Template:Chapter 4.15
4.15 - A Critical Assessment of the Utility of Manure Pellet Machines for Smallholder Farmers Experiencing Low Soil Fertility
Elisha Robbins,University of Guelph, Canada
Suggested citation for this chapter.
Robbins,E. (2022) A Critical Assessment of the Utility of Manure Pellet Machines for Smallholder Farmers Experiencing Low Soil Fertility. In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org
Climate Change and Declining Soil Fertility
There are many threats to future food security, but perhaps one of the most impactful is soil degradation. The world’s soils have been rapidly depleted as a result of human development, much of it stemming from land conversion for agricultural purposes (Food and Agriculture Organization, 2015). The loss of natural vegetation to instead grow crops and graze livestock has led to loss of soil organic carbon, nutrient depletion, erosion, and a loss of biodiversity (Food and Agriculture Organization, 2015). Additionally, the ramifications of global climate change, including higher temperature averages, extreme storms, floods, and droughts are expected to further degrade soil fertility by an overall reduction in moisture, nutrients, and more pronounced erosion (Food and Agriculture Organization, 2015).
Implications for the Global South
Rubber and cloth are the two main kinds of gloves produced (Melco, 2016). They both have their own benefits and drawbacks respectively. A benefit from rubber gloves is their ability to resist water from coming in contact with a farmer's skin, see part two, (Espasandín-Arias & Goossens, 2014). While cloth gloves can be beneficial because they can draw moisture away from their hands and can be easily washed to be cleaned. Because rubber gloves are usually meant to be disposed of after single use they tend to be cheaper to make and thus cheaper to buy. Yet some rubber gloves can be made thicker to reuse and are slightly more durable (Melco, 2016). Cloth gloves are designed to be washed after being used and last a long time under normal working conditions.
Areas in the global south are poorly equipped to manage the impacts of climate change due to their natural disposition in the globe’s most affected regions, as well as the lingering effects of colonialism. Colonialism has caused the loss of traditional knowledge and indigenous crops for much of the global south, in favour of crops and agricultural practices dominant in the global north (Frankema, 2014). The crops and practices that replaced the means of local agricultural production ended up being largely inappropriate for the local climate and geographic conditions in many cases (Pechlaner, 2008). According to critics, the industrialization of agriculture also spread from the global north to the global south through the Green Revolution and has had a disproportionately heavy focus on efficiency and immediacy of output, rather than on long-term sustainability (Pechlaner, 2008). While healthy soils are vital for agricultural production, the maintenance of long-term soil health has been largely disregarded in favour of short-term solutions, such as synthetic fertilizers (Chew, 2019). Furthermore, the critics suggest that the Green Revolution perpetuated these issues in Africa by promoting the use of irrigation and fertilizers inaccessible to smallholder farmers (Frankema, 2014). To regain food sovereignty and security, smallholder farmers in the global south, particularly in Sub-Saharan Africa, must be given the tools to restore and improve their soil health.
A Solution: Using a Manure Pellet Machine
Many smallholder farmers lack access to commercial fertilizers and irrigation to improve the health of their soils. Manure pellets are a natural solution to improve soil fertility and crop yield, which are more effective and better for the environment than synthetic fertilizers (Cai, et al., 2019; Chew, 2019). Many smallholder farmers in the global south have both livestock and subsistence crops, but the manure produced by livestock is often not used to maximum efficiency and is also sometimes discharged into the environment, where it contributes to water quality issues (Teenstra et al., 2015). Many areas in the global south experience water scarcity and frequent droughts, so safeguarding the quality of available water is of utmost importance. Barriers to efficient manure management are inadequate storage, lack of knowledge, lack of labour, as well as limited access to credit for the tools to manage manure safely and effectively (Teenstra et al., 2015).
A technology that is recommended to improve smallholder manure usage is the manure pellet machine. Manure pellet machines convert composted manure into compact, light-weight, low-odor pellets. These qualities reduce the amount of labour needed to fertilize fields and improve the storage potential of the manure, combatting two of the challenges faced by smallholder farmers. Low-cost manure pellet machines are not very complex. First, dried, composted manure is fed into the manure pellet machine. The manure pellet machine then processes the manure into pellets by extrusion rollers, centrifugal force, or aerodynamic force, dependent upon the model (Yushunxin, 2020). The compact pellets are then expelled by the machine.
To produce manure pellets, the composting of manure must first take place, which requires watering and turning the manure in a pile (Augustin & Rahman, 2016). This labour must be performed regardless of the form of manure application, unless raw manure is used; however, raw manure poses food safety risks due to the presence of harmful bacteria, otherwise removed during manure composting (Augustin & Rahman, 2016). After composting the manure, it must be dried and added to the manure pellet machine where the pellets are formed. Producing pellets that are well balanced and safe can be taught if done step-by-step (Pampuro et al., 2018). Extension workers should educate farmers about supplementing their manure with other organic matter or biochar to provide robust and targeted nutrition for crops (Pokharel & Chang, 2019).
A study by Shin et al. (2021), found that including 40% biochar in the formulation of manure pellets improved plant uptake of nitrogen, reducing the amount manure needed to experience crop yield improvements in Asian rice (Oryza sativa L.) by 60%. In most crops, the production of biochar is a relatively simple process that sequesters more carbon and improves crop yields compared to standard manure pellets (Ippolito et al., 2012). Smallholders can make biochar by digging an earthen pit to burn wood and other organic matter slowly; the key is that there must be very little space for oxygen to get through. In areas where clay is available, a kiln can be made from mixing sand with a bit of clay and shaping it into a hollow cylinder, or it can be made from a cylindrical placement of bricks (Garcia-Nunez et al., 2017). The kiln should be open at the top with an additional small opening in the side to stoke the fire. Kilns are more efficient than pits and produce less smoke, so they are the preferred zero-cost/low-cost method (Garcia-Nunez et al., 2017).
The Environmental Benefits of Using Manure Pellet Machines
Using manure pellets is better for the environment than raw manure, composted manure, or synthetic fertilizers. In a study by Smith et al. (2007), composted pig and chicken manure were shown to elevate phosphorus (8.4 mg/L) and ammonium (10.3 mg/L) in water leachate (run-off) initially after fertilization, but this risk decreased quickly, while synthetic fertilizers persisted longer in the environment (2.6 mg/L, 29 days after fertilization) (Smith et al., 2007). Compared to these other methods of fertilization, manure pellet application leads to a further reduction in nutrient rich runoff and subsequent contamination (Hara, 2001). Manure pellets perform better in this respect due to the slow release of nutrients that they produce, which leads to enhanced plant uptake and reduced nutrient leaching (Townsend et al., 2012; Reza-Bagheri et al., 2011). As such, manure pellets function better than traditional fertilizers on hillsides that are prone to erosion and runoff, which make up many of the smallholder farms, particularly in East Africa. Furthermore, the slow release of nitrogen into the soil from manure pellets progressively improves soil health over time (Alemi et al., 2010). Additionally, manure pellets sequester more carbon and reduce N2O emissions in comparison to all of the aforementioned methods (Ball et al., 2004). Manure pellets have also been shown to reduce NH3 emissions by 97.82% compared to un-pelletized organic fertilizers (Šarauskis et al., 2021). By utilizing animal and organic waste products in the production of new crops, farmers are taking advantage of their resources and reducing their total waste and the demand for costly, harmful chemical fertilizers.
The Economic and Social Benefits of Utilizing Manure Pellet Machines
The economic and social benefits of manure pellet machines are robust and multifaceted. Firstly, fertilizing crops improves yield and doing so with already available resources is more accessible and affordable (Hao and He, 2020). Spreading manure pellets is also much less labour intensive than spreading unprocessed manure, due to their ease of application, lighter weight, and reduced odour, creating a better work environment (Liu & Wang, 2020). Manure pellets also have better storage capacity, making them easier to keep and transport, which is otherwise a significant barrier to manure use by smallholder farmers (Hara, 2001). Due to the attractive qualities of manure pellets, the production of one’s own supply can open up another revenue source through selling excess fertilizer pellets. Women are often the ones collecting manure from animal pens; therefore, manure pellet machines have the potential to directly benefit smallholder women farmers. It is suggested that manure pellet machines be implemented on a community-wide basis to make the technology less cost restrictive, where adequate infrastructure such as roads and transportation exist. Smallholder women farmers could then collectively own a set of manure pellet machines and produce pellets from composted manure for a small profit. Farmers could bring their manure to the local women’s cooperative for processing, or the women themselves could collect manure and sell it back to farmers, after being put through the manure pellet machine. Should women farmers wish to participate, it could enable them to produce a value-added commodity; therefore, benefits would flow through the community, in a bottom-up model that empowers women. It is essential that the women operating the manure pellet machines are educated on the mechanics of them. While implementation through a single person may be easier and less costly for education purposes, teaching multiple people how to operate manure pellet machines builds resiliency. In a community-based implementation project, responsibility for repairs would be shared to resolve any problems that arise.
The Challenges of Implementing Manure Pellet Machines on Smallholder Farms
While manure pellet machines pose as an environmentally, socially, and economically beneficial technology, there are many challenges to their implementation. One such challenge is the educational and technical capacity of smallholder farming communities. Smallholder farmers may first need to learn how to properly compost their manure efficiently and be empowered with the tools to do so as a preliminary step to manure pellet production. Additionally, the application of manure pellets works differently than other fertilizers because the release of nutrients is slow; therefore, yield improvements are not universal (Harmsen, 1991). There are some crops that will only benefit marginally from manure pellets. A study by Masayuki Hara (2001), broadly categorized the crops that benefit most from pellet application in Japan as being vegetables that grow during the spring and summer, whereas those that grow in the autumn and winter do not see the same benefits; these results suggest the influence of crop-climate interactions. Furthermore, a study by Reza-Bagheri et al. (2011), showed greater yield improvements from pelletized manure application than by urea application, experiencing a significant increase in corn grain yield (12.247 kg ha-1). It is suggested that research and a cost-benefit analysis should take place for different crop varieties, soils, and living situations in the global south, which is time consuming for agricultural extension workers (Alege et al., 2021).
Manure pellet machines are also heavy pieces of equipment, leading to complications in transporting them within the community. Due to the size and weight of manure pellet machines, there may also be hidden transportation costs to move the machinery from the supplier to remote rural locations. Manure pellet machines are also technical and if they fall into disrepair the community may not be able to fix them or have access to the parts needed. Shipping the machine back to the supplier would be a cost born by the smallholder farmers. Carefully reviewing individual manure pellet machine suppliers and their policies is something that agricultural extension or development assistance workers will need to undertake with the community before selecting a model.
Manure pellet machines can also be costly to purchase and utilize. Manure pellet machines require electricity or gas power to run them; there are currently no alternative means of powering manure pellet machines (Yushunxin, 2020). Access to electricity is not always available or affordable for smallholder farmers, which is a barrier to actualizing the benefits that manure pellet machines can deliver. Manure pellet machines also have a significant upfront cost of four hundred dollars to upwards of a few thousand dollars (USD), which individual smallholder farmers cannot afford (Alibaba, 2021). Even as a community, the cost of manure pellet machines is restrictive; however, a government subsidy, small loan with a low interest rate, or foreign aid intervention could make the technology more accessible.
Conclusion
Although manure pellet machines generate many social and environmental gains, the risks of implementing them outweigh the benefits if they are promoted without supporting knowledge and technologies. Advocating for the adoption of manure pellet machines must be done at a certain threshold of community development, when the knowledge and technical skills of smallholders are sufficient to be able to experience the benefits that manure pellet machines can provide. There must also be collaboration between agricultural extension workers and smallholder farmers to ensure that the dominant local crop and landscape will markedly benefit from the implementation of manure pellet machines. For example, manure pellet machines may be worthwhile for smallholder farmers positioned on hillsides, but not for those on different terrain. For some, composted manure may be sufficient, or there may be alternate technologies that are more suited to the individual farm in question. A first priority should be educating farmers on the benefits of using composted manure, teaching them how to properly compost their manure, and providing them the technologies to do so safely and less labour intensively. There should also be research done to make manure pellet machines more practical for the global south, which can be accomplished by decreasing their reliance on electricity or petrol. Manure pellet machines could be designed to include solar panels on the apparatus, which would power a battery to fuel the machine. A less desirable, but useful modification could also be manually operated machines, though farming for smallholders is already extremely labour intensive.
Useful Resources
- A guide to composting animal manure: https://www.ag.ndsu.edu/publications/livestock/composting-animal-manures-a-guide-to-the-process-and-management-of-animal-manure-compost
- Information about the different commercial models of manure pellet machines available: https://manuretofertilizer.com/manure-pellet-machine/
- A ‘low price’ disc granulator pellet machine model, available on Alibaba for around $2000 USD, https://www.alibaba.com/product-detail/Low-price-High-capacity-granule-machines_1600356152678.html?spm=a2700.galleryofferlist.normal_offer.d_image.5a0a1299ohHSbc
- A video of a small scale manure/feed pellet machine available for purchase (https://manuretofertilizer.com/manure-pellet-machine/ ), similar models are available on Alibaba for $400 USD and upwards (https://www.alibaba.com/product-detail/low-consumption-manure-pelleting-press-machine_1600370528572.html?spm=a2700.galleryofferlist.normal_offer.d_image.5a0a1299ohHSbc, https://www.alibaba.com/product-detail/low-price-rabbit-chicken-pig-animal_1600071183103.html?spm=a2700.galleryofferlist.normal_offer.d_image.5a0a1299ohHSbc) These machines can be used for manure and organic matter with a moisture content of 10-12 % (Mieldazys et al., 2017)
- A practice brief from the Food and Agricultural Organization about manure utilization the global south: https://www.fao.org/3/bl516e/bl516e.pdf
- A journal article describing the energy requirements of producing different types of feed, which can be used to estimate how much energy different forms of organic matter would require to be processed into pellets https://fagr.stafpu.bu.edu.eg/Agricultural%20Engineering/3670/publications/Mokhtar%20Ibrahim%20Elsayed%20Dabbour_Energy%20Consumption%20in%20Manufacturing%20Different%20Types%20of%20Feeds.pdf
- A short and succinct explanation of why organic fertilizers is preferable to synthetic fertilizers: https://www.youtube.com/watch?v=qBgE85eNerE
- A video describing how to make a kiln from sand and clay: https://www.youtube.com/watch?v=XjpxfkSBPgo&t=3s
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