Sunday, July 24, 2011

Few experiments with sun-hemp

I have been thinking about replacing the grass in my farm with some legume. Ferility in my farm was improving with just grass growing all around. Fukuoka san advises this in one straw revolution and he had clover in the mandarin orchard which made the land fertile quickly. Recently had gone through presentation by B.N.Nandish and he concludes that a few monocot grasses won't make land fertile and hence advises legumes.Organic farmer Manoj from Wayanad told in one conversation that if we keep mulching the plants may develop a yellowish color for some time and it will vanish by itself later. The yellowish color is because of the nitrogen deficiency which gets created on adding more carbon and microbes consumes nitrogen from soil. But they don't take it way, once they die, it again becomes available for plants.

Some information which I got from an article on looking for this specific information.

The amount of nitrogen available for plants is determined by the net balance between the rate of nitrogen mineralized from decomposing organic matter and the rate of nitrogen that is immobilized by growth of soil microbes.
Microbes are considered to be stronger competitors than plants for nitrogen . In soils where nitrogen is limited, microbes generally outcompete plants for nitrogen, resulting in plant nutrient deficiencies and decreased plant growth. In fertile soils, there may be enough nitrogen to adequately support both microbial and plant growth. 

So I thought of trying some legume, my earlier experiments with cow pea/black gram was not that successful. So thought of trying daincha or sun-hemp. Got 3 Kgs of these from coimbatore and since I read sun-hemp can grow in drought condition also, so broadcasted some in summer among grass, which didn't sprout. A few seeds were put in soil and watered it once and it sprouted well and grew up. It is growing really tall, not it is around 5.5 ft height. Made some raised bed for planting ginger, turmeric etc and broadcasted some seeds, this was done after rain had started. On three raised beds they are growing thick and green and no competition from grass and they produce enough mulching material. Typically turmeric and ginger is planted with hay or coconut husk as mulch which is brought from outside. If farmers can grow sun-hemp for two months and then plant ginger/turmeric this can be avoided. This is easily possible in permanent raised beds.

Recently on one paddy field I broadcasted sun-hemp and then cut and mulched the grass above this. This also has sprouted well and I am looking to grow rice on this place in the next season. There is a threat from cow grazing, if this doesn't happen I will be able to try paddy on sun-hemp legume.

I also have bought 10 Kgs of sun-hemp and planning to put in coconut orchard... will come up with this experience later.


GG said...

Hi Nandan,

How is this sun hemp doing now, have you already cut it down?. Is the sun hemp grown in that area sufficient to mulch the same area?.

Nandakumar said...

Sunhemp in the paddy field was cut and mulched. It produces lot of bio-mass, but when it get dried, it looks like it is not much, still it is a good amount. In that area, there was no grass so far, only a few creepers are coming up.

Unknown said...

Hi Nandan,

I am also interested in trying out sunn hemp. Your comments please. 5.5 feet within 60-90 days is great going. Have a few questions. Will be glad if you can clarify

1. Does it self seed or do we need to sow it again next season.
2. What is the ideal time to sow sunn hemp seeds.
3. Will it work if we broadcast the seeds after weeds have been established or does it have to be done before the weeds establish themselves (beginning of monsoons).
4. How much time does it take to flower. 60-90 days.
5. What happens if we do not cut it even after flowering. Will it die by itself or will it reproduce and colonise the area.
6. How difficult it is to cut a sunn hemp say after 2 years. Is there any disadvantage of not cutting sun hemp after 60-90 days. (Will the C/N ratio increase causing delay in availability of nitrogen)
7. what is the rate of re-growth after cutting.

8. Did you find any other cover crop that gives you so much of bio-mass?
9. Does the bio-mass disintegrate as fast as say gliricidia leaves(seema konna)?

Thank you

Nandakumar said...

Thought had answered this....
1. The pods does not self burst, hence has to reseed
2. I do it at the start of the monsoon
3. If weeds are established, you have to sow the seed and cut the weed
4. typically 90 days
5. It won't colonise, some plants will come in the next season
6. Its stem will become strong, so it is good effort to cut it. I am not sure about C/N ratio, how do we know about this?
7. will be generally slow
8. Daincha also is similar type, Pureria family also produce lot of biomass
9. Not as fast as glyrecidea

Thanks and Regards,