Lower Farm Trials


Harvests in 2007-2012 from the dug and undug experimental beds at Lower Farm, Somerset, UK.

Background to the experiment

The four beds of 1.5×2.5m (5×8′) were created in March 2007 from old pasture on clay soil, and the first section below is a record of their total harvests over six years. Below that are tables of the harvests in 2011 and 2012. In their sixth year without any soil disturbance, the two undug beds have performed better than ever.
This experiment has now finished as I have moved from Lower Farm, and am running a new one at Homeacres.
 
Each November or December, as soon as the last harvest is taken, I spread a large wheelbarrow load of compost or manure (two inch depth or 5cm) on the two undug beds and I dig the other two, at the same time as incorporating an equal amount of compost or manure at the bottom of 15-20cm (6-8′) spits*.
 
The idea is to have two pairs of beds with the same ingredients, but in a different profile – also one of the beds has undisturbed soil, one has disturbed soil.
 
In November 2008, beds 1 and 2 (undug and dug respectively) received home made compost while beds 3 and 4 received horse manure from the neighbour’s well rotted pile.
In November 2009, beds 1 & 2 received well rotted cow manure – purchased from a neighbouring farm and checked for aminopyralids by doing a germination test – while beds 3 and 4 received home made compost. 
In November 2010, beds 1 & 2 received home made compost, beds 3 & 4 received cow manure.
In November 2011, vice versa again.

The data here is of harvests weighed, trimmed and graded to my normal standard for selling produce. I also append some comments on any problems encountered and on quality of growth. 

All beds carry a mixture of single and double crops, so there is rarely any empty space in the growing season. Plants are raised in my greenhouse in modules filled with organic multipurpose compost from West Riding Organics.

*My digging method (single dig) is to put the first spit of soil into a wheelbarrow, from a 25cm (10’) row across one end of the bed to be dug, then manure or compost is placed in this first trench before soil from making a second trench is put on top of it. The barrow of soil is used at the end to fill the final trench and the whole process takes just under two hours.

Total yields – 2007-2012

Vegetables (2007-2012) Dig (Two Beds) kg No Dig (Two Beds) kg
Beans, dwarf – 6 years 8.38 7.6
Beetroot – 6 years* 15.55 18.01
Cabbage, red/wh – 4 years 12.29 8.87
Calabrese – 1 year 1.12 0.62
Carrot – 5 years* 13.34 16.52
Celeriac – 5 years 21.18 24.42
Chard – 2 years 12.33 11.59
Endive and chicory – 5 years 16.45 19.07
Kale – 5 years 10.90 11.81
Leek – 5 years 16.68 18.47
Lettuce – 6 years 51.17 55.07
Onion – 6 years 36.06 40.07
Peas, Tall Sugar – 5 years* 41.03 40.86
Parsnip – 5 years 56.10 57.68
Potatoes, early – 5 years* 18.46 17.64
Radish – 4 years* 2.37 2.92
Salads, autumn leaves 5.71 7.36
Spinach – 5 years 23.09 29.34
Turnip, radish – 4 years 14.03 12.30
Total 376.24 400.38
Early harvests* 213.36 229.30
Late harvests 162.88 171.08

* Early harvests are beetroot, chard, lettuce, onion, peas, potatoes, radish and spinach. Late harvests are all other vegetables listed here. The last two columns show how the no dig beds start growing more quickly in spring, followed by the dug beds catching up somewhat in late summer and autumn.

2012 – Sixth Year

Comments and comparison with 2011

Experiment harvests last two years

There are differences between both dug and undug, and between 2011 and 2012: notice the lower yields in 2012 when the incessant rain had more impact on dug soil, from what I can see here and from the comments of other gardeners. Undug soil preserves its structure in wet conditions, and also can be accessed more easily as it does not damage from being walked on.

 

Harvests 2012 Dig (Two Beds) kg No Dig (Two Beds) kg
Radish 0.42 0.62
Spinach 1.72 2.87
Cabbage 2.29 1.86
Lettuce 11.61 12.06
Potato 4.31 4.67
Beetroot 2.95 3.72
Snap pea 7.26 7.72
Carrot 0.11 1.15
Onion 6.64 7.25
Endive (after pea) 2.60 2.69
French bean (after potato) 1.19 1.19
Wild rocket parsley (after onion) 0.95 1.20
Kale (after lettuce) 3.01 3.03
Celeriac 4.05 4.60
Parsnip 11.41 10.95
Late cabbage (after beetroot) 1.23 1.26
Totals by end November 61.75 66.84

 

Harvests 2011 Dig (Two Beds) kg No Dig (Two Beds) kg
Radish 0.36 0.27
Spinach 4.94 5.11
Lettuce 10.45 9.76
Carrot 1.24 2.88
Potato 6.34 4.83
Beetroot 3.08 3.78
Snap pea 10.26 10.02
Onion 9.21 10.29
Leek 4.63 5.22
French beans (after roots) 2.70 2.19
Kale (after lettuce) 4.06 4.88
Purslane, rocket, late lettuce 0.38 1.31
Chicories (after peas and beets) 2.09 1.96
Radish (after onions) 1.03 1.38
Celeriac 4.89 4.00
Parsnip 13.26 14.52
Totals by end of year 79.62 82.40

Summing up, less good weather in 2012, lower yields, most noticeably on the dug beds which have suffered most with a 28% reduction compared to a 19% reduction on the undug beds. Root vegetables all better on the undug, except for parsnip and that is a puzzle as in 2011 it was the other way around. These results are indications of the enduring validity of a no dig approach, and highlight some intriguing variations for each vegetable.

Beds were sown with parsnips and radish in late February, planted with spinach, lettuce, potato, onion, beetroot, cabbage and tall peas in mid March, with carrots sown too. Then all four beds were covered with fleece, and the three photos below show what was happening under this fleece by early April.

May 2nd

Harvests already of 1.7kg lettuce, spinach radish from Dug and 2.4kg from undug, both lettuce & radish higher yielding on latter.

Through large parts of April, early May, June and the first half of July, the area as a whole was something of a quagmire, the paths running with water on some days, thank goodness for raised beds!

June 3rd

Harvests have been steady off both dug and undug beds, and yesterday I even pulled the first  beetroot, by carefully twisting out the largest root from four of the five clumps on each bed.

The most notably different harvests have been of spinach, which is much stronger and darker on the undug bed, and of cabbage which was more hearted on the dug bed. Presumably this is related to their different rooting habits, and I have heard that brassicas use no fugal mycorhizae to grow their roots, and digging destroys many soil fungi, so this would make sense – the spinach presumably does use mycorhizae.

Look at the soil differences in these photos:

Harvests to July 4th

RADISH, April harvests of 0.42kg dug bed, 0.62kg undug bed: less slug damage to undug radish.
LETTUCE: harvests to end June of 9.06kg dug bed, 9.62kg undug bed, similar quality
SPINACH: total harvests of 1.72kg dug bed, 2.87kg undug bed, glossier leaves and less slug damage on undug bed
CABBAGE (Greyhound): harvest 31st May, 2.29kg dug bed, 1.86kg undug bed
BEETROOT: total harvests of 2.95kg dug bed and 3.72kg undug, more difference than it appeared
POTATOES: total harvests of Swift first earlies, 4.31kg dug bed and 4.67kg undug, four plants each bed, ‘earthed up’ in late May with a bucket of well rotted manure
PEAS: harvests of 1.59kg dug bed and 2.27kg undug after two picks of swollen snap peas
TOTALS SO FAR: 22.31kg dug beds, 25.63kg undug beds – a similar pattern to previous springs and I expect the dug beds to catch up through summer

July

August

This table shows harvests off both pairs of beds up to end August. I am about to start harvesting french beans and kale, with more endive and salad to follow, then parsnip and celeriac in late autumn.

Harvests 2012 Dig (Two Beds) kg No Dig (Two Beds) kg
Radish 0.42 0.62
Spinach 1.72 2.87
Cabbage 2.29 1.86
Lettuce 11.61 12.06
Potato 4.31 4.67
Beetroot 2.95 3.72
Snap pea 7.26 7.72
Carrot 0.11 1.15
Onion 6.64 7.25
Endive 0.46 0.28
Totals Late August 37.77 42.20

Growth continues to look healthier on the undug beds, assess it for yourself in these four photos, all taken on 29th August.

The celeriac were harvested late October and although looking nice, they turned out to have many slug holes with woodlice too. Whereas the same plants grown in beds without wooden sides had almost no damage, so that is an interesting result too!

2011 – Fifth Year

 

Through April and May growth was steady in above average temperatures, and I watered all the beds about once a week. Lettuce and spinach are being picked weekly, potatoes and beetroot are almost ready and peas are flowering. Carrots have germinated better on the undug bed, I think there were more slugs on the smooth clay surface of the dug bed.

By September 2011 there are many second and even third plantings, such as Redbor kale after lettuce on beds 1 & 2, where french beans have grown after potatoes and carrots, and after them we planted winter purslane and spinach. It has been interesting to watch the growth of salads planted in September because of the much greater slug damage on both dug beds, compared to same plants on the undug beds. It looks as though slugs are more comfortable slithering over a surface of clay soil (where compost has been incorporated) as opposed to a surface of crumbly and less smooth compost:

On the other hand the dug bed’s celeriac is bigger and the chicories are showing more heart! Whereas the winter radish in front has grown more strongly on the undug bed. 

Harvests 2011

Final totals, more detail at bottom:

Beds 1 & 2

  Dug kg Undug kg
Parsnip (2 rows of 5ft) 13.26 14.52
Radish 0.36 0.27
Spinach 4.94 5.11
Lettuce, 18 plants 10.45 9.76
Carrot 1.24 2.88
Potato, 4 plants 6.34 4.83
French beans (after roots) 2.70 2.19
Kale (after lettuce) 4.06 4.88
Purslane (after beans) 0.03 0.59
Totals to date 43.38 45.03

 

Beds 3 & 4

  Dug kg Undug kg
Sugar Pea 10.26 10.02
Beetroot 3.08 3.78
Leek 4.63 5.22
Celeriac 4.89 4.00
Onion* 9.91 10.29
Chicories (after pea, beets) 2.09 1.96
Radish (after onion) 1.03 1.38
Rocket (late lettuce after leeks) 0.35 0.72
Total to date 36.24 37.37

 *no mildew this year, the cleanest bulbs since 2003, after I stopped growing overwintering Japanese onions in 2009

Observations on 2011 Harvest Differences

NB all weights are of saleable leaves, roots, pods, after trimming damaged stems etc

Parsnips, higher quality with less canker and forking on undug bed
Radish grew better on dug bed, for the first time in five years
Spinach was earlier on the undug bed then the dug spinach almost caught up
Lettuce was similar, dug lost plants to slugs and replacements were higher yielding variety!
Carrot seedlings on dug bed were more eaten by slugs
Potatoes were more numerous under plants on dug bed
Kale on undug bed had thicker stems and darker, glowing leaf colour (stems weighed post harvest, 1.73kg dug and 2.00kg undug
Beetroot and leeks grew bigger on undug bed after getting away more quickly in spring
Celeriac caught up on dug bed and were much larger but also with more slug holes and woodlice
Onions were similar but undug onions started growing faster in April and May
Chicories hearted more strongly on dug bed
Rocket, 3 plants on each bed, then two dug rocket were eaten by slugs
Lambs lettuce was noticeably larger and glossier on undug bed
Winter purslane grew so much better on undug bed, was slug eaten on dug bed, spinach too

2010 – Fourth Year

Harvest

All beds were fleeced 22 March – 20 April.

Beds 1 & 2

  Dig kg No Dig kg
Onion 4.42 6.61
Beetroot 1.37 1.54
Pea 7.00 8.07
Celeriac (4 per bed) 5.20 5.22
Leek, multi-sown modules 2.76 3.41
Leaf radish (after onion) 1.17 1.09
Dwaft French bean (after beats) 0.96 1.51
Chicory P. Rossa (after peas) 1.93 1.75
Totals 24.81 29.20

Beds 3 & 4

  Dig kg No Dig kg
Parsnip 15.15 16.52
Radish 0.41 0.63
Lettuce 8.35 7.97
Spinach 6.92 9.47
Early Potato 3.56 2.36
Kale (after lettuce) 3.95 4.02
Dwaft French Bean (after spinach) 1.42 1.20
Endive (after potato) 1.97 2.37
Totals 41.73

44.54

 Combined Totals

All Four Beds

Dig kg

No Dig kg

First crops

54.14

61.80

Second crops

11.40

11.94

Season Total

66.54

73.74

2010 totals a little lower than 2009, from growing no turnips or chard and from some damage by leek moth. See This Month December 2010 for some commentary on these results

All first sowings and plantings complete by late March and beds were covered with fleece for one month. Worse slug damage on the dug soil as slugs prefer the clay surface to lumps of less smooth compost. More lettuce replaced on dug bed in early April. Second plantings in July & August.

Parsnip quality much higher on undug bed, little forking compared with more than half of dug parsnips forked and a little more canker on surface.

2009 – Third Year

Beds 1 & 2

  Dig kg No Dig kg
Radish French Breakfast 9/3, one row direct sown between parsnip
Harvested 29.4 – 4.5, all with some slug damage, poor germination, old seed,
0.23 0.27
Spinach Toscane 9/3, two rows direct sown
Harvested 5.5 – 15.6, taking larger leaves only. This is a slow to flower cultivar and yields were impressive, up to 3kg weekly off both beds. There was more yellowing of lower leaves and more slug damage on the dug bed.
6.83 8.56
Lettuce Freckles, Grenoble Red, Bijou 11/3 (sown 22.1) – 18 plants in 3 rows, fleeced for 3 weeks after planting
There were 13 weekly harvests, 14.4 -14.7, in a warm spring, with the highest weekly harvest in early July (2.5kg off both beds) thanks to high temperatures (28C). Lower yields on dug were partly due to slug damage, and leaf quality was higher on the dug bed – glossier, thicker leaves.      
9.22 11.31
Swiss Chard 6/4 (sown 9.3) one row of 5 plants
The only leafy spring crop to perform better on the dug bed; perhaps an indication of the importance of mycorrhizae, which beets, apparently, do not use and which are damaged by digging. Harvested 31.5 – 25.6; there was some bolting by late June and plants were smothering the germinating carrots nearby (chard has hungry roots and is a bossy plant).
8.50 6.49
Potato Epicure 9/3, four plants in one row
Undug potato plants were looking darker green and slightly larger by late May, with leaf curl on the dug plants’ leaves. There were more misshapen and knobby tubers from the dug bed, unlike last year, and the dug potatoes were relatively more smeared with soil. Two harvests on 3.6 and 11.6.
2.53 4.29
Parsnip Javelin F1 9/3  two rows with radish between
Dug plants were a little ahead in late May, partly from less kicking of the surface soil by blackbirds, who were rummaging for worms in the compost surface of the undug bed. The harvest on 29th October revealed many lovely roots, noticeably straighter and cleaner from the undug bed (no forked roots compared to one half forked on dug bed), but the dug roots were broader shouldered.
10.76 9.74
Carrots Berlicum 16/6 undug bed only, one row planted after spinach in paper pots, sown 1.6
Most of the roots were forked and short, harvested 10.9.
  0.83
Celeriac Bianco de Veneto 14/5 (sown 9.3) one row after spinach on dug bed only
Harvested 2 – 19.11, fair quality but a poor variety with too much leaf.
2.28  
Leek Siegfried 27.6 (sown 4.4) – 2×11 plants, 2 rows planted between the lettuce. Dig leeks went yellow towards the end
2.16 3.33
Red Cabbage Drumhead 27.6 (sowed 28.5) – one row of 4 plants, after the chard
Growth was average and was poor on the undug bed thanks to gall weevils eating out three of the plants’ growing points, compared to only one on the dug bed. Brassicas again better in dug soil
 0.92 0.22
Carrot James Scarlet Intermediate 11.6, one row direct sown after harvest of potatoes
Roots were pulled in early November, by which time there was a fair amount of slug and carrot fly damage in both beds. The dug roots were shorter but more numerous from better germination. I think that woodlice nibbled many tiny leaves on the undug bed’s emerging seedlings in late June and early July.
 5.01 2.69
Totals
48.44 47.73

  Beds 3 & 4

  Dig kg No Dig kg
Tall Sugar Pea 9/3, two wigwams in space of two rows, eight plants of two or three seedlings each (sown 11/2) 
Dug peas were ahead in late May and grew slightly more strongly throughout. Harvesting started and finished earlier than usual, between 18th June and 15th July. Each bed yielded about 1kg weekly every three days from 25.6 – 13.7.
9.31 8.55
Beetroot Boltardy 30/3 (sown 3.3) one row of five modules, four/five seedlings per module
Harvests from 4th to 17th June were mostly similar. Larger roots were carefully twisted out on the first two harvests, before clearing the bed so as to plant leeks.
2.69 3.16
Carrot James Scarlet Intermediate 21/3, one row sown direct
The whole row of undug carrots was eaten by slugs or woodlice and kicked around by blackbirds looking for worms in the rather strawy horse manure. I decided to plant celeriac instead and to do a similar celeriac/carrot cropping, but with celeriac on dug and carrots on undug, on beds 1 and 2. The carrot harvest was from 17.6 to 6.7, roots were rather stumpy and with some slug damage.
2.56  
Celeriac Bianco de Veneto planted 14.5 (sown 9.3), staggered row of 6 plants
Growth was good in a wet summer but this is a poor cultivar from Seeds of Italy, with disproportionately abundant leaf growth and relatively small roots. Harvested in November.
  4.39
Onion Santero 31/3 – 5 plants of 3 or 4 onions each – and Red Baron – 2 plants of 4 onions each – (all sown 11/2), one staggered row
By late May there was a massive difference in growth, with the dug onions much smaller and paler, and the undug onions remained darker and stronger until they were all pulled on 4th August. Bulbs were trimmed and weighed on 11 August, then left to finish drying in a crate in a barn.
4.95 6.31
Turnip Manchester Market 5.8, one row direct sown after peas.
Germination was a little better on the dug bed and these plants grew more strongly, all roots were harvested on 15th November.
2.12 1.38
Endive Bubikopf 1.8, one row planted after peas (sown 12.7) 
There were lovely hearts in mid October, but I harvested them in November when leaves were scarcer and more valuable – as a result, many leaves had to be trimmed off because of rotting and slug damage. Plants on the undug bed looked healthier throughout with slightly larger and glossier leaves.
0.78 1.15
Leek Autumn Mammoth Tornado 17.6 (sown 17.3), one staggered row of 15 plants, after beetroot 
Growth of the undug leeks was stronger, with darker green leaves, but there were 9 bolting leeks on this bed by the end, compared to two on the dug bed. Bolting stems and most of the flag were removed before weighing, harvests from 8.9 – 19.11.
4.12 3.19
French Bean Polka 6.7 (sown 27.6) one row of 4 plants after carrots on dug bed
Reasonable growth after a slow start in the wet July and early Augusts, harvests from late August to end September
1.08  
Turnip Manchester Market 9.8, one row after onions
Germination and growth was better on the dug bed.
1.95 1.59
Endive Bianca Riccia da Taglio 22.8, one row of 5 plants after onions
Small harvests in October and November of outer leaves.   
0.43 0.42
Totals 29.99 30.14

Totals for all four beds in 2009:
Dig: 78.43kg
No Dig: 77.87kg