SWEET CLOVER

New Zealand Journal of Agriculture, Volume 73, Issue 6, 16 December 1946, Page 567

SWEET CLOVER

DURING the past two years the growing of sweet clover by Messrs. McCaw Brothers, of Hakataramea, has created considerable interest among farmers throughout New Zealand. This article by T. A. Sellwood, Instructor in Agriculture, Oamaru, summarises the methods adopted in America, where the crop has been widely grown, and results secured up to the present at Hakataramea.

SWEET clover belongs, to a group of plants the generic name of which is Melilotus. These are leguminous plants which,. ,in the comparatively young stages,, are ' superficially somewhat like lucerne. Three species have become well established as weeds or

ueuuiiic cultivated plants in many countries of the; world. In New Zealand they have been present in various parts for the past 50 to 60 years, during which time . they have come into periodic prominence either as weeds or as crop plants. These three plants are: Melilotus indicus, called “King Island melilot.” It is a yellow-flowered annual plant growing about 2ft. high as a rule. It is a common coastal weed in some parts of New Zealand. Melilotus altissimus, a biennial plant called “yellow sweet clover.” It has yellow flowers but is otherwise . very similar to white sweet clover. It is not common in New Zealand. Melilotus alba, called “sweet clover,” “white sweet, clover,” and ‘Bokhara clover.” It is a biennial, white-flowered plant, reaching a height of -8. to. 10ft. when in full flower. This is the plan' that has been used to a considerable ■ extent in America and which has been grown by Messrs. McCaw Brothers at Hakataramea. When it is young the stems and leaves are succulent, but as ■ it matures' the stems - become hard, woody, and- unpalatable. The root system is deep and carries a nodule formation • similar to that of lucerne and most clovers.

American Experience ‘ ' Summarising the -literature from the United States of America, it may be stated ' that sweet clover is more drought resisting than red clover and lucerne, and that it is seldom . winter -killed' Sweet clover grows best on a good soil with a high lime contentin fact the.name is probably derived from the fact that -it thrives only on sweet soil and- not : from its -taste, which is rather • bitter. The same bacteria are required as for lucerne

establishment, -.. and" therefore -it is essential to inoculate the , seed with . lucerne culture before sowing. -. Sweet clover does not yield as much leafage .for grazing as does.lucerne, particularly in . its first year.: In the second year, however’, ...sweet clover can be grazed from , early spring to late summer. When fed ■ alone *it is. said to cause digestive troubles and to be unpalatable to. livestock at the first feeding. In the second year it makes such rapid growth that heavy stocking is required to cope with the feed produced. -

Because of uneven ripening, shattering of the seed, and* the large size of the / plant, no .entirely satisfactory., method of harvesting has been worked out, but the crop is sometimes cut with the . binder, though / that ■ results in loss of seed. The combine harvester is also used. Sweet clover is reputed, to make good hay in the first year, but the quality obtained in the second season is poor.

It is difficult to decide whether sweet clover ; is used more for pasturage or for soil. improvement, but it is regarded in America, as a useful dualpurpose crop. Its. value as a soil improver lies largely in its ability to .fix atmospheric nitrogen in the nodules on the roots—a feature common to most leguminous plants. ....

On the whole it is apparent from the literature available that sweet clover has been rated very highly in the United States for the past 30 years or so.

Results at Hakataramea Some 13 years ago initial trials with sweet clover , .were carried, out by Messrs. McCaw Brothers on 2| acres.of good land. The land was ' not limed or the seed inoculated. Results were poor, and the crop was finally, grazed by stock. ' ■

In the spring of 1939, 31b. of seed were sown on J acre of land which had previously been sown ini; lucerne. The results of the second attempt were very satisfactory, probably .. because the seed benefited from nodule bacteria established by the lucerne crop. This crop.was grazed by cows for: a.while, and ' subsequently 401 b. of seed , was saved. . ,

In the spring of 1941 a further.-trial was sown on light, shingly land which did not require lime, but on this occasion the seed was inoculated .with lucerne' culture. The . first season s growth amounted to only 6iri., but during the following spring growth s was / rapid. The average height of the mature seed crop .was 6ft. and in - the;• better . patches • 9ft. The crop was difficult to harvest, and it; had to. be ~ cut in the ' early .morning- while it was damp -to prevent loss of seed by shaking.

; The maintenance of soil fertility has always been a feature of the -McCaw Brothers’ farming practice. Before the use of - sweet clover,, crops such, as . - lucerne and' Montgomery red clover were used, some 500 acres of the latter being sown out. Today • the area sown to sweet clover is : from 400 to 500 acres, which is ’used for. seeding, . graz- • ing, and green manuring.

Methods of Sowing

Methods of sowing sweet clover are; 1. Lightly drilling in the .spring on autumn-sown wheat. 2. Sowing with rape in the spring. 3. Sowing in December on ground.thatwas’ploughed out of Montgomery red clover- in October. Sowing down with wheat is the most., economical practice, -. as the seed-bed is already prepared and the - drill coulters give the wheat a spring cultivation. In some seasons sweet clover may cause a peculiar taint in wheat . if the crop is direct headed. This is caused by the sweet clover - growing as . high as the . wheat a condition more likely to occur if the season is ■. wet— and the juice of ■ the leaf soiling the .wheat “berry” during threshing. In these circumstances the usual practice is to windrow the wheat. In a normal season in Hakataramea, however, the sweet clover would not attain such growth, and the wheat would be headed direct without possibility of' tainting. ..

Fertilisers and Lime

Since the work on sweet clover was initiated by Messrs. McCaw Brothers further investigations have , shown that liming and inoculation are essential to establishment, there being a marked difference in establishment when liming is omitted. When sowing sweet. clover McCaw Brothers now give an initial application of 1 ton of carbonate of lime , an acre. . One hundredweight -; of superphosphate is sown with the wheat, and the f sweet clover sown in • the spring will probably benefit from this fertiliser. .

Green Manuring

Up- to the present only, a few acres of sweet clover have been ploughed in for green manure. This operation was carried out on a field which had grown two successive wheat crops before the sweet clover. At' the time of ploughing in the over-all height of the crop was Bft.,- and though there was a large. bulk the ploughs turned the green material under with comparative ease, and - also made an excellent job of. burying it. Arrangements are in train for a Departmental co-operative trial in which Montgomery red clover and sweet clover are to l be tried out for green , manuring. In the meantime there- is little evidence of the’, valueof sweet clover as a green mauring. crop because the greater portion of Messrs. .McCaw Brothers’ crop has been;, held for seed production. Grazing The growth in , the first year is normally from 1 12 to Min., but the

practice ■is to . graze the first season s growth when the crop is 8 to lOin. high. In the second season'the sweet clover may be grazed from early spring until the plant becomes too woody to be palatable. During the first year it should not be grazed too closely, but in the second season it makes rapid and prolific growth. <-■ It is important that sufficient stock be put on the second season’s growth to keep it well controlled. If it is not well controlled, the - sweet clover becomes too rank and woody, and the plants then bloom, seed in the summer, and die. If it is kept closely grazed, it will continue to produce sweet, nourishing growth throughout the second season.

'Messrs. McCaw Brothers consider that sweet clover can be used for fattening lambs.. This opinion has been formed from observations extending over two wet seasons. ' No comparative information about ? lamb fattening on Montgomery red clover is available, as usually the first draft, of lambs goes off toward the ; end of January as fats off the mothers. Any grazing, obtained from Montgomery red clover between : the . spring . and the beginning of November is mainly for control, measures before the area is closed for seed production. Ewes have grazed sweet clover during lambing', from mid-September : to ' mid-October. This grazing ; has been obtained: only in the second’, spring, and particularly if the crop; has -been sown in, the spring with wheat. Sheep grazing sweet clover have to acquire a taste for it, but lambs prefer sweet clover to rape.

Requirements of Crop A For the successful establishment, of sweet clover the following points should be kept. in mind:—’ ’-.d Lime: Like all legumes, sweet clover thrives well on sweet land; liming is necessary and heavy applications are required. Generally, J to 1 ton of lime should be applied v before. sowing. "Where , liming has been. carried put previously 2cwt. of lime .drilled with; the seed is beneficial. . •., . /. . Fertiliser: Sow lcwt.. of /superphosphate with the crop;' if convenient, -it is advantageous to pre-drill it. That: is achieved .when sweet - clover is sown after autumn-sown wheat, it being the practice for. farmers to-sow lcwt., of superphosphate with the cereal crop. . Inoculation: Sweet clover must be inoculated.... For ' successful establish -

ment it -is just as necessary to inoculate sweet clover as it is lucerne. The same inoculum, obtainable through merchants, is used. v ' Preparation of seed-bed: A fine, firm, compact seed-bed is required. Sow as shallow as possible. The seed is sown ,at the rate' of 6 to 101 b. an acre; it may be mixed with 2cwt.-of lime and sown through the manure box . or ■through the rape box of the. drill. Though sweet clover is found in many parts of New Zealand, it has made little, headway as a farm crop up to the present. The recommendations made are only, tentative, - and -are based on results ■ secured ■ by Messrs. : McCaw Brothers;. -to whom thanks are extended ; for the information in this article. As' additional information becomes available from Hakataramea and other districts where, sweet clovgr is now being, grown it will be published in the. “Journal.”