Contribution of Plant Mineral Nutrition to Global Food ... · Plant Mineral Nutrition • The study of how plants obtain, distribute, metabolize, and utilise mineral nutrients •

Contribution of Plant Mineral Nutrition to Global Food Security

Philip J. White

Environment Plant InteractionsProgramme at SCRI

UWA Institute of Agriculture, 1st February 2011

Babylonian Proverb

A man who has food has many problems

A man who has no food has only one

UWA Institute of Agriculture, 1st February 2011

Outline of Talk

• Plant Mineral Nutrition

Principles of Plant Mineral NutritionA Short History of Mineral Fertilisers

• Food Security

Challenge 1 – Sufficient FoodChallenge 2 – Nutritious FoodChallenge 3 – Safe Food

• Can We Achieve Food Security?

Plant Nutritional Requirements

• Plants are capable of making all necessary organic compounds from inorganic compounds and elements in the environment (autotrophic)

• They are supplied with all the carbon, hydrogen, and oxygen they need as CO2 and H2O

• All other elements must be obtained (often) from the soil solution by roots

Plant Mineral Nutrition

• The study of how plants obtain, distribute, metabolize, and utilise mineral nutrients

• Mineral: An inorganic element

• Nutrient: A substance needed for survival or necessary for the synthesis of organic compounds

White & Brown (2010) Ann. Bot. 105: 1073-1080

Essential Mineral ElementsRequired for plant growth and/or reproduction

Cannot be replaced by another element

Have unique physiological or biochemical roles

Essential & Beneficial Elements

Essential Elements – Deficiencies & Toxicities

White & Brown (2010) Ann. Bot. 105: 1073-1080

Essentiality Critical Leaf Concentrations (mg g-1 DM)Element Plant Animal Sufficiency ToxicityNitrogen (N) yes yes 15 - 40Potassium (K) yes yes 5 - 40 > 50Phosphorus (P) yes yes 2 - 5 > 10Calcium (Ca) yes yes 0.5 - 10 > 100Magnesium (Mg) yes yes 1.5 - 3.5 > 15Sulphur (S) yes yes 1.0 - 5.0Chlorine (Cl) yes yes 0.1 - 6.0 4.0 - 7.0Boron (B) yes suggested 5-100 x 10-3 0.1 - 1.0Iron (Fe) yes yes 50-150 x 10-3 > 0.5Manganese (Mn) yes yes 10-20 x 10-3 0.2 - 5.3Copper (Cu) yes yes 1-5 x 10-3 15-30 x 10-3Zinc (Zn) yes yes 15-30 x 10-3 100-300 x 10-3Nickel (Ni) yes suggested 0.1 x 10-3 20-30 x 10-3Molybdenum (Mo) yes yes 0.1-1.0 x 10-3 1

Sodium (Na) beneficial yes - 2-5Selenium (Se) beneficial yes - 10-100 x 10-3Cobalt (Co) beneficial yes - 10-20 x 10-3Iodine (I) - yes - 1-20 x 10-3

Plant Mineral Nutrition and Crop YieldLiebig’s Law of The Minimum

Crop yield is determined bya critical input that is inshort supply: the limitingfactor. This is often N.

Inputs that do not correctthe limiting factor aregenerally ineffective inincreasing yield.

Essential Mineral Elements

P=200 kg/ha, K=100 kg/ha

0

5

10

15

20

0 100 200 300 400 500N fertiliser (kg/ha)

DM

yie

ld (t

/ha)

N=500 kg/ha, K=100kg/ha

0

5

10

15

20

0 50 100 150 200P fertiliser (kg/ha)

DM y

ield

(t/h

a)

N=500kg/ha, P=200kg/ha

0

5

10

15

20

0 50 100 150 200K fertiliser (kg/ha)

DM y

ield

(t/h

a)White et al. (2006) In: Potato Biology and Biotechnology,

Advances and Perspectives, pp.739-752

Responses in potato yields to N, P and K fertilisation predicted by simulation models (http://www.qpais.co.uk/)

nitrogen phosphorus potassium

Soil Fertilisers are Ancient History

Crop production began

Ancient Chinese using organic manures

Ancient Greeks and Romans using animal manures, composts, bones, plant ash (potash), seaweed, saltpeter (potassium nitrate) as fertilisers, and liming materials to correct soil acidity

Egyptians and Mesopotamians using river silt

10,000 1,000 100 10 1 0years before present

Chemical fertiliser industry began about 250 years ago…

Nitric acid 1771

Chilean Nitrate 1830Ammonium sulphate (from coal) 1830Superphosphate 1842

Nitrogen from the air 1911

Nitrogen from the Air (1911)

The Haber-Bosch process, is the production of ammonia from nitrogen and hydrogen gases over an enriched iron or ruthenium catalyst.

The Haber-Bosch process produces about 500 million tons of nitrogen fertilizer per year, mostly in the form of anhydrous ammonia, ammonium

nitrate, and urea, consumes about 1% of the world's annual energy supplyand sustains 40% of the world’s population.

The Haber-Bosch process has been called “the most important invention of the 20th century”.

It “detonated the population explosion”, driving the world's population from 1.6 billion in

1900 to 6 billion in 2000.

Smil (1999) Nature 400, 415; Fryzuk (2004) Nature 427, 498

The Green Revolution Norman Borlaug “the man who defused the population bomb”

Breeding for Improved Varieties

“Plant Breeding is responsible for about 50% of crop productivity increase over the last century, while the

remainder of the yield increase comes from better crop management (e.g. fertilization, irrigation, weeding)”

Food and Agriculture Organization of the United Nationshttp://km.fao.org/gipb/

Fertilisers and The Green Revolution

Grain yields at Rothamsted Broadbalk Field (since 1843)

Grain yields at Rothamsted Broadbalk field

0123456789

10

1850 1900 1950 2000

Gra

in (t

/ ha

)

PK + 144 kg N

PK + 48 kg N

Unmanured

Flan

ders

Brim

ston

e

fung

icid

es

wee

dkill

ers

Red

Ros

tock

Red

Clu

bSq

uare

head

M

Squa

rehe

ad M

Red

Sta

ndar

d

Cap

elle

Des

prez

Apol

lo

Fertilisers and The Green Revolution

Australian Wheat Yields

Kirkegaard & Hunt (2010) J. Exp. Bot. 61, 4129-4143

Production of Commodity Crops (1965-2008)

The use of fertilizers accounts for approximately 50% of the yield increase, and greater irrigation for another substantial part.

Nellemann, et al. (2009) The Environmental Food Crisis, UNEP

Crop Production and Resource Consumption

Nellemann, et al. (2009)The Environmental Food Crisis,

UNEP

Increased crop yields are paralleled by increases in:the consumption of nitrogen and phosphate fertilisers

the amount of irrigated landthe use of pesticides

Global Increase in Crop Yield

Breeding of improved varieties (especially shorter cereals and disease resistance)

Improved weed control

Improved pest and disease control

Application of fertilisers

Irrigation (especially S and SE Asia)

Evans (1993) Crop Evolution, Adaptation and Yield.Cambridge University Press.

Potential Losses to Pests and Diseases(Expressed as % Yield)

Oerke (2006) Crop losses to pests. J. Agric. Sci. 144, 31-43

Crop Weeds Animals Pathogens Viruses TotalWheat 23 9 16 3 50Rice 37 25 14 2 77

Maize 40 16 9 3 69Potato 30 15 21 8 75

Soybean 37 11 11 1 60Cotton 36 37 9 1 82

Losses to Pests and Diseases(Expressed as % Yield)

Crop Without Pest Control Using mechanical, biological & chemical control measures

Wheat 50 28Rice 77 37

Maize 69 31Potato 75 40

Soybean 60 26Cotton 82 29

Oerke (2006) Crop losses to pests. J. Agric. Sci. 144, 31-43

Postharvest Losses are Significant


There are significant postharvest losses in:Fresh fruits and vegetables

Fluid milkProcessed foods and vegetables

Meat, poultry and fishGrain products

Caloric sweetenersFats and oils

Other foods (including eggs and other dairy products)

Food Security - Definition

“Food Security exists when all people, at all times, have physical and

economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an

active and healthy life”

FAO World Food Summit (1996)

Challenge 1 – Sufficient Food for Nine Billion

global population is projected to increase from 6.8 billion in 2009to over 9 billion in 2050

Source: UN Population Division, World Population Prospects: The 2008 Revision, medium variant (2009)

Feeding The Nine Billion

Source: FAO, USDA, Goldman Sachs Commodity Research

“strong demand will require a substantial increasein acreage, which has been virtually unchanged

for decades”

“in the past demand growth has been met throughyield growth, however the strong demand growth

ahead will create a need for substantialacreage expansion”

Feeding The Meat Eaters

Source: FAO, USDA, Goldman Sachs Commodity Research

“food demand is stable, feed demand is rising,and fuel demand is exploding”

Projected Contributions (%) to Increased Crop Production between 1997/99 and 2030

Land area expansion

Increase in cropping intensity

Yield increase

All developing countries

21 12 67

Sub-Saharan Africa

27 12 61

Near East/North Africa

13 19 68

Latin America and Caribbean

33 21 46

South Asia 6 13 81East Asia 5 14 81

J Bruinsma (2003) World Agriculture: towards 2015/2030: an FAO perspective. Earthscan Publications Ltd.

Land Suitable for Rainfed Crops


Yield Gaps

The difference between actual and potential crop production.

“By definition, yield potential

is an idealized state in which a crop grows

without any biophysical limitations other than

uncontrollable factors, such as solar radiation,

air temperature, and rainfall in rainfed systems”

Lobell et al. (2009) Annu. Rev. Environ. Resour. 34, 179-204

Global Yield Gap for Wheat

Global aggregated yield gap = 43%(cf. 60% for maize and 47% for rice)

Neumann et al. (2010) Agricultural Systems 103, 316-326

Major Contributors to Yield Gaps


Biophysical factors Socioeconomic factorsNutrient deficiencies & imbalances (N,P,K,Zn…) Profit maximization

Water stress Risk aversion

Flooding Inability to secure credit

Soil problems (salinity, alkalinity, acidity, iron, aluminum, or boron toxicities, compaction…)

Lack of knowledge on best practices

Weed pressures Limited time devoted to activitiesInsect damage

Diseases (head, stem, foliar, root)

Suboptimal planting (timing or density)

Lodging (from wind, rain, snow, or hail)

Inferior seed quality

Analysis of Yield Gaps

A wide range of yield gaps exists – 20 to 80% of yield potential

Estimates most difficult in rainfed conditions

Many irrigated cropping systems have yields at, or approaching 80% of potential – difficult to improve

Closing yield gaps will depend on developing technologies that address husbandry, mineral nutrition, irrigation, soil conditions, crop protection


Plant Mineral Nutrition and Crop YieldLiebig’s Law of The Minimum

Crop yield is determined bythe limiting factor.

Inputs that do not correctthe limiting factor aregenerally ineffective inincreasing yield.

Current Constraints to Crop ProductionWater

Current Constraints to Crop ProductionSoil

Phytoavailability of Mineral ElementsLimits Crop Production on Many Soils

agricultural soils: acid (35-40%, red), alkaline (25-30%, blue), saline (5%)

crop production is limited by soil pH

wikipedia

Phytoavailability of Mineral Elements

• Each element has an optimum pH for availability

• Most elements available between pH 6 to 7

• High pH limits the uptake of P, B, Fe, Zn, Cu and Mn

• Plant roots can acidify the rhizosphere

• Liming can be used to adjust pH if soil is acidic

Root Traits for Acid SoilsTarget the Limiting Factor – Aluminium Toxicity

Al exclusion allows roots to grow

Chelate Al in the rhizosphere by releasing organic acids or mucilage at root tip

Raise rhizosphere pH

Increase Al-binding to cell wall

These also improve P acquisition

Sequestering Al in root vacuoles

Delhaize et al. (2007) FEBS Letters 581: 2255-2262

Control

TaALMT1

Management for Alkaline Soils

Poor soil structure and a low infiltration capacityOften have hard calcareous layer at 0.5 - 1 m depth

Soil alkalinity is associated with calcium carbonateOr, on alkaline sodic soils, sodium carbonate

Low availability of P, N, Fe, Zn, Mn, Cu and B

Main constraint: lime-induced Fe and Zn deficiencies

The pH of alkaline calcareous soils, where crop production is limited by high pH, Ca2+ and bicarbonate concentrations, can be lowered by the addition of S, Fe-sulphates or aluminium sulphate and fertilisers containing urea, ammonium or phosphate

Root Traits for Alkaline Soils Target the Limiting Factor – Iron and Zinc Deficiencies

Rhizosphere acidification

Efflux of organic acidsEfflux of phytosiderophoresEfflux of phenolics

Mycorrhizal associationsBeneficial microbes

Management of Saline and Sodic Soils

Toxicities:Na and Cl on saline soilsB and Na on sodic soils

soluble salts accumulate with water flowsnear the surface of the soil

or in subsoil moisture

SSaline soils can be remediated by leaching soluble salts from the soil profile by flushing with fresh water

Sodic soils can be remediated by applying Ca2+, often as gypsum, followed by flushing with fresh water

Root Traits for Saline or Sodic SoilsTarget the Limiting Factor – Sodium or Boron Toxicity

Exploitation of “salt-free” zone

Exclusion of Na, B or Cl• Increased expression of B efflux transporters (BOR genes) in roots• Na exclusion from leaves by retrieval from xylem sap (HKT genes)

Prevent apoplastic bypasses

Sequestration in non-vital compartments

Munns & Tester (2008) ARPB 59: 651-681Reid (2010) Plant Science 178: 9-11

Efficiencies of Wheat Production(and the most limiting factors in different regions)

Factors affecting yield gaps vary by region and are related to complex social, economic and political processes

Neumann et al. (2010) Agricultural Systems 103, 316-326

Can We Produce SufficientFood for Nine Billion?

9.5 billion

Increase Agricultural LandProvide Appropriate InputsPrevent Preharvest LossesPrevent Postharvest Losses

Koning & van Ittersum (2009) Curr. Opin. Environ. Sustain. 1, 77-82

Can We Produce SufficientFood for Nine Billion?

we are approaching the necessity of increased yields

by increasing the level of complexityof agricultural systems

and increasing energy inputs

research priorities “for advancing global welfare” as ranked by eight of the World’s top economists

SOLUTION CHALLENGE1 Micronutrient supplements for children (vitamin A and zinc) Malnutrition2 The Doha development agenda Trade3 Micronutrient fortification (iron and salt iodization) Malnutrition4 Expanded immunization coverage for children Diseases5 Biofortification Malnutrition6 Deworming and other nutrition programs at school Malnutrition & Education7 Lowering the price of schooling Education8 Increase and improve girls’ schooling Women9 Community-based nutrition promotion Malnutrition

10 Provide support for women’s reproductive role Women

http://www.copenhagenconsensus.com/About%20CC08/The%20Basic%20Idea.aspx

Challenge 2 – Nutritious Food

Of the 6 billion people in the world,

60-80% are Fe deficient, over 30% are Zn deficient, 30% are I deficient and about 15% are Se deficient

Mineral Elements with Low Phytoavailability

White & Broadley (2009) New Phytologist 182, 49-84

Of the soils in the world,

25-30% are alkaline with low Fe, Zn, Cu & Mn availability many lack sufficient I and Se for adequate animal nutrition

Through Agronomy

the application ofmineral fertilisers

Increasing Mineral Concentrations In Crops

White & Broadley (2005) Trends in Plant Science 10, 586-593White & Broadley (2009) New Phytologist 182, 49-84

Biofortification with selenium

Screening potato genotypes

Through Genetics

select or breed varieties that accumulate minerals

Biofortification – Agronomic Strategies

• If mineral elements are absent from the soil they must be applied to crops as soil or foliar fertilisers (plants cannot synthesise mineral elements)

• If mineral elements are present in the soil, either agronomic or genetic strategies are developed to increase their phytoavailability, or mineral elementsmust be added as soil or foliar fertilisers


Agronomic Biofortification with Zinc(Anatolia, Turkey)

Cakmak (2004)Proceedings IFS 552

http://www.harvestzinc.org/

Agronomic Biofortification with Zinc(Anatolia, Turkey)

Project of 1 million USD

Provided a Net Incomeof 100 million USD p.a.

The International Fertilizer Industry Association (IFA): The Anatolia initiative is oneof the world's first examples of using agricultural practices to address publichealth problems as well as improved crop production, and its successprovides a model for countless other nations. More soils throughout the world lackzinc than any other micronutrient. About 50 per cent of the world populationsuffers from iron and zinc deficiencies, which can be addressed throughthis cost-effective method. (http://www.fertilizer.org/ifa/aw_ 2005.asp).

Agronomic Biofortification with Iodine(China)

5% potassium iodate dripped into irrigation canalgiving 10-80 µg / L in water

increased water soluble iodine in soil from 19 to 277 µg / Limproved human and animal iodine status and health

Jiang et al. (1997) Arch. Environ. Health 52: 399-408

Mandatory Selenium Fertilisation(Finland)

Enrichment of fertilisers with Se in FinlandIncreased grain Se concentrations

and daily selenium intakesfrom below the RDI to the RDI

Broadley et al. (2006) Proceedings of the Nutrition Society 65, 169-181.

Biofortification – Genetic Strategies

• If mineral elements are absent from the soil they must be applied to crops as soil or foliar fertilisers

• If mineral elements are present in the soil, crops can be developed that acquire mineral elements or distribute mineral elements to edible tissues more effectively

• There are physiological constraints associated with the edible tissue consumed

• There are phylogenetic constraints associated with evolutionary events impacting mineral composition


Mineral Concentrations of Edible PortionsPhysiological & Phylogenetic Constraints

Movement of mineral elements to edible tissues


• Elements of dietary importance: zinc, iron, nitrogen

location of mineral elements in wheat grain

Cakmak et al. (2010) Cereal Chemistry 87, 10-20


White & Broadley (2005) Trends in Plant Science 10: 586-593

Zn (mg kg-1DM) Ca (mg kg-1DM)Fe (mg kg-1DM)0 100 200 300 400 500 0 100 200 300 400 0 1 2 3 4 0

Brassicaoleracea

(leaves)

Phaseolusvulgaris

(seed)

Triticumaestivum

(seed)

Possible Ca-deficiencyupon transfer from bean-rich to cereal-rich diet


Pfeiffer & McClafferty (2007) Crop Science 47, S88-S105

Within-Species Variation inConcentrations of Mineral Elements

There is considerable genetic variationin mineral concentrations in edible portions of:

maize, wheat, polished rice, barley, pearl millet, sorghum,beans, cowpea, lentil,

cassava, potato, sweet potato and yams

QTL Impacting Mineral Concentrations inEdible Portions of Diverse Crop Species

Few genes underlying QTL for mineral concentrations have been identified

Crop Species Elements QTL Tissue ReferencesRice (Oryza sativa)

FeFe, ZnPhytate

33, 22

graingraingrain

Gregorio et al. (2000)Stangoulis et al. (2007)Stangoulis et al. (2007)

Bean(Phaseolus vulgaris)

Fe, ZnFe, Zn, CaZnFe, Zn, CaFe, ZnPhytateTannin

7, 112, 1, 21013,134

seedseedseedseedseedseedseed

Beebe et al. (2000)Guzmán-Maldonado et al. (2003)Cichy et al. (2005)Gelin et al. (2007)Blair et al. (2009)Cichy et al. (2005)Guzmán-Maldonado et al. (2003)

Brassica oleracea Ca, MgFe, Zn

7, 4 leafleaf

Broadley et al. (2008)Broadley et al. (2010)

Brassica rapa Ca, Mg, CuFe, ZnPhytatePhytate

0, 1, 01, 252

leafleafleafseed

Wu et al. (2008)Wu et al. (2008)Zhao et al. (2007)Zhao et al. (2007)

Potato(Solanum tuberosum)

Fe, ZnCa, Mg, Cu

tubertuber

White et al., unpublishedWhite et al., unpublished

Summary – Sufficient Food – Increasing Yields

plants require at least 14 mineral nutrientssupplying these in fertilisers has increased crop yields

yields still limited by phytoavailability of mineral nutrients

in the immediate future need to address “yield gaps”yield gaps can be addressed through agronomy

and/or germplasm can be developed for hostile soils

reduce losses to pests and diseasesreduce postharvest wastage

need to produce more with less resource

roots of the second green revolution…

Summary – Nutritious Food – Biofortification

many people are at risk of mineral deficienciesagronomic biofortification of crops can be successful

if minerals are present in the soilcrops can be developed to accumulate them

there are physiological and phylogenetic constraintsto the accumulation of minerals

there is significant variation between genotypesin mineral acquisition and accumulation in edible tissues

roots of the second green revolution…

Plant Roots Acquire Mineral Elements(provided they are available in the soil solution)

Lynch JP (2007) Roots of the Second Green Revolution. Australian Journal of Botany 55, 493-512.

Contribution of Plant Mineral Nutrition to Global Food Security

Sufficient, Safe & Nutritious Food

Documents

Contribution of Plant Mineral Nutrition to Global Food ... · Plant Mineral Nutrition • The study of how plants obtain, distribute, metabolize, and utilise mineral nutrients •