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Digging deep

Posted by Guy Barter on 06 Jan 2010 at 10:33 AM

Frozen ground means manure shifting time.  Cultivations are best left to the New Year on sandy soils as they slump if left loose and exposed to winter rains becoming what is technically called 'sad'.   A lorry-load of composted horse  manure was bought off a local manufacturer.  The owner assures me that he takes the greatest care to keep weedkiller contaminated manure out of his supply chain, but no one is perfect, so the propagator was cranked up to full heat and beans sown in the prescribed way.  After three weeks all is clear and the weedkiller-free manure can now be spread.

A generous barrow-load is tipped every 1.5m ready to be raked out to be incorporated by rotovator as soon as the ground dries up.  There is no rush, so in the meantime the hand-digging takes place for early crops and where there is question mark on soil quality.


The early runner beans, courgettes and stick tomatoes were a tad disappointing in 2009 for reasons that are not clear.  The area they occupied had been under late brassicas such as purple sprouting broccoli.  These were harvested in wet winter weather leading to trampled soil and to make matters worse their pigeon protection nets were demolished by snow last February and had to be hastily  rebuilt while the soil was still saturated by meltwater.  This led to damaged soil that I thought I had remedied by rotovating in a useful dressing of garden compost plus a boosting subsequent crops by heavy use of fertiliser.

As this area came free of crop in October I decided to take the opportunity to double-dig this area - about 56 square metres - to remove any compaction and incorporate  some organic matter down to 50cm deep rather than the usual 20-25cm deep digging, or 18-20cm deep rotovating.  It is scheduled, under the rotation, to go into broad beans and peas in 2010 which need early sowing, but only a modest amount of manure.


The procedure is to divide the strip into two parallel rows and work down pone row and up the other to where the soil excavated at the start is waiting to refill the 60cm wide trench.  The base of the trench is dug over mixing the crop debris and some manure into the bottom 25cm and adding manure to the top 25cm.  The dry autumn has led to easy digging conditions.


How worthwhile this work is depends on the depth of rootng for the crops over the next few years and on rainfall.  Drought and deep-rooting broad beans, then very beneficial; rainy summer and shallow rooting peas then no  significant benefit.


The 'post-mortem' on the runner beans, courgettes and tomatoes showed, on uprooting the spent plants, fair roots, but not as good as they should have been - this is consistent with damaged soil structure.  Some roots from nearby oak trees were also found suggesting that these might have been robbed the crops of some moisture.  Yet another factor that seems to be involved is that this area was cropped through black plastic and it is likely that late summer rain failed to replenish soil beneath the plastic after the June dry period, despite extra watering to counter this. 


A row of broad beans is now planned between trees and plot.  This should finish in July and this strip will again be deeply dug in mid summer to break any new tree roots before replanting with cell-tray raised French beans. 


With the completion of the double-digging, this area should now be restored to full productivity and need no further deep-digging for at least four years.



Digging deep - Spud Grubber's Blog Tree Me said:

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on 06 Jan 2010 at 01:59 PM