Thursday, 21 November 2013

Soil fertility, minerals and fertilisers.

Summer has arrived.  The low rainfall for the past two years means that the soil is very very dry,  and the deeper I dig,  the dustier and drier is the soil.  The old soil that is here,  is very fine grained (quite the opposite to sandy soils) with clay particles so small that the whole makes "non-wetting" soils.  This means that when one waters with a hose or a bucket,  the water runs off, leaving the underneath layers dry and dusty.  Gypsum helps,  but organic matter and soil organisms make the soil much healthier.
There has been no rain for three weeks and little for the past year or so…  we will not get up to our "average rainfall" again this year (361 mm so far, when "average" is about 480 mm.)

Crops are ripe and being harvested… the summer colours are here….
 …. and the size of my vegetable patch is being reduced.  In summer,  I reduce the area that I maintain in order to reduce the amount of water that is needed.
The broad beans have jsut about finished producing (it's too hot) and the garlic is mostly harvested.  I have onions, some greens and plenty of springtime herbs remaining.
The first of the "green beans"  (though mine are "purple king" this year) are growing,  potatoes are drying off and I am digging plenty of those and there are small tomatoes "by the dozen" on the various tomato plants.  Other summer plants are still coming along…. it is exciting to watch.

After my recent addition of rock dust to the soil in much of the garden,  plants are looking very healthy…  better than usual.  I "dug out" several books about soil fertility, mostly old-fashioned and pre-superphosphate fertiliser.  The acres and acres of crops that aare waiting to be harvested are almost grown hydroponically, with seed, fertiliser and pesticides being applied to almost sterile soils to produce  our grains and oil seeds.
Today I have been reading "Soil Fertility" by E Pfeiffer….
I bought this book, "Soil Fertility" by E Pfeiffer, for a dollar at a library sale some years ago.  The original version was published in the same year as another book that I have referred to previously, "The Soil anad Health - A study of organic agriculture"  by Albert Howard…  the year 1947,  the year that I was born!  

Both of these authors consider the maintenance of soil fertility,  including the requirement for minerals and trace elements, in order that the food grown in that soil should also contain those minerals.  

This is no doubt an issue in all intensive agriculture,  but even more so in the ancient soils that make up our continent.  Native Australian plants are famous for needing minimal fertiliser (in fact,  rich fertilisers can harm the plants) and don't seem to notice the lack of trace elements.  Over thousands of years,  as the soils became leached and depleted,  the plants have adapted to suit the conditions.  

Introduced plants on the other hand, those that come from continents with younger, less leached out soils need special care and additives to grow successfully in my area.  This applies to most of our vegetable crops as well.  I have found that beets and its relatives won't grow without added boron here. Other vegetables require various trace elements.    Beans and peas need some additives also. I'm not sure which mineral they need,  because I now add rock dust which includes (in a less soluble form) silica, iron, calcium, magnesium, sodium, potassium, phosphorus, manganese, sulphur, zinc, copper, molybdenum and boron… a real multi-mineral mix.   The crushed rock that I add to the soil probably includes even more elements than these, but these are the main ones.  I sprinkle a handful of the material over each square metre or so and plants that I have had difficulty growing are doing very well… they are much healthier and producing food for me very well.

This has made me think further.  Surely animals,  human and otherwise, also need these trace elements. One can buy vitamins with added minerals or fortified foods, especially flour, with added iodine or selenium. 

While I understand that many people criticise the bio-dynamic methods as "muck and mystery" and consider that planting by the moon (a practice followed by my grandmother) to be bizarre, it it probably just as well to refrain from throwing the baby out with the bathwater.  As the cost of fertilisers rises, not to mention their unavailability without cheap oil, it is probably useful to look at some of these older and reliable methods of producing food that is healthy and reliable.  

My "library discards" have proven to be extremely useful… food for thought as well.






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