Autumn Saved Pasture in a High Frost Environment

Abstract

<jats:p>Herbage mass, moisture content and in vitro OMD of autumn saved ryegrasslwhite clover pasture grown on irrigated flats in the Upper Waitaki Basin were monitored over four winters from 1979-82. During the winter of 1981 and 1982 the effect of closing date and nitrogen application was examined. In addition Merino ewes were all-grasswintered from mid June to mid September without supplements on a feed allowance of 1.2 kg DMlhd.day to determine effect on liveweight. Mean herbage mass and OMD loss from mid May to early September were 25 and 13% respectively and the moisture content of the pasture decreased from 73 to 45%. Herbage mass by mid May was less for March and April than for February closing, although for March closing this deficit was offset through use of nitrogen. Approximately 50% of the sward was frosted by mid September with OMD of the f-m_.c-.tAcd rnwn,rti.nIVn.I IC,*"O"/. ,v, .-vrvrmlllnv-~-r~C~.ul-l~ +L-U k0-1.a.y. Ewe liVeWeightS initialiy ieii but recovered during the latter half of the winter despite the constant fall in herbage OMD. Sward desiccation exceeded loss in digestible herbage mass over the winter, suggesting increasing rather than decreasing food value. Keywords: High country, herbage losses, frosting, in-vitro OMD, irrigated pasture, autumn-saved-pasture, nitrogen, feed value, all-grass-wintering, Merino ewes</jats:p>

Oversown Tussock Country Lessons From 30 Years of Improvement and Management on Tara Hills

“…Thus it is not surprising that white clover was most frequent on shady aspects (Figure 1). At Tara Hills grazing research relevant to high/shady landscapes as defined in this paper has shown management has little influence on white clover cover (Allan 1985). The data presented here supports this, and shows the same thesis applies to high/sunny and low/shady landscapes.…”

“…Ryegrass seed is seldom included in high country oversowing seed mixes (Scales et al 1975) probably because the species is not successful under uncontrolled utilisation and is considered inferior in its ability to carry well into the winter. But recent evidence shows ryegrass quality does not deteriorate greatly when frosted (Daly & Allan 1985, Scott & Maunsell 1986, and the authors feel that if a good level of utilisation (eg 60-70%) is intended, then ryegrass must be included in the oversowing mix.…”

“…This response was consistant for all aspects and altitudes except high/shady where for one block (site 3) ryegrass was never oversown. New Zealand bred ryegrasses will not tolerate very cold landscapes (Allan 1985) and therefore have limited application on high/shady sites. More cold tolerant ryegrasses of European origin are now under grazing evaluation at Tara Hills.…”

“…This mix is still widely used despite clear evidence that the performance of individual species varies greatly according to temperature, moisture, fertility and management (Scott et al 1985). While the climatic and nutrient tolerances of species used in high country oversowing are generally appreciated, there is limited information on the additional long-term effects of grazing management on such species (Allan 1985).…”

Quantity and quality changes of autumn-saved pasture in a high country winter

“…Such a protective layer was not evident in the 1982 season when autumn ADM levels were much lower. Daly & Allan (1985) found herbage was desiccated during winter at Tara Hills (near the present study) in their study on autumn-saved pasture. A protective layer probably causes air to become drier underneath, dehydrates and lowers the freezing point of the green herbage, and reduces consequent frosting damage, in the manner described by Primault (1979).…”