January 2009


Updates from January 2009.

Gardening For Food January 2009.

DIG / NO DIG HARVEST SUMMARY 2008

December’s blog explained the background to my dig/no dig experiment and gave the results of all harvests in 2007. Soon after posting that, I finished the year’s harvesting off all four experimental beds, and the summarised results for the whole calendar year of 2008 are set out below.

It was another wet year, with over 1400mm (56”) of rain and the raised beds never dried out. Temperatures were about average (year’s mean just below 10C), while sunshine was well below average. These conditions favoured winter crops such as parsnips, leeks, cabbage and celeriac more than summer vegetables such as french beans. Onions were affected by mildew but no other diseases were prevalent and I just about kept on top of the slug population, by having no weeds and with some night patrols in the summer.

Please see the tables below for the Dig vs. No-dig growth differences.

Summarising the growth differences, it was noticeable again that early spring growth of all plants was stronger on the undug beds, such that by early August they had yielded 24kg of leaves, roots and fruits compared to 21kg from the two dug beds. Meanwhile, the red cabbages were again growing more strongly on the dug beds, where soil had supposedly been ‘opened’ by digging. An intriguing refutation of the maxim that cabbages like firm soil. Or perhaps the undug soil is, in fact, better aerated by worms and undisturbed soil life.

Parsnips provided a fascinating comparison. The dug bed’s heavier crop was slightly offset by its poorer quality, with more canker and root branching. Both beds’ parsnips were prised up with a fork and the undug bed’s roots came out markedly cleaner, taking less time to make presentable. Notice in the photo how the dug parsnips are smeared with mud, indicating a soil with too little structure, unable to aggregate in colloidal lumps.

I was also intrigued by the difference in late salad growth, with both lambs lettuce and land cress growing darker and more strongly on the undug bed. Maybe this late growth potential is why leeks again came out heavier on the dug bed. Still plenty of questions!

I am running this experiment because I really want to understand the differences caused by soil cultivation and inversion, and I hope the results and photographs are helping you also, to understand how best to treat soil.

Charles Dowding

Beds 1 & 2 Dug Not dug  
Beetroot Boltardy 2.41kg 2.52kg growth similar in all respects
Sugar Snap Peas, Tall 7.20kg 7.50kg excellent crops
Carrot Ideal Red 1.25kg 0.76kg better germination on dig – poor variety though – back to Nantes next year
Red Onion Furio 0.28kg 0.38kg harvested as salad onion
Onion Bunton’s 0.43kg 1.09kg mildew!
French Bean Nomad 0.52kg 0.23kg – bad early summer for beans
Total first crops 12.09kg 12.48kg
 
Turnip Manchester Market 4.80kg 3.97kg larger rooted variety than 2007
Broccoli Raab 0.64kg 0.71kg
Endive scarole 1.50kg 1.36kg
Leek Autumn Mammoth 1.65kg 1.81kg
American land cress 0.73kg 0.80kg
Lambs lettuce D’Orlanda 0.16kg 0.25kg
Total second crops 9.48kg 8.90kg
 
TOTAL 21.57kg 21.38kg

Bed 2 was dug on 28th November, its clay rather sticky and I worked off a board, incorporating one large wheelbarrow of 70% homemade compost, and 30% mushroom compost in the trenches. Bed 1 received a barrowload of the same compost on its surface, which took about an hour and a half less time, and made less mess!

Beds 3 & 4 Dug Not dug
Radish F. Breakfast 0.95kg 1.13kg faster growth on no dig
Spinach Tarpy 2.68kg 3.33kg – stronger growth on no dig
Lettuce 3 varieties 3.52kg 4.28kg – about 250g/plant on no dig, only 65% of last year
Potatoes Swift 1.72kg 1.49kg – better shape on dig (rounder), but soil more lumpy after harvest
Onion Sturon 0.97kg 0.95kg
Total first crops 9.84kg 11.18kg
 
Cabbage Red Flare 4.31kg 2.62kg – 4 heads each bed
Camberley 0.07kg 0.23kg slugs ate seedlings
Endive frisee 0.91kg 1.44kg
Celeriac Prinz 2.52kg 2.48kg 4 heads/bed, after spinach
Swede Helenor 3.40kg 3.36kg – more root fly damage on undug – grew where potatoes had been
Parsnip Gladiator 7.65kg 5.95kg – fatter (not longer) roots on dug bed, harder to clean
Total second crops 18.86kg 16.08kg
 
TOTAL 28.70kg 27.26kg
 
Grand Totals both beds 50.27kg 48.64kg

Bed 4 was dug on 25th November when I incorporated one large barrow of well rotted horse manure and spread the same amount of manure
on top of bed 3.