Influence of stage of growth at cutting on lucerne production
Abstract A 5-year field trial confirmed that for maximum production lucerne should not be mown frequently when it is growing vigorously. Lucerne repeatedly cut when 20 cm high had 73% of the yield and 115% of the percentage leaf of lucerne cut at early flowering, but continuous mowing at a vigorous growth stage caused severe reduction in lucerne vigour and delayed its recovery growth. This in turn reduced lucerne stand longevity and favoured ingress of weeds.
The effects of cutting frequency on yield of Hunter River lucerne grown at wide and close spacing in the Mediterranean climate of South Australia
Hunter River lucerne, sown in April, June, and August, was planted out at 60 cm X 60 cm or 20 cm X 20 cm spacings on a red brown earth soil. Plants were cut 2.5 cm above ground level every six to eight weeks (standard cutting), or twice as often (frequent cutting), for two years : the yield of dry matter and number of stems per plant were measured at each cut. Yields were smallest in late summer and autumn, and largest in late spring and early summer. Treatments generally had little effect on the seasonal growth rhythm. Frequent cutting nearly always decreased yields. The relative decrease was greatest when standard cut plants were growing most rapidly in late spring, and it was also greater with wide spacing than close spacing. Wide-spaced plants yielded more per plant, and less per unit area, than close-spaced plants, except in late summer. Sowing time influenced yield only until the middle of the first summer. Number of stems per plant, and the mean weight of each stem, were both smallest in autumn and winter, and largest in spring and early summer. Frequent cutting slightly, and increasingly, decreased stem numbers relative to the number present with standard cutting during the experiment. The number of stems per plant was largest, and generally increased throughout, at wide spacing, whereas at close spacing maximum stem numbers were attained in the establishment year. Weight per stem showed greater seasonal variation than numbers. Low winter yields and low yields with frequent cutting could both be largely attributed to the small stem weights. Some implications of these results for lucerne management, and breeding for yield improvement, are discussed.
A preliminary study of the agronomic factors affecting the yield of extractable leaf protein.
Several species have been selected for their ability to synthesise protein rapidly. The main factors influencing their protein production were nitrogenous fertiliser, age at harvest, seed rate and climate. Some of the best species were grown either alone or in sequence at optimum rates of seed and N, and harvested to make maximum use of the growing season. The annual yields of extracted protein reached 2000 kg/ha in a good year with winter wheat followed by two crops of mustard or fodder radish. The grasses have not extracted well in the past; however, with recent improvements in agronomy and machinery, cocksfoot yielded 1670 kg/ha in a very dry year and can be expected to yield 2000 kg/ha regularly in wetter parts of the British Isles. It is hoped that similar knowledge will lead to much higher yields in the wet tropics.