VALUE OF LUCERNE.

New Zealand Herald, Volume LXVII, Issue 20593, 18 June 1930, Page 18

VALUE OF LUCERNE.

BV 11.8.T

CULTIVATION METHODS.

SECURING PERMANENCE.

Tlio virtues of lucerne as a permanent crop which will produce a maximum amount of fodder from any laud to which it is adapted, need hardly bo stressed. During tlio last 10 to 15 years farmers havo realised that in summcr-timo and even during periods of_ severe drought, it can ho depended upon to produce an abundance of succulent fodder of a high nutritive value, while as material for tlio making of hay, ensilage or chaff for winter feeding, it cannot bo surpassed by any permanent crop.

Only comparatively few years have elapsed sinco lucerne has been widely cultivated in New Zealand and naturally mistakes havo been made by (ho pioneer cultivators, both in the selection of the. typo of soil and sub-soil on which to grow it, and in its after-treatment to secure permanence Briefly, thero are only three soil conditions in which lucerne will not thrive—whero tho soil is water-logged throughout a considerable period of tho year; where there is a hard pan close to tlio surface which is quite impenetrable to the plants' roots, and whero tho soil and subsoil aro excessively acid.

The Soil's Water Content.

I have often heard it stated that lucerne will uot thrive whero the normal water level in the soil is closo to the surface. 1 n a groat many instances this is untrue, for I havo seen fields of lucerne tjiriving whero tho winter water-level was not moro than two feet below tlio surface. But—and hero is tho important feature —the surface soil for that two feet was "freo and porous, and well-drained despite the high level of the subsoil water. Whero tho surface soil is heavy and clayey and the water-level high, lucerne certainly will not thrive. Lime hard-pan, common in many districts in the North Island, is another bugbear which frightens many farmers. Although hard-pan is certainly a disadvantage in growing lucerne, it is not an insuperable barrier, except where tho land is flat and is consequently sodden in winter and hard-baked in summer. If the lime hard-pan is on a slope from which there is reasonable drainage, and provided thero is from 18in. to 2ft, of soil covering it, lucerne will thrive when properly treated.

In the spring, when lucerne makes most of its root growth, this pan is comparatively soft, as any farmer who lias sunk post-holes through it will admit. I have known of several instances where pits or wells have been sunk through this hard-pan in lucerne fields and the roots have followed down to great depths in the underlying subsoil. Impervious ironpan is practically the only obstruction which lucerne cannot negotiate. Correcting Soil Acidity.

Soil acidity can frequently be corrected by proper drainage, and (he application of lime, and even though tho process may be fairly expensive, the returns from lucerne, when onco successfully established, will very soon repay the farmer. Tho ideal conditions are, of course, a free, well-drained soil and subsoil with a large amount of lime in its make-up. Frequently farmers get a good stand of lucerne, and after cutting it three or four times during the summer to provide green feed or winter fodder, graze the last autumn growth close with sheep or cattle during the early winter months. This is fatal to permanence. In the first place lucerne, having a big rooting system requires a reasonable amount of " top " to provide tho number of buds from which abundant new growth can bo mado in spring. If eaten close down all new growth must come from the " crown "and is consequently limited in quantity and spindly and weak in character. Again, lucerne makes a Jot of useful root growth during tho winter, and to promote this it is essential to allow a reasonable amount of leaf to remain, for in these the sap must be digested and the carbon-dioxide extracted from the air, incorporated with it before growth can take place. If the leaf is kept eaten off entirely, the root becomes quite dormant, and growth comes away very slowly in tho spring.

Lucerne Needs Aerated Soil

Ono must realise that lucerne, in common with other legumes, harbours beneficent bacteria in small nodules, like warts, which they form on the roots, and particularly on thoso roots within 2ft. of the surface. These bacteria extract nitrogen from the air in the soil and make it available to their host plant which cannot Jive without nitrogen. If the soil is tightly compacted by trampling stock, tho air cannot penetrate, or is at best restricted in supply, and these bacteria, and consequently their host plant, die from lack of nitrogen. Water in tho surface soil also prevents tho access of air, hence water-logged soil will not grow lucerne. Similarly, with heavy clayey soils, tho air cannot penetrato freely because they retain the moisture. Unless very regular and thorough cultivation is undertaken, lucerne is seldom permanent in this type of soil. As a free circulation of air in the snrfaco soil is so essential to tho prolific growth and permanence of lucerne, it should be obvious to farmers that thorough cultivation and opening-up of the surface soil should be practised at regular intervals to break up the pust which will form even without trampling the land with grazing stock. The injury which tho crowns of a few plants may sustain from this cultivation is as nothing compared with the benefits of admitting air to the soil. Cultivation, if it is thorough, will also keep down shallow-rooted grass and weed growth which, if allowed to persist, chokes out. t lie valuable lucerne in a few year's time.