This topic contains 18 replies, has 6 voices, and was last updated by Don Foley 8 years ago.
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At Lower Farm one of my best seasons was 2012, fifteen years after starting the first garden and having spread 1-1.5in compost from different sources every year. Quite a bit was the neighbour’s horse manure, 18-24 months old.
A different neighbour assures me that “farmyard manure” (he does not say how old, whether its composted) causes build-up of P, as a result of which their peas are always stunted.
However my peas at Lower Farm in 2012 were excellent.
So what gives?I trust the growth of plants more than soil tests.
Growing can be made to seem complicated by chemists and others who claim to understand “plant food requirements”.
In undug soil, the biology is busy sorting things out, and its more about interactions between plant roots, fungi and soil nutrients than about quantities of molecules.
I would sow, plant and observe, your plants will tell you more than laboratories can.Hi Charles/Hawfinch,
Could it be that you are adding too much compost, i.e., adding more than is actualy required by the plants your growing.
I wonder if it might be an idea not to add any compost for one season and see where your soil is at then.
I think what Charles says is the most accurate test of how good or bad your soil is and what its requirements are, observe the plants.Don.
Hi Helle,
When you say you have lots of leaves do you mean Leafmould or something else.
If youare only adding less than the 1-2inch recommendation the problem might be with the mulch or it might be down to the original condition of the soil before you started cultivating it.Don.
Hi Hawfinch,
I believe that is your problem, Tree leaves contain significant amounts of phosphorous.
It would appear you have been overdoing the mulch.Don.
Hi Helle
Nature has fed the soil underneath trees since time immemorial with leaves, plain and simple, so I would find it surprising if adding leaves (over a three year period?) was causing a problem of excess phosphorous. I suppose the caveat is the amount you are putting on, but my guess is that you would have to put on an excessive amount (whatever that means!) for leaves to have a detrimental effect. Another caveat is that it is suggested that the leaves of some tree species, such as eucalyptus, should be used sparingly.
Is your veg showing signs of phosphorous excess, such as stunting of peas, or do you have veg which takes first prize at the county show? As Charles says it is better to use your produce as a guide rather than changing your inputs on the basis of a soil test.
Of course, like everyone else who writes on the forum, I am the leading expert in this field so you may need to take my comments with a healthy dressing of sodium – not too much mind you.
It would be useful to have Charles’ opinion on the use of leaves.
John
Hi Helle/John,
I am not suggesting that you shouldn’t use Leafmould, you should of course. But what I am saying is don’t overuse it. Its a simple case of too much of a good thing……….
In the same way as too much compost can be a bad thing also, depending on what you are growing.
As John and Charles both suggest, it is how your crops develop that should be your guide.Don.
Interesting discussion, I would go back to your original post and ask how reliable the test is?
Also what is the % organic matter? how was it measured?
The only test I had done on my soil at Lower Farm gave “low” readings for fungi in beds where I was harvesting bumper crops and I am wary of results since then.Charles
I”m no expert on the subject, but I get the impression that fungi are most valuable for plants when soil and moisture conditions are particularly suboptimal, as the symbiosis allows the plants to access minerals and moisture from far greater areas than alone?
In market gardening situations where you replenish the soil with compost once a year, I would reckon naively that the absolute need for fungi was less, although of course they will still be beneficial.
My other reading suggests that the fungi can decrease in population if they go 3 months or more without plants to interact with, so if there is no winter crop or green cover, then there is the possibility over a few seasons for levels to drop far below what you might see with e.g. a grass-covered field.
Thus the use of fungi may be most beneficial for gardeners who cannot access large amounts of high quality compost every year for their vegetable patches??
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