Wednesday, March 4, 2009

Homemade Organic Fertilizer

So I made some fertilizer the other day and the results have been great. I got the recipe from Gardening When It Counts by Steve Solomon. The author strikes me as a bit of a crochety old hippy (in a good way... some of my dearest friends and family qualify as crochety old hippies). He gets preachy about his weird ideas sometimes. On the other hand his ideas, mainly that hard times are imminent and people will have to garden to survive at some point, don’t seem so crazy these days. Apparently other people feel this way too as seed sales are up across the country this year.

What I like about Gardening When it Counts is that it advocates a cheap, easy and effective approach to vegetable gardening that overall agrees with the training that I got in agronomy at UC Davis. The book is largely reactionary to the Jeavons’ biointensive method, advocating direct sowing of seeds, wide spacing between plants, and goes into depth about fertilization rather than simply instructing you to apply more compost.

Keeping fertility up and soil borne disease down is a part of gardening that was lost on me in the beginning. The concepts are related because it takes sufficient fertility to help plants recover from certain diseases that would stress or kill them if there weren’t enough nutrients around to help them along. In my first vegetable gardens I had healthy happy plants because I broke new ground that had either never grown vegetables or hadn’t in a long, long time. They had also been growing annual weeds, essentially a cover crop, for years, so they were naturally fertile and free from disease thus the plants never looked stressed out. For most gardeners this honeymoon period lasts for the first couple of years in the same spot.

For me, the trouble came when I moved to Davis and started gardening in the experimental college community garden. Most of the plots in the garden have been cropped continually for years by novice gardeners who pay little attention to soil improvement or crop rotation. The result is that plants in the garden are sickly.

What can I do about it? In a perfect world I'd have two large garden plots and let one go fallow, or use it as pasture while I garden in the the other, then rotate every three years or so, this suppresses disease. But as rotation on that scale is just not possible in my current garden, the long term solution is to build up my soil with organic matter so that there is a healthy soil ecosystem in place.

In a healthy soil ecosystem there is plenty of N P K and trace minerals present, but they are incorporated in the bodies of the microorganisms in the soil. Every time a microorganism gets eaten or dies, the nutrients in its body become available to the plants. So the plants have a constant source of nutrition that can’t wash away with rain and irrigation as it does when we apply chemical fertilizers. Another benefit of a healthy soil ecosystem is that organisms living in the soil can out compete some of the disease organisms attacking my plants. But good compost is hard to get and takes a long time to make, so making my own organic fertilizer to help plants along is my short term solution.

The fertilizer is designed to provide N, P, K and trace minerals, as well as provide calcium that improves soil structure. Solomon’s recipe calls for Seedmeal, Kelp Meal, Agricultural lime, dolomite lime, and Gypsum. There are some substitutions you can make for the kelp meal (it’s expensive) and you can add blood meal as a higher nitrogen option.

I made some of my own changes to the recipe because I know a little about the soil here in Davis and some of the ingredients Steve calls for, namely the dolomite lime, seem unnecessary or even downright dangerous for our soil. The soil here on the Westside of the Sacramento Valley, unlike most of the rest of the world, is very high in Magnesium, almost dangerously high so it didn’t seem like a good idea to add the dolomite lime which is Calcium and Magnesium Carbonate. I opted to eliminate the agricultural lime, calcium carbonate, too because it raises soil pH, and the pH of the soil here is already neutral to High. I do however want the benefit to my soil structure of adding calcium, so I subbed gypsum, which is basically pH neutral, in the mix, and reduced the overall quantity of lime since our ground tends to be salty. Check out the gypsum bag where it says "works like millions of tiny hoes."

Marion's Organic Fertilizer Recipe for High pH Soils

4 parts soy bean meal

1/2 Part Gypsum

1 Part Kelp Meal or rock phosphate or bonemeal or high phosphate bat guano or basalt dust

For a higher nitrogen option, best for leafy green veggies in spring, replace one part of the seedmeal with bloodmeal or fishmeal

Mix all ingredients together in a large rodent proof container. Note that measurements are by volume, not by weight.


Preplanting: Broadcast 4-6 quarts of fertilizer on each 100 square feed of bed space and cultivate in. During the growing season you may want to side dress heavy feeding vegetables with a small amount of fertilizer every few weeks. Use a total of about 4-6 quarts over the growing season for side dressing your high demand veggies.

The seedmeal I ordered from my local feed store, I bought soybean meal and it was $16.95 for a forty pound bag. It is the byproduct of soybean oil extraction and it is usually fed to cattle. Maybe if Obama ends stupid crop subsidies it won’t be so cheap in the future, but for now I’m going to use it’s cheapness to my advantage and feed it to my plants for a Nitrogen Boost.

The Kelp Meal I bought at Sparetime Supply in Willits, CA where my Brother in law works. I forget how much I spent on it, but it was pricey. The Gypsum came from the local hardware store and was cheap. You can buy any of the ingredients except for the seedmeal from Peaceful Valley.

I mixed the three ingredients together in a metal garbage can (varmints like to eat soybean meal as much as plants do) and Voila! a garbage can full of powdered organic fertilizer, just like the stuff at the hardware store only much, much cheaper. I figure the whole can full cost me around $40, that’s the price of two little boxes of the stuff at Ace.

I applied the fertilizer, fudging the rate a little bit, and cultivated it in to the first couple inches of soil just before a rainstorm hit. Now, a week and a lot of rain later, the plants are looking much better!

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