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CHAPTER 5: USE AND MANAGEMENT OF MANURE BY SMALLHOLDER FARMERS AND THEIR EFFECT ON THE ENVIRONMENT
Introduction
In 2010 the livestock population of Ethiopia was estimated at about 53.4 million cattle, 48.3 million shoats, 8.1 million equines and 1.1 million camels (FAOSTATA, 2012). The average annual livestock population growth rate was 1.3%, 1.0% and 0.9% for cattle, sheep and goats, respectively (Getachew and Gashaw, 2001). That meant the production and availability of animal feeds has to increase at a higher rate than the livestock population growth rate (Alemayehu, 2005). In general, human and livestock populations in Ethiopia have grown at an alarming rate (Ahmed et al., 2003). As a result, there has been a lot of pressure on natural resources. Livestock overgrazed pastures and crop residues became major sources of animal feed in the highlands. Forests and bushes were cleared for crop production, grazing and fire wood (Alemu, 2002). Likewise, animal manure became a significant source of fuel energy for households (Tesfaye et al., 2004).
Manure production, collection and storage vary with management practices (Tesfaye et al., 2004). In the case of indoor management practices, manure was collected through a drainage gutter in a pit in liquid form. For outdoor management practices, manure was collected from the kraals at night and at day time from the fields while animals were grazing (Harris and Yusuf, 2001). The use of manure varies with management practices as well. For indoor management practices, biogas is used for fuel energy and slurry for fertilization. However, the transport of slurry from homesteads to the fields is the major challenge limiting wider use (Brandjes et al., 1996). In outdoor management practices, the loss of manure in the field was higher due to droppings not being picked and urine being absorbed into the soil.
Manure has become a major energy source as cooking fuel in the rural areas (Asres, 2003). The amount of manure stored has become an indicator of wealth for rural households. Manure has also become one of the major contributors to household income, of about 25% of household income for poor farmers (Tesfaye et al., 2004). The use of manure for cooking fuel and sales has a serious environmental impact as far as soil nutrient recycling (Fernandez-Rivera et al., 1995) and greenhouse gas emissions are concerned ( FAO, 2006).
Although livestock production has several advantages in smallholder agriculture, it is also the largest global source of methane emissions representing 20 to 25% of all sources of methane (IPCC, 2001). In addition, it is the greatest generator of N2O which contributes to global warming (IPCC, 2001; Kurihara et al., 2002). Livestock mismanagement is also blamed for soil degradation through overgrazing, trampling and compaction (de Hann et al., 1998).
Animal manure is more efficiently utilized in crop production than commercial fertilizer because a larger fraction of nutrients from manure is absorbed by crops (Brandjes et al., 1996; FAO, 2006). However, manure storage in the open causes volatilization of ammonia due to the high temperature and the leaching of NO3, P and K (Jackson and Mtengeti, 2005). Surface spreading of manure without mixing it with soil during periods of high precipitation on fallow lands, may also lead to volatilization, leaching and surface runoff (Brandjes et al., 1996).
Although manure remains an important organic source of fertilizer and fuel energy, its impact on the environment has never been given adequate research it deserves, particularly under mixed crop and livestock production systems (Tesfaye et al., 2004). One of the purposes of this study was therefore, to document the effect of manure storage and age of storage on the loss of nutrients under mixed crop and livestock production systems of smallholder farming.
Research on the use and management of manure in the highlands was done by Tesfaye et al. (2004) who described the types of manure storage, means of transport and the level of use as fertilizer. However, their report did not describe the effect of different types of manure storage and management practices on the loss of nutrients and the pollution level under smallholder farming systems. Getente (2003) reported the effect of manure and N fertilizer on the establishment, herbage yield and seed production of perennial grasses in a research station in the Ethiopian highlands. The National Meteorological Service Agency in Ethiopia-NMSA (2001) and Asres (2003) undertook a greenhouse gas emissions inventory for all sources in Ethiopia based on the guideline from IPCC (1996), including level of pollution level. However, they did not report about the impact of different manure management practices on the local environment and did not scale it down to household level.
The current study attempted to assess the different manure management practices and their benefits to smallholder farmers. The study addressed:
- the trends of livestock holdings in the past three decades,
- the use, handling and storage of manure and their benefits,
- loss of nutrients from different types of manure storage and the age, and
- household gas emission levels due to the mismanagement of manure.
Information on these research issues was captured through household interviews, focus group discussions and manure sampling for chemical analysis.
The objectives
The objectives were:
- To document the production and storage of manure under smallholder farming.
- To assess the handling and use of manure under smallholder farming and the limitations to the use of manure as organic fertilizer.
- To estimate household loss of nutrients and gas emissions due to the mismanagement of manure.
Materials and methods
The study area
The study area was Adaa district which has a high potential for mixed livestock and crop production systems. It is one of the 12 districts in East Shoa zone in Oromia regional state of Ethiopia. It is located southeast of Addis Ababa at 38o51’ 43.63’’ to 39o04’ 58.59’’ E and 8o46’ 16.20’’ to 8o59’ 16.38’’ N, on the western margin of the Great East African Rift Valley. The altitude ranges from 1 500 m to ≥ 2 000 m above sea level. There are two major agro climatic zones: the mountain zone located ≥ 2 000 m and covers 150 km2 (9%); and the highland zone that covers ≥ 1600 km2 (91%) of the area. The average annual rainfall is 839 mm. Mean minimum temperature is 8oC and mean maximum temperature is 28oC. The mean temperature at the time of sampling was 18.5oC. The dominant soil types were vertisols, which are fertile but poorly drained and difficult to work on (IPMS, 2004).
The district is best suited for diverse agricultural production systems, both for intensive and extensive agriculture. Teff (Eragrostis teff) and wheat are the most abundant crops that grow in the district in addition to pulses. Most farmers rotate chickpeas with cereals, and livestock production is an integral part of the agricultural production systems. Oxen are used as draught power for ploughing, threshing, while equines are used for threshing and transportation.
Research design
The study used both biological and socio-economic approaches. The biological approach used target sampling to assess different losses of nutrients due to the type of manure storage and age, and their implications on the environment. The biological data were then validated by socio-economic data from interviews and group discussions with owners of the manure.
Socio-economic survey
The data used in this study were collected in a socio-economic survey which was undertaken in 2009. A total of 110 smallholder farmers were selected from representative villages and were interviewed. The data were analyzed using SPSS version 17.0.1 (2008). The information obtained from the survey included livestock ownership trends, manure collection methods, storage type, benefits and the limitations to the use of manure. Focus group discussions were also carried out with owners of manure that was sampled for laboratory analysis.
Biological study
Heaps of manure in different households were identified and classified according to their size, age and storage conditions; then sampled as described by Tadesse et al. (1991). A total of 25 pooled samples were collected. The storage conditions were classified as shaded, open and fresh (not in a heap) as shown in Table 5.1. Sampling of manure was done by scooping subsamples from four random spots on each manure heap at different heights i.e. 0 to 50 cm, 50 to 100 cm, 100 to 150 cm and ≥ 150 cm at the depth of about 30 cm (Zhang, et al., 2001; Jackson and Mtengeti, 2005). The four subsamples from each representative height of the manure heap were pooled and a sample of approximately 1 kg was taken and stored in a plastic bag before chemical analysis. The pooled samples from each manure heap were air dried and ground to pass through a 2 mm screen ready for further analysis based on guidelines described by Tadesse et al. (1991).
DECLARATION OF ORIGINALITY
ACKNOWLEDGEMENT
TABLE OF CONTENTS
LIST OF FIGURES
ABBREVIATIONS
ABSTRACT
CHAPTER 1: INTRODUCTION
1.1 Background
1.2 Problem statement
1.3 Research aims and objectives
1.4 The significance of the study
1.5 The outline of the report
CHAPTER 2: LITREATURE REVIEW
2.1 Introduction
2.2 The demand for livestock products in Ethiopia
2.3 Climate change scenarios in Ethiopian context
2.4 Impacts of climate change on agriculture in Ethiopia
2.5 The role of livestock in climate change
2.6 Environmental problems associated with livestock and humans
2.7 The impacts of environmental changes on livestock production
2.8 Adaptation measures to climate change
2.9 Conclusions
CHAPTER 3: RESEARCH METHODOLOGY.
3.1 Aims and objectives
3.2 Research design
3.3 The study area
3.4 Materials and methods
CHAPTER 4: LAND MANAGEMENT PRACTICES AND THE ROLE OF LIVESTOCK IN CARBON STORAGE UNDER MIXED CROP-LIVESTOCK PRODUCTION SYSTEMS
4.1 Introduction
4.2 Materials and methods
4.3 Results and discussion
4.4 Conclusions and recommendations
CHAPTER 5: USE AND MANAGEMENT OF MANURE BY SMALLHOLDER FARMERS AND THEIR EFFECT ON THE ENVIRONMENT
5.1 Introduction
5.2 The objectives
5.3 Materials and methods
5.4 Results and discussion
5.5 Conclusions and recommendations
CHAPTER 6: THE CONTRIBUTION OF LIVESTOCK AND ANTHROGENIC FACTORS TO HEAVY METAL LOAD
6.1 Introduction
6.2 Materials and methods
6.3 Results and discussion
6.4 Conclusions
CHAPTER 7: LIVESTOCK AND WATER INTERACTIONS IN MIXED CROP AND LIVESTOCK PRODUCTION SYSTEMS
7.1 Introduction
7.2 The objectives
7.3 Materials and methods
7.4 Conclusions and recommendations
CHAPTER 8: LIVESTOCK, CLIMATE CHANGE AND TECHNOLOGICAL OPTIONS
8.1 Introduction
8.2 Research methodology
8.3 Results and discussion
8.4 Conclusions
CHAPTER 9: CONCLUSIONS AND RECOMMENDATIONS
9.1 Conclusions
9.2 Recommendations
REFERENCES
GET THE COMPLETE PROJECT
ASSESSMENT OF ENVIRONMENTAL-LIVESTOCK INTERACTIONS IN CROP-LIVESTOCK SYSTEMS OF CENTRAL ETHIOPIAN HIGHLANDS
