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Patterns of nutrient allocation and management in smallholder farming system in Massingir District, Mozambique. A case study of Banga village

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Wilson José Leonardo

MSc Thesis Plant Production Systems

June 2007

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Patterns of nutrient allocation and management in smallholder farming system in Massingir District, Mozambique. A case study of Banga village

Wilson José Leonardo

MSc Thesis Plant Sciences

PPS 80436

June 2007

Supervisor: Ken E. Giller (Plant Production Systems)

Advisor: Jessica Milgroom (Plant Production Systems)

Examiner: Nico de Ridder (Plant Production Systems)

Plant Production Systems Group

Wageningen University

P.O. Box 430, 6700 AK, The Netherlands

Table of contents

Acknowledgments 1

Summary 3

Abbreviations and acronyms 7

List of figures 9

List of tables 11

1. Introduction 13

1.1 Limitations of nutrient balances 16

1.2 Objective of the study 18

1.3 Hypothesis 18

1.4 Outline of the thesis 18

2. The study area 21

2.1 Biophysical description 21

2.2 Socio-economic description 24

2.3 Justification and criteria for the selection of the research site 24

3 Materials and methods 27

3.1 Literature review 27

3.2 Interviews with keys informants 27

3.3 Rapid farming system characterization (RFSC) 27

3.4 Classification of farmers in classes according to their wealth 28

3.5 Livelihood strategy: Analytical framework 28

3.6 Individual household survey 29

3.7 Nutrient balances 30

3.7.1 Soil sampling 32

3.7.2 Nutrient stocks 33

3.7.3 Calculations of nutrient balances 33

3.8 Statistical analysis 40

4 Results 41

4.1 The history of the village 41

4.2 The different types of fields found in Banga 43

4.3 Nutrient flow maps 49

4.4 The five capitals and soil fertility management 49

4.4.1 The natural capital 49

4.4.2 Financial capital 51

4.4.3 Social capital 53

4.4.4 Human capital 54

4.4.5 Physical capital 55

4.5 Agriculture 55

4.5.1 Farming system in Banga Village 55

4.5.2 Cropping season and labour allocation 56

4.5.3 Livestock and grazing system 58

4.6 Wealth groups division 60

4.7 Variability of the soil properties in different field types 65

4.8 Calculation of N, P and K balances 69

4.8.1 Partial balances 69

4.8.2 Full balances 70

4.9 Maize yield (kg ha-1) in different wealth classes 72

5 Discussion 73

6 Conclusions 81

References 85

Appendices 93

Appendix 1. Household interview (first Rapid Farming System Characterization-RFSC) 95

Appendix 2. Individual questionnaire used in individual interview 98

Appendix 3. Nutrient stocks in different field types found at Banga Village 101

Appendix 5. Total area covered by Gowene and Banhine’s fields at Banga Village 103

Appendix 6. Manure inputs (IN2) and wet deposition (IN3) (kg ha-1) 104

Appendix 7. Biological N fixation (IN4) and harvest product (OUT 1) 105

Appendix 8. Crop residues (OUT 2) and leaching N and K (OUT 3) 106

Appendix 9. Denitrification (OUT 4) 107

Appendix 10. Erosion (OUT 5) 108

Appendix 11. Partial nutrient balances for maize (kg ha-1) 109

Appendix 12 Analysis of variance of variables SOC, N, P, K, CEC and C:N ratio. 110

I dedicate this thesis to:

The farmers in Banga Village who regularly watch their crops fail due to the drought.

I wish I could provide you with small-scale irrigation equipment, and more drought tolerant germplasm.

Acknowledgments

I am indebted to the International Fellowship Programs (IFP) for providing me with funds to pursue this MSc study. I would like to thank my IFP contact person - Dra Célia Diniz, for always supporting me throughout the course of my studies. She also assisted me in all the administrative issues related to this scholarship.

I would like to express my appreciation to the people of Banga for having allowed me to do this study there. I am especially thankful to all who gave me the opportunity to interview them. Thanks to the staff at Agriculture Directorate, especially to Mr. Filimone and Mr. Marcos for helping me to select the village.

I am thankful to my supervisor Prof. Ken Giller who’s academic guidance and advice was crucial. When I first arrived at Wageningen University I was fortunate enough to meet Ken. By attending his course, I discovered that he was an interesting person to work with. His knowledge of the complexities and heterogeneities of smallholder farming system in Sub-Saharan Africa inspired in me an interest in working with him as my supervisor. Thanks for giving me the opportunity to explore the area of soil nutrient management.

I would like to thank my advisor Jessica Milgroom for her continuous support in the thesis. She was always there to listen and give advice. I remember the discussions held with her at different stages of the research. These discussions inspired me to think about the best way to conduct this study.

I would like to thank Dr. Roland Brouwer from Eduardo Mondlane University in Mozambique for assisting me in different stages of writing the report. He provided suggestions and critical comments to improve the thesis. He has been playing an important role in my education career since he was my lecturer at university during my BSc.

They are many people who did not contribute directly to the thesis, but have been friends and colleagues since I arrived at Wageningen University, so I would like to thank them for their unconditional support – Adugna, Munisi, Deon, Yann, Byjesh, Jéróme, Jobert, Guillaume, Solenn and Alex.

I would like to thank ICRISAT-Mozambique staff- Dr. Dominguez, Celso, Ivone, Gino and Vilanculos for let me use your office, and your friendship during my fieldwork.

I will not forget the contribution received from Milly during the ups and downs of my studies. Sometimes, when I felt depressed, she was there supporting me.

To my brothers and sisters Benvinda, Júlia, Mariza, Bernardo and Quincardete who understood the importance of this course to my career. I will never forget your support.

Summary

The alarming picture of nutrient depletion that emerged from the nutrient balances calculated by Stoorvogel and Smaling at different scales in Sub-Saharan Africa, motivated researchers to carry out multi-scaled studies in order to understand the underlying causes behind this nutrient depletion. Some of these studies have confirmed that nutrient depletion leading to poor soil fertility is largely determined by past and current land use systems and management practices, and pointed at the importance of differences in farming techniques between poor and wealthy households. In some farming systems, one common scenario is reported: positive nutrient balances for wealthiest farmers and negative for poorest farmers.

In Mozambique, the soil nutrient balance studies which were conducted at the national level in different land use types showed annual depletion rates for cultivated fields of 33 kg nitrogen, 7 kg phosphorus and 25 kg of potassium per hectare per year on average. For small-scale farming, the studies showed annual depletion rates of 47.9 kg ha-1 of N, 9.9 kg ha-1 of P and 36.5 kg ha-1 of K for maize, which is the most important crop in Mozambican smallholder cropping systems. These studies did not take into account the wealth status of the farmers despite of the widespread acceptance that land use systems and management practices differ between poor and wealthy households.

It has also been argued that in some farming systems the gradients of nutrient depletion increase with the distance from homestead. This occurs because farmers tend to concentrate manure collected from the ‘kraals’ and other organic matter (ashes, kitchen scraps, garbage) in the fields closer to the homestead, while fields further away often receive no fertilizers amendments.

The main objective of this thesis was to test if the patterns of nutrient depletion reported in many studies conducted in sub-Saharan Africa holds true in Mozambican smallholder farming systems. In order to achieve this objective, soil nutrient stocks and partial nutrients balance analysis were carried out at field level, in Banga Village, Gaza province, Southern Mozambique. General information about the farming systems in these villages was gathered through interviews with key informants, focus group discussions, field visits and semi-structured interviews with individual farmers. About 25 households participated which were randomly selected out of 90 households. Eight households comprising of different wealth groups within the village were selected for detailed characterization of their farming systems. The information collected covered the main characteristics of the households, land availability, main activities, main crops, production constraints, production orientation, nutrient management, coping strategies and wealth indicators.

Agriculture and livestock husbandry are the main activities practiced in two different land units: the alto (closer to homestead) and baixo (far-away). Agriculture is practiced without using external inputs and is highly dependent on rainfall. Maize is the main crop in the village and is cultivated in all land units, although those further away are considered to have better yields. Drought is a recurrent phenomenon in the study area and it severely affects the maize yield. A lack of other crops which are tolerant to drought have limited farmers from diversification of crop production. The sale of charcoal, animals, remittances and local brews constitute the main sources of income when crops fail. There are different exchange relationships that underpin their livelihood strategies including kukashela, xicoropa, tsimo and kuwekissa. All these are related to the exchange of labour for land preparation.

Farmers indicated cattle ownership as the main factor in dividing wealth classes. Based on this, four groups were identified: the Very Low Resource Endowment (VLRE), the Low Resource Endowment (LRE), the Medium Resource Endowment (MRE) and High Resource Endowment (HRE).

Soil nutrients stocks and chemical properties (N, P, K, SOC and CEC) were significantly higher (p ................
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