Sour clover (Melilotus indicus)

Datasheet

Description

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Indian sweet clover (Melilotus indicus) pods, France

Common names

Sour clover, sweet clover, california lucerne, hexham scent, hexham scent melilot, Indian sweet clover, King Island melilot, King Island clover, senji, small melilot, sourclover, annual yellow sweetclover, Bokhara clover, small-flowered sweet clover, common melilot, small-flowered melilot, sweet melilot [English]; mélilot de l'Inde, mélilot des Indes [French]; carretón oloroso, coroa-de-rei, meligón, meliloto, mielca borde, trébol de olor [Spanish]; trevo-de-cheiro, anafe-menor, trevo-de-namorado [Portuguese]; Intianmesikkä [Finnish]; Kleinblütige Steinklee [German]; Dvärgsötväppling [Swedish]; حندقوق هندي [Arabic]; 印度草木犀 [Chinese]

Species

Melilotus indicus (L.) All. [Fabaceae]

Synonyms

Melilotus parviflorus Desf., Melilotus tommasinii Jord., Trifolium indicum L.

Related feed(s)

Description

Sour clover (Melilotus indicus (L.) All.) is an erect annual forage legume, up to 50-80 cm high. It has a deep taproot, down to a depth of 1.2 m. The stems are branched, glabrous or sparsely pubescent. The foliage is heavy, somewhat succulent with high water requirements. The leaves are alternate, trifoliolate, with oblong to obovate leaflets 0.8-2.5 cm long x 2-9 mm broad. Inflorescences are racemose, apically or axillary, borne on 1-3 cm long peduncles. The flowers (10-16 per raceme) are papillonaceous, sweet smelling, sparsely pubescent and yellow in colour. The olive-green fruits are one-seeded, reticulately veined, 1.5-4 mm long, indehiscent pods. The seeds resemble those of alfafa and are ovoid, glabrous, yellow-brown, about 2 mm in length. They may be hard-seeded (about 5 to 20%) and thus will not germinate in the first year (UC SAREP, 2006; Wilken et al., 1998; Arora et al., 1997)

Sour clover is a multipurpose plant. It is a valuable green manure or cover crop, and can be used as fodder. In California, in the 1920’s, it was one of the leading winter cover crops and was particularly cultivated in citrus orchards (UC SAREP, 2006). In India, it is valued as a drought resistant legume forage (NDDB, 2012).

Distribution

Melilotus indicus originated from the Mediterranean and south-western Europe, and from India (UC SAREP, 2006). It became naturalized throughout Europe, warm temperate North America (southern and Pacific USA), Chile, Australia, Japan, southern Africa and Hawaiii, and is now widespread in all continents (Wilken et al., 1998).

Sour clover occurs in gardens, roadsides, fields, waste places, disturbed sites, coastal salt marshes, freshwater wetlands, riparian habitats and cultivated fields (US Forest Service, 2013; Wilken et al., 1998). A pioneer plant, Melilotus indicus quickly builds dense stands and reduces native species richness. It is considered a weed in some places (USDA, 2013). It grows in areas where mean annual temperatures range from 7.2 to 22.5°C and annual rainfall is between 900 and 1200 mm. It has moderate cold resistance and may survive frost. It does well on a wide range of soil types with preference for well-drained neutral or alkaline soils (pH ranging from 5.0 to 8.2). Sour clover withstands saline soils (3-6 dS/m or 5-8 in gypsiferous soils) (UC SAREP, 2006).

Forage management

Sour clover can be sown alone or in a mixture with barley, oats, rye or purple vetch (Vicia benghalensis). It should be sown in autumn, in a dry seed bed, at about 1 cm depth. Weeding during the early stages of growth may help establishment. Sour clover can be cultivated in rainfed conditions or under irrigation (Duke, 1981). In India, since it can be grown in unirrigated areas, it is sown immediately after the monsoon crops, so that the residual moisture present in the soil can be utilized for seed germination. It is then harvested from April to June, in 2 to 4 cuttings, once it reaches full-bloom or after seed formation (NDDB, 2012; Duke, 1981). Sour clover yields 4 to 9 t DM/ha which is comparable to common vetch (Vicia sativa) or berseem (Trifolium alexandrinum) (Feedipedia, 2013; UC SAREP, 2006; Göhl, 1982). If sour clover is cut before bloom and used for feed, bloat is more likely to occur than if it is cut during flowering (UC SAREP, 2006). Chopped forage should be fed in mixtures with other dry forages. If sour clover is fed alone or in excess to cattle, it can cause health problems such as lethargy, tympanites and paralysis, and taint the milk. Coumarin imparts a bitter flavor and some toxicity to the forage, but low-coumarin varieties exist (Duke, 1981).

Environmental impact

Green manure and soil remediation

An N-fixing legume, sour clover has been widely used as green manure. It then is sown in autumn and ploughed in during early spring. It is reported to provide 151-252 kg N/ha and 336 kg N/ha (UC SAREP, 2006). Thanks to its ability to grow on saline soils, sour clover may help reclaim salt-affected soils while providing valuable fodder for livestock (Al Sherif, 2009).

Nutritional aspects

Nutritional attributes

Sour clover contains about 18% protein (14-28% range) in the DM, and has a rather high fibre content (ADF 36% DM, lignin 9% DM).

Potential constraints

Coumarin

If poorly harvested or ensiled, sour clover produces coumarin, a fragrant organic chemical compound in the benzopyrone chemical class that interacts with blood coagulation (Langer et al., 1991; Göhl, 1982). Deaths from internal bleeding have been reported (Göhl, 1982). Reported values for coumarin content in India and Australia are in the range of 1000-5000 mg/kg DM (Gupta et al., 1980a; Gupta et al., 1980b; Nair et al., 2010). Coumarin content may depend on cultivation stresses such as salinity (Nair et al., 2010), and increases with maturity (Gupta et al., 1980a). Cultivars with low coumarin content have been reported (Duke, 1981).

Risk of bloat

Sour clover should be cut when the pods are just being formed. If cut earlier, the risk of bloat is higher (Curasson, 1956).

Ruminants

Information about sour clover as a forage is limited and rather ancient. In the USA, sour clover is used as green forage for cattle, including dairy cows, and as a maintenance ration for heifers. It is also grown for silage. Sour clover is however less productive and palatable than annual white sweet clover (Duke, 1981). An early experiment reported a rather high in vivo OM digestibility of 70% (Lander et al., 1936). In vitro DM digestibility values ranged from 60 to 84% in Indian varieties (Gupta et al., 1980a; Gupta et al., 1980b). In India 2 cultivars tested in buffalo calves contained respectively 10.2 and 9.9% digestible protein (Nandra et al., 2007).

Nutritional tables

Tables of chemical composition and nutritional value

Sour clover (Melilotus indicus), aerial part, fresh

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used