Template:Chapter 4.9

4.9- Improving Biofertilizer Application for Smallholder Farmers using Pivot Bio Nitrogen Fixing Bacteria on Maize (Corn)Crops

Jessica Desouza, University of Guelph, Canada

Suggested citation for this chapter.

Desouza,J. (2022) Improving Biofertilizer Application for Smallholder Farmers using Pivot Bio Nitrogen Fixing Bacteria on Maize (Corn) Crops. In Farmpedia, The Encyclopedia for Small Scale Farmers. Editor, M.N. Raizada, University of Guelph, Canada. http://www.farmpedia.org

The Importance of Nitrogen to Maize Crops

The application of nitrogen fertilizer is critical to the growth and reproduction of crops as it is a building block for chlorophyll (Maathuis, 2009; Pérez-Montaño et al., 2014). Nitrogen fertilizer production requires natural gas, increasing global greenhouse gas (GHG) emissions which exacerbate the climate crisis (Snyder et al., 2009) . Furthermore, applying too little or too much nitrogen can disturb a healthy crop. Nitrogen-deficient soil will stunt the growth of crops, significantly reducing crop yield (Pérez-Montaño et al., 2014). Due to heavy rains, the potential for nitrogen leaching in the tropics is highly probable. This is worsened by decreased soil organic matter within the soil which would otherwise bind and retain applied nitrogen fertilizer (Harter, 2002). Low soil organic matter is especially problematic in the dry subtropics of Africa and South Asia, as low rainfall cannot support the yield of many crops (Erenstein et al., 2012). Tropical soils are also acidic, which prevent the uptake of nitrogen (Koutika et al., 2014). Since the majority of global malnutrition occurs in the tropics and subtropics (Mata, 1975), the need for a nitrogen amendment that directly functions on the plant root surface is warranted in these regions (Jones & Jacobsen, 2005). Conversely, nitrogen applied in excess is known to degrade soil, surrounding waterways, and the atmosphere (Walling & Vaneeckhaute, 2020). Nitrogen in excess can be released into the atmosphere as nitrous oxide (N2O) – a potent GHG that contributes to the climate change crisis (Walling & Vaneeckhaute, 2020). Nitrogen from traditional methods such as manuring can runoff and leach, contributing to the emission of N2O into the atmosphere (Walling & Vaneeckhaute, 2020). The potential contamination of drinking water supplies with excess nitrate is also a concern (Sharpley et al., 1998). Developing countries often lack the infrastructure to purify drinking water in rural areas (Sharpley et al., 1998). Excess synthetic nitrogen fertilizer can lead to the acidification of both the soil and water, thereby prohibiting the growth of crops such as maize (Olson & Sander, 1988). According to the Food and Agriculture Organization (FAO, 2017), sub-Saharan African smallholder farmers were anticipated to use 2,201,000 tonnes of nitrogen annually. Globally, 118,763,000 tonnes of nitrogen are anticipated to be used on farms to increase crop yields and maintain healthy crop growth annually. Therefore, sub-Saharan African smallholder farmers potentially utilize approximately 2% of the global supply of nitrogen fertilizers per year. This low usage may be due to the high energy costs associated with the production of nitrogen fertilizer, reducing accessibility to the highly sought-after amendment. A technology that delivers nitrogen directly to the root surface in a sustainable and affordable manner will significantly decrease the negative consequences posed by insufficient or excess application of this important macronutrient.

Pivot Bio Nitrogen-Fixing Bacteria: A Viable Solution to a Lack of Soil Nitrogen

Bacteria can assist in producing bio-available nitrogen to crops. Nitrogen-fixing bacteria (that inhabit root nodules of legumes such as soybeans) are capable of converting atmospheric nitrogen gas (N2) to a bio-available form at the roots (Hirsch & Mauchline, 2015). Unfortunately, maize does not form root nodules, and therefore cannot produce its own nitrogen. A start-up company in the United States, Pivot Bio, has developed a strain of nitrogen-fixing bacteria for maize so that the crop can produce its own source of nitrogen without root nodules (Pivot Bio, 2021). This bacteria is based on genetic modifications to Klebsiella variicola, which is part of a species complex with Klebsiella pneumoniae. These bacteria have long been known to promote nitrogen fixation in cereal crops (Iniguez et al., 2004). To apply Pivot Bio nitrogen-fixing bacteria , microbes must be applied by tractor during planting of the crop’s seeds (Pivot Bio, 2021). The microbes will then form a symbiotic relationship with the crop’s roots (Pivot Bio, 2021) and the plant will uptake the bio-available nitrogen.

The Use of Pivot Bio Nitrogen-Fixing Bacteria on Smallholder Farms

The following section aims to investigate the potential benefits and limitations regarding the use of Pivot Bio nitrogen-fixing bacteria on an average smallholder farm in Africa and Asia. The use of Pivot Bio nitrogen-fixing bacteria begins with contacting a sales representative of the company. Despite being a potentially viable solution, this product is currently only available to farmers within the United States (Pivot Bio, 2021). Though machinery is used to apply the bacteria in the United States, the product can be distributed by hand with personal protective equipment (PPE) employed. According to Pivot Bio nitrogen-fixing bacteria’s Material Safety Data Sheet (MSDS), this product is “not a physical, health, or environmental hazard”. However, the use of this product will require the use of certain PPE such as safety goggles and disposable rubber or latex gloves (Pivot Bio, 2020). Despite some limitations to the use of this product, its use on smallholder farms has the potential to increase yield. A study conducted on 100 commercial farms across the United States in 2019 showed a 76% positive yield response (Pivot Bio, 2020). This study intended to determine the effect of Pivot Bio’s microbe on the crops’ above-ground nutrient uptake, and nutrient accumulation in the plant (Pivot Bio, 2020). This was accomplished by comparing crops that had synthetic fertilizer applied (at the farm’s usual rate) with crops to which Pivot Bio’s nitrogen-fixing bacteria were added. It is likely that the lack of a baseline nitrogen application at every study site could have misconstrued results. Moreover, the results were based on a single crop season in the United States; the product’s efficacy in other nations/regions with different climates and extreme year-to-year climatic variation is unknown. Since the plants treated with Pivot Bio nitrogen-fixing bacteria were not compared to plants with low nitrogen levels, it is unclear whether Pivot Bio’s product could benefit soils in the tropics and subtropics. Also unknown is the effect of soil pH and low soil organic matter or salinity, which are also significant challenges in the tropics and subtropics. Therefore, further research is required into how this product (and similar products in the future) may aid smallholder farmers. Even if Pivot Bio nitrogen-fixing bacteria assists in increasing crop yields, there are obstacles to the storage and transportation of the product. According to Pivot Bio (2020), their product must be stored in its original container in a cool, well-ventilated, dry area. This warrants the use of a refrigeration unit in the hotter climates of Africa, where these appliances are out of reach of smallholders who lack a reliable source of electricity (Kaygusuz, 2011). Fortunately, it is important to note that the retail cost of this product to an American farmer is estimated to be $8 per hectare applied (Pivot Bio, 2021). Since most smallholder farmers in Africa usually own less than 2 hectares (Njeru, 2013), this expense is insignificant to the benefit it may provide to a maize crop. However, limitations such as its inaccessibility on the market, the lack of access to reliable refrigeration, and unknowns such as its viability in tropical and subtropical soils, currently reduce its promise to many smallholder farms in Africa.

Critical Analysis: The Application and Use of Pivot Bio Nitrogen-Fixing Bacteria

Pivot Bio nitrogen-fixing bacteria replaces synthetic nitrogen fertilizers which are usually applied early in the growing season. In areas with high amounts of precipitation, high heat, water logging and/or low nutrient sandy soils, the likelihood of nitrogen leaching through the soil profile or volatizing into the atmosphere increases (Cabrera et al., 2005). This is especially problematic because the peak demand for nitrogen in maize is during grain formation (Aslam et al., 2012). The nitrogen-fixing bacteria within this product, however, claims to function late in the growing season to match peak demand. Unfortunately, little information is available on the functioning of these bacteria in high-heat conditions. Studies suggest that nitrogen-fixing bacteria populations decline when exposed to high temperatures (McGill et al., 1981), indicating a potential limitation during the storage, transportation, and use of this product on crops in smallholder farms in the tropics and subtropics. Moreover, low literacy rates and inaccessible scientific jargon may pose a hinderance to a smallholder farmer’s understanding of the application and use of the product, requiring the use of more appropriate training materials in form of videos, picture-based manuals, etc. (Devkota et al., 2020). Lastly, although this product succeeds on commercial farms in the United States, the competitive biofertilizer industry in India may prove to be more accessible to smallholder farmers in Africa. According to Patra et al. (2021), Indian scientists have already begun to introduce certain nitrogen-fixing bacteria in the form of biofertilizers. A more recent development includes the coating of seeds with biofertilizer, reducing the need for initial application. If the use of Indian biofertilizers prove successful to smallholder farmers, then it may be more feasible to utilize a product tested in a similar climate. Other companies that specifically develop nitrogen-fixing bacteria for maize (such as Azotic, Bioconsortia, etc.) may also prove to be beneficial to smallholder farmers, yet their products may suffer from the same constraints as PivotBio and would require further investigation.

Alternatives to Maize Nitrogen-Fixing Bacteria

There are numerous methods that can increase soil nitrogen, including crop rotation (intercropping) and the use of manure, compost, or leaf litter. Crop rotation or intercropping with legumes is a viable alternative to providing nitrogen to the crop’s soil without applying fertilizer, manure, or maize nitrogen-fixing bacteria (De Notaris et al., 2018). Since legumes naturally host nitrogen-fixing bacteria within root nodules, plant-available nitrogen will be deposited into the soil after decomposition of stems and roots. Utilizing manure, compost, or leaf litter (i.e., practicing no-till on the field) can also provide nitrogen to the soil. However, these alternatives could potentially result in increased runoff, volatilization of nitrogen gas, and leaching – contributing to contaminated waterways and degraded soil (Eghball & Power, 1999). However, when applied properly, these agricultural amendments should not harm the surrounding environment and should prove to be low-cost alternatives to solve a lack of soil nitrogen for smallholder farmers in Africa, allowing them to be self-reliant

Useful Resources

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