# Does nitrogen fixation plants consume nutrients from soil

I am a farmer. I have lot of "touch me not" plants (Mimosa pudica)in my coconut plantation field. Many people are saying I have to get rid of them for two reasons:

1. It is very difficult to walk in the field for routine works.
2. These plants consume nutrients from main crops.

I am bit reluctant to remove these plants. I understand that these plants help in $$\small\mathsf{N_2}$$ fixation. Also these plants may protect my field from some of the animals I thought though it is inconvenient to walk. So my main question is: Do these touch me not plants consume nutrients from the fertilizer I put on coconut plants? Are there any ill effects of these plants?

• it says here it is a weed in coconut farms en.wikipedia.org/wiki/Mimosa_pudica – trond hansen Nov 6 '19 at 7:15
• If they don't interfere with your operations or present a fire hazard, I'm not sure they are a serious problem. They may be hard to get rid of without the environmental and money costs of herbicides and you may need more fertilizer. Maybe test a small area and see if removing them helps or hurts your production. Good luck! – haresfur Nov 8 '19 at 3:59

## 1 Answer

I'm not familiar with the plants you mention, unless they are the ones whose leaves rapidly move away from you when touched. I saw some in Malaya. However, the plants well known for fixing nitrogen from the air and enriching the soil are legumes, belonging to the same group as peas, beans, alfalfa and clover. There are hundreds of them, and they all have similarly shaped flowers, though of many different colours.

They all have nodules on their roots which harbour the bacteria which do the actual nitrogen fixation. Like any other plant they also extract minerals from the soil, so the soil will be enriched with nitrogen but depleted in minerals. Farmers get round this difficulty by rotation of crops.

If the flowers of the plants you mention are similar in shape to the flowers of peas and beans they probably enrich the soil, and it is unlikely they remove enough minerals to harm your coconut palms. In England, farmers sometimes sow a legume like clover or alfalfa, then plough it back in so that the soil is enriched with nitrogen but not depleted in minerals. Perhaps you could do the same with your mimosa plants.

Most fertilisers contain nitrogen, and if yours contains anything else your mimosa will probably use a bit of it, but not enough to worry about. If your plants are indeed a kind of legume, that should enable you to use less fertiliser. If your touch-me-not plants have thorns on them, that's the only ill effect I can think of.

• Yes, I am talking about the same plant whose leaves close when touched. According to en.wikipedia.org/wiki/Mimosa_pudica , such plants fix Nitrogen. They do have thorns and plucking them is not easy.Need brush cutters and it is bit expensive. I removed some plants and I could see bubble like formation on their roots. in general if any N2 fixing plants such as Mimosa, legumes etc are really benefit us or will they act as weeds and consume lot of fertilizer we use for other plants. How we can balance this so that organic farming is benefited from these plants. – Rajesh Nov 7 '19 at 16:54
• I see from Wikipedia that mimosa isn't a legume,but fixes nitrogen in the same way as legumes.I don't know what legumes are best suited to your climate,but I'm sure there are some.You could try cutting your mimosa back and composting or burning the cuttings,which would return the minerals to the soil,but I doubt that the small amount of minerals they take would harm your coconut palms.They also prevent more harmful weeds growing there.You could try growing a small patch of legumes on your land to see how well they grow and whether it would be worth clearing some of your mimosa to grow legumes. – Michael Walsby Nov 7 '19 at 19:09
• I am from Mangalore in India and very humid condition exists here. Legumes does grow if we water them to some extent and that is my concern. Also if legumes like horse gram is present, other weeds still come in this area. That is why I thought touch me not could be ideal and does not need water and they grow. I have planted thorn less touch me not plants and they do come up very fast. Though these weeds may not affect coconut plants, I am planning for inter corps in this plantation and I am worried if these plants create problem. They grow fast and removing later will be an issue – Rajesh Nov 8 '19 at 1:21
• As you suggested, I am planning to go for composting. Laborers face problems due to thorns and probably that is the only issue. I also read many articles about benefits of touch me not plants in Ayurveda medicine. I hate using round up like weed killers, which kill millions of other important resources from the soil. Even I do not like burning because they pollute the environment. Need to balance and looking for best way to balance these plants. – Rajesh Nov 8 '19 at 1:24
• Couldn't your labourers use long handled sickles to avoid the thorns? Avoid using weed killer if you can, it's not healthy for the land or the user. Usually plants respond to trimming with new, more bushy growth, and that will help the mimosa suppress other weeds. Try some very small scale experiments with legumes. There are hundreds of different kinds, so it's probably a question of finding the right one for your purpose. If thornless mimosa can be used as fodder for livestock, you could perhaps solve the problem of eradication by letting livestock graze it. – Michael Walsby Nov 8 '19 at 8:33