Megathyrus maximuscv. Mun River

formerly Panicum maximum

It was introduced into Thailand from Costa Rica in 2015 and was evaluated in 3 years of field trials by Ubon Forage Seeds before being released in 2019.


Mun River guinea grass is a perennial, tall, leafy grass, similar to Mombasa guinea grass but with broader and softer leaves. Mun River has a high proportion of leaves (80-85%). It is a perennial and will grow for 10 years or more under good management. It is a very productive leafy grass, producing between 15-20t/ha dry matter per year on poor soils in Thailand.

Mun River is not tolerant of waterlogging and only has moderate drought tolerance, It does not tolerate salty soils.


Mun River can be established by sowing seed or transplanting seedlings or tillers with roots from a nursery.

  • For seed sowing, broadcast 8-10 kg/ha into a well-cultivated seed bed. Cultivate by ploughing, discing and harrowing to produce a fine seed bed.
  • Broadcast the seed over the field and then cover the seeds with 1-2 cm of soil by gently brushing or raking or harrowing. A light roller can also be used to press the seeds into the soil.
  • If planting tillers, plant the rooted tillers in rows, 50 cm apart into moist soil. Irrigate if no rain falls on the day of planting.



Apply 200 kg/ha of NPK fertilizer (15:15:15) at seed sowing and then after every forage cut or grazing.


  • First cut is at 60-80 days after planting or when the plants are between knee and waist height (60-80 cm high). Cut down to about 10-15 cm or at ankle height.
  • After the first cut, cut thereafter every 40-45 days in the wet season or when the plants reach between 60-80 cm in height. If the grass is too tall (over 80 cm high) it is low in quality (low crude protein and high fibre).
  • In the dry season, cut when the plants reach between 50-70 cm in height or about every 60-70 days if there is no irrigation.

Crude Protein Levels

8-12% crude protein in Thailand on poor soils and 12-14% crude protein on better soils.

Digging out seedlings with roots for transplanting
Planting seedlings
Field of Mun River 80 days after planting
Field of Mun River for seed production