Thus the total production figures may fairly be taken as representative of the ryegrass production in all comparisons made. In all fields white clover was the main species other than ryegrass, species other than ryegrass or white clover contributing less than 20 per cent, to the total production. This trial has not been designed to give critical comparisons of total herbage production, as the treatments are not replicated and yields cannot be compared statistically. Further, all comments made apply to pastures dominantly ryegrass (perennial or short-rotation) and white clover. It has shown, however, two main features. First, short-rotation ryegrass will persist for at least 8 years under sheepgrazing conditions, providing the management is such that the areas can be spelled periodically and fertility maintained by topdressing. Secondly, pastures containing appreciable quantities of short-rotation ryegrass may be expected to give consistently greater production during winter months, June to August, inclusive, than those where perennial ryegrass is the dominant constituent. Although the evidence available cannot be considered conclusive, there is every indication that the yearly production of fields containing short-rotation ryegrass will not be less than those where perennial ryegrass is dominant under conditions similar to those obtaining at Marton.

SHORT-ROTATION RYEGRASS

Year Actual r d period . Yields of dry matter (lb. per acre) Yields relative to Field 1 (perennial ryegrass) = 100 Field 1 Perennial ryegrass Field 2 Perennial and shortrotation ryegrass Field 3 Shortrotation ryegrass Field 2 Field 3 1942 (18 months) 12-1-42 to to 25-8-42 2,971 4,120 4,388 138.7 147.7 1942-43 26-8-42 to to 1-9-43 8,548 8,402 7,227 98.3 84.5 1943-44 2-9-43 to to 29-8-44 8,722 9,536 9,728 109.3 II 1.5 1944-45 30-8-44 to to 27-8-45 11,955 12,490 13,539 104.5 13.3 1945-46 28-8-45 to to 19-8-46 10,062 10,812 10,365 107.5 103.0 1946-47 29-8-46 to to 16-9-47 10,243 11,271 9,522 110.0 93.0 1947-48 17-9-47 to to 30-8-48 5,516 6,239 5,869 113.1 106.4 1948-49 31-8-48 to to 16-8-49 10,978 11,905 11,568 108.4 105.4 Totals (8 years) 12-1-42 to to 16-8-49 68,995 74,775 72,206 108.4 104.7

TABLE 1: YIELDS OF DRY MATTER OF PASTURE HERBAGE IN YEARLY PERIODS

Year Actual period Sheep days per acre Sheep days relative to field 1 Field 1 <— 100 — 100 Field 1 Field 2 Field 3 Field 2 Field 3 1942 .. 4-2-42 to 25-8-42 2,524 2,689 2,714 106.5 107.3 1942-43 26-8-42 to 1-9-43 3,544 3,559 3,615 100.4 102.0 1943-44 2-9-43 to 29-8-44 2,966 ' 3,005 . 2,949 101.3 99.4 1944-45 30-8-44 to 27-8-45 3,574 3,751 3,991 104.9 111.7 1945-46 28-8-45 to 19-8-46 2,388 2,466 2,389 103.3 100.0 1946-47 20-8-46 to 16-9-47 4,277 . 4,332 3,920 101.3 91.6 1947-48 17-9-47 to 30-8-48 3,757 3,873 3,814 103.1 101.5 1948-49 31-8-48 to 16-8-49 4,710 4,753 5,125 100.9 108.8 Totals (8 years) 4-2-42 to 16-8-49 27,740 28,428 28,517 102.5 102.8

TABLE 2: SHEEP DAYS PER ACRE IN YEARLY PERIODS

Year Yields of dry matter of to field herbage In pounds per acre, and yields relative 1 (perennial ryegrass) — 100 Field 1 > (perennial ryegrass) Field 2 (50:50 mixture) Field 3 (short-rotation ryegrass) Yield Relative to (1) = 100 Yield Relative to (1) = 100 Yield 1942 498 792 159 790 158 943 1,280 1,646 129 1,843 144 1944 .. .. 853 1,405 165 1,736 204 1945 .. 954 1,094 115 1,707 179 1946 .. .. 1,032 1,493 145 1,779 172 1947 .. .. 1,962 2,085 106 2,115 108 1948 1,422 1,608 113 1,974 137 1949 1,555 1,822 17 1,591 102 Average (8 years) 1,194 1,493 125 1.694 142

TABLE 3A: HERBAGE PRODUCTION FOR 3 WINTER MONTHS (JUNE-AUGUST)

Year Yields of dry matter of to field herbage in pounds per acre, and yields relative 1 (perennial ryegrass) = 100 Field I (perennial ryegrass) Field 2 (50:50 mixture) Field 3 (short-rotation ryegrass) Yield Relative to (1) = 100 Yield Relative to (1) = 100 Yield 1942 3,799 3,254 86 ... 2,418 64 943 4,126 4,351 105 4,180 101 1944 4,594 4,765 104 5,084 III 1945 3,825 , 3.728 98 3,579 94 1946 2,852 3,274 1 15 3,200 112 1947 3,116 3,304 106 2,915 94 1948 4,676 5,040 108 5,359 1 15 1949 4,008 4,625 1 15 4,121 103 Average (8 years) (8 years) 3,874 3,874 4,043 4,043 104 104 1 3,857 3,857 99 99

TABLE 3B: HERBAGE PRODUCTION FOR 3 SPRING MONTHS (SEPTEMBER-NOVEMBER)

Yields of dry matter of herbage in pounds per acre, and yields relative to field 1 (perennial ryegrass) = 100 Year (includes (nerennial F,eld 2 (50:50 mixture) F,eld 31 ' 011 December of previous year) ( r y egra ss) " - ryegraSS) Yields of dry matter of to field herbage in pounds per acre, and yields relative 1 (perennial ryegrass) = 100 Field 1 (perennial ryegrass) Field 2 (50:50 mixture) Field 3 (short-rotation ryegrass) Yield Relative to V i»m Relative to Relative to Yield Yleltl (1) = 100 Yield (1) = 100 Yield Relative to (1) = 100 Yield i 942 .. .. 973 1,542. 158 1,648 170 973 1,542 158 1,648 170 943 .. .. 2,119 2,165 102 1,774 84 2,119 2,165 102 1,774 84 1944 .. .. 2,121 2,141 101 1,990 94 2,121 2,141 101 1,990 94 1945 .. .. 3,989 4,201 105 4,445 HI 3,989 4,201 105 4,445 111 1946 .. 2,658 2,934 HO 2,462 93 2,658 2,934 110 2,462 93 1947 .. .. 2,883 2,994 104 2,294 80 2,883 2,994 104 2,294 80 •948 .. .. 759 1,014 (34 674 89 759 1,014 134 674 89 1949 .. .. 2,848 2,784 98 2,778 98 2,848 2,784 98 2,778 98 Average (8 years) 2,294 2,472 108 2,258 98 2,294 2,472 108 2,258 98

TABLE 3C: HERBAGE PRODUCTION FOR 3 SUMMER MONTHS (DECEMBER-FEBRUARY)

Year Yields of dry matter of herbage In pounds per acre, and yields relative to field 1 (perennial ryegrass) — 100 herbage In pounds per acre, and yields relative 1 (perennial ryegrass) = 100 Field 1 (perennial ryegrass) Field 2 (50:50 mixture) Field 3 (short-rotation (50:50 mixture) Field 3 (short-rotation ryegrass) Yield Relative to (1) = 100 Yield Relative to (1) = 100 Yield 1942 1,500 1,786 119 1,950 130 1943 1,349 1,337 99 1,192 88 1944 1,622 1,639 101 1,821 112 1945 2,417 2,430 100 2,303 95 1946 2,548 2,657 104 2,546 100 1947 2,547 2,917 114 1,913 75 1948 220 312 142 306 139 1949 1,898 2,260 119 1,841 97 Average (8 years) 1,500 1,349 1,622 2,417 2,548 2,547 220 1,898 1,763 1,786 1,337 1,639 2,430 2,657 2.917 312 2,260 1.917 119 99 101 100 104 114 142 1 19 109 1,950 1,192 1,821 2,303 2,546 1,913 306 1,841 ,734 130 88 112 95 100 75 139 97 98

TABLE 3D: HERBAGE PRODUCTION FOR 3 AUTUMN MONTHS (MARCH-MAY)

Year Field 1 (perennial ryegrass) Field 2 (perennial and short-rotation ryegrass) Field 3 (shortrotation ryegrass) Actual Period Field 1 (perennial ryegrass) Field 2 (perennial and short-rotation ryegrass) Field 3 (shortrotation ryegrass) Lb./acre Per cent, of total yield Lb./acre Per cent, of total yield Lb./acre Per cent, of total yield 1942 .. 12-1-42 to 25-8-42 25-8-42 2,582 2,582 87 87 3,783 3,783 92 92 4,166 4,166 95 95 1943 .. 26-8-42 to 1-9-43 1-9-43 6,863 6,863 80 80 6,444 6,444 77 77 5,942 5,942 82 82 1944 .. 2-9-43 to 29-8-44 29-8-44 7,080 7,080 81 , 81 6,856 6,856 72 72 6,445 6,445 66 66 1945 .. 30-8-44 to 27-8-45 27-8-45 8,932 8,932 75 75 8,399 8,399 67 67 10,350 10,350 76 76 1946 .. 28-8-45 to 19-8-46 19-8-46 6,463 6,463 64 64 6,381 6,381 59 59 7,897 7,897 76 76 1947 .. 20-8-46 to 16-9-47 16-9-47 7,689 7,689 75 75 7,986 7,986 7! 71 7,074 7,074 74 74 1948 .. 17-9-47 to 30-8-48 30-8-48 4,462 4,462 81 81 4,948 4,948 79 79 4,490 4,490 76 76 1949 .. 31-8-48 to 16-8-49 !6r8-49 7,021 7,021 64 64 7,251 7,251 61 61 7,666 7,666 66 66 Average (8 years) 6,387 74 6,506 70 6,754 75

TABLE 4: PRODUCTION OF RYEGRASS IN YEARLY PERIODS