Siratro

Siratro (Macroptilium atropurpureum) is a tough trailing perennial legume from the Americas, now used across tropical pasture and cover-cropping systems worldwide. POWO records its native range as Mexico to western South America and Tobago, naturalised across the seasonally dry tropics.¹ Pakistani growers will not find a local Urdu name in regular use, so the cultivar name siratro stands. For a food-forest plot on the Punjab plains or near the Sindh coast, it is the dependable scrambling cover to throw under young fruit trees once the monsoon breaks.²

Where it thrives

Siratro suits the warm subhumid zones of Pakistan. Day temperatures of about 27 to 30 degrees Celsius drive best growth; the plant is frost-sensitive but regrows from a deep taproot once the cool snap passes.² It runs on a wide rainfall band from roughly 700 to 1500 mm, drops leaf size in dry spells, and tolerates a broader soil range than most tropical legumes, from dark cracking clays through red sands at pH 4.5 to 8.5.²³ Salt and aluminium tolerance are well documented, which makes it a fit for marginal land along the lower Indus.

Role in the system

Siratro sits in the groundcover stratum as a pioneer climber: a low scrambling vine that knits across the soil and twines up any standing stem. Its real jobs in a guild are three. It fixes substantial atmospheric nitrogen, with field estimates between 55 and 175 kg per hectare per year.² It holds soil and smothers weeds through a dense leafy mat. And it works as a living mulch under widely spaced perennials such as banana, mango or young citrus, where it carries protein and ground cover without bloating ruminants that may graze the alleys.² Treat it as a long-lived secondary-stage cover, not as a permanent neighbour to a delicate herb layer; the vine climbs aggressively and will swamp short companions.

Growing it

Establish from seed. Siratro has a high hard-seed fraction, so scarify mechanically before sowing; scarification can lift germination from around 10 percent to about 80 percent.³ Drill or broadcast at 1 to 2 kg per hectare into a clean, firm seedbed at the start of the monsoon, and inoculate with a cowpea-group rhizobium on fresh ground. Light grazing or a single mowing pass during the first season pushes it to thicken laterally rather than run vertically. Once established, the deep taproot carries the stand through dry spells; cut high enough to leave growing points.

What you get

The product is fertility, ground cover and grazing feed. Dry-matter crude protein sits around 16 percent on average, with leaf material running up to 27 percent, and the legume is reliably non-bloating in cattle.² Stands persist for several seasons under sensible cutting or grazing. Under tree crops it doubles as a soil cover that returns nitrogen and organic matter, much like centro or mucuna but more drought-hardy.³

Sourcing notes

Seed is not yet common in Pakistani retail and is most reliably brought in through a forage-research outfit or a regional pasture seed supplier; insist on scarified seed and a fresh batch. Plant beneath young mango, citrus or banana, or in mixed grass swards on canal banks. Keep it out of beds where it could climb into okra, brinjal or chilli, which it will smother.

Sources

1. Royal Botanic Gardens, Kew (2024). “Macroptilium atropurpureum (DC.) Urb.” Plants of the World Online.
2. Heuzé, V., Tran, G., Boval, M., Lebas, F. (2016). “Siratro (Macroptilium atropurpureum).” Feedipedia, INRAE-CIRAD-AFZ-FAO.
3. Cook, B.G. et al. (2020). “Macroptilium atropurpureum.” Tropical Forages: an interactive selection tool, CSIRO / CIAT / ILRI.