In the coconut orchard, I grow the following for making the land fertile...
1. Local fodder grass - This is seen locally and especially on the road sides, this has very vigorous growth - in rainy season, can be cut in every 15-20 days. Main attraction is that it is perennial and hence will remain green to some extend in summer also and hence there is year round coverage
2. Mexican sunflower - This was introduced after reading that permaculture people value this a lot and calls this as dynamic accumulator. This also is perennial and produce a lots of biomass and easy to cut and mulch. Leaves decompose very fast.
3. Super napier grass - This also is perennial and produce lots of biomass and will be ready for cutting in every 25-30 days
4. Pureria Javanica - This is leguminous and does not survive summer here
5. Subabul - This grows naturally and is an invasive species and hence many plants will be there under each tree. Leguminous and perennial
6. Other local weeds - typically annual
Super napier fodder grass and mexican sunflower grows to a height of 8 feet and it gives a wild view to the farm. Decided that will cut them at least twice an year. Cut mulch will be left there itself, some mulch will be piled under the coconut trees.