Exploring Feasible Yields for Cassava Production for Food and Fuel in the Context of Smallholder Farming Systems in Alto Molócuè, Northern Mozambique
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Exploring feasible yields for cassava production for food and fuel in the context of smallholder farming systems in Alto Molócuè, Northern Mozambique Sanne van den Dungen Msc thesis Plant Production Systems June 2010 Wageningen University, The Netherlands 2 Exploring feasible yields for cassava production for food and fuel in the context of smallholder farming systems in Alto Molócuè, Northern Mozambique Sanne van den Dungen MSc Thesis Plant Sciences PPS 80436 36 credits June 2010 Supervisors: Ir. Sander de Vries Dr. Ir. Gerrie van de Ven Examiner: Prof. Dr. Ken E. Giller (Plant Production Systems) Plant Production Systems Group Wageningen University P.O. Box 430, 6700 AK, The Netherlands 3 Preface and acknowledgements From the first contact I had with ir. Sander de Vries, Dr. Ir, Gerrie van de Ven and Prof. Dr. Ken Giller, I was able to express my personal motivations and wishes concerning this thesis. I would especially like to thank Sander and Gerrie for their patience and support during the length of this thesis. I was able to shape the research in, what for me was the reason to come to Wageningen: explorative research on farming systems in Sub‐Saharan Africa. I am very happy to have been able to pursue this dream. There are many people I would like to thank for making the four months of fieldwork research possible, in Northern Mozambique 2009. First of all I would like to thank Sicco Kolijn for his contaminating enthusiasm and motivation. I admire his network and am thankful for the help I received in finding a suitable region for research, for hospitality and concerns. Because of his connections I was able to link up to World Vision Quelimane under the supervision of Brian Hilton. I thank Brian for his support in introducing me to the district of Alto Molócuè and World Vision staff and thank World vision for all the support and facilities I received. At World Vision Alto Molócuè, I met Sansao Honwana, who has to been much more than a supervisor to me and providing me with a place to stay and all the support from his staff I could ask for. Thanks Raol for countless Saturdays picking me up from a week’s work in the villages even though it was your free day. In Mugema, Nacuaca and Gafaria I thank all the farmers co‐ operating in the research and being patient with me. Most of all I am grateful for the insights I was able to get besides their farming systems: the everyday of life, the stories, the food, traditions and customs. Antonio, Pedro and Gustodio have been amazingly patient with me during the length of fieldwork, Trying to answer all my questions and providing me with solid friendship and support. The guest families: the family of Antonio, Donna Celesta and the family of Xavier I show gratitude to their hospitality for letting me camp at their premises and joining their meals. I had the honour to have Bruno Golden as my translator in the beginning of the fieldwork. There is absolutely no way of expressing my appreciation to you. Many times during fieldwork I have thought about how to be able to show to you what it was like having you to help me. I trust you have felt it and I could not have wished for a better friend and expert to guide me. Thanks to Armindo Cambule and his staff at the University of Eduardo Mondlane, Maputo for analyzing the numerous soil samples I collected. When at the start of this project my dad told me “focus on success, focus on finishing” I confess I had trouble believing him. I could have never finished without the help of many people surrounding me. From a distance my parents have been supporting me in good and bad times, always there with good advice and motivation. I thank my sisters and brother for the support, my boyfriend Ofir Benjamin for overseas love and Eva Gies for on the spot help. My dear friend Loes Mertens wrote to me before leaving to Mozambique: “know that on your journeys the whole universe will come together to help you!” With countless people more to thank, she could not have been more right. 4 Summary Currently the world’s energy supply system for the 21st century is under intensive debate. Renewable energy sources, especially biomass, play an important role in the discussion where several scientists have tried to identify high potential areas for the production of biomass for energy. African countries such as Mozambique are currently under review, because of a favourable climate, ample land availability and low population density (Batidzirai et al., 2006). Cassava, a potential crop for the production of bio‐ethanol, is currently being discussed as a feasible option for biofuel production by smallholder farmers as well as maize and sorghum. However current (cassava) yields are low and farmers have very limited resources for yield improvement. This study was developed with the overall goal to explore feasible yields for cassava production for food and fuel in the context of smallholder farming systems in Alto Molócuè, Northern Mozambique with the objectives of i) assessing the heterogeneity between farms by making a rapid farm characterisation, ii) estimating current yields of cassava, sorghum and maize of selected smallholder farmers, iii) explaining current yields of cassava, sorghum and maize, iv) making a yield gap analysis between actual yields from selected crops from field estimations and feasible potential yields simulated using the FIELD model, v) collecting parameter input used in the FIELD model. Three villages (Mugema, Nacuaca and Gafaria) were selected in the district of Alto Molócuè to represent variability at district level. Experts, key‐informants, back ground information, and first approach farm characterisation interviews were used to describe and categorize bio‐physical, socio‐economic and farm management practices variability found at village, farm and field level. A farm typology based on expert knowledge and K‐means clustering was developed to analyse variability found at farm level. A dynamic simulation model FIELD was parameterized with field data, and simulation scenarios were developed from the rapid farm characterisation interviews and informal meetings with farmers. The model was run to study and quantify the cassava yield response of different farm management practices. Due to circumstances, model simulations were only based on soil fertility properties of the sampled fields. Simulated yield variability between sites was mainly explained by inherent soil properties, such as soil texture (clay %) which determined exchangeable K level for a large extent. Simulated no input yields in Gafaria were found higher compared to Nacuaca because of: a higher clay content, higher N and K level. Simulated yields for Gafaria ranged between an average of 2.0 and 10.8 t/ha and were found lower for Nacuaca: 1.8 and 3.9 t/ha. Within village, yields were grouped into low yielding fields (1st quartile), medium yielding fields (2nd and 3rd quartile) and high yielding fields (4th quartile). Simulations of continuous cultivation showed yields in Gafaria to drop in average by 24% for 2nd & 3rd quartile fields (stabilizing at 3.1 t ha‐1), 27% for 4th quartile fields (stabilizing at 8.0 t ha‐1), while yields of 1st quartile fields did not change during time and remained at around 2 t ha‐1 over a time span of 25 years. Yields in Nacuaca did not change over time for 1st and 2nd & 3rd quartile fields and remained at 1.8 and 2.3 t ha‐1. Yield of 4th quartile fields dropped in average by 22% till it stabilized around 3.2 t ha‐1 . Amongst farmers, a large variation of crop residue management was found. In Mugema, Nacuaca and Gafaria 48, 33 and 60% of the respondents of the rapid farm characterisation incorporated crop residues in the soil and 89% of all farmers asked included grass in preparing of the ridges/hills for cassava. 5 However a large part of the same respondents would use fire for clearing of the field: 59%, 80% and 50% in Mugema, Nacuaca and Gafaria. The effect of maize residue application on cassava fresh yield was analysed with the help of the simulation model FIELD. Addition of maize residues had a positive effect on fresh cassava yield with an increase in yield of between 156 – 237kg/ ha in Nacuaca and 189‐449 kg/ha in Gafaria over the three quartiles used per ton maize residue applied. In general most farmers would only consider the use of manure if they would produce horticultures. Generally manure was piled up and removed not to be of further use. Simulated yields comparing no manure and manure application showed an increase of 402‐482 kg and 433‐1034 kg increase/ ton DM manure applied for Nacuaca and Gafaria subsequently. Average yield response per kg applied nutrient was highly variable comparing villages and comparing quartiles. Increasing levels of potassium was most effective on soils in Nacuaca, while a higher response (increase kg fresh cassava / kg applied N, P or K ha‐1) for phosphorus was found in Gafaria. First and second quartile classified fields had a lower response and remained at a low yield level compared to the higher yielding fourth quartile fields. High increase in yield was obtained with NPK fertiliser application (100:22:83 N:P:K) ranging from 37 to 65 kg yield increase per kg fertiliser added in Gafaria and between 49 and 67 kg yield increase per kg fertiliser added in Nacuaca. Improved fertiliser management was developed to increase yield response per kg fertiliser applied with the help of available nutrients from crop residues and manure.