Alfalfa or Lucerne

Alfalfa is the most valuable, protein-rich forage legume which has a broad spectrum of utilization possibilities. It has a positive effect on soil fertility (draining and aggregate forming effect of root system, enriching in N etc.).

Botanical characteristics

Alfalfa is a widely grown perennial legume with a woody yet narrow crown, tap roots and flowers borne on racemes or spikes in various shades of blue, purple, cream and white.

Pods range in shape from sickle to spiraled with one or more coils. Leaflets are 9.5 mm to 3.2 cm long, obovate and sharply toothed towards the apex. Traditional varieties are trifoliate, however an increasing number of multifoliolate varieties have been developed.

The erect stems usually reach 30 to 90 cm (Figure 33).

Figure 33 Alfalfa

Phenological growth stages of alfalfa:

Vegetative phase

0 Early vegetative: Stem length ≤15 cm, no buds, flowers,or seedpods 1 Mid-vegetative: Stem length 16-30 cm, no buds, flowers or seedpods 2 Late vegetative Stem length ≥31 cm, no buds, flowers or seedpods Flower bud development

3 Early bud: 1-2 nodes with buds, no flowers or seedpods 4 Late bud: ≥3 nodes with buds, no flowers or seedpods Floweringphase

5 Early flower: node with 1 open flower, no seedpods 6 Late flower: ≥2 nodes with open flowers, no seedpods Seedproduction

7 Early seedpod: 3 nodes with green seedpods 8 Late seedpod: ≥4 nodes with green seedpods

9 Ripe seedpod: Nodes with mostly brown mature seedpods Alfalfa is 85-95% open-pollinating, fertilized primarily by wild bees.

101 Its primary center of origin is the region east from Kaspian Sea, the secondary being the Mediterranean. Alfalfa and all other legumes belong to the family Fabaceae/Leguminosae.

Cultivated alfalfa is tetraploid (2n=4x=32), its wild relatives are diploid (2n=16).

Environmental requirements

Alfalfa tolerates relatively well climate extremities. It is winter-hardy (-25 °C without snow-cover). Minimum temperature for germination is 2-3 °C. To achieve high yields it requires 600-800 mm precipitation (or supplement by irrigation).

Alfalfa does best on semi-cohesive soils with a pH of 6.5 or above, containing a high level of plant nutrients. Alfalfa is sensitive to excess soil water or the lack of good aeration.

Surface water should not be allowed to stand more than 2 4 hours during hot weather or 48 hours during lower temperatures.

Physiological stresses that may affect alfalfa plant appearance: soil pH outside of neutral range, poor drainage and limited moisture (particularly tap rooted types).

Cultivation

Small grain cereals (winter wheat and barley, spring barley) harvested prior to mid-July are the best forecrops. Legumes must be avoided. Rotation should not be shorter than 3-4 years.

Alfalfa requires a deeply cultivated root zone. A perfect seedbed should be firm to reduce air pockets, fine to obtain an even covering of seed, level with no places where water stands, and free from weeds that compete with seedlings for moisture and plant nutrients.

Basic fertilization and sowing data can be found in Tables 56 and 57, respectively.

Table 56 Nutrient requirement of alfalfa Nutrient uptake by 1 ton of hay

N: 27 kg/t P₂O₅: 7 kg/t K₂O: 15 kg/t CaO: 35 kg/t MgO: 3 kg/t Primarily, establishing without cover crops is recommended.

Cover crops can be useful in exceptional cases such as in fields threatened by erosion or deflation or if established as pasture.

Recommended grass species:

- dry conditions: smooth brome (Bromus inermis), orchardgrass (Dactylis glomerata) - soils of good water management, irrigation: meadow-fescue (Festuca pratensis), timothy-grass (Phleum pratense), perennial ryetimothy-grass(Lolium perenne)

Table 57 Sowing data of alfalfa

Sowing date: 10. March-10. April 10-25. August

Row distance: 12 cm or broadcasting

Sowing depth: 1-2 cm (on loose soil 2-3 cm)

Seed rate - 12 cm - broadcasting

12 million seeds/ha 6-7 million seeds/ha

13 million seeds/ha 7-8 million seeds/ha With cover crop

- spring barley - pea

- grasses

3 million seeds/ha 6-7 million seeds/ha

5-6 million seeds/ha 6-7 million seeds/ha

1000 seed weight 2.0-2.4 g

102

Alfalfa is drought-tolerant, using up to 70% of available soil water without undue stress or loss of production; if stressed beyond this limit, it will merely stop growing until soil water is available. There are limits, but plants recover from extremely dry periods. Production suffers, but the crop survives. Alfalfa can be a good crop for irrigators with limited water supplies.

Irrigation is most effective in the 1-2. years, at 10-15 cm aftermath. A possible irrigation order: 2. aftermath: 50-70 mm, 3. aftermath: 70-80 mm, 4. aftermath: 50-60 mm, 5.

aftermath: 40-50 mm, out of season: 60-80 mm, total: 200-250 (300) mm/season.

Diseases

Fusarium wilt (Fusarium oxysporum f.sp. medicaginis), Verticillium wilt (Verticillium alboatrum), Phytophthora root rot (Phytophthora megasperma f.sp. medicaginis), Aphanomyces root rot (Aphanomyces euteiches), Crown and root rot complex (Fusarium spp. and Rhizoctonia solani), damping-off (Pythium spp., Phytophthora megasperma and Rhizoctonia solani), Anthracnose (Colletotrichum trifolii), spring blackstem (Phoma medicaginis), summer blackstem (Cercospora medicaginis), Common leaf spot (Pseudopeziza medicaginis), downy mildew (Peronospora trifoliorum), Rust (Uromyces striatus), bacterial leaf spot (Xanthomonas campestris pv. alfalfae), alfalfa mosaic virus (AMV), stem nematode (Ditylenchus dipsaci)

Pests

Weevils (Sitonia ssp.), alfalfa weevil (Phytonomus variabilis), darkling beetle (Opatrum sabulosum), lucern beetle (Phytodecta fornicata), alfalfa ladybird (Subcoccinella vigintiquatorpunctata), alfalfa snout beetle (Otiorrhynchus ligustici), alfalfa plant bug (Adelphocoris lineolatus), lucerne flower midge (Contarinia medicaginis), cotton bollworm (Helicoverpa armigera), lucerne seed weevil (Tichius flavus), alfalfa seed chalcid (Bruchophagus roddi)

Harvesting

Green forage Usually it requires short wilting prior to be given to livestock. Quality depends on the phonological phase of alfalfa.

Hay It is the oldest method of conservation. In the course of the drying process, from the green material of 78-82% moisture content hay of 84% dry matter content will be produced. If dried on the field, main sources of loss are the falling of leaves and the decrease in ß-carotene content.

Alfalfa flour (green flour) This conservation method preserves the green material quality the best. Direct-cut green material is dried at 700-900 °C to 90% dry matter content, followed by grinding. If cut and wilted in the field, material of 70% moisture content goes to the dryer.

Conservation by fermentation (alfalfa silage and haylage) Alfalfa is hard to be fermented (high protein content, building of lots of alkalic intermedier compounds etc.).

Alfalfa silage Chop size of 2.5 mm is optimal, initial moisture content of chopped green material is 78-82%. Additives (e.g. corn semolina, artificial compounds) can be applied to help fermentation.

Alfalfa haylage In general, cut green material is let be wilted (40-50% dry matter) in the field prior to chopping and fermenting.

Main aspects for planning the cutting order:

- The two cuts of spring-sown alfalfa cultivated without irrigation are best for hay preparation in the first year. From the next year on, first cuts must be harvested before lodging starts, indepent from the development stage. First cut gives the highest

103 percentage (35-50%) of the yearly yield. For hay-making summer cuts are the best, especially those harvested at flowering. The time period between harvests usually ranges from 30 to 40 days. In the last year of culture, when feeding is the primary aspect, harvesting dates and conservation methods can be chosen freely. In irrigated cultivation systems, there is a shorter period between cuts. On the other hand, giving out 60-80 mm water requires reasonable time.

- The yield and the quality change according to the phenological phase. Highest yield can be achieved at the green bud – flower bud phase but best quality is reached prior to this phase. On the border of these phases can be found the balanced stage when the worsening feeding quality is compensated by the increasing yield, and the highest amount of crude protein, ß-carotene and minerals can be harvested (Table 58).

- In the second and succeeding seasons, the first harvest may be taken in the full bud stage, with other harvests being made at 10 percent bloom or before crown buds advance. The last growth must be allowed to grow and store the full amount of food reserves in the tap root before being killed by freezing temperatures. This provides the energy for the new plants to grow the following spring. Usually the last cut should be made no later than mid-September to mid-October. After complete killed by cold, the remaining frosted growth may be removed by harvesting or grazing.

Table 58 Composition of alfalfa depending on developmental stage Chemical composition in dry matter

Crude protein

Crude fat

Crude fibre

N-free extract

Crude ash

Ca P Dry

matter g/kg

Sprout 261 39 169 386 145 18.6 3.8 172

Young 235 30 233 380 122 17.8 3.6 215

Budding 204 29 279 371 117 16.8 3.5 228

Flowering 179 27 328 378 88 16.2 3.4 254

In document CROP PRODUCTION (Pldal 102-105)