Monday, November 3, 2014

Sufficiency levels of soil nutrients

After getting all excited about soil nutrients thanks to Steve Solomon's book The Intelligent Gardener, I banded together with a few local gardener types and got a bunch of soil tests done.  Having run the numbers through Solomon's worksheets, thought about the results a bit and read a little more widely, I've come to see that there are many perspectives on soil fertility.

Solomon preaches the base-cation saturation ratio (BSCR) method, which claims that there is an optimal ratio of cations in a soil (68% Ca, 12% Mg for a start).  He further believes that plants grown on such a "remineralised" soil will have a greater nutrient density than those grown on sub-optimal soils.  Now I haven't had the time to delve deeply into the evidence base for either hypothesis, but a quick look suggests that it is a bit thin.  Plant breeding appears to be a more likely culprit for decreased nutritional density over the years, hence applying fertilisers to reach some optimal ratio may be an unnecessary expense.

Having said that, there's nothing like trying something out for yourself to see what happens, which is exactly what I intend to do.

The conventional/mainstream agronomic view is that it is not the ratio of nutrients that is important, but rather the amount.  (This approach is either based on sound science, or biased by vested interests such as fertiliser companies, depending on your point of view.)  So they have come up with thresholds below which a nutrient can be considered deficient.  A strong argument against this approach is that such a threshold may be enough to avoid gross deficiency that exhibits visible symptoms, but not more subtle ones.  This is one reason for the growing use of plant tissue analysis to identify small deficiencies.  By testing both soil and plants, a farmer can gradually converge to a highly productive soil without resorting to broad-brush rules, be they thresholds or optimal ratios.  This seems to me to be a much more adaptive approach, allowing for variability in crops, soils, local climate and management.  However, a farmer will generally be managing for profitability (balancing inputs with production), whereas a home gardener may be more interested in maximising nutrient density.  A profitable crop is not necessarily a nutritious one (if soil fertility does indeed influence nutrient density).

Given that home gardeners and small-scale growers can't afford to do plant tissue tests, what are they to do?  They could follow the Solomon approach, but it might be quite expensive.  In particular, he advocates very high levels of phosphorus, which is an expensive nutrient.  Here is a summary of nutrient thresholds that I have found by scouring the internet.  I've also given the optimal range provided by AgVita on their soil reports.  AgVita is a Tasmanian testing lab that uses the Mehlich 3 method (unfortunately they are very expensive!).

Soil Acidity (pH)

pH is probably the most important thing to get right in a soil.  A slightly acid soil is most favourable to plants, and has the least risk of nutrient deficiencies and toxicities. The below just applies to acid soils - I'm not sure what to do with alkaline soils (pH >7.5).  Note that all pH values are as measured in a 1:5 water solution, not CaCl2 solution

Target: pH 6.5 (good for mixed veg)
Application rate: depends on soil texture.  According to Bill Cotching, 1t/ha of 100% NV lime will raise pH over 0-10cm as follows:
Sand: 0.5-0.7
Loam: 0.3-0.5
Clay: 0.2-0.3
Ferrosol: 0.04-0.1

Minimum application: 2.5t/ha
Maximum application: 7.5t/ha
Incorporate in top 10cm, response in 1-3 years.

Some similar figures, from Land & Water Australia:
Subtract soil pH from target.
Divide by conversion factor:
Clay: 0.3
Clay loam: 0.4
Sandy clay loam: 0.5
Sandy loam: 0.6

Surface applied lime only moves ~1cm/year down profile.  Need a big dose to get down to subsoil.

A nice table matching CEC to pH is given here.  Note that these are pH (Ca) values, and lime rates are to lift to pH (Ca) 5.5 in the top 10cm.


Another way is to use the buffer pH, which is a measure of how much the soil's pH changes per unit of lime.  An example for New York State is given here.  Note that I think these figures are calibrated for local conditions, so may not be applicable on your particular soil.

Example:
pH (water): 5.5
buffer pH (Mehlich): 6.6
CEC: 16
texture: sandy loam

Cotching: 2 t/ha
LWA: 1.67 t/ha
NSW DPI: 2.8 t/ha
NYS: 1.1 t/ha

So quite a lot of variability there!  I think I'd start with 2.5 t/ha and see how we go (since they are for 0-10cm, and we want to get down to 15cm).

Phosphorus (P)

The first thing to be aware of with phosphorus is that there are many ways of measuring available P.  Here is a table correlating the different methods (thanks to AgVita).


The short of it is that optimal P, as measured by the Mehlich 3 test, is 40-70ppm.  Since we're going for high production and nutrition, it can't hurt to aim towards the high end of that range.

50-100 ppm (UD)
56 ppm (Colorado)
AgVita: 40-90 ppm

Potassium (K)

160 ppm
90-180 ppm (UD)
70-140 ppm (NJ)
180 ppm (Colorado)
AgVita: 245-355 ppm (upper end of range may be CEC dependent, 4-6%)

Calcium (Ca)

Ca:Mg > 1:1 (reduced stability in heavy clays)
Ca:Mg 3-5 (AgVita, as measured in meq)

700-900 ppm (NJ)

AgVita: 1620-2700 ppm (appears to be CEC dependent, 60-70%)

Magnesium (Mg)

K:Mg < 1.5:1 (Spectrum)
K:Mg 0.3-0.5 (AgVita, as measured in meq)

70-150 ppm (NJ)

AgVita: 200-400 ppm (CEC dependent, 12-20%)

Sulphur (S)

12 ppm (Minnesota)
AgVita: 12-45 ppm

Boron (B)

1 ppm (Minnesota)
0.7 ppm (NJ)
AgVita 2.2-6 ppm

Zinc (Zn)

1 ppm (Minnesota)
1.5 ppm (Colorado)
AgVita: 2.2-11 ppm

Iron (Fe)

10 ppm (Colorado)
AgVita: 35-230 ppm

Copper (Cu)

5 ppm (Minnesota)
AgVita: 2.5-10 ppm

Manganese (Mn)

10 ppm (not Mehlich extract though ...)
Only use soil test if OM < 6%.  If OM > 6%, then Mn level is determined by pH:
< 6.0: high
6.0-6.9: optimum
> 6.9: low
(Wisconsin)
Foliar: 0.2-0.4 lbs/ac in 50-100 gal water (0.1-0.2 kg/200-400 L), 2-3 applications (Minnesota). Chelated form best.

Rutgers University uses an Activity Index:
      MnAI = 101.7 + 3.75Mn - 15.2pH

The index should be between 25-100 (ref).
They also have a table with sufficiency levels for different pHs, see here.  Anything above 8 ppm is fine, no matter what the pH.
Broadcast 20-30 lbs/ac or band 4-8 lbs/ac, or 0.5-1 lbs in 20 gal (0.2-0.5 kg/75L) water per acre (NJ).

AgVita: 18-70 ppm

Tuesday, September 16, 2014

Old book reviews from late 2010

I found these written on a piece of paper - thought I'd record them here for posterity and completeness.

4.5 stars
"1984" George Orwell
"Dirt: The Erosion of Civilizations" David R. Montgomery


4 stars
"All Quiet on the Western Front" Erich Maria Remarque
"Harry Potter & the Deathly Hollows" JK Rowling
"Three Cups of Tea" Greg Mortenson - since found out to be a fraud!
"Sword of Red Ice" JV Jones
"Watcher of the Dead" JV Jones
"The Name of the Wind" Patrick Rothfuss

3.5 stars
"Just Food" James E. McWilliams
"The Happy Economist" Ross Gittins

3 stars
"Family Friendly Farming" Joel Salatin
"Harry Potter & the Half-Blood Prince" JK Rowling
"Primal Blueprint" Mark Sisson
"Paleo Diet" Loren Cordain
"Why Men Are Necessary" Richard Glover
"Sword of Shanara" Terry Brooks
"Lifeboat Cities" Brendan Gleeson 
"The Totem Pole" Paul Pritchard

2.5 stars
"Public Produce" Damin Nordahl
"Back from the Brink" Peter Andrews

2 stars
"Amazon Adventure" Willard Price

Saturday, September 6, 2014

My top 10 transformative books

Here are my top 10 transformative books (in chronological order (of my life)):
1. Adventure, by Willard Price - for instilling a love of the natural world and adventure
2. The Belgariad by David Eddings - for opening me to the world of fantasy and epic reading sessions (honourable mention to Red Wall by Brian Jacques).
3. Into The Wild by Jon Krakauer - Alexander Supertramp, the wildest (and most naive!) of wildmen.
4. One Day in the Life of Ivan Denisovich by Aleksandr Solzhenitsyn - such joy, optimism and stoicism in the face of terrible hardship
5. The Omnivore's Dilemma by Michael Pollan - fertilised my interest in food systems and agriculture
6. Fooled by Randomness by Nicholas Nassim Taleb - brilliant paradigm-breaking ideas about systems and risk (if you haven't read Taleb before, jump straight to Antifragile)
7. Wild Fermentation by Sandor Katz - for unleashing experimentation in by kitchen
8. The Antidote by Oliver Burkeman - a wonderful collection of pragmatic wisdom on how to be happy
9. The Great Disruption by Paul Gilding (currently reading) - for making me deal with the coming crisis on a visceral & emotional level


That's only 9! Ah well, I'm sure it will come to me in the next day or two ...

Monday, March 10, 2014

Reading 2013

The 27 books I read in 2013:

"The Rosie Project" Graeme Simsion. 5 stars. Hilarious. Brilliantly done. Engrossing.

"The Secret Garden" Francis Burnett. 4.5 stars. The gentle awakening touch of nature, the Magic of life. Rang true and pulled the heart ...
"A Storm of Swords" George RR Martin. 4.5 stars. Blimey, he really hits his straps in this one. Great to be re-reading these.
"Mindsight" Daniel Siegel. 4.5 stars. Clear and rational explanation for how the brain/mind/emotions work. Very helpful & revealing.
"The Australian Moment" George Megalogenis. 4.5 stars. Politics and the economy as never been so interesting! Must read for recent Aus h ...
"The Antidote" Oliver Burkmann. 4.5 stars. A superb synthesis of pragmatic philosophies for how to live well. Must read!

"1835" James Boyce. 4 stars. A fascinating and revealing history of the founding of Melbourne.
"Antifragile" Nassim Taleb. 4 stars. Refreshing & eye-opening perspective on the world, but waffles on a bit.
"Chronicles of Prydain" Lloyd Alexander. 4 stars. Classic fantasy for young readers.
"Jack de Crow" AJ Mackinnon. 4 stars. Rollicking good yarn of sailing a dinghy across Europe.
"Feral" George Monbiot. 4 stars. Eye-opening and appealing entreaty for rewilding our world. Not so relevant in Australian context though.

"Mountain Solitudes" Aat Vervoorn. 3.5 stars. Humble and philosophical tales of solo mountaineering in NZ.
"The Mountain" Drusilla Modjeska. 3.5 stars. An immersive insight into PNG history and culture.
"The Farseekers" Isobelle Carmody. 3.5 stars. An improvement on book one. A good escapist read.
"Sweet Poison" David Gillespie. 3.5 stars. Illuminating on the potential evils of fructose. Implies it increases short-term appetite, bu ...
"The Long Earth" Terry Pratchett & Stephen Baxter. 3.5 stars. A great premise and absorbing read but lacking a few explanations.
"Dance of Dragons" George Martin. 3.5 stars. Slow progress, excess characters, but good times with Jon and Arya. Clumsy finish.
"Cooked" Michael Pollan. 3.5 stars. Interesting exploration of cooking of all types. Learnt a few things but not brilliant.
"Wool" Hugh Howey. 3.5 stars. Great post-apocalyptic premise, but lacks good characters.
"The Boy Who Wouldn't Die" David Vincent. 3.5 stars. Amazing story of a Sudanese boy and his long road to Australia. Reality check!
"The Gathering" Isobelle Carmody. 3.5 stars. Dark. Absorbing.

"Obernewtyn" Isobelle Carmody. 3 stars. Missed this as a young 'un. Some good ideas but a bit clunky, and ended too rapidly.
"Born on a Blue Day" Daniel Tammet. 3 stars. A window into an Aspergers mind. Synesthesiac numbers - amazing!
"Krakatoa" Simon Winchester. 3 stars. Well written, wide ranging if overly detailed pop science/history.

"The Scatterlings" by Isobelle Carmody. 2.5 stars. Passably written and mildly interesting post-apocalyptica.

"The Bone Season" Samantha Shannon. Two stars. Trash. Readable, but ultimately dissatisfying.

"Shift" Hugh Howey. 1.5 stars. Disappointing follow-up to Wool. Mostly boring.

Reading 2012


What I read in 2012, 31 books in all:

"A Place Of My Own" Michael Pollan. 5 stars. Boy can he write! A stunning account of building and architecture.
"Infidel" Ayaan Hirsi Ali. 5 stars. Wow. Eye-opening. Shocking. More than a little worrying! Compulsory reading.

"Sarah Thornhill" by Kate Grenville. 4 stars. So much tragedy. A beautifully but starkly crafted of a history we all share.
"I Can Jump Puddles" Alan Marshall. 4 stars. He rides! What a tough kid.
"The Liveship Traders" series by Robin Hobb. 4 stars. Pirates! Magic ships! Dragons! A rich world with great characters.
"Mockingjay" Suzanne Collins. 4 stars. War. Twisted humanity. The horror!
"The Last American Man" Elizabeth Gilbert. 4 stars. A fascinating insight into an extraordinary man. He is one messed up dude though!
"Master & Commander" Patrick O'Brian. 4 stars. Indulgent nautical terms, absurd wartime gentility, daring and dorky.

"The Painted Man" by Peter V Brett. 3.5 stars. Simply written, but a good premise and gripping tale. Demons and heroes!
"Pandora's Star" by Peter Hamilton. 3.5 stars. A touch long-winded but has some cool future tech ideas and a big bang of a finish.
"For the Term of his Natural Life" Marcus Clarke. 3.5*. Harrowing and relentlessly tragic. Plot a little too contrived.
"The Hunger Games" by Suzanne Collins. 3.5 stars. Twisted. Un-put-down-able.
"The Street Sweeper" Elliot Perlman. 3.5 stars. Very well told stories of the Holocaust and being black in America, but too convenient.
"Catching Fire" Suzzane Collins. 3.5 stars. A worthy sequel, and not as predictable as it could have been.
"Reframe" Eric Knight. 3.5 stars. Simple really: a widening of perspective can reveal solutions. Reaffirms bottom-up action.
"I Heard The Owl Call My Name" Margaret Craven. 3.5 stars. Paints the feeling of a Canadian Indian village beautifully, full of deep sad ...
"Biggest Estate on Earth" Bill Gammage. 3.5 stars. A great realisation of how dramatically Aboriginals shaped Australia.
"Rain Wild Chronicles" Robin Hobb. 3.5 stars. Simpler style but still sucked me in. Third book added a few plot lines. Have to wait for ...
"Second Nature" Michael Pollan. 3.5 stars. Some excellent chapters on nature and culture, and the philosophy of gardening. But others drag.
"All The Pretty Horses" Cormac McCarthy. 3.5 stars. Languid.
"The Left Hand of Darkness" Ursula LeGuin. 3.5 stars. Some great ideas and well executed, but lacking in engaging characters.

"The Desert Spear" Peter Brett. 3 stars. A passable sequel that covers a lot of the same ground and doesn't progress the story much.
"Little Women" by Louisa May Alcott. 3 stars. Sometimes just a little too wholesome and moralistic. But touching nonetheless!
"Paddy Clarke Ha Ha Ha" Roddy Doyle. 3 stars. Never quite connected with this.
"Eat Pray Love" Liz Gilbert. 3 stars. An enjoyable and varied read, a lot of which I could relate to.
"The Ways of the Bushwalker" Melissa Harper. 3 stars. A moderately interesting, occasionally suprising, history of bushwalking in Aus.
"The Comfort of Men" Dennis Altman. 3 stars. A pleasant insight into gay life, but in a secessionist Tasmania!
"The 100 Year Old Man Who Climbed Out The Window And Disappeared" Jonas Jonasson. 3 stars. Amusing, if rather absurd.

"We Want Real Food" Graham Harvey. 2.5 stars. Alarming expose of the dramatic fall in the mineral content of foods. Not rigourous.
"The Wild Shore" Kim Stanley Robinson. 2.5 stars. Dubious premise, poorly told.

"Organic Manifesto" Maria Rodale. 1 star. Poorly informed, simplistic understanding of food systems. Unconvincing and disappointing.

Reading 2011

Reading list from 2011, scraped from my twitter account:

5 stars:
"Born to Run" by Christopher McDougall. 5 stars. Brilliant. Perfect mix of story telling and popular science. Will make you want to run ...
"The New Organic Grower" by Eliot Coleman. 5 stars. The ultimate guide to market gardening. Some new ideas. Makes me want to try!
"Meat: A Benign Extravagance" by Simon Fairlie. 5 stars. A brilliant examination of livestock and farming systems. For the ag nerd.

4.5 stars:
"The Wise Man's Fear" by Patrick Rothfuss. 4.5 stars. I wonder where it will go but don't care. Getting there is such a pleasure.

4 stars:
"Prosperity Without Growth" by Tim Jackson. 4 stars. An excellent look at how to move away from a growth economy. A must read!

3.5 stars:
"Zen and the Art of Motorcycle Maintenance" by Robert M Pirsig - 3.5 stars. Moments of brilliance, sometimes a slog.
"A Short History of Progress" by Ronald Wright. 3.5 stars. Good concise overview of failed civilisations but degrades into a rant and do ...
"Persepolis" by Marjane Sastrapi. 3.5 stars. A graphic novel. Great way to learn something of Iran's recent history.
"Sunbathing Naked" by Guy Kennaway. 3.5 stars. A dark comedy, sometimes painful, about psoriasis. Terrifying how bad it can get.
"Slow Death by Rubber Duck" 3.5 stars. Oh god, chemicals are everywhere. We'll all be rooned! Learnt a lot about what to avoid.
"Acacia" by DA Durham. 3.5 stars. Engaging. Ruthless. But the way the story is told makes it hard to get emotionally involved.
"The Lieutenant" by Kate Grenville. 3.5 stars. Beautifully written history brought to life, but a disappointing climax.
"The One-Straw Revolution" by Masanobu Fukuoka. 3.5 stars. A great deal of wisdom, but we've learned very little of it.

3 stars:
"The Social Climbers" by Chris Darwin. 3 stars. A warts and all telling of mad foolishness: holding a dinner party on a 6800m mountain.
"The Carbon Diaries 2015" by Saci Lloyd. 3 stars. Carbon rationing. Natural disasters. Over the top, but readable.
"Bypass" by Michael McGirr. 3 stars. Who'd have though the Hume Highway could be so interesting. A comfortable and engaging read.
"Swallows and Amazons" by Arthur Ransom. 3 stars. An enjoyable flight of fancy. Should have read this when I was a kid.
"Life & Adventures of William Buckley" 3 stars. Amazing story. Reads like a litany of violent acts by the Aboriginals he lived with.
"The Catcher in the Rye" by JD Salinger. 3 stars. I didn't understand this book, but it's very well written.
"Biomimicry" by Janine Benyus. 3 stars. Fascinating in places, pedestrian in others. The promise in this book remains distant.
"The Longest Road" by Paul Pritchard. 3 stars. Not particularly engaging, but he must have a will of iron to keep pushing himself.
"Killing Mister Watson" by Peter Matthiessen. 3 stars. Fun to explore pioneering Everglades. Well told, but too few revelations.

2.5 stars:
"The Partner" by John Grisham. 2.5 stars. Somewhat clever light entertainment. Passable holiday reading.
"Riddley Walker" by Russell Hoban. 2.5 stars. Dialect requires concentration. Not much reward though! Didn't understand message.

2 stars:
"Pride of Carthage" D.A. Durham. 2 stars. Historically interesting but not all that engaging - I nearly have up on it.
"It's not about the bike" Lance Armstrong. 2 stars. Comes across as a typical arrogent American athlete. Bloody minded!