introduction into urban agriculture and agronomic aspects of organic waste reuse eawag peak course...

Introduction into urban agriculture and agronomic aspects of organic waste reuse

EAWAG PEAK Course

Dionys Forster

Duebendorf, June, 2005

2

• Introduction into urban agriculture– Definition

– Objectives

– Processes

• Characteristics of urban agriculture in Cuenca, Dakkar, Dar es Salaam, and Hanoi (Video)

• Agronomic aspects of waste reuse– Plant growth and soil fertility

– Crop nutrient requirements

– Integrated soil fertility management

– Simplified nutrient balance

Con

tent

s

3

• Demographic growth and increase in urbanisation – challenges of the next decade!

Intr

oduc

tion

World’s population living in the cities

- 1994 about 45%

- 2025 about 65%

(x 10)

Urban population living in cities [billion]

0

2

4

6

8

10

1994 2025 Urban Pop World Pop

Introduction into urban agriculture

4

Poor people in % of total urban population in in dev. countries

0

10

20

30

40

50

60

1988 2000

Poor people in urban areas

- 1988 about 25%

- 2000 about 56%

• About 90% of urban growth takes place in developing countries!

Intr

oduc

tion

5

• Urban agriculture (UA) can contribute to mitigating the problems in Third World cities – poverty and waste management!

• Today, roughly 800 million people are involved in UA– 200 million produce for the public market

– 150 million are full-time employees

• Main objectives are– food security

– poverty alleviation

– public health

– sustainable recourse management

Intr

oduc

tion

6

• Agricultural processes are – agricultural practices

– soil quality management

– irrigation

– animal feeding

– public health management

– urban policy and planning

• Products of UA are– food/ non-food products

– money

– compost

– emission

– health impact

– etc.

Intr

oduc

tion

7

Intr

oduc

tion

Definition of urban agriculture

• Urban agriculture comprises the production, processing and distribution of a diversity of foods (e.g. vegetables and animal products) within intra- and peri-urban area.

• Main motivation is food production and higher income.

8

Food security

• Definition: All people have access to enough food at all time for an active and healthy life.

• Why food security?– most of food is required by households

– dependence on market systems and

processed foods

– balancing the food diets

Intr

oduc

tion

Food security depends very much on employment and income!

9

Food security (cont.)

• UA rises especially the food security of low-income residents and vulnerable groups

• Farming households are better off in terms of– energy and protein

– vitamins (vegetable consumption)

• Vegetable supply through urban agriculture

Intr

oduc

tion

Hong Kong Karachi

Dakar

UPA

RA

Hong Kong Karachi Dakar

45 % 50 % 70 %

10

Poverty alleviation

• Production of food products generates– real income through product sales

– fungible income through substitution of market goods by self-produced food products

• Saved money can be spent for other basic needs or invested in businesses.

Intr

oduc

tion

Poor women can improve their household finances through UA activities!

11

Poverty alleviation (cont.)

• The opportunity to acquire healthy food is decreasing for urban poor and middle-class families– structural unemployment

– currency devaluation

– inflation

– no subsidies

Intr

oduc

tion

Food expenditure compared to income (%)

0102030405060708090

100

1 Food Income

• UA belongs to the informal economy (no contribution to GDP)

12

Public health

• Public health is aiming to – promote the well-being

– prevent diseases and disabilities

– enhancing quality of life

Intr

oduc

tion

RessourceManagement

Food security

Physical work

Clean air

Public Health

13

Sustainable resource management

• Deploring urban environmental

conditions in cities of DC

• Serious urban environmental

problem: Urban waste!

• Common attitude: Cities focus on getting rid of their waste and fail to recognise its economic asset!

• UA has a considerable potential for – improved water management trough wastewater use– closing the nutrient loop through reuse of organic waste– reducing the daily flow of food into cities, thus saving fossil fuelIn

trod

uctio

n

14

Characteristics of urban agriculture in Cuenca, Dakkar, Dar es Salaam, and Hanoi (Video)

Cha

ract

eris

tics

of U

A

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Agronomic aspects of waste reuse (i)

• Farmers’ main interest is to produce food and non-food products for subsistence or market selling

• Farmers’ focus is on good plant growth and high yields

What are the main factors influencing plant growth?

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ic a

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ts

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Growth factors are energy (light, warmth), carbon-dioxide, water, and soil and soil fertility including different types of nutrients.

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ts

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Nutrients for growth

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ic a

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ts

Mother Rock

Superficial soil layer with organic matter

Tree with roots to the mother rock

Nutrient uptake

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Organic matter

- Vast array of carbon compounds in soil- Created by plants, microbes, and other organisms- Living and dead plants and organisms

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ic a

spec

ts

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ts

quickly available for plant growth

Soil organic matter in virgin soils

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Effect of organic matter on soil properties

Organic matter improves all properties of the soil:

- Nutrient recycling is improved- Organic matter and clay form compounds that can store

nutrients- Micro-organism development is better - The water dynamics is positively influenced

- Soil water is stored over a longer time period

- Water infiltrates easier

- Soil water evaporation is reduced

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ts

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Organic matter improves further

- The formation of water resistant aggregates

- Reduces crusting, compaction

- Increases the number of soil pores and facilitates the exchange of gases

- Creates better conditions for root development

Other effects:

- Phytosanitary effect (depression of pests, diseases)

- Chemicals break down easier

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ic a

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Nitrogen - the most important plant nutrient

Nitrogen fixation through bacteria

Decomposition and mineralisation

Atmospheric N-fixationNitrogen fixing

legume

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ic a

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ts

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Organic matter: Soil organic matter and nitrogen function

- Strong influence of organic matter on soil organic matter in semi-arid regions

- 86 % of nitrogen used by plants comes from soil organic matter

- Type of crop and crop residues influence strongly the content of carbon in the soil and thus also the content of nitrogen

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ic a

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ts

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Function of N-P-K in the plant

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ic a

spec

ts

Element, Compound

Function Symptoms of deficiency

Nitrogen

(N)

Element for N-compounds like proteins, vitamins, chlorophyll photosynthesis

Plant development disturbed, yield reduced, reduced tillering

Phosphorus

(P2O5)

Important for protein compounds

Disturbed growth, root development and tillering is reduced, flowering and maturity is slowed down

Potassium

(K2O)

Activator of enzymes, controls the water household in the plant

Slowed down carbon- hydrate and protein production, bad tasting fruits

25

Agronomic aspects of waste reuse (ii)

• Farmers’ main interest is to produce food and non-food products for subsistence or market selling

• Farmers’ focus is on good plant growth and high yields

• Main factors influencing plant growth

What is the nutrient demand of specific crops and how can this demand be satisfied?

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ic a

spec

ts

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Crop nutrient requirements

• Crop specific fertiliser norm

• corrected with:- Natural factors (mineral particles, air, water, organic matter)

- Physical factors (texture, particle size, distribution, structure, compaction, soil depth)

- Chemical factors (nutrient contents, form and availability, storage capacity)

- Biological factors (organic matter, microbial biomass, CO2, O2 production, potential for N mineralisation)

Crop nutrient requirement

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ic a

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Crop-specific fertiliser application norms

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ts

Type of crop Norm yield

[t/ha]

N

[kg/ha]

P2O5

[kg/ha]

K2O

[kg/ha]

Cotton 4 250 175 125

W-Wheat 6 140 65 95

S-Wheat 5 120 55 90

Maize 8 110 95 240

Potatoes 45 120 90 400

Sunflower 3 60 60 400

Tobacco 2 60 90 70

Alfalfa (silage) 45 150 150 70

Mung beans 3 0 70 145

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Integrated Soil Fertility Management: Optimal use of different nutrient sources and protective measures

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ic a

spec

ts

Compost

Farmyard Manure

Green Manure

Crop residues

Crop

Mineral fertiliser

Agro-technical measures

Urban organic (liquid/solid)

waste

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Organic Fertilisers

Organic Fertiliser N

[kg/t]

P2O5

[kg/t]

K2O

[kg/t]

Cotton stems and dung compost 4 1.3 14

Vegetable waste compost 4.9 1.2 9

Garden compost 4 3 2

Cow manure 12 7.5 18

Sheep manure 10 6 14

Pig manure 6 3.5 3

Poultry (chicken) manure 20 25 14

Human urine 170 38 38

Human faeces 60 42 18

Nightsoil (fresh) 118 39 28

30

Organic fertiliser supplemented with mineral fertilisers

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Nutrient budget/balance at field level

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ic a

spec

ts P

Field

KPN N

KInflows Outflows

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Nutrient budget/balance at farm level

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ic a

spec

ts

Field 2

InflowsOutflows

Field 1

InflowsOutflows

Inflows Outflows

Field 1Field 2...

Field 1Field 2...

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Simplified nutrient balance calculation

- Simple method

- Rough estimation of the crop nutrient requirements

- Needs only few information- Crop requirements

- Obtained crop yield

- Amount and content of available fertilisers

- Correction of crop nutrient requirements

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Example: Calculation of the nutrient balance on the field level

A farmer...

- has 1 cotton field of 2 ha size- has usually a cotton yield of 1.8 t/ha- bought 36 tonnes of compost (0.4% N, 0.1% P, 0.9%

K) - uses for complementary fertilisation:

- Ammonium-phosphate (18% N, 55% P)

- Ammonium-nitrate (34% N)

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ic a

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Calculation of the nutrient balance on the field level

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ic a

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ts

Type of Crop: Cotton Yield Amount applied

Nutrients

[kg/ha]

Field size 2 ha t/ha t/ha Field [t] N P2O5 K2O

Fertiliser norm 4 250 175 125

Corrected norm

Farmyard manure/ compost

Difference = mineral fertiliser

Type of mineral fertiliser

Nutrient ratio kg/

haField [kg]N : P : K

Ammonium-phosphate

(18 %, 50 %)

Ammonium-nitrate (34%)

36



Nutrients

[kg/ha]



Corrected norm 1,8 113 79 56

Farmyard manure/ compost



Nutrient ratio kg/


Ammonium-phosphate

(18 %, 50 %)


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ic a

spec

ts

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Nutrients

[kg/ha]




Farmyard manure/ compost 18 36 -72 -18 -162



Nutrient ratio kg/


Ammonium-phosphate

(18 %, 50 %)


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ic a

spec

ts

38



Nutrients

[kg/ha]





Difference = mineral fertiliser 41 61 -106


Nutrient ratio kg/


Ammonium-phosphate

(18 %, 50 %)


Agr

onom

ic a

spec

ts

39



Nutrients

[kg/ha]







Nutrient ratio kg/

haField [kg]

0.67 : 1 : 0N : P : K

Ammonium-phosphate

(18 %, 50 %)


Agr

onom

ic a

spec

ts

40



Nutrients

[kg/ha]







Nutrient ratio kg/

haField [kg]

0.67 : 1 : 0N : P : K

Ammonium-phosphate

(18 %, 50 %)0.36 1 0


Agr

onom

ic a

spec

ts

41



Nutrients

[kg/ha]







Nutrient ratio kg/

haField [kg]

0.67 : 1 : 0N : P : K

Ammonium-phosphate

(18 %, 50 %)0.36 1 0 122 244 22 61


Agr

onom

ic a

spec

ts

42



Nutrients

[kg/ha]







Nutrient ratio kg/

haField [kg]

0.67 : 1 : 0N : P : K

Ammonium-phosphate

(18 %, 50 %)0.36 1 0 122 244 22 61


-- -- -- 65 130 22

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ic a

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ts

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Calculation of the nutrient balance on the farm level

Inflows Outflows

Field code N P2O5 K2O N P2O5 K2O Field code

Field 1 50 20 30 84 39 63 Field 1

Field 2 100 20 35 188 131 94 Field 2

Field 3 40 15 25 69 59 150 Field 3

Total inflows 190 55 90 341 229 307 Total outflows

Deficit 151 174 217 - - - Surplus

Total balanced 341 229 307 341 229 307 Total balanced

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ic a

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Summary

• Urban agriculture comprises the production, processing and distribution of a diversity of foods (e.g. vegetables and animal products) within intra- and peri-urban area.

• Four main objectives: food security, poverty alleviation, public health, sustainable recourse management

• Farmers’ focus is on good plant growth and high yields to produce food and non-food products for subsistence or market selling

• Integrated soil fertility management makes use of various nutrient sources and agro-technical measures

• The simplified nutrient balance calculation allows a rough calculation of the nutrient balance based on an estimation of the crop nutrient removal

introduction into urban agriculture and agronomic aspects of organic waste reuse eawag peak course...

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