65
“Soil Health” Prune Day, Griffith Karl Andersson, DPI Orange
“Soil Health”
Prune Day, Griffith
Karl Andersson, DPI Orange
Soil Health
H lth h i l h i l d bi l i l ti d th• Health = physical, chemical and biological properties and the management requirements and effects on them
• Not simply = soil quality, which is “fit for a purpose”p y q y p p• Eg – sandy soil for vegies
– Easily sterilised (pathogens), well drained (aeration), highly permeable (control water) not easily compacted (trafficable under diff conditions) low(control water), not easily compacted (trafficable under diff conditions), low nut retention (control supply)
– Not necessarily a healthy soilRobust & resilient for plant requirements & ecosystem functions• Robust & resilient for plant requirements & ecosystem functions
• Soil properties and their management for certain situations and plants– Can be targeted to certain limitationsg– May have other effects – positive or negative to other soil properties– Does the management system become dependant on the treatment?
Fit & healthy: SOC may not change but more growth and breakdown• Fit & healthy: SOC may not change but more growth and breakdown (cycling of nutrients, diff bug activity) better than nothing…exercise better than sloth
Physical
Backplain
Clays
Levee
Sandy Red Earth
Meander plain
Red-brown Earth
Subsoil lime….lt t d th?
Free draining,M b idi salt at depth?May be acidic
Gilgai soil
Soil profiles
Recent, layered alluvial soil
Some development
Older,strong differencesalluvial soil development strong differences
Windblown dust
• Dusts blown from arid areas can contain salts • Covers large areas in south eastern Australia
Improving soil structure using gypsum (CaSO4)p g g gyp ( 4)
• increased friability
• improved infiltration and water entry
• increased soil water storage
• increased soil workability
• reduced erosion
Chemical
pH and nutrient availability or toxicity
pH (H2O)
General indication of relative availability for a given nutrient.General indication of relative availability for a given nutrient.
Actual amount depends on fertility, fertiliser, history.
Effects of AcidityEffects of Acidity
Aluminium toxicity stunts root growth Different tolerances – crop optionsstunts root growth p p
Plant Yield Response To Soil Salinity100% Cotton
80%
Barley
Corn
60%d (%
)
Oats
Rice, paddy
40%
entia
l Yie
l
Sorghum
Wheat, durum
Couch grass
20%
Pote Couch grass
Paspalum
Phalaris
0%0 2 4 6 8 10 12 14 16 18 20 22
Phalaris
Orange
Lucerne, Hunter River0 2 4 6 8 10 12 14 16 18 20 22
Soil Salinity ECe (dS/m)
I iti l iti it iInitial sensitivity variesRate of yield decrease steeper for more sensitive plants
Irrigation water quality
• Salts are applied even in good quality irrigation waterirrigation water
• These salts need to be leached beyond the yrootzone to avoid accumulating to high amounts
• This requires an extra amount of water more than the plant needs to flush the salts calledthan the plant needs to flush the salts, called the “leaching fraction”
• The leaching fraction amount depends on the water quality and the equilibrium target soil salinity
Leaching fraction• Leaching fraction = ECiw
2.2 x ECe
• Eg ECiw = 0.1, ECe = 2LF = 0.1/(2.2x2) = 2%
E ECi 0 5 EC 2• Eg ECiw = 0.5, ECe = 2LF = 11%
• Space for leaching…clay subsoils have 10% effective pore spacespace– 10 ML (1000 mm/ha) applied with 10% LF ~ 100 mm– 100 mm in 10% space = 1m water table rise if it is slow to drain
Drip irrigation
• Salt bulge
How much nutrient?
• At a bulk density of 1.2 g/cm3 there is 1200 t soil/ha to 10 cm
Units given as ppm or mg/kg• Units given as ppm or mg/kg10 ppm = 10 mg/kg =10 g/t
> 12 k /h h 10 f il=> 12 kg/ha each 10 cm of soil
• Units given as meq/100g (or cmol+/kg)1 meq/100g =
Nutrient mg/kg kg/ha each 10 cm
C 200 240Ca 200 240Mg 122 146K 391 470
• 2 t canola removes 13 kg P ~ 11 ppm
How much nutrient?
• 2 t canola removes 13 kg P ~ 11 ppm19 kg K ~ 0.02 cmol(+)/kg20 kg S ~ 17 ppmg pp8 kg Ca ~ 0.033 cmol(+)/kg8 kg Mg ~ 0.055 cmol(+)/kg
• 4 t wheat removes 11.2 kg P ~ 9.3 ppm16 kg K ~ 0.034 cmol(+)/kg
8 8 k S 7 38.8 kg S ~ 7.3 ppm2.4 kg Ca ~ 0.01 cmol(+)/kg5.2 kg Mg ~ 0.036 cmol(+)/kgg g g
• 10 t lucerne removes 30 kg P ~ 25 ppm220 kg K 0 47 cmol(+)/kg220 kg K ~ 0.47 cmol(+)/kg20 kg S ~ 17 ppm
100 kg Ca ~ 0.4 cmol(+)/kgg g50 kg Mg ~ 0.34 cmol(+)/kg
1 t 7 k K 0 015 l(+)/k
How much nutrient?
• 1 t prunes remove 7 kg K ~ 0.015 cmol(+)/kg0.4 kg Ca ~ 0.0023 cmol(+)/kg0 5 kg Mg ~ 0 003 cmol(+)/kg0.5 kg Mg 0.003 cmol( )/kg
• Gypsum-> 1t pure gypsum ~230 kg Ca, 186 kg S~ 1 cmol(+)/kg Ca 155 ppm S 1 cmol( )/kg Ca, 155 ppm S
• Lime• Lime-> 1t lime ~ 400 kg Ca~ 1.67 cmol(+)/kg Ca
• Potash (KCl) 50% K( )-> 100 kg potash ~ 50 kg K~ 0.1 cmol(+)/kg K
Biological
Good organic carbon
• Dark, soft, friable, stable soilstable soil
Organic matter• stubble on surface protects the soil• stubble on surface protects the soil• recent organic matter (including roots) is a source of food and energy for microbes
and a source of nutrients• glues from roots and microbes hold particles• decayed (humus) long, charged ropes
- hold sand, silt and clay together Fungalhold sand, silt and clay together- contains, holds and slowly releases nutrients
cations - eg Ca2+
i NO
Fungal hyphae binding particlefanions - eg NO3
-
Soil aggregates
particles
silts, fine sands
20 μmclays silts
A11
A12
A11
A12
B2A12
CB2
BC
B2BC
C
Low organic carbon, slightly dispersive topsoils
Pale, h d thardset, unstable
pH 5 2pHCa 5.2Al% 1.4
pHCa 4.7p Ca
Al% 7.5
Organic amendments
• Persistent OM or OCdoes not supply nutrients it may store and release– does not supply nutrients, it may store and release
– May buffer pH, toxins, improve WHC• Labile
– supplies energy and food for bugssupplies energy and food for bugs– This and further bug procs mineralise N, S, other
nutrientsnutrients
• FLNFPSO• PSO
• Ratios• Organic fertilisers
Rhizobium/legume symbiosis
• Rhizobium strain selection > 100 yrs• Careful innoculant production application to• Careful innoculant production, application to
legume seed• Nitrogenase and O2 don’t mix
– Implications for free living bacteriaImplications for free living bacteria– Soil solutions ~ 360 µM O2
C t li it O diff i– Cortex limits O2 diffusion– Legheamoglobin binds O2
– Internal concentration 10 nM
Free living N fixers• Incomplete understanding, little research• Plants pump out 25-30% fixed C
– Food for micro organisms– Beneficial, benign, pathogenic
• FLNF are in the soil – crops, pastures, legumes, forests, roadsides
• Organisms fix N when it is limiting• Rhizobial N2-fixing symbiosis ~25% C fixed, some others 5-
15%15%• FLNF ~1/10th as efficient as legume/rhizobium smbiosis
Need good energy supply crop residue rhizosphere– Need good energy supply – crop residue, rhizosphere• Seed inoculation with FLNF:
– Correct conditions in rhizosphere (low O2, low N, food supply)p ( , , pp y)– No publications to date showing worthwhile gains
Free living N2 fixing organisms (FLNF)• 90 genera of orgs produce nitrogenase• N2 fixation difficult to measure
– Forests & grasslands – 0.01 to 5 kg/ha/yrCereal fields estimates generally < 5– Cereal fields estimates generally < 5
– Aust ests: 20 (Gupta et al 2006), < 10 (Unkovich & Baldock 2008)• Fertiliser regimes include these amounts – estimates and tests• Can fixation be increased??
f• FLNF are in the soil – crops, pastures, legumes, forests, roadsides• Organisms fix N when it is limiting• Trifolium repens
– spend 4-13% C taking up NO3/NH4+p % g p 3 4
– Rhizobial N2-fixing symbiosis ~25% C fixed • FLNF ~1/10th as efficient as legume/rhizobium smbiosis
– Need good energy supply – crop residue, rhizosphere• Low O condits• Low O2 condits
– wet or waterlogged soils– Produce a gum to limit O2 diffusion– High respiration to lower O2 – 10-50 x normal (meaning high energy cost)
• Seed inoculation:• Seed inoculation:– Correct conditions in rizosphere (low O2, low N, food supply)– No publications to date showing worthwhile gains– As could be expected given their relative inefficiency
P solubilising organisms
S l t P l bili• Some plants are P solubilisers– Phosphatase to access organic Pp g– Organic acids (citrate, malate)
• Bond to Ca or Al dissolving P containing mineralsBond to Ca or Al, dissolving P containing minerals• Adsorb to soil surfaces displacing P
Cluster roots can mine P from very low P soils– Cluster roots can mine P from very low P soils• Low P soils – micorrhizae useful• High P soils – normal plants get enough• Finding P solubilisers• Finding P solubilisers
– Make a soil extract, streak onto a plate containing P l bili d lagar: P solubilisers produce clear agar
P solubilising organisms
L P il i hi f l• Low P soils – micorrhizae useful• High P soils – normal plants get enough • Need a lot of organic acid to have an impact
– citrate best (need >1 mM)( )– Oxalic, malic, tartaric ok (need 1 mM)– Half lives of 2-3 hrsHalf lives of 2 3 hrs– Don’t move far (0.2-1 mm)– Lot of energy to keep making so much organic acidLot of energy to keep making so much organic acid
• Cluster rooted plants are slow growingTrials in India by Neal Menzies:• Trials in India by Neal Menzies:– P responsive sites, Inorganic and organic fertilisers +- P
solubilising orgs > no sig increase in P uptake or yieldsolubilising orgs -> no sig increase in P uptake or yield
Soil testing and interpretation (Koppitke and Menzies 2007)
• We want to test phytoavailability of a nutrientInstantly available (intensity) (soil solution)– Instantly available (intensity) (soil solution)
– Total amount available (quantity) (eg CEC)– Buffering capacity (replenishment of soil solution)
• InterpretationDiffi lt t l t l ti l d t t h t il bilit– Difficult to relate analytical data to phytoavailability and plant growth
– Two methods• SLAN• BCSR
Soil testing and interpretation (Koppitke and Menzies 2007)
• SLAN (sufficiency level of available nutrients)SLAN (sufficiency level of available nutrients)– Once a nutrient is available in sufficient quantity growth will be maximal
(for that nutrient) until toxicity levels occur– Fertilise according to plant’s needs– Levels vary for different plants but…
• Ca 0 5-1 5 cmol(+)/kg (or meq/100g)• Ca 0.5-1.5 cmol(+)/kg (or meq/100g)• Mg 0.2-0.3• K 0.2-0.5
• BCSR (base cation saturation ratio, aka mineral balancing)Id i th t th i b l d ti f ti f th d th t– Idea is that there is a balanced ratio of cations for max growth and that growth is decreased at other ratios. Amount not as important as ratios
– Fertilise according to soil’s needsg– Ratios…
• Ca 65%, Mg 10%, K 5%, H 20% (Bear et al. 1945)C 65 85% M 6 12% K 2 5% (G h 1959)• Ca 65-85%, Mg 6-12%, K 2-5% (Graham 1959)
• Ca 65-75%, Mg 10-20%, K 2-5%, Na 0.5-5%, H 10%, others 5% (Albrecht 1975)
Relating your numbers
• 2 t canola removes 13 kg P 11 ppm• 2 t canola removes 13 kg P ~ 11 ppm19 kg K ~ 0.04 meq/100g20 kg S ~ 17 ppm20 kg S ~ 17 ppm8 kg Ca ~ 0.033 meq/100g8 kg Mg ~ 0.055 meq/100g
• 4 t wheat removes 11.2 kg P ~ 9.3 ppm16 kg K 0 034 meq/100g16 kg K ~ 0.034 meq/100g8.8 kg S ~ 7.3 ppm2.4 kg Ca ~ 0.01 meq/100g2.4 kg Ca 0.01 meq/100g5.2 kg Mg ~ 0.036 meq/100g
10 t l 30 k P 25• 10 t lucerne removes 30 kg P ~ 25 ppm
220 kg K ~ 0 47 meq/100g220 kg K ~ 0.47 meq/100g20 kg S ~ 17 ppm
100 kg Ca ~ 0.4 meq/100g
Changing ratios
• Easy to misinterpret– OM bufferingOM buffering– gypsum solubility
low absolute CEC (small change in number >– low absolute CEC (small change in number –> bigger change in %)
• CEC 10, ESP 10% to 5%,– need in the order of 4 t gypsum (exchange
efficiency of 10%)efficiency of 10%)– double gypsum required if double CEC or ESP%
shiftshift– lime more complex due to OM buffering
Soil testing and interpretation (Koppitke and Menzies 2007)
SSSAJ, Vol 71, No2, March-April 2007 pp259-265Research Update for Growers/Advisers - Northern Region - Aug/Sept 2005, Neal Menzies, Reader in Soil Chemistry, School of Land and Food, University of Quee
• Research pre 1930sR ti f b ti (1892) th t hi h li– Ratios from observation (1892) that high lime (Ca) and Mg were toxic when in large excess wrt
h th R ti d (1901) R d teach other. Ratio proposed (1901). Raw data showed wide suitable range.
– Lipman (1916) review showed no basis for ideal ratios
• Trials had wide range of maximal growth• Lime was used to adjust Ca:Mg but pH effect on toxic j g p
Al and Mn nor increase in available P were accounted for
– Moser (1933) review said low yields in soils with low Ca:Mg was due to low Ca, not excess Mg
Soil testing and interpretation (Koppitke and Menzies 2007)
Current “ideal” conceptCurrent ideal concept
– Bear et al.’s (1938) tentative proposal from New Jersey soils in pot trials or homoionic clay methods of Albrecht and McCalla. Toth (1948), and Bear and ( )Toth (1948), proposed ratios of Ca:Mg 6.5, Ca:K 13, Ca:H 3.25, Mg:K 2., gUnclear how these were established.
T k f h i l h ill– Taken out of context to say that optimal growth will ONLY occur at these ratios.
– Bear et al. stated there was a wide range!
– Also advocated Ca as a means of reducing luxury K uptake which was expensive to replace
Soil testing and interpretation (Koppitke and Menzies 2007)
Current “ideal” conceptCurrent ideal conceptAlbrecht– flawed experiments on need for high Ca saturation– flawed experiments on need for high Ca saturation
• confounded pH and [Ca] (not measuring pH at different [Ca])[Ca])
• mix of H+ saturated clays @ pH 3.6 and Ca saturated clays at pH 7y p
• some Ba saturated clays => Ba toxicity or S deficiency (low solubility of BaSO4)
– flawed interpretation• said poor nodulation on legumes was due to low Ca rather p g
than pH (1937, 1975). However data showed no nodulation at 4, 4.5 or 5 with any [Ca]. Only got nodulation when pH >5 5when pH=>5.5
Soil testing and interpretation (Koppitke and Menzies 2007)
Yield quantityYield quantity– Giddens and Toth (1951) – no specific ratio produced best yield – clover,
4 soils at 7 ratios. Even up to 40% K or 40% Mg were no different to 5% K d 10% Mand 10% Mg
– Mclean (had worked with Albrecht) and Carbonell 1972 on millett and lucerne – no yield diff on Ca:Mg from 2.2 to 14.3lucerne no yield diff on Ca:Mg from 2.2 to 14.3
– Hunter (had worked with Bear) – no lucerne yield diff on Ca:Mg 0.25 to 31– Key et al. (1962) soy in sand-resin mixes w variety of CEC and Ca:Mg y ( ) y y g
from 0.02 to 50. If Ca:Mg >1 then fine– WANTFA 2005 – wheat, barley, canola, lupins – field trials over 6 yrs – no
real influence from Ca:Mg 0 4 to 17real influence from Ca:Mg 0.4 to 17– Hunter 1943 – lucerne, Ca:K from 1 to 100 ok– Bear et al 1951 – K:Mg ‘even more important’ but data showed no diff in– Bear et al. 1951 – K:Mg even more important but data showed no diff in
tomato from K:Mg 1 to 20• It is understood that high K fertiliser can reduce Mg uptake
– Ologunde and Sorenson 1982 – K:Mg up to 7.7, no sorghum penalty so long as sufficient absolute amount
Soil testing and interpretation (Koppitke and Menzies 2007)
Yield quality– Bruce et al. (1988) – adding Ca as CaCl2 or gypsum -> no diff
at pH(H2O) of 4.6 to 5.6 unless pH increased. Add as lime -> longer rootsS (200 ) diff i li f C M 2 6– Stevens (2005) cotton – no diff in quality from Ca:Mg 2.5 to 7.6
– Schonbeck (2000) vegetables in Virginia trial. Ca <65%, Mg 18 28% Addi li > M th 11 21% b t h i B i18-28%. Adding lime -> Mg then 11-21% but no change in Brix soluble solidsKelling et al (1996) no effect from Ca:Mg on lucerne yield or– Kelling et al. (1996) no effect from Ca:Mg on lucerne yield or crude protein
– Foy (1984) & many others – low pH -> increase in Al and Mn inFoy (1984) & many others low pH > increase in Al and Mn in solution -> damages plants
– Alva et al. (1987) – acidic and Al -> lower nodulation inAlva et al. (1987) acidic and Al lower nodulation in legumes
Soil testing and interpretation (Koppitke and Menzies 2007)
G i• Grazing– Albrecht 1941, 1942 lime and phosphate
i d lit d h lth d t iti f i i l• increased crop quality and health and nutrition of grazing animals• also increased yield – so poor quality before probably due to
growth limiting factors g g• optimum application rates were not determined and the soil was
not measured!!t > l i l i ht i li i > l P t• some rates -> less animal weight gain…overliming –> less P, trace
elements
• Mg deficiency in stock – even when enoughMg deficiency in stock even when enough Mg…warming temperatures after cool wet conditions sees luxury K in grasses…Mgconditions sees luxury K in grasses…Mg consumption by livestock may be lower (Grunes et al.1970). The ‘ideal’ Mg ratio still not relevant here ) g(McLean and Carbonell 1972)
Soil testing and interpretation (Koppitke and Menzies 2007)
• Soil physical– Mg soils also Na soils wide rangeMg soils also Na soils…wide range,
management important, salinity level
• Soil biology– Not much data around on biology and ratios– Vegetable trial (Schonbeck 2000) no effect onVegetable trial (Schonbeck 2000) no effect on
om, biol activity, weeds, disease, disease or pest damagep g
– Kelling et al. (1996) – no variation in earthworms or weedsearthworms or weeds
Soil testing and interpretation (Koppitke and Menzies 2007)
• Cost– Kojonup – BCSR cost $700/ha over several years cf SLAN
$60/ha for same or less returns – Nebraska 8 yr period – fertiliser use comparison saw BCSR
t d bl th t f SLAN d ticost was double that of SLAN recommendations– Local recommendation comparison
BCSR 5 t 4 2 t li• BCSR: 5 t gypsum + 4.2 t lime• SLAN: no gypsum, 1.4 t lime
• Conclusion– There is no narrow ideal ratio. This was explicitly stated by p y y
McLean et al. (1983). McLean worked with Albrecht in the 1940s
– Supply nutrients in sufficient, but not excessive, amounts– BCSR is an inefficient use of resources
Wheat (Matong) Dd 1988Barley (Schooner) Dd 1988Triticale (Currency) Dd 1988
40003500
4500
3000
3500
2500
3000
3500
4000
2500
g/ha20
04
2000
2500
g/ha 2500
3000
g/ha
1500
2000
grai
n k
Liu
et a
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1500grai
n kg
1500
2000
grai
n kg
500
1000
L
500
10001000
1500
0
500
0 10 20 30 40 50 600
500
0
500
0 10 20 30 40 500 10 20 30 40 50 60
Ca:Mg0 10 20 30 40 50 60
Ca:Mg
0 10 20 30 40 50
Ca:Mg
Wheat (Matong) Dd 1988
pH
Barley (Schooner) Dd 1988Triticale (Currency) Dd 1988
40003.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
pH
35003.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
pH
45003.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0
pH
3000
35003000
3500
3500
4000
4500
2004 2500
3000
ha 2000
2500
ha 2500
3000
3500
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Ca/Mg
pHL
1000
1500 Ca/Mg
pH
500
1000 Ca/Mg
pH1000
1500 pH
0
500
0
500
0 10 20 30 40 50 600
500
0 10 20 30 40 500 10 20 30 40 50 60
Ca:Mg
0 10 20 30 40 50 60
Ca:Mg
0 10 20 30 40 50
Ca:Mg
Wheat (Matong) Dd 1988
7
Barley (Schooner) Dd 1988
7
Triticale (Currency) Dd 19887
6.5
7
6.5
7
6.5
5 5
6
5 5
6
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6
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pH2004 5
5.5
pH 5
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Liu
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30 10 20 30 40 50 60
30 10 20 30 40 50 60
30 10 20 30 40 50
Ca:Mg0 10 20 30 40 50 60
Ca:Mg0 10 20 30 40 50
Ca:Mg
Matong Dd 1988Schooner Dd 19883500
Currency Dd 1988
3500
40003000
3500
4000
4500
3000
3500
2500
3000
3500
2000
2500
kg/
ha
2004
2000
in k
g/ha
2500
3000
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a
1500
2000
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3 3 5 4 4 5 5 5 5 6 6 5 7pH
3 3.5 4 4.5 5 5.5 6 6.5 7
pH
3 3.5 4 4.5 5 5.5 6 6.5 7
pH
wheat tissue vs soil Ca/MgBarley tissue vs soil Ca/Mgtriticale tissue vs soil Ca/Mg
3.003.50
triticale tissue vs soil Ca/Mg
3.00
2 00
2.50
2 50
3.002.50
1.50
2.00
nt C
a/M
g
2.00
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e C
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Tiss
ue
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0.50
0.50
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0 00
0.50
0 10 20 30 40 50 60
soil Ca/Mg0.00
0 10 20 30 40 50 60
0.000 10 20 30 40 50
Soil Ca/MgSoil Ca/Mg
Liquid organic product fertilisersD. C. Edmeades (2000) The effects of liquid fertilisers derived from natural products on crop, pasture, and animal
d ti A i
• 810 field trials measuring the effect of 28 li id f tili d i d f i
production: A review
liquid fertilisers derived from organic materials on crop yields:– 15 from seaweed, 4 fish waste, 5 vegetable, 2
animal products– 328 cereals, 227 root crops, 88 legumes, 59
pastures, 52 vegetables, 15 rape, 8 peanuts, 6 t b 25 thtobacco, 25 other.
– 4 trials on animal performance
• Edmeades found that the products do not contain sufficient concentrations of plant nutrients, organic matter, or plant growth substances to increase in plant growth when applied as recommended
Eg: pH• Soil quality and health issue • Acidic = state of that property poor healthAcidic state of that property, poor health• Manage to improve health, change state
– N mgt, liming products, stubble & pasture mgt
Mgt options, promotions…• Legal issues associated w advice• Legal issues associated w advice• Verification of claims often limited• Eg Doug Edmeades
• eg N fixation (T = 1012 = Mt)– Biol 90-140– Biol 90-140– Lightning <10
Symbiosis w crop legumes– Symbiosis w crop legumes • Soybean 16• Peanut 2• Chickpea 0.6
– Pasture legumes 12-25– Fertiliser 160
Bell moody etc• Nthn• Declining SOC w cropping, degree varies w soil type• Changing tillage has little impactg g g p• Pasture phases +ve but tillage and fallow negate benefits• less biol suppression, more and worse soil borne diseases• Poor physical env (compaction, infiltn, hardsetting)
– See paper from India, Soil Science March 2010• Little assessment of C quality…less inputs and diversity in crops will limit diversity
of inputs• Cane: quicker breakdown of the large biomass > no increas in SOC• Cane: quicker breakdown of the large biomass -> no increas in SOC• Nutrient balances:
– Cereals - -ve– Sugar - +ve N, P, -ve K, Sg , , ,– Hort – excessive everything
• Horticulture: inadequate or non existent guidelines for many crops• Fertilisers only small % of cost• Water quality (off site) will drive reforms• Acidifn:
– N leaching, short term breeding toleranceImplications for biota and rotation spp– Implications for biota and rotation spp
– Cost for remediation
stapper• -ve impacts in Qld – Bell 2005• Soil health – organisms breaking down OM and toxic compounds,
controlling pathogens, helping obtain nutrientsg p g , p g• “science has resulted in research within very narrow boundaries…linear,
mechanistic thinking…confusion between cause and effect…Soils…have become partitioned into …chemistry, physics and biology…degradation
t b l d ith i di id l h j t d t d b…cannot be solved with many individual research projects conducted by various specialists” but by generalists espousing banalities
• “research needs to be planned, executed and analysed by a transdisciplinary team working across ecosystems at representativetransdisciplinary team working across ecosystems at representative scales, that is, in agroecology” which is the same thing as compiling ‘narrow’, ‘partitioned’ research projects!
• “C can help stop dryland salinity (Jones 2006)”C can help stop dryland salinity (Jones 2006)• “Over the past 60 years, mineral density of foods has declined to less than
half of former levels (Bergner 1997, McCance and Widdowson 2000)”• “Worthington (2001) and the Soil Association (2002) found genuineWorthington (2001) and the Soil Association (2002) found genuine
differences in nutrient content of organic and conventional crops –improvements which could be even greater if all organic crops are actively managed with microbes and minerals”
