We were sit­ting in the win­ter sun in his gar­den when I idly asked a keen veg­etable-grow­ing friend what his soil was like.

NZ Gardener - - CONTENTS -

Mary Lovell-Smith gets down to earth to look at the won­ders of soil

He shrugged his shoul­ders. “Dunno,” he replied. “Heavy? Sandy?” I sug­gested. He re­mained un­in­ter­ested. “Wouldn’t have the faintest. As long as it grows good veg­eta­bles, does it mat­ter?”

There’s a bit of wil­ful ig­no­rance go­ing on here, a lack of cu­rios­ity and a missed op­por­tu­nity to de­velop a deeper con­nec­tion with his en­vi­ron­ment.

For soil is par­tic­u­lar to its site, of­fer­ing gar­den­ers a close sense of place and time. It is a ma­jor fac­tor they have to con­tend with reg­u­larly when they gar­den, be it plant­ing, weed­ing, wa­ter­ing, or sim­ply work­ing out why one plant is thriv­ing and another not. A site’s soil con­tains a whole ge­o­log­i­cal his­tory.

So when I mut­ter to my­self about mine, about how bone hard it is to dig into in sum­mer and how sticky and dank it is in win­ter, re­flect­ing on its ori­gins eases the pain a lit­tle.

My gar­den is on the lava flow of an an­cient vol­cano.

Its cen­tre was near the mid­dle of Lyt­tel­ton Har­bour (the port of Lyt­tel­ton sits in­side the crater). The soil is heavy clay, pos­i­tively puggy in places; in other parts there is lit­er­ally no soil, just be­drock. And here and there in be­tween, there is some­thing re­sem­bling a fri­able loam.

The vol­cano first came to life about 20 mil­lion years ago and car­ried on for 14 mil­lion years, spew­ing out basalt and other ig­neous rocks, which over a few more mil­lion years were cov­ered with a man­tel of loess. These fine par­ti­cles of greywacke were car­ried by the winds to Banks Penin­sula from the South­ern Alps and are eas­ily recog­nised in the yel­low clay banks all over the penin­sula.

Then came the over­lay of col­lu­vial soil, eroded from the be­drock. Next – and much much later – came the thin layer of top­soil built up from veg­e­ta­tion and tiny or­gan­isms.

Of course, the lay­ers are not as clearcut as this all sounds, with col­lu­vial and loess mix­ing with each other and with the var­i­ous pe­ri­ods of vol­canic ac­tiv­ity.

Christchurch poet Den­nis Glover in his 1970s poem Pi­geon Bay summed up the soil pro­file beau­ti­fully: “Over the hard lava. A khaki clay bal­a­clava And a thin shirt of dirt.”

I have learnt to live with the khaki clay bal­a­clava.

I don’t dig into it un­less plant­ing a tree or shrub for it is rock-hard when dry and sticky when wet. For beds, I pile on top of the clay as much or­ganic mat­ter as I can muster, such as pea straw as well as com­posted horse and cow ma­nure. I dis­turb the clay as lit­tle as pos­si­ble. I have tried gyp­sum to “break it down”, heaps of it, but the ver­dict is out on its ef­fi­cacy. I strug­gle to grow lemons and no longer even try with rhodo­den­drons but take so­lace in how beau­ti­fully my roses bloom and my fruit trees pro­duce.

My shirt of dirt is in­deed thin in places, non-ex­is­tent where the bones of “hard lava” poke through. These I try to ap­pre­ci­ate for what they are: a sem­blance of “nor­mal“soil and a de­sign fea­ture.

To be fair, my friend lives in a small back sec­tion in the up­mar­ket Christchurch sub­urb of Merivale.

Maybe it is harder to iden­tify or have any sense of tu­ran­gawae­wae on a patch of dirt with no other de­ter­min­ing nat­u­ral phys­i­cal char­ac­ter­is­tics.

Soil for him is the sweet-smelling and rich com­post he makes him­self for the raised beds in which he grows his veges. Soil is the medium in which his wife grows or­na­men­tals in the rest of the gar­den, and to where he re­luc­tantly re­lin­quishes the re­main­der of his com­post.

Very likely he knows the ge­o­log­i­cal his­tory of Christchurch and the plains upon which it stands, but I doubt he feels it deep in his bones, and maybe won’t till he im­merses his hands in the soil.

Which of course, he won’t. That’s what his wife and the gar­dener are for! ✤

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