Saturday, December 14, 2013

What my garden told me: results of the 2013 garden dialogue


Back in May I posted about using the scientific method to conduct a dialogue with my garden in my effort to learn to work more skillfully with Nature’s patterns. While I want to grow a lot of food in a small space (and perhaps inspire some of you to do the same thing), I also want to leave that small space better than I found it. In order to do that, I have been conducting an informal scientific dialogue with my garden for the past 15 years. In the linked post I discussed how I use the scientific method to help me become a better gardener as well as the particular questions I asked my garden to answer this year. Now that most of the harvest is in, it’s time to find out what my garden told me.

In early 2013 I had learned about soil re-mineralization and its beneficial effects on gardening from Steve Solomon’s 2013 book The Intelligent Gardener: Growing Nutrient-Dense Food. The result was that the major question I asked my garden to answer this year is, what effect would proper soil mineralization have on the yields that I am able to obtain? I wanted to know the answer to this question because I am trying to grow a larger fraction of the vegetables that Mike and I eat, and some evidence suggested that lack of a properly balanced soil mineral base might be one issue that is keeping the yields I measure lower than what appears to be possible.

To help answer this question, I had a soil test done by the laboratory Steve Solomon recommended early in the gardening season and used the process in his book to develop a complete organic fertilizer tailored to remedy the mineral deficiencies in my garden soil that the soil test revealed were present, as I discussed in this post. Then I formulated a set of questions for the garden to answer in 2013, in the form of hypotheses that I thought were reasonable to expect from a more appropriately mineralized soil. The hypotheses were:

            Yield, defined as pounds harvested per 100 square feet, should increase for those varieties I grew in 2013 that I have also grown in past years, or at least not decrease.
            Those minerals that were in excess in my soil at the start of the gardening season should show a reduction in excess, and those minerals that were deficient should show a reduction in deficiency, by the end of the growing season.
            Varieties that I have grown in past years might have improved flavor and/or improved pest and/or disease resistance this year.

Besides these questions, I also grew several new varieties of vegetables to see if the new varieties offered any improvements versus the ones I have grown in the past.

Now that most of the rest of the harvest is finished and the 2014 seed catalogs are hitting my mailbox, it’s time to finish the analysis so that I can decide on the questions I’d like answered in 2014. Because some of you might be interested in the data (not to mention checking to see if my analysis is correct), I’m reporting it below. But many of you just want to know the conclusion. So for you, a summary of what my garden told me:

Yields were affected by many different factors, but in the few cases where the effect of soil re-mineralization could be clearly discerned, it was positive.
Taste was mostly not affected, but a few varieties seemed to taste better. Pest and disease pressures were reduced compared to previous years.
The effect of soil re-mineralization on post-season mineral levels is unclear and will require a lot of thought to determine what the soil told me and how to respond.

This year’s results were sufficiently positive that I’ll re-balance the soil minerals next year and see what my garden tells me as a result. No doubt I’ll ask other questions of my garden in 2014. Once I’ve formulated them, I’ll put up a post or two on what my garden and I will be discussing in 2014.
___________________________

Now for those of you who want to see all the data and my analysis of it, and for those of you who might be considering if you want to ask your gardens some questions in 2014 or make use of my results in your gardens, keep right on reading. It’ll be a long post so you might want to have your favorite long-post-reading beverage at hand.

While you read the following, keep in mind these different aspects of the art of scientific dialogue:
knowing what questions you want to ask;
knowing how to set up the dialogue so the garden gives you the answers to the questions you asked rather than to some other questions you didn’t realize you asked till the end of the season; and
figuring out what questions you, the garden, and the larger environment asked that you weren’t aware of or could not have known at the start, and how those questions affected your ability to answer the questions you wanted to ask.

Because I’m working with a living system that is inherently powerful and unpredictable and that is connected to a far more powerful and unpredictable environment, I have to accept that the garden and the environment will ask and answer some questions of their own which may hinder how well some or all of my questions can be answered. Among those questions this year were the effect of a hot, dry fall on the fall lettuce, which prevented my obtaining an answer to the question of which of the lettuce varieties I tried to grow did best in the fall garden.

As I expected, I did not ask the question about yields as skillfully as I could have because I allowed too many other controllable aspects of gardening to vary. Among those, I did not include controls (varieties I’ve grown in the past) for some of the crops that I grew, and I did not plant some crops at the same spacing as I did in the year in which I had the highest yield. Since not all varieties perform the same even when everything else is held constant, not including a control often prevented me from determining if the yield in 2013 increased for that crop. Similarly, since yields depend on crop spacing, in those cases where I changed spacing for a control variety I could not determine if the yield increased in 2013. Such is life. Since I didn’t decide to ask the question about the effect of soil re-mineralization till I had already planned out the garden, purchased seeds, and started some of the plants, I knew that I didn’t design my garden trials as well as I could have to obtain the answers I wanted. But I still grew lots of food and enjoyed myself and learned a lot from my garden. And as they say, there is always next year.

Back to learning what my garden told me. I’ll address the three big questions I asked it in turn.

Question #1: did soil re-mineralization result in increased yields?

The best way to answer that question would be for everything else – weather, planting dates, crop varieties and spacing, added compost amount and composition, and so forth – to be exactly as it was in previous years, with only the soil fertilization added to each bed changing. The weather varies a lot from year to year and that inevitably affects how well I can answer any gardening question. In addition, I have changed crop varieties, spacing, and planting dates for some of the crops that I have grown over the years and changed how much compost is added to each bed, as well as other (sometimes unintended) changes. In order to disentangle effects due to re-mineralization from effects that might be due to some other change, I’ll start with a table of the previous highest-yielding varieties of various crops along with the varieties that I grew this year. I’ll include the recommended spacing from the 8th edition of the book How to Grow More Vegetables by John Jeavons, the spacing and planting date for the year in which I got the best yield previous to 2013, and the 2013 spacing and planting date.

Table 1. Planting information for highest yielding crop varieties and varieties planted in 2013.
Crop
Variety
HTGMV spacing, inches
Past spacing, inches
Past planting date
2013 spacing, inches
2013 planting date
Dry bush bean
Midnight Black Turtle
6
In-row 6, between-row 6
5/18/09


Dry bush bean
Beefy Resilient Grex (F4)
6


3 seeds planted in each spot; in-row 12, between-row 12
6/12
Beet
Cylindra
4
In-row 4, between-row 4
4/15/12
In-row 6, between-row 6
5/17
Beet
Sugar
7
In-row 6, between-row 6
5/23/11
In-row variable, between-row 12
5/17
Bok choy
Prize Choy
Not given
12
Sown 2/28/10, TP 4/24
12
Sown 2/15, TP 5/13
Broccoli
Green Goliath
15
15
Sown 2/1/06, TP 4/14


Broccoli
Nutri-Bud
15
15
Sown 2/7/12, TP 4/19
15
Sown 2/15, TP 5/11
Cabbage
Early Jersey Wakefield
15
15
Sown 2/1/06, TP 4/14
15
Sown 2/15, TP 5/11
Cabbage
Golden Acre
18


18
Sown 2/15, TP 5/11
Carrot
Danvers 126
3
In-row 4, between-row 4
4/15/12
In-row variable, between-row 6
5/17
Corn, flint
Cascade Ruby-Gold
15


In-row 12, between-row 12
6/24, 6/27, 6/28
Corn, pop
Unknown yellow
15
In-row 12, between-row 24, 3 to 4 seeds per spot
6/21/09


Eggplant
White (store-bought)
18
In-row 12, between-row 12
Planted 5/11/12


Eggplant
Black Beauty
18


In-row 12, between-row 12
Sown 3/13, TP 5/22
Eggplant
White Beauty
18


In-row 12, between-row 12
Sown 3/13, TP 5/21, 5/22
Garlic
Inchelium Red
4
4
Planted 11/16/99
In-row 6, between-row 6
Planted 11/10/12
Leek
Giant Musselburg
6
6
Sown 2/1/06, TP 4/14/06


Leek
Bleu de Solaize
6
6
Sown 2/3/12, TP 3/29
In-row 6, between-row 12
Sown 1/22, TP 4/24
Lettuce
Anuenue
12
9
Sown 3/7/11, TP 5/7
9
Sown 3/13, TP 5/13
Lettuce
Bronze Arrow
12
12
Sown 3/7/11, TP 5/7
12
Sown 3/13, TP 5/13
Lettuce
Pirat
9
9
Sown 2/28/10, TP 4/23
9
Sown 3/13, TP 5/13
Onion, multiplier
Potato
Not given
6
Planted 11/26/05
8
Planted 11/10/12
Onion, bulb
Dakota Tears (yellow)
4
In row 6, between-row 6
Sown 2/28/10, TP 4/8
In-row 6, between-row 12
Sown 1/22, TP 4/24
Onion, bulb
Rossa di Milano (red)
4
6
Sown 2/3/12, TP 3/28
In-row 6, between-row 12
Sown 1/22, TP 4/24
Pea, shell
Little Marvel
3
In-row 6, between-row 6
Sown 4/3/12
In-row 6, between-row 6
Sown 4/5
Pea, snow
Blizzard
3
In-row 6, between-row 6
Sown 4/3/12


Pea, snow
Oregon Giant
3


In-row 6, between-row 6
Sown 4/5
Peanut
Tennessee Red Valencia
9


In-row 12, between-row 24, 3 to 4 seeds per spot
Sown 6/3
Pepper, sweet
Carolina Wonder
12


In-row 12, between-row 12
Sown 3/13, TP 5/21
Pepper, sweet
Italian Frying
12
12
Sown 1/27/07, TP 4/30
In-row 12, between-row 12
Sown 3/13, TP 5/21
Pepper, sweet
World Beater
12
In-row 12, between-row 12
Sown 2/4/08, TP 4/30
In-row 12, between-row 12
Sown 3/13, TP 5/21
Potato
Elba
9


In-row 12, between-row 24
Planted 5/1
Potato
German Butterball
9
In-row 12, between-row 24
Planted 4/18/11
In-row 12, between-row 24
Planted 4/30
Potato
Rose Gold
9
9
Planted 4/7/06


Radish, winter
Black Spanish Round
Not given
In-row variable, between-row 12
Sown 8/13/08
In-row variable, between-row 12
Sown 8/16
Radish, winter
Red Meat
Not given
In-row 6, between-row 6
Sown 7/20/09
In row variable, between-row 12
Sown 8/16
Squash, summer
Benning’s Green Tint
15


In-row 12, between-row 48
Sown 7/12
Squash, winter
Lady Godiva
18
In-row 48, between-row 48
Sown 7/6/09


Squash, winter
Sweet Meat – Oregon Homestead
18


In-row 24, between-row 48
Sown 7/3
Squash, winter
Waltham Butternut
18
In-row 48, between-row 48
Sown 7/2/11
In-row 24, between-row 48
Sown 7/11
Squash, zucchini
Dark Green
18
In-row 36, between-row 48
Sown 6/20/09


Squash, zucchini
Costata Romanesca
18
In-row 48, between-row 48
Sown 5/23/12
In-row 12, between-row 48
Sown 7/12
Sweet potato
Ivis White Cream
9
In-row 15, between-row 24
Planted 6/21/08


Sweet potato
O’Henry
9


In-row 12, between-row 48
Planted 5/29
Tomato
Arkansas Traveler
18
In-row 12, between-row 12
Sown 2/17/12, TP 5/12
In-row 12, between-row 12
Sown 3/13, TP 5/22
Tomato
Hungarian Italian Paste
18
In-row 12, between-row 12
Sown 2/17/12, TP 5/11
In-row 12, between-row 12
Sown 3/13, TP 5/21
Turnip
Purple Top White Globe
4
In-row variable, between-row 6
Sown 8/16/08
In-row variable, between-row 12
Sown 8/16

In the table above and in the rest of the post, HTGMV refers to the 8th edition of How to Grow More Vegetables. HTGMV suggests planting on a triangular grid to maximize overlap of the crowns of the plants at maturity. The HTGMV column gives the spacing, in inches, to use for each crop according to the Master Charts in HTGMV. The Master Charts do not differentiate potato onions (a perennial onion that splits into smaller bulbs, grown by planting single bulbs in mid to late fall) from bulb onions, thus there is no entry in the HTGMV column for potato onions. Winter radishes are not differentiated from salad radishes and bok choy is not shown in the Master Charts so these also lack entries in the HTGMV column.

Table 1 shows that I now plant most varieties at a different spacing than HTGMV suggests and often in rows, sometimes short rows across the width of the bed (my beds are all 4 feet wide by 25 feet long), sometimes long rows down the length of the bed. Note how much farther apart I plant many varieties now than I did in the year when I got the highest yield, and how much some of the sowing and planting dates have changed. I’ll talk more about that when I discuss the yield results shown in Table 2 below.

Table 2. Possible yields from HTGMV, best previous yields, and 2013 yields. All yields are given in pounds per 100 square feet.  The HTGMV column shows possible yields using the HTGMV method of gardening, based on Ecology Action’s research. They suggest beginners use the low number for planning and comparison purposes, good gardeners the middle number, and excellent gardeners with favorable climates and soil the high number. The next two columns are the best previous yield I have obtained with a variety and the yield I obtained for that variety in 2013. An asterisk shows harvests that have been completed but not yet weighed, thus yield data is currently unavailable.
Crop
Variety
HTGMV yield
Previous best yield
2013 yield
Dry bush bean
Midnight Black Turtle
4 / 10 / 24
12

Dry bush bean
Beefy Resilient Grex (F4)
4 / 10 / 24

*
Beet
Cylindra
110 / 220 / 540
34
104
Beet
Sugar
91 / 182 / 364
141
179
Bok choy
Prize Choy
Not given
182
121
Broccoli
Green Goliath
26 / 39 / 53
76

Broccoli
Nutri-Bud
26 / 39 / 53
12
40
Cabbage
Early Jersey Wakefield
96 / 191 / 383
167
77
Cabbage
Golden Acre
96 / 191 / 383

156
Carrot
Danvers 126
100 / 150 / 400+
122
187
Corn, flint
Cascade Ruby-Gold
11 / 17 / 23+

*
Corn, pop
Unknown yellow
11 / 17 / 23+
16

Eggplant
White (commercial strain)
54 / 108 / 163
151

Eggplant
Black Beauty
54 / 108 / 163

50
Eggplant
White Beauty
54 / 108 / 163

57
Garlic
Inchelium Red
60 / 120 / 240+
39
12
Leek
Giant Musselburg
240 / 480 / 960
107

Leek
Bleu de Solaize
240 / 480 / 960
96
34
Lettuce
Anuenue
75 / 150 / 300
90
113
Lettuce
Bronze Arrow
75 / 150 / 300
89
52
Lettuce
Pirat
75 / 150 / 300
104
68
Onion, multiplier
Potato
Not given
78
33
Onion, bulb
Dakota Tears (yellow)
100 / 200 / 540
44
18
Onion, bulb
Rossa di Milano (red)
100 / 200 / 540
54
34
Pea, shell
Little Marvel
25 / 53 / 106
17
10
Pea, snow
Blizzard
25 / 53 / 106
17

Pea, snow
Oregon Giant
25 / 53 / 106

5
Peanut
Tennessee Red Valencia
4 / 10 / 24

5
Pepper, sweet
Carolina Wonder
68 / 136 / 204

48
Pepper, sweet
Italian Frying
68 / 136 / 204
126
99
Pepper, sweet
World Beater
68 / 136 / 204
83
54
Potato
Elba
100 / 200 / 780

75
Potato
German Butterball
100 / 200 / 780
35
38
Potato
Rose Gold
100 / 200 / 780
111

Radish, winter
Black Spanish Round
Not given
123
15
Radish, winter
Red Meat
Not given
120
32
Squash, summer
Benning’s Green Tint
75 / 150 / 307

39
Squash, winter
Lady Godiva
50 / 100 / 350
87

Squash, winter
Sweet Meat – Oregon Homestead
50 / 100 / 350

71
Squash, winter
Waltham Butternut
50 / 100 / 350
47
22
Squash, zucchini
Dark Green
160 / 319 / 478+
44

Squash, zucchini
Costata Romanesca
160 / 319 / 478+
36
313
Sweet potato
Ivis White Cream
82 / 164 / 492
74

Sweet potato
O’Henry
82 / 164 / 492

64
Tomato
Arkansas Traveler
100 / 194 / 418
647
500
Tomato
Hungarian Italian Paste
100 / 194 / 418
948
458
Turnip
Purple Top White Globe
100 / 200 / 360
101
9

Knowing what the garden told me about yield for each crop I grew, I have to translate what it said into answers to the questions I asked as well as the questions I didn’t realize I was asking and that the garden and environment asked. To do that I need to discuss a number of factors that can affect yield in addition to soil re-mineralization. Then I’ll look at each crop in turn to tease out the different effects.

Crop Spacing. There is a complex relationship between spacing and yield. Crops that are planted too close together compete for nutrients and thus don’t yield as well on a weight per unit area basis. Increasing the spacing increases yields, but only up to a point. Once the spacing gets so large that some of the soil minerals go un-utilized by the crop, yield begins to decrease. HTGMV’s suggested spacing is supposed to be that for which yield is highest for each crop. Table 1 indicates that I have tended to use wider spacing than HTGMV suggests for many crops. This in turn suggests that my yields will tend to be low for those crops.

Planting date. Crops need to be planted at the time when the weather patterns are favorable for their growth and development. In general, that means that crops that like cool spring weather should be planted in late March or April here, while plants that need many weeks of warm to hot weather should be planted in May or June and crops that need cool fall weather should be planted from June through August depending on their maturity date. Examination of Table 1 suggests that in some cases I planted too late in 2013, based on both generally accepted planting dates for this area and the planting date I used in the year of highest yields.

Crop variety. Gardeners and farmers find that some varieties are better adapted for their conditions than are others. In general, the better adapted a variety is, the higher yield it can give, other factors being constant. In other cases certain varieties are larger or smaller than other varieties of a particular crop wherever they are grown. A larger variety planted at the same time and at the same distance might be expected to yield more than a smaller variety, unless excess competition becomes a factor.

Shading. Some of the crops I grew, notably the peppers and eggplants, were shaded by more-vigorous crops grown next to them. Shaded crops will not yield as much as their less shaded or un-shaded counterparts.

Nutrient demand. Some crops do not need as much nutrition as do others. Steve Solomon includes a table of low, medium, and high demand vegetables on page 16 of his book Gardening When It Counts. All else being equal, proper soil mineral balance might be expected to have the biggest positive effect on high-demand veggies and the least on low-demand veggies.

Weather conditions. Excessive heat, cold, rain, or drought compared to what is experienced in an average season can reduce the yield of crops susceptible to their effects. In 2013 spring proved to be cool and wet. June and July tended cool and wet while August through October were warmer and dry. Late August through September was excessively warm and dry, with negative effects on fall crops.

With that in mind I will look at each crop to consider how the various factors may have affected the yield I obtained in 2013 compared to past years.

Beets. The yield I obtained is somewhat higher in 2013 than in 2011 while I harvested the same number of sugar beets per unit area this year as 2011 according to my records.  That suggests that soil re-mineralization may have had a mild positive effect on this low-demand crop.

For ‘Cylindra’ beets, even though I used row planting, I got about the same number of beets as I would have if I had used HTGMV’s triangular planting pattern and suggested spacing. Planting in rows is much easier so I plan to continue to do so. The yield of ‘Cylindra’ may have benefitted most from growing the beets more thickly as I harvested about three times as many beets this year per unit of space, and the yield increased by a factor of three as well.

Bok choy. Table 1 shows that I planted bok choy about three weeks later in 2013 than in the previous best year. Because the St. Louis area has very short springs followed by hot summers, spring-planted crops have little leeway in planting date to obtain the best yield. The reduction of yield this year may be due to late planting and perhaps stunted growth resulting from the three months between seed sowing and transplanting versus the two months generally recommended and done in the best-yielding year.

Broccoli. Another crop I planted late and after too long in the seedling stage, which may have lowered yield in 2013. However, varietal differences in yield cannot be ruled out as a possible factor in the results in Table 2. To learn this I would need to grow both broccolis the same year with all else held constant. Note that the yield of ‘Nutri-Bud’ broccoli increased by a factor of 3 in 2013 versus 2012, despite being planted late in 2013 versus at the correct time in 2012. Since broccoli is a high demand crop that would be expected to show a significant increase in yield with proper fertilization, this seems to be evidence of the beneficial effect of soil re-mineralization on its yield.

Cabbage. The 2013 yield of ‘Early Jersey Wakefield’ cabbage is strong evidence of the deleterious effect of late planting, as I have planted this variety at the same distance for many years. Interestingly, ‘Golden Acre’ cabbage had double the yield of ‘Early Jersey Wakefield’ despite the planting distance being larger and other factors the same. I will grow both cabbages again next year.

Carrot. I harvested about twice the number of carrots per unit area in 2013 as in 2012, so the increase in yield in 2013 may be attributable to that rather than soil re-mineralization, as carrots are a low-demand vegetable.

Eggplant. Eggplants are a medium-demand vegetable so one might expect that they would have yielded better in 2013 than in past years. Comparing 2013’s two varieties to the ‘White’ eggplant of 2012, this year’s plants underperformed. However, the ‘White’ eggplant of Table 1 was a purchased plant, possibly a higher-yielding variety, as opposed to the two open-pollinated varieties I grew from seed in 2013. The purchased eggplant was also much larger than my homegrown seedlings, which may have allowed it to start yielding earlier. Still, of the several other open-pollinated varieties of eggplants I have grown in the past, none yielded as well as this year’s two varieties. Thus soil re-mineralization may have had some benefit on yield, especially considering that ‘Black Beauty’ has a reputation for low yields.

Since our hot, long summers should favor eggplants I have wondered why my eggplants have not performed closer to the mid-range yield listed in HTGMV. A close perusal of the Master Charts suggests that I may have been overcrowding them. The suggested spacing in HTGMV amounts to about two square feet of space per plant while I have been allotting them one square foot of space per plant. That fact, and the fact that the 2013 eggplants were crowded up against much taller tomatoes and may have suffered from excess shading and competition from them, may explain the rather low yields this year.  A good test of this possibility would be to plant some of the 2014 plants at one plant per square foot and others at one plant per two square feet and monitor the yield at each spacing. I will also ensure they are not shaded by taller plants.

Garlic, leeks, and onions. The beds with the garlic, leeks, and onions were planted before the soil test results arrived, thus they did not receive the mix designed to re-mineralize the soil. In addition, all of these vegetables were planted at a larger planting distance than in the years with the highest yields resulting in fewer plants per unit area, and the bulb onions were planted late in 2013. Thus I expected none of these to match the highest past yields, and none of them did. I planted next year’s garlic and potato onion crops at a 6 inch spacing, hypothesizing that the combination of soil re-mineralization and a closer spacing will result in higher yields in 2014 compared to 2013.

Lettuces. ‘Anuenue’ yielded slightly better in 2013 than its previous best year, ‘Bronze Arrow’ and ‘Pirat’ worse. ‘Anuenue’ is a later-maturing, long-standing lettuce developed for hot climates. That may be why it did better than the other two in a year in which they were planted later than is recommended for Missouri.

Peas and peanuts. The peas and peanuts were planted in a bed that was prepared for planting before the soil test results arrived, thus it did not receive the soil re-mineralization mix. In addition, the peas showed poor germination, perhaps because I did not pre-sprout them before planting. (I did not pre-sprout in 2012 either but that was a much warmer spring than 2013, reducing rotting due to cold soil.) Also, the peas sprawled too much due to my not supporting them. Thus the low yield in 2013 was not a surprise. I was gratified that the peanuts yielded as well as they did since it was the first year I grew them. I will grow them again.

Peppers. I expected pepper yields to be higher than they were because peppers are a high demand crop that would likely benefit from soil re-mineralization. However, the ‘Carolina Wonder’ and ‘World Beater’ plants suffered from considerable shading by taller crops on either side of them, while the ‘Italian Frying’ plants were less shaded. Its lower yield than in the best previous year may be partially attributable to being planted three weeks later and partially attributable to the shading it experienced. See below, however, for a different and noticeably positive effect of soil re-mineralization on the pepper crop.

Potatoes. The spacing used for the highest-yielding potato crop is equivalent to that recommended in HTGMV and is far closer than the spacing I use now, thus I did not expect to match the best past yield even if the plants responded positively to re-mineralization. I use the much wider spacing because of the sprawling nature of potato plants: it keeps them from shading nearby crops, and I can hill up the widely spaced plants. The result of note this year was how much better the yield of ‘Elba’ was than ‘German Butterball’. ‘German Butterball’ yielded 7.6 times the planted weight while ‘Elba’ yielded 15 times the planted weight! It also produced a few large potatoes per plant that were easy to harvest and it tasted delicious. I’ll be planting ‘Elba’ from now on.

Winter radishes and turnips. These seem to have suffered from excessively hot fall conditions and from my not thinning and weeding them in a timely manner. I planted them in the area where cabbage and broccoli had grown without adding more fertilizer, so there may have not been adequate nutrition left for them to fulfill their potential.

Squash. The low yield of ‘Bennings Green Tint’ doesn’t reveal that this was the first year after a number of years of trying that I got any of this squash at all. The very much higher yield of zucchini in 2013 is likely due to a combination of soil re-mineralization (it is a medium demand crop) and a variety well suited to my conditions. At first glance the planting date for winter squash appears very late for this area and suggests reduced yields versus HTGMV’s possible yields, but past experience has shown that earlier planting results in much less squash due to squash bug attacks killing the vines. However, I may try earlier planting again since other pest problems seemed less this year, a point covered more below. The ‘Sweet Meat’ squash yielded better in 2013, but the later planting for ‘Butternut’ may have had a negative effect on its yield.

Sweet potatoes. I planted the equivalent of 40 plants per 100 square feet of ‘Ivis White Cream’ in 2008 while I planted the equivalent of 25 plants per 100 square feet of ‘O’Henry’ this year, yet the yield of ‘O’Henry’ was not much below that of ‘Ivis White Cream’. Given this, ‘O’Henry’ made a better showing. I do not know if this is because ‘O’Henry’ was planted about a month earlier, because the larger spacing meant it had less competition, because it is a higher-yielding variety, or because of the soil re-mineralization (sweet potatoes are a medium demand crop).  I prefer to plant at the 48-inch between-row distance because it is easier to dig out the crop. But I might alter the plant spacing across the bed in 2014 and keep track of the yields of the different parts of the bed to get a better idea of the optimum spacing for ‘O’Henry’.

Tomatoes. While I did not see much difference in yield for ‘Arkansas Traveler’ from 2012 to 2013, yields were much lower in the six preceding years. I had trouble with disease affecting the plants in the wet years of 2008-2011 while 2012 was very dry, which I suspect greatly reduced disease problems that year and thus boosted yield. Compared to 2012, 2013 was a wet year so I was pleased that this tomato yielded so well, close to its best. ‘Hungarian Italian Paste’ yielded about twice as much in 2012 but it also yielded less in the six years preceding 2012 than it did in 2013.

Overall, therefore, where the effect of soil re-mineralization could be separated from other changes from year to year, the effect seems to be positive. However, I’ll need to pay more attention to plant spacing, planting dates, and varieties grown in future years to better answer this question.

            Question #3: effect of re-mineralization on flavor or pest or disease resistance

The most noticeable change in flavor was in the ‘Early Jersey Wakefield’ cabbage. My notes say that this year’s crop was very sweet with none of the off-flavor that cabbage sometimes gets. I cannot attribute that entirely to soil re-mineralization because the weather was cooler and wetter than usual while it was growing, but a balanced soil may have contributed. ‘Anuenue’ lettuce also had excellent flavor with no bitterness whatsoever and the heads were very dense and crispy. I wasn’t as impressed with it in previous years, but the Fedco seed catalog does list these as varietal attributes. It may be that soil re-mineralization allowed it to reach its full potential as lettuce is a medium demand crop. At any rate I will grow ‘Anuenue’ again. ‘Bronze Arrow’ lettuce also seemed less bitter this year, but ‘Pirat’ lettuce seemed more bitter and I may look for a replacement for it. Otherwise I noticed no flavor differences in those crops whose taste I know well.

While I had hypothesized that I might have less trouble with harlequin bugs and squash bugs, I did not predict that cabbage moths would be less trouble, which turned out to be the case and was most welcome. I didn’t notice any harlequin bug problems as I sometimes have with cabbage-family crops after midsummer. The squash bugs did eventually show up but by the time they did, the squash had already set fruits. I think I had some squash borers also but they did not seem to be much of a problem. Overall pests seemed to be less of a problem in 2013, which I attribute to the re-mineralized soil since I know of no other way to explain this.

Over the past few years I have been plagued with one or more diseases affecting the pepper and tomato crops. This year every single pepper plant survived the entire season! Although yields were lower than the best I’ve gotten, they were improved over those of the past few years. All of the tomato plants of the two varieties in Tables 1 and 2 also survived the season. I think this can be attributed to soil re-mineralization since the wet conditions in May and June would have promoted disease as noted in previous wet years.

            Question #2: effect of soil re-mineralization on post-season mineral levels

After receiving the post-season soil test results and comparing them to the pre-season results, and while re-reading Solomon’s The Intelligent Gardener, I realized that I need more time to ponder what the soil told me this season. It’s a complex (and fascinating!) topic that deserves a post of its own. It may be awhile before I get to that post since I will likely write the post on the questions I’m asking the garden to answer in 2014 first. But I do plan to re-balance soil minerals in 2014 since wherever I could discern its effect, it was positive.

4 comments:

  1. Hello. Fantastic work. Really interesting stuff.

    The weather can have a large impact on your yields too. It varies here quite markedly from season to season. I noticed you mentioned the impact of your warm autumn on yields. Out of interest are your seasons getting warmer? They seem to be here.

    The other thing you may want to consider is that as the years progress, you'll have a higher number and diversity of bacteria and fungi in your vegetable beds and this will assist your yields, as well as the overall pest and disease resilience. Do you purchase your compost or mulches from the same place? You never know what you'll bring onto your property. I assume you threw the minerals onto the surface of the soil, or did you dig them in?

    The other thing that comes to mind is that you may be building up larger and more diverse colonies of propagating insects and predator insects. Mineralizing the soil does make plants less attractive to pests too, which will also increase your yields through lower losses.

    You have a huge variety of vegetables. Do you save the seeds? This may improve your yields as the years go on too. I let many plants follow their own cycles and they become really hardy, plus they tell me when they are ready to grow and fruit etc.

    Crop spacing is less of an issue here as the sun is too strong. As an alternative perspective, the UV rays from the sun sterilise the top layers of soil so I try to leave no soil without plant material shading it. Shading doesn't seem to be as much of an issue here. Dunno.

    It was interesting what you were writing about the garlic. I suspect that it has lower fertility requirements than other plants. I'm part of a growing trial here (35 varieties out of a possible 80) and some of the local growers who have better soils than here are reporting problems and we are theorizing that excess fertility may be a problem. Again, dunno, the commercial growers are having problems this year too.

    Well done.

    Chris

    ReplyDelete
    Replies
    1. Hi Chris,

      Thanks for your comment! I admire your work with your garden so I am grateful for the thoughtfulness you put into your comment and the encouragement you gave me.

      Yes, I do notice our seasons are warming overall, though that can be masked by the wide variations from one year to the next that are typical of locations in the middle of large continents. I have lived here since 1984 and it is very clear to me, at least, that winter lows are considerably milder than during the first 15 years I lived here. The coldest lows in winter used to drop below 0F/-18C several times every winter and most winters the coldest low would dip to -10F/-23C or less. However, the official winter low hasn't dropped below 0F since 1999 and hasn't gotten as low as 5F in the past three winters, nor so far this winter. Spring-flowering trees like dogwood and redbud are blooming about two to three weeks earlier on average than they did when I first moved here. The average yearly total of heating degree days, a rough measure of how much heating fuel is needed, has dropped and that of cooling degree days has increased. The growing season seems to be somewhat longer as well.

      I make my own compost from garden and kitchen wastes because of the concern you mentioned. Some people in different parts of the U.S., though not here that I know of, have had gardens destroyed from purchased compost that included plants treated with a systemic herbicide that did not get broken down in the composting process. I use autumn leaves from the huge oak trees in our neighbors' yards for mulching because I know they aren't using any treatment on their lawns. I also have a pile of wood-chip mulch, used on the perennial beds, that came from one of our trees and whatever else was in the truck bed before grinding up our tree. It has proven itself good by use and was free besides.

      Up to now I have dug in the minerals up to a foot/30cm deep on the annual vegetable beds. But now I am not sure that is the best way to re-mineralize the soil. Right now I am leaning toward scratching in the minerals to only a few inches at most, perhaps just scattering them on the surface if that seems best or if I am lazy. The cottonseedmeal and compost I will just toss on the surface. I want to avoid digging even in most of the annual beds this year and move toward more cover-cropping and scattering of any amendments and compost. Certain beds, like potatoes and onions, will be dug of necessity. With rotation moving those beds each year, that may be enough digging. I hope so; I'd like to avoid as much of that work as possible.

      I do save the easy seeds and have a goal to learn to save the more-difficult or more space-consuming seeds over time. It would be fun some year to compare crops grown from seeds that I've saved to those grown from seeds of the same variety that are commercially available, to see what if any differences exist. I suspect you are right about that improving yield.

      Delete
    2. I had to break up my reply due to Blogger's character limit. Here's the rest.

      I had to look at our globe to figure out what you meant about the sun being too strong where you are. I see you must not be too far off 30 degrees south while I am at 39 degrees north, thus you get stronger sunlight than I do, plus you have more problem with loss of the ozone layer than I experience. We are supposed to put vegetable gardens where they will get at least 6 hours, preferably 8 or more hours, of full sun during the growing season. Perhaps that will change as warming continues. Maybe I won't mind the neighbor having planted that oak tree to the east of my veggie gardens after all ...

      Like you, I think garlic doesn't need that much fertility. My biggest problem with it and the potato onions is getting them through the winter without having them heave out of the ground due to freeze/thaw cycles. Mulching works for that, but I have found it is critical to remove the mulch in early March, else the developing leaves perish. And I have to be careful to weed them well and not over-water them, and remember to harvest the potato onions right when the leaves dry up.

      I see it is way too hot where you are; my sympathies, and I hope it cools off soon! Do you normally get rains during the summer or is that a dry season for you? Around here winter is drier but the growing season averages enough rain except during the hottest spells. However, the way the jet stream has been getting itself stuck in loops the last few years, unpredictability has been worse than it normally is. The loop it is stuck in now has brought us colder and drier than normal weather so far this winter.

      Delete
  2. Thanks so much for taking the time to share your garden data! I'm amazed by how detailed it is. This will be my second growing season in St. Louis city, so I'm still trying to figure out the best times to start seeds and get plants in the ground!

    ReplyDelete