BeeBalmClover
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Joined: Wed Oct 24, 2018 8:19 pm

Looking to improve soil by planting alfalfa

I've recently developed an interest in gardening and in improving my small piece of property with the goal of eventually having a lawn that is reasonably free of weeds and suitable for growing vegetables. My idea includes cultivating alfalfa to improve the soil while attracting beneficial insects, so I've started by ridding the weeds from a patch of ground and digging up the soil to remove the larger stones. They range in size from a grape to a very large grapefruit. Also, the deeper I dig, the more clay is in the soil. How deep should I dig in order to remove stones and mix the clay into the rest of the soil?

imafan26
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Posts: 13947
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

Alfalfa is a good cover crop, but like sun hemp and pigeon pea, it has relatively deep roots and not the easiest thing to remove if it is kept too long. It is hard to dig up by hand.

I prefer to use other legumes like fava beans, cowpeas for nitrogen fixing and buckwheat for biomass. Remember a true cover crop only benefits the soil if it is able to develop the nitrogen fixing nodules on the roots and if the nitrogen stored in the plants are returned to the soil and not lost to harvesting. Cover crops need to be turned in when they start to flower for maximum nitrogen return. You also need to turn over most cover crops because they are by their very nature weedy. For me, the soil in one of my plots is extremely alkaline and fungal dominant so legumes need to be inoculated first to get any kind of nodulation. Normally, the rate without inoculation is 0-4 nodules. Even double cropping after inoculation, the level falls back to baseline. With inoculation the average is 8-12 nodules.

If you live in an area with snow, and your cover crop is not winter hardy, then the problem is solved. Nature will do the killing and over the winter the nutrients will sequester and slowly release as it decomposes.

https://www.growveg.com/guides/green-ma ... er-garden/
https://www.growveg.com/guides/green-ma ... -the-ugly/

Luckily, I live on land that was once a pineapple field so rocks are pretty rare, and the land is mostly fill. I do however, have a red clay oxisol.

The depth can be anything you like 18 inches to 2 ft will get most of the root zone for the majority of your root crops unless you are planting parsnips or gobo. If you have clay, or your garden is being located in a low spot, you should check the drainage by doing a percolation test. Rocks in the soil will actually help drainage, you just don't want too many of them where your plants will be growing.
https://www.dummies.com/home-garden/gar ... -drainage/

Improving clay soil can usually be done by adding organic matter. Organic matter breaks down and will have to be added regularly. Over time the organic matter will fluff up the soil, improving soil tilth, and depending on what kinds of compost and manures you add, you can effectively change or stabilize pH over time. Chicken manure will alkalize acidic soils, and Peat moss will lower the pH of alkaline soils.

Usually I mix equal volumes of compost with soil. Unless I am going for a specific effect, like acidifying the soil, I usually use a blend of different composts and composted steer manure. I test my soil about every 3 years. Compost does contain phosphorus which I don't need, but all the fertilizer I actually add is sulfate of ammonia. I do use synthetic fertilizers, I don't like to use animal byproducts, even manure in quantity. Manures contain salts as well and more than just the nitrogen I need.
https://garden.org/learn/articles/view/1310/

BeeBalmClover
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Posts: 2
Joined: Wed Oct 24, 2018 8:19 pm

What an informative post! Thank you so much for taking the time to type all that out and share it!

I will probably rethink planting alfalfa in a large area since it sounds like more work than I can handle. It's actually not my first choice, but it is what was recommended when the seeds were bought and I'd still like to have some for nitrogen fixing and for extra organic matter. Buckwheat might be a good idea... I'll do more research. My go-to choice is white dutch clover; hopefully it'll be in stock next time I check. I live in Ecuador and it can be a challenge to find everything I'd like, not because it doesn't exist here but because I can't just go online and find out what store has it. It can be a lot of legwork to get things (I don't have a vehicle).

Thanks for the links, too. Very useful information there! I have them bookmarked.

I think what I'll do as far as digging up stones is take your outside recommendation of two feet. I leave in anything that's smaller than a grape or thereabout since I don't want to compromise drainage.

Thank you again; your reply is very much appreciated!

imafan26
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Posts: 13947
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

I usually use cowpeas or black eyed peas (some are pink eyed). Soy beans, fava beans and peanuts are other alternatives. Since these are also used for food, it is easier to obtain them. Sometimes you can get dried (not roasted) beans in the markets and they will grow. It is usually where I get my pigeon pea, peanuts, and lima beans from. As long as the dried beans have not been sitting on the market shelf for a long time and the market is air conditioned so the temperature has been fairly constant, dried beans will still sprout. I sometimes find mung beans in the asian section. If they are dried and not split, they will grow to make bean sprouts. I used to be able to get sprouting seeds of fenugreek, alfalfa, buckwheat, and spelt. I did get some quinoa and grew a few. I may try again. Quinoa won't grow here except in the cooler months.



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