INFLUENCE OF THE TIMING AND DURATION OF PASTORAL FALLOWING AND NITROGEN-FERTILIZER ON PASTURE AND WHITE CLOVER (TRIFOLIUM-REPENS) GROWTH INHILL-COUNTRY

In a hill pasture in New Zealand, pastoral fallows starting from Decem ber, January, and February and terminating in June significantly (P < 0.01) reduced the tiller density of grasses, the dominant species in t he sward. At the conclusion of these fallows, the plant population (gr ass + legume + weed) density was only 29-49% of the grazed control. Fa llows from December and January to June significantly (P < 0.01 and P < 0.05, respectively) increased the internode length of white clover. Only the December fallow significantly (P < 0.05) increased the viable seed population of grasses, whereas for other treatments and other sp ecies in the December fallow there was no significant difference betwe en the fallowed and grazed swards. The addition of fertiliser nitrogen significantly (P < 0.05) enhanced the decline in tiller density for t he March to June fallow from the time of application. It improved the specific stolen weight of white clover and reduced the viable seed pop ulation of weeds and rushes (P < 0.05). It is concluded that pastoral fallows starting from December, January, and February or March with ni trogen addition and ending in June considerably reduced plant populati on density for oversewing new plant species. However, attention to nat ural reseeding from grass species should be given when the December to June fallow is used. The increased dispersion of white clover stolons by internode elongation in the fallowed swards, especially in the Dec ember and January to June fallows, may improve the distribution and co ntent of white clover.