Aid To Lucerne Growth In Mackenzie

Press, Volume CII, Issue 30064, 23 February 1963, Page 7

Aid To Lucerne Growth In Mackenzie

A technique of pre-soaking lucerne seed to aid establishment and growth on second class country in the Mackenzie Country ia showing promise, according to Mr D. G. Reynolds, farm advisory officer of the Department of Agriculture at Fairlie.

In recent years there has been a considerable increase in interest in lucerne growing in the Mackenzie Country, writes Mir Reynolds. Last year, for example, about 600 acres of new lucerne was sown. Much of this interest can be attributed to the need to provide winter feed for use with oversown areas for rearing good quality young stock. The well reared hogget is recognised as the foundation of a sound flock. Whale lucerne was confined to several thousand acres of first class land in the Mackenzie there were few problems involved in growing it provided care was taken with preparation of a good seed bed, freedom from weeds, fertility requirements and so on. On much of this country lucerne can become the dominant plant once it is established. Extension In recent years, however, the demand for lucerne has required that it be grown on soils which, initially at least, are second class. There establishment methods have not been so straight forward and while good strikes have been obtained subsequent establishment and bulk of growth were not encouraging in ■ comparison with results' on better soils and the relatively high cost of sowing lucerne in these more remote areas.

Examination of the possible causes of these near failures covered a wide field. In the first place it was obvious that many runholders were not being thorough enough in their cultivation procedures. Seed beds suitable for crap or pasture were just netadequate for lucerne where evenness of sowing and carefully controlled depth are so important. Areas which had been previously cropped and were possibly in sown pasture were not satisfactory due to difficulties with soil structure and weeds like twitch and yarrow.

Investigations finally established that the best ground was virgin country in dean tussock. Preferably the tussock Should be burnt before cultivation started to reduce the amount of rotting down required later. Cultivation consisted of chisel ploughing five or six times, with trailing harrows, over a period of a year from October, with ail but the final harrowings being done before winter. Any debris should be left on the surface where it rots more quickly, protects the soil from wind blow and does not eventually compete with young plants for nitrogen.

Weed Problem

Sowing after a feed crop is not satisfactory because of the abundance of weeds, particuiary sorrel and fathen. and no case can be made out for the value of the feed crop usually grown. A lucerne variety trial also showed that there was no hope of surmounting initial weakness in this way. All varieties established end grew normally within the growth patterns expected. As in other areas New Zealand certified, Marlborough and Provence are the best types. The grazing of creeping strains are not satisfactory as their production is too low. Fertility regulrements had been largely determined by using red, white and alsike clovers as indicator plants showing quite clearly the deficiencies of sulphur and phosphate in different soils and climates. However this did not seem to overcome the obviously unthrifty appearance of the lucerne plants on these second dess soils. Recognising the rather more demanding requirements of lucerne, a series of tests were made with lane, potash and trace etemerats end as well tt heavier rates of sutphivr and phosphate and several other materials were also tried out Ail these proved relatively unimportant except when quite uneconomic rritrogen-oontain-tog fertiliser were tried.

This indicated that ail was not well with lucerne’s all important function of efficiently fixing atmospheric nitrogen through the nodules on its roots—in spite of the fact that the nodules appeared to be forming normadiy though rather slowly. It was considered that part at least, of the trouble lay in the great variation of soil temperature and moisture which can occur in these areas between sowing and

establishment, even when all nutrient demands are satisfied. It was obvious then that anything that could be done to hasten germination and at the same time give the applied inoculum a better chance for survival and multiplication would be of advantage.

The only way of doing this was to begin the germination process before sowing and this was achieved by a presoaking process, much on the lines of soaking peas for the home garden. To begin with nothing was known about ■how long to soak or how much solution would be necessary. Eventually it was determined that the optimum period of soaking was about 16 to 24 hours and that lucerne seed will conveniently absorb up to 80 per cent of its own weight in moisture.

So far skim milk has been used, either fresh or made up from skim milk powder. The seed was inoculated with agar based culture after the soaking process. The seed by this stage was quite soft and it was obviously going to have to be sown in a bulky manure rather than through the turnip box to avoid damage. It was considered that even contact with well reverted super might be harmful so all the seed was dusted with skim milk powder immediately before mixing. This made rather a

stocky mess but was easily broken into the manure for mixing. Results so fair have been quite outstend'ing. The lucerne did not appear to strike any more rapidly than after any other treatments, but once the four-leaf seedling stage was past the difference became more apparent and it continued with increasing prominence until the onset of summer drought.

Modulation was rapid, as it Had been hoped, and the nodules developed quickly to a healthy size and number. The spread of nodules on the rooting system was not so good, but this may be just a matter of time and in any case it did not interfere with the plant’s ability to grow.

Nine weeks after sowing, pre-soaked lucerne was 8 inches tall and denser and a darker green than other treatments which were 6 inches tall, rather spdndlystemtned and weak with bleached looking leaves. Examination of the rooting system revealed a tap root three times as thick Just below the surface of the ground, twice as long and with a greater lateral spread. Future A full programme is planned for next season to investigate such matters as the kind of solutions to use for pre-soaking, whether the inoculation is better included before or after soaking and what medium to use for sowing the seed. It may also be possible to increase the germinating ability of the seed sometime prior to sowing and use it re-dried, which would be of considerable value from a practical point of view, The more scientific aspects will be investigated in the laboratory to determine the movement and rate of growth of the bacteria. In the meantime, farmers who experience difficulty in obtaining good quick establishment of lucerne may care to try the method described and help to add a sound practical background to the work being undertaken. Any method which with virtually no extra cost will add 50 to 80 per cent, to production and extend the range of usable country is worth considerable effort.