CULTURE OF LUCERNE.

Sun (Christchurch), Volume III, Issue 826, 3 October 1916, Page 9

CULTURE OF LUCERNE.

AUSTRALIAN EXPERIMENTS. Commenting on the results of the lucerne manurial experiments at Werribee, Australia, Mr Richardson, the Agricultural Superintendent, gives some valuable information in the "Journal of Agriculture." He says the water requirements of lucerne have been determined by carefully controlled tests, to amount to 7in for each ton of lucerne hay per acre. This may best, be realised by taking the annual rainfall of the northern irrigation areas at 20in; and then show-ing that, for five tons of hay per season in five cuttings, an irrigation of 3in for each cutting will be required. Mr Richardson states, however, that when allowance for evaporation is made, it. will hardly be possible to grow a lon of lucerne hay, under Victorian conditions, en much less than 9-10 in of rain or irrigation water. This means a minimum irrigation of ."/in at each application for a five-ton crop per season. I believe that this estimate is too high. Six cuts of lucerne, each of at least a ton, have been obtained in Victoria, with a much lower rainfall than 45in, and under conditions which precluded the help of underground water. The heaviest average rainfall in Victoria is in South Gippsland, and only reaches 40in. That of ('ape Otway is 39in. It may be pointed out, too, that the. amount lost by evaporation can be considerably reduced by watering lucerne just before cutting. The "duty" of water is a very important point in irrigation; and experience teaches that, invariably, too much water is used at first, and that the higher the duty the better the results. Though not stated, the figures given are probably based on pot-experiments, which are not reliable.

The similarity of the Werribee soil to | that of the (ioulburn Valley irrigation ! districts, ami the fact that, for years, the land in both localities has been used for growing cereals, make these experiments particularly valuable. The success of lucerne-growing at Werribee may be attributed to the preliminary subsoiling carried out to a depth of 12in, which broke up the stiff clay subsoil, rendered even stiffer by the tramping of men and horses, and the sliding of the base of the plough in the furrow during the years of cropping. A block { of 15 acres, so rcated, gave a return of \ (ij tons per acre the first season from j six cuts, which must be regarded as satisfactory. A point which has not; yet been studied at Werribee, but which! must be considered sooner-or later, is; that of drainage. Like the Goulburn Valley areas, natural drainage is eon- \ spicuous by its absence. Manurial Experiments.

As the supply of water at Werribee! during the last two seasons has been deficient, the returns have been corre-1 spondingly modified. Still, the application of a ton of lime per acre has already been paid for in increased returns, and the effects will last for an-1 other year or two, which reduces the; cost. Strange to sa} 7 , however, super-j phosphate alone gives almost the same! result as when used with lime. The most : striking results, however, have been re-; ceived from the application of super- j phosphate. The addition of 2cwt super., costing 10/- 1o 12/-, increased \ the yield of hay by one ton per ar-re| where the land was limed, thus showing! a clear profit of £2 per acre. Mr Rich! ardson points out that the most suitable time for applying top-dressings is just: before soil temperatures begin to rise.! if the soil is dry enough, sheep may be I put in to cle.iii up weeds,, and graze the | lucerne close. Then the ground is work- | ed with the spring-tooth cultivator two ways early in August, and lime is applied, followed a week afterwards by the superphosphate. This is put in with a drill at the rate of 2ewt. per acre., every two years, or lewt per acre per! annum. The addition of superphosphates alone gave an increase of Hocwt over the unmanured plot in the two years, which is profitable enough. It is well known that lucerne, in com-! mon with other leguminous plants, can \ extract nitrogen from the air, still the; application of nitrogenous manures, combined with super, and lime, gave a gain in yield of 2:j tons per acre over! the unmanured plot, or of nearly one j ton over the plot dressed with lime and, super., so that apparently on this soil 1 the practice is likely to prove profitable.! It has several times been asked lately why sulphate of ammonia, one of the I by-products in the manufacture of coal gas, which contains about 20 per "cent, of nitrogen, is not employed by fanners; here, but is sent away to sugar-planters, i As a rule, it is sufficient to say that nitrogenous manures are not required here for most crops, though market garden | ers do use them to a limited extent.!

These experiments show that they may be more extensively used. Sulphate of ammonia, however, uses up the lime in the soil, and, as om soils are generally deficient in lime, this is a serious mafjter, since the lime is needed, and, in its absence, ammonium sulphate leaves an I acid residue in the soil, which does not suit most plants. I As might be expected, on land which has been cropped so continuously, stable I manure has given very satisfactory results at Werribee. Ten tons of stable Imanure gave practically the same rej.suit as a combined dressing of 2cwt 'super, and lewt nitrate of sodn. The ; plot which was only limed yielded 84 itons hay per acre in the two years. The (addition of 10 tons stab.'e manure result- | ed in an increase of over two tons hay j per acre, so that the net profit is esti | mated at £2 5/-. It is pointed out that, | when the bulky manure is applied as a top-dressing in winter, and worked in, it helps to prevent surface caking, acting as a mulch, and permitting the entrance of air and water. While the 'amount of stable manure on the farm is J limited, a supply can often be picked jup cheaply in the township. The effects ]of one good application will last for ! years.