Introduction into urban agriculture and agronomic aspects of organic waste reuse

1. 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 Contents

3. World’s population living in the cities - 1994 about 45% - 2025 about 65% Urban population living in cities [billion] (x 10) 10 8 6 4 2 0 1994 2025 Urban Pop World Pop Introduction into urban agriculture • Demographic growth and increase in urbanisation – challenges of the next decade! Introduction

4. About 90% of urban growth takes place in developing countries! • Poor people in urban areas • - 1988 about 25% • - 2000 about 56% Introduction

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 Introduction

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. Introduction

7. 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. Introduction

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 Introduction Food security depends very much on employment and income!

9. Hong Kong Karachi Dakar 45 % 50 % 70 % 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 Introduction

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. Introduction Poor women can improve their household finances through UA activities!

11. Food Income 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 • UA belongs to the informal economy (no contribution to GDP) Introduction

12. Food security Clean air Public Health Ressource Management Physical work Public health • Public health is aiming to • promote the well-being • prevent diseases and disabilities • enhancing quality of life Introduction

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 fuel Introduction

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

15. 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? Agronomic aspects

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

17. Tree with roots to the mother rock Superficial soil layer with organic matter Nutrient uptake Mother Rock Nutrients for growth Agronomic aspects

18. Organic matter • Vast array of carbon compounds in soil • Created by plants, microbes, and other organisms • Living and dead plants and organisms Agronomic aspects

19. quickly available for plant growth Soil organic matter in virgin soils Agronomic aspects

20. 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 Agronomic aspects

21. 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 Agronomic aspects

22. Atmospheric N-fixation Nitrogen fixing legume Nitrogen fixation through bacteria Decomposition and mineralisation Nitrogen - the most important plant nutrient Agronomic aspects

23. 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 Agronomic aspects

24. Function of N-P-K in the plant Agronomic aspects

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? Agronomic aspects

26. 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 Agronomic aspects

27. Crop-specific fertiliser application norms Agronomic aspects

28. Urban organic (liquid/solid) waste Green Manure Farmyard Manure Crop Crop residues Mineral fertiliser Compost Agro-technical measures Integrated Soil Fertility Management: Optimal use of different nutrient sources and protective measures Agronomic aspects

29. Organic Fertilisers

30. Organic fertiliser supplemented with mineral fertilisers Agronomic aspects

31. Nutrient budget/balance at field level N P N Outflows K Inflows P K Agronomic aspects Field

32. Nutrient budget/balance at farm level Inflows Outflows Field 1 Field 2 ... Field 1 Field 2 ... Agronomic aspects Inflows Inflows Outflows Outflows Field 1 Field 2

33. 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 Agronomic aspects

34. 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) Agronomic aspects

35. Calculation of the nutrient balance on the field level Agronomic aspects

36. Calculation of the nutrient balance on the field level Agronomic aspects

37. Calculation of the nutrient balance on the field level Agronomic aspects

38. Calculation of the nutrient balance on the field level Agronomic aspects

39. Calculation of the nutrient balance on the field level Agronomic aspects

40. Calculation of the nutrient balance on the field level Agronomic aspects

41. Calculation of the nutrient balance on the field level Agronomic aspects

42. Calculation of the nutrient balance on the field level Agronomic aspects

43. Calculation of the nutrient balance on the farm level Agronomic aspects

44. 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