Making COF

The last few years I've had success using a combination of store-bought compost and manure and various mixtures of organic fertilizers. Generally speaking, organic fertilizers are not as potent or as fast acting as synthetic chemical fertilizers, so one must use a greater volume, more often. With twice the garden space as last year (up to almost 3000 sq ft now!), I'll need so much that I decided to mix my own complete organic* fertilizer (COF). The famous Steve Solomon developed a mix tailored to our slightly acid and heavier northwest soils that I used as my guide. I followed the recipe given here, on the third page of an excellent article about homemade fertilizers written by Steve.

I bought ~50 lb bags of each ingredient, all of which I was able to source at local feed stores (I had to go to two to get everything).


The components in the mix can vary, based on what's available locally (and cost!). In my mix I am using (CCW from upper right) 4 parts cottonseed meal , 1 part kelp meal, 1 part rock phosphate, 1/2 part limestone flour (calcium carbonate), and 1/2 part dolomite lime.

The finished product.

Total initial ingredient cost was about $130. The kelp meal is about $75 of this, and I could have used blood or bone meal instead and saved money, but you can read in the article I linked to and see why I chose kelp meal. This made about 25 gallons of fertilizer, enough to cover all my ~3000 sq ft @ 4-6 qts/100 sq ft. I will probably go through half of another bag of seed meal this year to have enough for side dressing the heavier feeding vegetables, but the other ingredients should be enough for the next 2 or 3 years. That boils down to ~$60 a year over the next 3 years for all the fertilizer I need, and my compost is free.

This system (compost, COF, and cover crops) is far better than simply using water soluble synthetic fertilizers; it provides all the major and minor plant nutrients, improves the soil tilth with the addition of decomposed organic matter, feeds soil biota and increases soil biological activity, controls soil erosion and nutrient leaching, and builds a solid foundation of soil health that will help the garden produce for years. $60 a year seems like a pretty good deal to me.

*the cottonseed meal in this batch is not organic and probably GM, but the kelp meal is organic. I have since found that I get organic linseed meal locally, which is what I will use in the future. The mined substances, rock phosphate (OMRI listed) and limes, are minerals so they're pretty much organic...

Cover crop cutting

Clover. Lots of clover.

The crimson clover cover crop sown late in the fall is doing great in some beds, and not so good on others (the far beds in the photo). Our winter came very late this year, and I held off on clearing out the beds and getting the cover crop sown for as long as possible so I could keep picking off my tomatoes, peppers, eggplant, and beans. Turns out I waited too long. I got half of the garden beds planted early enough, but I was too late in getting the other half the cover crop in, so it was frozen out after a few months. Not a huge deal, but I didn't like the beds sitting bare while winter and spring rains pounded down on them with no protection from erosion, compaction, and leaching away of nutrients. Learned my lesson.

I started cutting it by hand (slowly) with my little Japanese hand-held scythe, but soon enough brought out the weed-whacker, which made shorter work of it. Raked it all up and put it on the compost pile. Hopefully the roots remaining in the soil will break down over the next couple weeks as the bed starts to dry out, and I'll be able to turn over the top 6" of each bed, add compost and fertilizer and plant!

It didn't create as much organic matter as I thought it would; mixed with horse manure this will break down and probably only provide enough compost for maybe an inch over two 25' beds. So next year I need to get it planted earlier in all the beds, or possibly sow a large area of crimson clover in a section of the pasture just for composting material...I think chickens will eat it too, so it can be turned into eggs!