For the potassium, use poultry manure.

For the other minerals, try a mixture of comfrey, yarrow, dandelion, and nettle. Grow a special bed of them or just tuck them in waste space, harvest the leaves, macerate, and make tea. Marine plants concentrate the nutrients more, though, so you will need more of the land plants. The "weeds" all have deep root systems that collect minerals from subsoils, then the plants put them in the leaves where they can rot into the surface soil.

This might not replace kelp, but it could considerably reduce the amount you use.

Thanks!

What about deep rooting cover crops like rye or oats? Do these plant do the same thing, far as bring forgotten nutrients from the subsoil to the topsoil?

Maybe that is also another "kelp" replacement method...

I've never heard the grasses mentioned in that context, though naturally any deep-rooted plant would be bringing something up - the question is in what amount. And of course the deep-rooted cover crops, as any deep-rooted plant, have the benefit of introducing organic material very deep down through their ever-decaying and regrowing root hairs. The four plants I mentioned are specifically used because they bring up lots of nutrients which will benefit other plants as the leaves rot. Dandelions, for example, preferentially bring up calcium and store it in the leaves, to the point that dandelion greens have as much calcium as milk.

Thanks!

Now I have another question: What do you do when you have exhausted most of the micronutrients that were in the deep subsoil, by years of growing and consuming up your crops and cover crops? How do you replenish those nutrients back into the soil system, without going outside your farm site and obtaining something like extra kelp products or maybe comfrey, stinging nettle weeds, etc. from a remote site, in order to build up your soil system?

Yes, I do collect my urine in 50 gallon rain barrels of water, mainly for free nitrogen in all my composting and tea brewing recipes. I collect various green weeds on my property also for extra NPK. I have access to an unlimited amount of horse manure and sawdust. Horse manure is rich in NPK and calcium. Sawdust is rich in carbon and potassium.

However I was wondering if all the above alone, would supply all my crops those rare micronutrients that some crops need that is native in seaweed products.

It seems to me that if you are making compost from a mixture and plant and animal source, the finished compost ought to maintain pretty much the mix of micronutrients that were present in the raw materials. Admittedly, some micros might be of limited availability owing to off pH, cold and wet soils, and other negative edaphic conditions.

You seem to be focusing on micronutrients as similar to vitamins when in fact there are just what they represent: elements needed in very minute quantities compared to NPK and even the secondary nutrients. Micronutrient deficiencies are common to some soil and in some seasons but mosly are readily available in a living soil supplied with adequate organic material.

Thanks that helps!

I bought a 40lb bag of greensand at local farm supply store.
It's suppose to be a good longterm source of potassium and
contain many micronutrients..But that might get pricey for
a large farm.
Swanz

Alfalfa meal is great - so is fish meal. You might also try either shrimp meal or crab meal.

I've read that seaweed is excellent for initially establishing fertility
in a soil but should be used sparingly thereafter.. It said that you
can quickly build up toxic levels of certain micronutrients . I think
it mentioned iodine, biotin and sodium and a few others.
Swanz

from what i have read seaweed or kelp meal can not be substituted by anything. the whole purpose is to provide trace nutrients that could be lacking. some of these elements are not even needed by plants such as iodine yet are essential to animal health so it is indirect consumption first getting the nutrients into the plants then eating the plants. arsenic is another essential to animal life yet totally unneccesary to plants as well as we currently know. sea products tend to contain almost every mineral in trace amounts so fish meal or emulsion could possibly contain some or all of the things kelp or seaweed provides. Kelp meal is recomended at 1 cup per 100 square feet annualy in a book gardining for maximum nutrition so it is used in very minute qty. I can't help but wonder why bother with secondary igestion why not just consume minute qty of the meal directly in say stews soups gravies etc. Part of the logic no doubt is that the application to the soil also allows for any trace elements lacking in your local ecosystem and thus not present in localy produced organic debris. Importing components of the compost heap from distant sources may also have some advantagous effects such as using stable cleanings that have sawdust from nonlocal trees and feed comprised of products from several regions. so there is no substitute for seaweed or kelp meal to the best of my knowledge. I have yet to find a reasonable priced source. Anyone living near the coast could simply harvest rinse the salt and add the seaweed or kelp to the compost heap those of us inland must import to obtain it and prices seem to be way to high for what it is. Anyone knowing of low cost commodity co-op type suplies please post them.

There is no substitute for seaweed.

If the trace and micronutrients come out, they have to go back from somewhere.

That said, many plants do well under less than perfect conditions.

Kelp Meal is a commodity. This means that shipping costs are often higher than the cost of the kelp meal, itself.

Gene Logsdon talks about harvesting the "pond scum" off his pond weekly in high summer to use for mulch and compost stock. Much of what is in pond scum is an algae, as is seaweed.

Katey

Just discovered this great forum! Agree with the alfalfa meal/pellets (plus cayenne or tobassco) as superb. One of my favorite mulches for my blueberries is alfalfa hay-2nd cutting. Sometime, we do not make enough sawdust in the woodshop for our berries-and find it hard to get non walnut or non-plywood sawdust. When I pull weeds, I often place the healthy ones in five gallon buckets-fill with water and make my own "Weed and Feed." Let set til you get around to diluting it and you just feed your plants-at their bases or as a spray. Over a lifetime of gardening, it seems that once soil is producing tasty crops, it has nearly all it needs. Look to the woods-only leaves,rain, and plant and animal carcasses take care of growth. About every five years, I spread a cup of powdered sulfur around each blueberry bush. Beets, asparagus and some of the fruit trees get a sprinkling of wood ashes each spring. Equilibrium is so hard to achieve if one is planting on construction abused or chemically abused sites. Good luck...if weeds grow well-so will anything that fits in your zone! cella jane ky-6

I have been seeing some information on volcanic rock dust for the mineral content and the gardens grew well and would seem to be a nutrient mineral powerhouse. A company on this site uses blue green algae and volcanic rock dust. Probably a little spendy for acreage, but you may be able to find cheap sources nearby with a quaries rock dust.

You can still get a 10lb bag of Kelp Meal for around $25.00.
Not bad when you consider all the benefits it has. The link below almost always has some kind of special on the stuff.

Here is a link that might be useful: Kelp Meal

we are professional seaweed powder(pure)manufacture of China. Any customers need this product ,please contact with me for more details.

Hello,do you have pure kelp powder?

Comfrey (Symphytum officinale) is probably the most popular dynamic accumulator. Permaculturists swear by it, and organic gardeners use it frequently.

https://www.gardenmyths.com/comfrey-dynamic-accumulator/