Lucerne, called Alfalfa in America, is a valuable leguminous forage plant which is grown in Europe, North and South America, Southern Africa, Australia and New Zealand. The plant is a true perennial and when properly fertilized will continue to produce heavy crops of forage for several years. Lucerne is a very deep‐rooted plant with roots going down over 2 metres into the soil which enables the plant to draw water and nutrients from parts of the soil which other plant roots never reach.
The leaves of lucerne have high protein content making the plant a valuable feed for cattle. Lucerne is grown under irrigation and either cut for hay or cut and fed green to cattle particularly dairy cows. There is also a good market for lucerne which has been cut, dried, ground and sold as lucerne meal. This is included in both cattle and poultry rations.
Figures 1 and 2: A leaf of a lucerne plant (left) and he plant and flower (right)
Source: lincoln Source: lucernehayforsale.wordpress
2. SOIL AND CLIMATE
Lucerne can be grown on a wide variety of soils provided that the soil is deep and well drained and the acidity is correct for growing lucerne. Lucerne does not thrive in water‐logged conditions but will grow in a fairly shallow soil provided the roots can penetrate the underlying material. The soil should be deeply ploughed and the surface worked down to a fine tilth. If a plough pan is formed this should be broken up by means of sub‐soiling. The other very important thing to remember is that it likes lime, and will not grow at all in an acid soil. The pH of the soil should be between 5.6 and 8 andif the soil is below this lime should be applied and harrowed into the seedbed at the rate of at least 1 ton per hectare of ground limestone. If the crop is irrigated with water containing lime future applications of ground limestone should not be necessary. Lucerne improves both the fertility and soil structure of the soil which greatly benefits any following crop.
Lucerne prefers a dry climate and the crop grows best during the hotter and drier periods of the year. At high altitudes it will become almost completely dormant during the cooler mid‐winter periods. At lower altitudes such as in the Lowveld, lucerne will continue to grow all winter, but during the damp summer conditions suffers from leaf diseases.
Lucerne needs 800 – 1200 mm of water during the growing season (about 75 mm of water per 1 ton of dry matter produced).
Temperature: Optimum day temperatures 15 ‐ 27⁰C with night temperatures of 10 ‐ 20⁰C. Growth decreases above 30⁰C and below 10⁰C. Mean July temperature should be less than 16⁰C.
The best varieties are PAN 4884, PAN 4961 and Sardi 7. Since lucerne is a legume with bacterial nodules being developed on the roots of the plant, seed should be soaked in an inoculant before planting. This solution contains the correct strain of Rhizobrium bacteria and can be obtained from any seed merchant.
As lucerne is grown as an irrigated crop, it should be sown between February and June (depending on the climatic regions) so that the young plants are established before the cold weather. The seed bed should be fine, smooth and level especially where surface irrigation is being used. The seeds being small should be planted 12 mm deep. Under dryland conditions with the mean annual rainfall less than 500 mm row spacings should be 900 mm wide with a sowing rate of 5 kg/ha. Where the mean annual rainfall is above 500 mm row spacings are 250 mm apart or can be broadcast at a rate of 10 – 15 kg/ha. Under irrigation production one can broadcast the seed at a rate of 25 kg/ha. After sowing either in drills or broadcast, the seedbed should be rolled to press the soil down around the seed. Seed can be broadcast by hand or sown in drills using a maize planter or a wheat drill.
Figure 3: Lucerne seed
It is always necessary to send a soil sample from the land where lucerne is to be planted for analysis so that the nutrient status of the soil is known. General fertiliser recommendations are as follows:
An application of 20 – 30 kg per hectare at planting time will assist the seedlings before they start nodulation and so produce their own nitrogen. Where nodulation in the mature crop is poor and the leaves show a pale green colour a dressing of 40 kg/ha of nitrogen can be given each year in the spring. Nitrogen can be given in the form of a compound fertiliser such as ammonium nitrate. sulphate of ammonia should not be used on lucerne as this is an acid fertiliser and tends to reduce the pH.
Phosphate hardly moves in the soil therefore, the placing of the initial dressing is important. Phosphorus removes 3 kg/ton in dry matter. One should use a super phosphate as it supplies the
necessary sulphur requirements. The feeding roots of lucerne are most active in the zone just above the water table and in the few centimetres just below the surface of the soil. The seed bed dressing of fertiliser should be mixed with the soil as deeply as possible before the seed is sown.
Table 1: Phosphate requirements of lucerne
|Soil with Adequate||Soil Deficient in||Soil very Deficient in|
|Seedbed Dressing||40 – 60 kg/ha||60 – 100 kg/ha||100 – 140 kg/ha|
|Annual Top Dressing||40 – 60 kg/ha||60 – 100 kg/ha||100 – 140 kg/ha|
It is better to use sulphate of potash rather than muriate of potash either in a compound fertiliser or as a straight. Sulphate of potash supplies extra sulphur which is an important element to leguminous crops. Lucerne removes 15 – 25 kg/ton potassium therefore it is essential to replace this nutrient in the soil. Apply 200 kg/ha of KCI at spring time and again in the middle of summer if necessary especially if one is producing hay.
Table 2: Potash Requirements of lucerne
|Soil with Adequate||Soil Deficient in||Soil very Deficient in|
|Seedbed Dressing||Nil||200 kg/ha||200 kg/ha|
|Annual Top dressing||20 – 40 kg/ha||200 kg/ha||200 kg/ha|
This element is often lacking in most soil types. This shows on the plant leaf which turns yellow with pink tints. Boron deficiency can seriously affect the growth of lucerne allowing weeds and weed grasses to develop. Dressings of 2 kg/ha of Boron should be applied on sandy soils and 3 kg/ha on heavy clay soils.
Lucerne is a crop which lends itself equally well to both sprinkler and flood irrigation. On medium to heavy soils with even slopes not exceeding 1%, it would be safe to say that flood irrigation should be favoured as both the initial and operational costs would be considerably less than for sprinkler irrigation. On light sandy soils particularly those with undulating slopes or slopes exceeding 1% a sprinkler system should be favoured.
When designing a sprinkler system for lucerne, it is quite safe to use a precipitation rate of 10 mm per hour even on heavier soils as being a perennial crop the impact of the droplets is broken by the covering vegetation before the drops hit the soil.
If flood irrigation is to be practised, then a system of border strip irrigation, corrugation irrigation, or contour flooding irrigation in that order of preference, should be used. The farmer is advised to consult an expert for advice on the best lengths of run to employ width of beds to use etc., to suit his particular soil type. Ridge and furrow irrigation is for obvious reasons quite unsuitable for this crop.
Frequency and depths of irrigation will vary considerably according to climatic conditions and the texture of the soil on which the crop is to be grown. It can, however, be generally accepted that frequent light irrigations are less satisfactory for lucerne than more infrequent but heavier application. The aim should be to bring the soil up to field capacity to a depth of 1 metre (depending
on the soil depth) after each irrigation and not to allow the soil to dry out to below 50% of field capacity between irrigations.
In practice this will mean applications of 20 – 30 mm on light sandy soils, 50 – 80 mm on medium soils and from 80 – 100 mm on heavy clays.
In the hot summer months the average interval in days between irrigations on these 3 broad soil types would be in the order of 5 to 8 days, 8 to 10 days and 10 to 13 days respectively. In the cooler months (April through to September), the interval should be increased to 10 to 14 days, 16 to 20 days, and 20 to 25 days respectively.
The best system and one which is being practised by many farmers today is to base irrigation frequencies on pan evaporation figures. It is suggested that the daily consumption of lucerne is for practical purposes equivalent to 75% of the daily evaporation from an open pan.
In the Lowveld, with its warm climate irrigation is continued throughout the year. In the Highveld, however, the cold winter does not promote the growth of lucerne especially during the months of June and July and it is therefore not necessary to continue a strict schedule of irrigation during the period that growth is severely restricted. It is not advisable to withhold irrigation completely during this period. The interval between irrigations can safely be increased to 1 month or even to 6 weeks.
Irrigation should cease about 1 week to 10 days before cutting but it is important to irrigate as soon as possible after cutting. Failure to irrigate within 3 or 4 days of cutting will set the crop back, andallow weed growth to get ahead of the lucerne.
6. WEED CONTROL
Ensure that the seed used is free from dodder (Cuscuta campestris or C. suaveolens) and that the land to be planted is as clean of weeds as possible. Once the lucerne rows can be clearly seen, cultivation between the rows by hand should be done as and when necessary.
Chemical herbicides can be used to control weeds in lucerne, 2.4 ‐ DB ‐ salt may be applied at doses up to 3.5 kg per hectare to seedling lucerne provided that most of the seedlings have reached the first trifoliate leaf stage (2.4‐D has been prohibited from being applied aerially in KwaZulu‐Natal, and in the Camperdown, Pietermaritzburg and Richmond areas it has been outlawed completely). The optimum time of treatment is between the first and fourth trifoliate leaf stages as this is the period of maximum sensitivity to weed competition.
Bentrol Super may be applied to established lucerne for the control of grasses at doses up to 1 – 1.5 litres of active ingredient per hectare at medium or high volume. Under temperate conditions it has been recommended that lucerne should be sprayed with Bentrol Super while it is in the dormant growth stage. The effect upon the grass is most marked when the chemical is applied at a time when the grass is making vigorous growth.
7. PESTS AND DISEASES
Larvae of the Clouded Yellow butterfly are a pest of lucerne which sometimes build up and cause concern. They can be controlled by spraying the land within 14 days of cutting with mercaptothion + pyrethrins (pythion 5% DP) and is to be used at the rate of 10 – 30 kg/ha.
Figure 4 and 5: A clouded yellow butterfly (left) and a clouded yellow butterfly larvae (right)
Source: silviareiche Source: ukbutterflies
Leaf Spot (Pseudopeziza medicaginis) and Rust (Uromyces striatus) are the most common diseases of lucerne. Both are spread by airborne spores, develop rapidly under warm, humid conditions and, when the incidence is severe defoliate the plant. To reduce the effects of these diseases keep the lucerne growing vigorously and cut it before it is defoliated.
Figures 6 and 7: Leaf spot (left) and Rust (right)
Source: insectimages Source: informedfarmers
Young lucerne should not be grazed until it is 1 to 2 years old. Rotational or strip grazing gives a better utilisation than prolonged grazing especially if an electric fence is used or many small paddocks are created in the area under the lucerne. 3 Days grazing followed by 30 to 35 days of rest is approximately correct if this method of utilisation is to be used. Very lush lucerne or lucerne which has been wilted or frosted is liable to cause bloat in ruminants. To avoid this, hungry stock should not be allowed to graze lucerne. They should first be fed dry roughage and watered.
If a strip is mown several days before a lucerne paddock is grazed cattle or sheep will readily take the mown material and this will greatly reduce the chance of bloat occurring.
The best time to cut lucerne is when it is about 10% in flower. If it is cut earlier than this on more than one or two occasion’s plants will be weakened. This will also happen if the level of cutting is so low as to damage the crown and very young shoots.
Care must be taken to avoid loss of leaf when handling lucerne as the leaf is the most valuable part of the plant. After cutting, plants should be windrowed and allowed to dry out for a few hours before being built into cocks. No hard and fast rules can be laid down regarding the length of time
that lucerne should be left in the windrow or in the cocks before being stacked. The length of time can be judged by handling the crop in the early morning after the dew has evaporated or in the late afternoon when the leaves are less brittle. It is worth remembering that excessively damp hay heats up and that if the temperature in the stack rises and it starts to decompose. Pick‐up moisture content is a common practice which results in good baler on the windrowed lucerne when the moisture content is about 20%.
When weather conditions preclude the making of hay consideration should be given to the possibility of ensiling the crop. Lucerne makes excellent silage either alone or when mixed with a non‐leguminous crop such as maize in the ratio of one part lucerne to two parts of other.
Figures 8 and 9: Cutting lucerne (left) before it is windrowed then made into bales (right)
Source: commercialrealestate Source: .j‐f‐s
Depending largely upon its treatment, particularly in regard to the application of fertiliser nutrients and the technique of cutting employed, yields of green matter per hectare per year will vary from 10 to 12 tons per hectare in the first year (equivalent to 3 – 3 ½ tons of hay) up to as much as 50t/ha in the second and third years (equivalent to about 14t/ha of hay).
If the crop is grown for seed, it should be possible, under good conditions to reap 2 crops each of about 450 to 500 kg per hectare.
Lucerne cut at the early flowering stage contains the following Digestible Crude Protein:
Table 3: Type of Lucerne Feed and its Dry Matter and Crude Protein