.E. W Vartha and P. T. Clifford Grasslands Division.
Department of Scientific and Industrial Research, Lincoln.
[n the May 1971 Review we illustrated how clover-dominant herbage grown in late summer and autumn on part of a tu~ock
block and fed prior to winter, markedly influenced the perform-·
ance of ewes. We uggcsted that improved nutrition of stock might be prolonged into winter by the choice of appropriate grasses for sowing with the clovers. These grasses would need to be of high nutritive quality, capable of some winter growth or able to retain their feeding value into winter when conserved
ac; '!>tanding hay·.
This article describes the resultc; from experiments in the Mackenzie country in which we have compared the perform- ance of several grasses under sheep grazing. One experiment
wa.c; at Ben Ohau Station, four miles south of Pukaki township.
The site was on a fertile c;oil that tended to dry out in summer and provided a good tcc;t of the performance of grasses under low winter temperatures, fro ts of - I 7°C being recorded here.
Sowings of 'Grasslands Ariki' ryegrass, 'Grasslands Apanui·
cocksfoot, 170 tall fescue and 'Massey Basyn' Yorkshire fog with alsike, red and "' hite clovers were made on cultivated soil. Fescue tusrock was first ploughed in 1962 and had been lefl fallow until July 1965. The seeds mixtures were sown broadcast in September 1965 with 2 cwt per acre of molybdic sulphur-superphosphate. owing rate of grasses were deliber- ately low, aiming to obtain a gra<;S density similar to that desired from ovcrsowing, topdressing and applying good man- agement. Similar numbers of viable seeds were sown for all gral'S species, based on the rate of 8 lb of 'Grasslands Ariki' ryegrass per acre. Pastures were lightly grazed in the first growing c;eason. In the ccond growing season they were inter- mittently grazed for short periods of two days with sufficient
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stock to ensure close grazing. On lhe experience of perform- ance of cocksf oot and tall
feJcue in the second growing season, it was decided to graze these grasses Less seuerely iii subsequeT&I growing seasons.
Cumulative grass )'ields onJy are shown in Figure I. In the 1966-67 and 1967-68 growing seasons, clovers yielded 2,400 to 3,400 lb dry matter per acre but in 1968-69 growing season, only 800-1200lb. Growth of Yorkshire fog and rye- grass was superior to tall fcscue and cocksfoot. The relative merits of these two groups of species were reversed for keeping quality as 'standing hay' in late-autumn and carly-w1nter.
Yorkshire fog and ryegrass herbage was rapidly decomposed when frosted, the process slower for cocksfoot and tall rescue.
In practice we did not graze after March in the second and lhird growing seasons and after January in the fourth growing season, summer-autumn weather in the latter season being particularly dry.
ln-uitro digestibiJity values in June J 969 were 74 percent for cocksfoot and 77 per cent for tall fescue. By Auguc;t these vaJues had declined to 56 percent and 65 percent. llt that time only 4 percent of the cocks/ oot herbage was liuing, compared with 27 percent of the lall fescue herbage. Values were not obtained for the other grasses becau e these were decomposed by frost by June. The results from this experiment indicated that whilst Yorkshire fog and ryegrass have superior growth in-season tall fescue and cock.'>foot were of more value for provision of out-of-season feed.
Initial Fertiliser Rates
An experiment at Dusky tation, I 0 miles north of Pukaki to\.vnship investigated the effects of different rates of initial fertiliser application on performance of grasses and clovers ovcr- sown into cover-depleted tu~k on stecpJaad soil. The site
was of north-easterly aspect at 2,000 ft. The seeds mixture which was oversowa in August J 965, contained equal numbers of viable seeds of ryegrass, Yorkshire fog, cocksfoot and tall f escue ( totaJ of 22.5 lb gra~ per acre), with alsike, red and white clovers. Fertiliser applied was either 1 !,4 cwt or 3 cwt
per acre of molybdic-sulphur-superphosphatc. Subsequently, dres.sings of 1
Yicwt per acre of that fertiliser were made ~t
two year intervals. Pastures were lightly grazed in the first growing season. In subsequent growing seasons they were inter- mittently grazed for short periods of two days with sufficient stock to ensure close grazing. Numbers of grazings varied from four in the second growing season ( 1966-67} to two in the sixth growing season ( 1970-71 } , the latter being characterised by extremely dry weather.
Clovers were the major contributors lo herbage yield in the second to fourth growing seasons, but in the filth and sixth growing seasons clovers gave considerably lower contributions than grasses.
The top sector of Figure 2 shows clovers established by the second year from sowing.
Provision of a higher level of nitrogen through increased clover growth with higher rate of topdressing, improved estab- lishment of ryegrass as shown in Table l .
Table 1: Numbers of Grass Plants per Sq. Ft. Two Years from Sowing Rycgrass Yorkshire Cocksfoot Tall
Lower initial rate of topdressing 0.36 Higher initial rate of topdressing 0.65
The numbers of Yorkshire fog plants include those resident because these could not be distinguished from those sown.
This experiment was sown prior to the development of coating treatment for grasses wlhich we have shown can mark- edly improve their establishment (see Review for March 1969). Because the results from the first sowing of grass were poor (Table l ) , we decided to resow, but with coated ryegras.s only at the equivalent rate of 12 lb seed per acre.
Time of Sowing
The normal time for sowing grass with clover in an initial improvement is late-winter. Where clovers are already estab-
lish~d it might be easier to establish grasses from early-autumn sowing.
Comparison was thus made between late-winter and early- autumn resowings as shown in Table 2.
Table 2: Numbers of Ryegrass Plants per Sq. Ft. at Two Years from Resowing
Lower initial rate of topdressing resown late-winter 1.80 resown early-autumn 0.89 Higher initial rate or topdressing resown late-winter 2.08 resown early-autumn 1.82
The effects of time of sowing differed according to fertiliser treatment. Denser ground cover, with more fertiliser, may have given better protection of seedlings establishing from the early- autumn resowing, than was the case with less fertiliser.
The lower sector of Figue 2 shows grass established from resowing in late winter, on both fertiliser treatments.
Because of particularly dry weather in 1969-70 and 1970-71 growing seasons, clovers had almost died out by autumn 1971 and thus were resown in late winter. Results in Table 3 shows that by that time, effects of fertiliser treatments and sowing dates on ryegrass persisted. Cocksfoot was present in small
amount, but presence of tall fescue and Yorkshire fog was negligible.
Table 3: Percent Frequency o( Grasses in Winter 1971 Rycgrass Cocks foot Tall Yorkshire Lower initial rate or topdressing: Fescue Fog
resown with ryegrass in late-
winter ( 1967) 73
resown with ryegrass in early- 12 4 3
autumn ( 1968) 40
Higher initial rate of topdrcssi11g:
resown with ryegrass in late-
winter (1967) 90
resown with ryegrass in early- 8 2
autumn (1968) 77
CLOVER AND GRASS FROM OVERSOWING Lower initial rate of fertiliser topdressing.
ON FESCUE TUSSOCK AT DUSKY STATION.
Higher initial r:1te of fertiliser topdressing.
Photos: E. W. Vartha from transparencies.
If the bulk of herbage grown in-season on improved tussock grassland is from clovers, then the place of sown grasses seems basically to be for provision of winter feed.
Where winter temperatures were severe, ryegrass was inferior to tall fescue and cocksfoot.
However, the latter grasses were harder to establish than rye- grass from oversowing and where ryegrass was over-sown on warmer country, it was able to extend the growing season of herbage for early winter and early spring use. It is emphasised that these results refer to areas with 635j 1016mm rainfall per year, which allowed for satisfactory establishment and growth of ryegrass. The results indicated that grass overSowing may be better done when fertility has been built-up under clovers in cover-depleted areas, but this is not conclusive.
Subsequent work has shown that use of coated grass seed in initial sowings has increased the numbers of plants estab- lished compared with the use of uncoated grass seed. That result is important because grass development is largely restricted to growth in size of the plants established, unlike white clover which can spread by growth of stolons to increase density.
Therefore the question of whether or not to sow grass with clover in the initial oversowing remains to be answered from further research.
The research mentioned in this article does not answer the question of whether or not it is desirable to oversow grasses.
Rather, the results provide the agronomic background leading to the type of grazing assessment needed, similar to that we have described for clover-improved tusrock grasslands in the previous is.sue of Review.
J.A. P. Cameron of Ben Ohau Station, the late I. H.
Wardell of Dusky Station. The Lands and Survey Department provided field facilities for this work.