Spring is just around the corner, and many of you are itching to start your gardens. How do I know this? Because every place that sells seeds is sold out! Poor Baker Creek, which has struggled to maintain stock since COVID-19 hit the United States, warns that orders will take 30 days or more to ship.
Once you can score some seeds, do you know what to do with them? There’s a lot more to gardening than tilling up some soil and planting your seeds. Your soil is almost definitely missing nutrients and minerals necessary to grow healthy and healthful vegetables.
There are endless debates over what amendments make for a great garden. Some of it is dependent on your soil, but there are some things that are universally needed, like nitrogen, phosphorus, and potassium, as well as a variety of micronutrients.
David the Good and Steve Solomon are two of my favorite gardening authors because they focus on gardening for survival. If you want to improve the fertility of your gardens, I recommend David’s Compost Everything: The Good Guide to Extreme Composting and Solomon’s The Intelligent Gardener: Growing Nutrient-Dense Food.
David recently moved to a place in Alabama with sandy, dead soil. His soil test was so abysmal that he called Solomon for help. Solomon studied his soil test to formulate a special blend of organic fertilizers for his garden. David decided to run an experiment using 12 separate beds, each treated with a different fertilizer. He compared the beds not only based on how well they grew but also on how well vegetables tasted.
The most important bits:
- Steve Solomon’s fertilizer mix performed the best for growth and turnip flavor
- Biochar soaked in Dyna-Gro also produced well and made for the best-tasting radishes
- The no-till lasagna garden also performed well without additional additives but didn’t make for great-tasting vegetables
- The worst-tasting vegetables were produced by the 10-10-10 chemical fertilizer
- Everyone’s soil is different, so it’s worth getting a soil test before amending your garden so you know what it needs (and what it doesn’t)
- Liquid fertilizers aren’t enough on their own. They need organic matter in the soil to soak into.
If you’re unfamiliar with Solomon, he’s known for strong opinions about gardening. Among other things, he advocates a mix called Complete Organic Fertilizer, which has changed a bit over the years. In Gardening When It Counts, it was a mix of seed meal, agricultural lime, gypsum, dolomite lime, and optionally, bone meal and kelp meal. Solomon expanded the formula significantly in The Intelligent Gardener. For David, he recommended a custom variant based on the soil test:
- 4 quarts cottonseed meal
- 1 quart garden lime (better to use 2/3 quart garden lime and 1/3 quart dolomite)
- 2 cups pelletized gypsum
- 3.5 cups bonemeal
- 2/3 cup potassium sulfate
- 1.5 tbsp borax
- 2 tbsp manganese sulfate
- 2 tbsp zinc sulfate
- 2 tsp copper sulfate
- 1 quart kelp meal
- 1/8 tsp sodium molybdate
David the Good decided to test the (rather expensive) mix against some other fertilizers. He used a tractor to build 11 borderless raised beds (plus one more), each with a different treatment:
- Steve Solomon mix: As described above. David also refers to it as Solomon’s Gold in some of his posts.
- Liquid compost: What he calls “Dave’s Fetid Swamp Water” (DFSW), it’s a mix of water, compost, and weed trimmings that ferment in a barrel. It’s mostly free, though he threw a couple of dollars of kelp meal and Epsom salts in.
- Worm castings: Good, old-fashioned worm poop. You can raise your own worms, but he bought $30 worth to add to that bed.
- Dyna-Gro: A liquid fertilizer that’s primarily intended for hydroponics, David estimates he added about $4.50 worth to the bed.
- Biochar charged with Dyna-Gro: Biochar is a type of charcoal you can make and add to a garden. But biochar absorbs crucial nutrients as it breaks down, so David soaked it in Dyna-Gro to “charge” it and keep it from taking nutrients from the plants. He estimates that he spent 75 cents total on this bed.
- 6-1 diluted urine: You may not want to drink urine, but it can be diluted and used as free fertilizer.
- 10-10-10: Classic chemical fertilizer. David used ¼ of a pound from a 40-pound bag, totaling a whopping six cents.
- Nothing: He left one bed completely untreated as a control.
- Neptune’s Harvest: This is a brand of fish emulsion, which is a popular (and smelly) organic fertilizer. He used $1.44 worth.
- Lasagna garden: This bed is completely different. Instead of digging a bed out of the ground, he layered manure, mulch, and other biodegradable ingredients to build a “no-till” bed above the soil. He scrounged all of the ingredients except $1 of alfalfa.
- Alfalfa meal: He covered one bed in alfalfa, about $2 total for 1/10 of a bale, and tilled it in.
- Rye and peas: For the final bed, he simply covered it in a cover crop of nitrogen-fixing rye and peas. This is also called a “green manure,” which adds organic matter, nitrogen, and other nutrients to the soil.
He planted white daikon radishes and white turnips on October 23rd, 2020.
On December 30, 2020, David posted an update on his garden. Before we get to the results, it’s important to understand that these amendments may work differently in your soil than it worked in his. It’s always a good idea to get a soil test before amending your garden. Your local university extension office probably offers soil testing, but the results might be a simple analysis of nitrogen, phosphorus, and potassium. An independent lab like Logan Labs can give much more detailed information.
The untreated control bed performed poorly, even worse than expected. Only a handful of plants germinated. Weeds didn’t even grow in the bed.
The four beds that were treated with liquid fertilizer all performed poorly. That includes the dilute urine, Dyna-Gro, fetid swamp water, and Neptune’s Harvest fish fertilizer. David suspects that heavy rains diluted the fertilizer and he probably didn’t apply enough over time.
Plants grown in 10-10-10 grew okay but weren’t especially healthy. The alfalfa meal and earthworm casting bed also grew okay but had poor germination rates.
The three beds that grew the best were the Dyna-Gro-infused biochar, the lasagna bed, and the bed treated with Steve Solomon’s mix, with the latter doing the best by far.
But growth doesn’t tell the entire story. Your soil content has a huge effect on the flavor of your vegetables. So once he regained his sense of taste back from a bout with COVID-19, he and his wife performed some taste tests.
David picked radishes and turnips out of the six beds that gave good yields:
- Charged biochar
- Lasagna bed
- Solomon mix
- Worm castings
For both the radishes and turnips, the Solomon mix and charged biochar consistently tasted the best, and the alfalfa meal beds also did well. 10-10-10 produced the worst-tasting radishes, with both being tough and bitter.
I’ve never made a batch of Solomon’s fertilizer because the ingredients are hard to source and rather expensive. But the results here are hard to argue with, so I may have to whip some up for my spring garden. Steve Solomon has some pretty unorthodox and dogmatic opinions about gardening, but it turns out that he really knows his stuff.
I had never heard of Dyna-Gro and I’ve never tried biochar (unless tossing leftover charcoal from the grill into the compost pile counts). I certainly never thought to soak biochar in a fertilizer. That’s another technique to try.
I’d also never thought to use alfalfa in a garden bed. Alfalfa pellets are readily available as horse feed, so that’s something else worth experimenting with. I might try using some as a mulch for my spring beds.
Liquid fertilizers aren’t bad, but they aren’t enough on their own. You need organic matter in the soil because otherwise, the liquid fertilizer will quickly drain away, at least if you’re growing in sand. Cover crops are also a good thing, but again, not enough on their own.
David is now building a spring bed with layers of manure and alfalfa, plus Dyna-Gro-charged biochar and the Steve Solomon mix. Subscribe to his YouTube channel to see how it turns out.
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