Alfalfa has pretty high nutrient requirements....likely much more so than most ornamentals. And a strong dislike of very acidic soils (anything much lower than 6.5). You might find this link helpful in comparing your soil test results to see where any significant deficiencies exist and then correct accordingly. Soil and Nutrient Management for Alfalfa.

That's very helpful, thank you. I don't know if you can help with this issue as well, but I couldn't find any info on it.

From the soil test the pH is 5.41, and in order to correct that, the recommendation is to put down 170 lbs. per 1000 sq ft of dolomitic limestone.

Magnesium is low (99 lbs per acre- "below optimum" and "medium" on the bar graph) as is Calcium (552 lbs. per acre- "below optimum" and "very low" on the graph). To get the correct amounts, the recommendation is to put down 2-1-2 fertilizer in the proper amount.

What I have on hand is a fairly large bag of K-mag, also a bag of Cal-phos, if I remember correctly. I would like to use what I have on hand rather than purchase additional supplies. To use what I have, do you have any idea which type of lime would be better to correct the pH, calcitic or dolomitic, if I use the K-mag and Cal-phos to get the magnesium and calcium within range? I hope this explanation hasn't been too confusing. Thanks again for any help.

I would use the dolomitic lime - that should be adequate to get Mg to proper levels as well reduce acidity. And it will help with the C as well, although not sure if enough to get to the proper level. You may still need to supplement C.

Either of the limes will correct the pH since they are both carbonates and it's the carbonate part that affects pH. They just have different Ca and Mg ratios. Agree with gg above to use the dolomitic since you need Mg. It's not all Mg, so you'll still get Ca.

It takes a much larger volume of lime to change pH than it does NPK fertilizers to boost nutrients. Seems to me you could almost ignore the Mg and Ca from the fertilizers - it's not going to affect Ca:Mg ratios as much as the lime.

Sounds like alfalfa doesn't particularly like acidic conditions anyway...any chance you could grow something else for this purpose that likes your conditions more?

Yup, could grow anything. I just picked alfalfa for the high nutrient value. I have several Comfrey plants growing along fence lines along the property line, and I'm just trying to figure something else I could grow for purposes of producing high nutrient compost.

I've heard comfrey is good stuff. Best of luck in your search - I've never had the kind of space to do that myself!

the real value of alfalfa is the tremendous tap roots. 8ft in 12 months. then your subsequent plants will go down to that depth too. so plant it where you will want your garden to be. In my experience, alfalfa fades away when you plant taller plants in it, so it is really a perfect cover crop. has nitrogen too.

Thanks. We raised 4 kids in this suburban house, but now they're all grown and gone. No more ball playing, "Extreme Croquet", BMX track building, etc... in the backyard, so we're looking to make it useful. I lurk more than I post here, but have learned alot and have become a bit of a whacko. But I just love doing it. Looking to improve.

"the real value of alfalfa is the tremendous tap roots. 8ft in 12 months. then your subsequent plants will go down to that depth too."

Not necessarily. Alfalfa does produce a tap root but its depth of penetration into the soil profile will depend on the local water table and the soil conditions. A high water table or easy access to groundwater and hardpan, heavy clay or bedrock will limit root depth.

And unless anything else you are growing also produces a tap root - typically just a morphological response to drought or arid soil conditions - the roots will remain at a normal level for that plant, usually within the top 12 inches. That is where the majority of nutrients are concentrated and adequate oxygen. That is where the vast majority of ALL plant roots - even large trees - are located.

Alfalfa is also a perennial crop and will regrow easily and pretty rapidly after the top growth is harvested. If you want to plant something else there later, you will need to remove at least a portion of the root mass.

I disagree. Sure once you hit the water table you stop, and you may not get 8 ft in very heavy clay. But there is overwhelming evidence that roots follow channels of previous crops (path of least resistance). A crop like alfalfa does improve (dramatically) the penetration of subsequent crops if the soil is not disturbed. With attendant savings in water and fertilizer.

glib, you can disagree all you want but feeder roots of virtually all plants are concentrated in the top layer of the soil profile, as they have the primary responsibility for accessing soil moisture, soil nutrients and oxygen. And any mycorrhizal activity. That's where all of these essentials are located. And you do not have to take my word for it - this is extremely well tested and documented.

So roots of any other herbaceous, non-tap rooted plants will only penetrate as deep as they need to go to access these items.

what we disagree with is that plants have a natural root depth. What they do instead is allocate a fixed fraction of energy to root development. Then the more penetrable the soil the deeper they will go. Not a difference on a beach but for clay soils there is. The primary difference, of course, is water intake, but there will be secondary differences, such as nutrient recycling, the deeper the roots the higher the chance of catching those falling molecules. Because it is water intake the main issue I appreciate that people in the PNW will be blase' about it, but even in Michigan it matters. There is a reason why soil scientists suggest to start with one+ year of alfalfa if one wants to go fully biological, and it is not the nitrogen.

*passes the popcorn*

while wondering why you'd want the work of 1000 square feet of alfalfa. For compost?

Yes, for a high nutrient base for the compost. The nitrogen/greens I have are somewhat limited. From what I've been reading, I could get a cutting every 28 days or so in the summer- add in the comfrey cuttings that I get and it sounded like a good base for decent compost. I collect quite a bit of leaves in the fall for the browns. I just enjoy doing it, and the alfalfa sounded like a good idea.

It would be far easier...and probably cheaper, just to do annual cover crops. Let it grow, cut it down, compost the tops, start over.

Alfalfa as a perennial crop...it's not as perennial as you might think. Winter die off is common, depending on freeze/thaw cycles (not good for alfalfa), and snow cover (you want reliable snow cover).

Getting a cutting every 28 days? You're talking fertilizer. Quite a bit. What are you using for harvest? I'm used to using typical forage equipment, and we were always careful not to cut too late...we wanted enough stalk to grow to provide some cover for the winter. If you're planning on hand harvest or mowing equipment...i'm a fish out of water.

I'm full of cheer on the subject, aren't i.

Wayne- Thanks for the insights. I know nothing about growing alfalfa. I would use a scythe for harvesting. Our winters here in South Jersey have become more and more mild over the past 35 years that we have lived here, so we don't get a consistent snow cover over the winter. I didn't realize that to get that much out of cutting it that frequently would require a large amount of fertilizer. I will keep thinking through this. Thanks again for the added info.