The Effects of Wind on the Extension Growth of Pinus contorta Douglas

The effect of wind on the extension growth of young Pinus contortawas investigated using a controlled environment wind tunnel.Extension rates of leader and lateral shoots were reduced byabout 20 per cent by high wind speed. The ratio of the finallength of the laterals to that of the leaders (‘apicalcontrol’) was unaffected, as was the radial growth ofstems. Water potentials were slightly higher in plants subjectto high wind. In another experiment, rates of needle extensionwere reduced 30 per cent by wind. The experiments are discussedin relation to field observations by others and it is arguedthat wind is a potent ecological factor adversely affectingtree growth.     

PREDICTING THE BEST TIME TO APPLY NITROGEN TO GRASSLAND IN SPRING

A great number of experiments with varying dates of N application to grassland showed that the most suitable time of applying spring N in tbe Netberlaods varies, as a result of weather conditions, from year to year from mid-February to mid-April. In such experiments the best time of spring N application, which needs to be known in advance, can only be determined after the grass bas been harvested and weighed. The results of these experiments supported the opinion that the best application date coincides with the banging of grass growth. However, at that time it was not possible clearly to define the begimiing of grass growth. When in 1959 a measuring disc was put into use the beginning of grass growth could be precisely determined and it was then found that the beginning of grass growth was closely correlated to a certain accumulated temperature from 1 Jan. from which the date of the beginning of grass growth can be predicted. This date is the most suitable one for applying spring N to grassland.     

COMPARATIVE STUDIES OF PERENNIAL RYEGRASS. TIMOTHY AND MEADOW FESCUE.

Hays made, mainly in May, from pure swards of perennial ryegrass, timothy and meadow fescue were fed to 8-month old steers in 1963 and to yearling steers in 1964. High-quality hay was obtained, but no significant differences in growth rate were observed between calves fed on hays from the 3 species. In 1963, barley (1.5 kg DM/ head per day) was fed, in addition to the hays, to half the animals and resulted in a significant increase in live weight gain. The productivity, in terms of liveweight gain/ unit area, of each species when managed for hay and‘zero grazing', or hay and grazing, was calculated. On this calculation perennial ryegrass was the most productive species.     

The Optimum Siting of Roads for Winch Extraction

When timber is extracted by double-drum winch there will bean optimum extraction distance, which will give lowest over-allextraction costs. A method is suggested of calculating thisoptimum distance and from this a guide is obtained as to thebest position for road construction in small woods where onlyone road is required.     

THE USE OF CATTLE WITH OESOPHAGEAL FISTULAE IN GRASSLAND EXPERIMENTS

Oesophageal-fistulated calves and cattle were used in various experiments during 1963 to 1966; results for 1966 are reported.
The method of inserting the fistula, the routine care of the animals and the methods of sampling through the fistula, are described.
Individual stall-feeding experiments in 1966 gave recovery values of 99.7% for herbage extruded through the fistulae, in relation to herbage eaten. The in vitro organic-matter digestibility of the grass offered and of the extrusa samples were identical. The digestibility of the grass fed in these experiments was high, but was comparable with that of herbage used in the grazing experiments reported. Grazing studies on grass/white clover pastures are reported. The digestibility was determined on all samples and they were separated into various plant fractions. Results obtained were compared with herbage samples cut at the same time. In most cases the digestibility and % N of the extrusa sample was higher than that of the corresponding herbage sample. The quantity of dead material present increased, and more was eaten, as the season advanced; it was of low digestibility. Results of intake studies with grazing animals are presented and the use of oesophagea-istulated cattle as an aid in such studies is discussed.