You’ve seen me conduct taste tests and brix tests of field trial crops,
but so far I haven’t shared yield results in a video.
Though we still have more tomatoes and peppers to harvest,
I thought I’d let you know where things stand now in hopes of beginning to answer the question
“do rock dust and biochar increase crop yields?”.
All growing season, I’ve been weighing all of the crops harvested from our field trial beds.
That includes crops from our rock dust, biochar, and control groups.
Each group was planted in a 4 x 4 raised bed that was filled with the same blend of compost and worm castings.
The rock dust bed was amended with 16 pounds of Azomite,
the biochar bed was amended with 8 pounds of charged biochar,
and the control group received no additional amendments.
The growing season got off to a great start, with some of the largest collard greens we’ve ever grown.
We planted 2 collards in each group and they grew like crazy until they they succumbed to soft rot bacteria in July.
This is a challenge we’ve faced in our garden from the very beginning.
I was curious to see if rock dust might offer some protection from soft rot,
but unfortunately plants from all groups were equally affected and all of them were lost.
Despite the early loss of our collards, we still managed to get some pretty good yields.
The rock dust group had the highest yield with 2,642.2 grams.
The control group came in a close second with 2,253.8 grams,
and the biochar group came in last with 1,913.6 grams.
Next, in late July, we harvested mangel beets.
I know these would have gotten larger if left in the ground,
but I wanted to harvest them before the roots became woody.
With 3 beets grown in each group, once again the rock dust group had the highest yield with 827.8 grams,
including both the root and the leaves.
The biochar group came in a very close second with 825 grams,
and the control group had the lowest yield with only 320.3 grams.
So, after harvesting collards and beets, the rock dust group had the highest yield,
but that was about to change as the numbers for the kale and tomato harvests came in.
The control group’s kale harvest was strong enough to move the control group from lowest total yield to highest.
With 3 dinosaur kale plants in each group, the control had by far the highest yield at 5,352.4 grams.
The rock dust group came in a distant second with 2,817.9 grams,
and the biochar group was last with 2,704.5 grams.
The rock dust group’s descent in the rankings continued with the tomato harvest.
The biochar group, from early on in the trials, had the healthiest plants.
Here you can see what the plants look like today.
The rock dust and control group plants have been set back by blight and have few tomatoes left.
The biochar plants, on the other hand, are less affected by blight and are still loaded with tomatoes.
Though there are more tomatoes to harvest, let’s take a look at where things stand now.
With 4 tomato plants in each group, the biochar group has the highest yield with 8,592.7 grams.
The control group has the second highest with 7,277.3 grams,
and the rock dust group is a distant third with only 3,868.3 grams.
That’s a mere 45% of the biochar group’s yield,
and only 53.5% of the control group’s yield.
The strong showing from the biochar group moved it to second place in total yield,
while the control group’s respectable tomato yield kept it in first place,
and the rock dust group dropped to a distant third.
Though our field trial pepper harvest has been almost too meager to mention,
I’ll include the results here for the sake of full disclosure.
The plants spent a good part of the summer in the shade of our collards and kale and just didn’t get enough sun.
Nevertheless, the control and biochar groups have produced healthy ripe peppers,
but the rock dust group has not.
So far, the only rock dust peppers to ripen looked like this.
All other peppers in the entire garden have been perfectly healthy.
So, with one poblano pepper plant in each group, the rock dust pepper yield is 0,
and the control and biochar yields are tied at 96.4 grams.
This leaves the control group with the highest yield so far at 15,300.2 grams.
So, does rock dust increase crop yields?
Clearly the results from the first year of our field trial do not support this.
Though the rock dust group had the highest collard and mangel beet yields,
its kale and tomato yields are much lower than those of the control group.
And its total yield is only 66% of the control group’s yield.
And what about biochar?
At the moment, the biochar group also has a total yield that is lower than that of the control group.
However, with many more tomatoes left to harvest, it could end the season with the highest total yield.
If it does, however, it will be entirely on the strength of its tomato harvest,
as its collard and kale harvests were the lowest of the three groups and well below the control.
So, on balance, even if the biochar group edges out the control by the end of the season,
I’d still prefer the more balanced yield produced by the control group.
So, at this point, in the first year of the trials,
the results don’t support the claim that rock dust and biochar increase crop yields.
In addition to bringing you the final results for the season next month,
we plan to continue the trials into a second and third year to determine if rock dust and biochar produce better yields over time.
In addition, Stephen Legaree, who is conducting field trials following the same protocols,
is having his field trial soil professionally analyzed to determine the impact of rock dust and biochar on soil pH and nutrient levels.
Well, that's all for now.
Thank you very much for watching,
and until next time remember
you can change the world one yard at a time.