Regenerative horticulture

I was excited to learned that pasture could sequester as much carbon as forest, and I have been on farms where it is happening. My first career was in horticulture, but the prospect of building soil carbon in pasture seemed simpler, as growing food, especially vegetables, often involves carbon destroying practices, such as rotary hoeing.

So I was delighted to learn from John Kempf. He outlines how crops, even for example strawberries, can sequester carbon. His two top strategies for building plant and soil health are enhancing photosynthesis and innoculating the soil biome.

Its all about photosynthesis!

John Kempf states that plants typically photosynthesise at 25% efficiency. At that level, the sugars produced are rationed between leaves, fruits, roots and the soil. But if photosynthesis is increased, surplus sugars go into the roots and the soil.

At 20% efficiency, corn will produce 10,000 lbs of carbohydrate per acre.

Uptake of sugars	20% photosynthetic efficiency, 10,000 lbs		60% photosynthetic efficiency, 30,000 lbs		Gain
Plant biomass	35%	3,500	25%	7,500	4,000	Increased yield
Grain	35%	3,500	25%	7,500	4,000	Increased yield
Root biomass	15%	1,500	25%	7,500	6,000	400%
Root exudates	15%	1,500	25%	7,500	6,000	400%

Table 1: Sugar production in corn (1lb per acre = 1.12kgs/hectare)

Notice how the energy of the sun generates five times more sugar at 60% photosynthesis for roots and the soil. It is transported to roots and soil via what Christine Jones calls the “liquid carbon pathway”. This reverses conventional wisdom – rather than building the soil to support health plants, healthy plants build healthy soil.

In addition to building soil, the abundant supplies of sugars build plant health. When plants have plenty of sugars they convert them to lipids (fats) therefore boosting their reserves and immunity.

Figure 1: John Kempf’s plant health pyramid (click here for the original)

Improved immunity increases as the plant’s health grows in four levels as outlined in figure 1.

1. Immunity from soil borne fungi pathogens
2. Immunity from insects with simple digestive systems, such as corn ear worm, aphids, leaf hoppers, thrips
3. Airborne fungal pathogens, such as powdery mildew
4. The entire beetle family and nematodes.

How do you achieve increased photosynthetic rates?

John Kempf recommends foliar sprays of magnesium, manganese, nitrogen and iron.

	kgs/ha		grams/m2
	min	max	min	max
Nitrogen	1.1	11	0.11	1.1
Magnesium	0.56	2.24	0.056	0.224
Manganese	1.1	2.2	0.11	0.22
Iron	1.1	2.2	0.11	0.22

Table 2: foliar application rates (from the University of Delaware)

Foliar application is tricky. The iron and magnesium have to be chelated and the minerals used should not reduce. If you are serious about trying this, I suggest contacting John’s company, Advancing Eco Agriculture.

I am trialing foliar sprays in my home garden. My property is quite shady in the winter, so I hope that enhancing photosynthesis will increase sugars in winter fruits and help to reduce the pest and disease burden further.

Here is one of John’s many videos – this one is long, but a good place to start.