The following information is a synopsis of an updated white paper written in collaboration by the Ithaka Institute and IBI authored by Kathleen Draper, entitled The Potential for Biochar to Improve Sustainability for Maize Cultivation and Processing.
Maize, also referred to as corn in many parts of the world, has been cultivated by humans for millenia. By weight more maize is grown globally than any other grain. In some parts of the world corn is one of the most important crops grown for human consumption. It can be eaten raw or cooked, roasted, ground, popped, fermented, soaked, boiled or converted into liquid form (e.g. whiskey). Maize is found in countless foods, and is also converted into oils, syrup, starches and more.
Yet in some of the largest corn growing regions of the world the amount of maize grown for human consumption represents a small fraction of the overall production. The vast majority is grown to feed livestock or to produce ethanol. Increasingly even in the developing world small holder farmers are being paid as contract farmers to grow maize for livestock on marginal soils unable to grow higher value crops. All manner of livestock and pets eat maize, either kernels only or as silage. Silage makes use of all parts of the plant by shredded, compressing and fermenting. Ethanol, a gasoline additive that, according to some, reduces pollution and dependence on fossil fuels, also makes use of the whole plant.
While debates about the environmental impacts of using massive amounts of arable land to grow food for livestock or fuel are on-going, maize is an enormously important crop both in the developed and developing world. As with many other crops, it future is threatened by warming temperatures, increasing droughts and other recurring threats brought on by climate change.
This paper reviews some ways that biochar, a solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment, is being incorporated into maize production and processing systems to improve overall economic and environmental impacts. Given the wide variety of end uses and residual plant material that results from the different
Environmental benefits of producing and using biochar within the context of growing and processing maize accrue not only to soils, but to air, water and climate as well. These impacts, when viewed through the lens of the United Nations Sustainable Development Goals (SDGs) support progress towards achieving Food Security, Health and Wellness, Renewable Energy, Economic Development, Responsible Consumption and climate change mitigation and adaptation.
The methodology used in this paper combines a review of recent, relevant peer-reviewed literature with a survey of selected maize and biochar demonstration projects. Although extensive research has been done in academic settings related to using biochar with maize, particularly in the developing world, few long-term and large-scale demonstration projects have been conducted, particularly in the larger maize producing countries.
Recommendations for future research are detailed in the Next Steps section. As with many high volume, low value crops it is vital to understand the value proposition for using biochar in order for its use to broadly adopted. While low tech biochar producing stoves utilize the substantial amount of heat produced during carbonization, larger scale production heat could be used in different maize processing scenarios such as ethanol production or drying. A robust comparison of the life cycle assessment of growing and processing maize with and without biochar would also be of benefit is a world focusing on carbon reduction practices. Finally as with most crops, more real world biochar demonstration projects are needed so that optimized application rates and techniques can be determined for different soils used for maize production.
The Maize Growing Challenge
Maize is one of the most ubiquitous crops grown on the planet. Global production for 2017/2018 was estimated at 1.034 B metric tons. The top three producers; U.S., China and Brazil account for 64.9% of global production. (USDA) Land dedicated to growing maize totals more than 183 million hectares. Yields per hectare vary enormously. The U.S. leads at 11.08 t/ha while Zimbabwe has the lowest at 1.15 t/ha.
With such variability it is difficult to generalize about the challenges maize farmers face. Yield is obviously not a concern in the U.S. in most years. But the painfully low yield and heavy reliance on maize in countries with growing populations in Africa and Asia leaves large numbers of people vulnerable to food insecurity. Drought, flooding, pests or just exhausted soils can lead to mass emigration if yields are lower than normal. India dedicates more than 9M ha to growing maize, yet produces only 24.12 M t/y, just 26% of the U.S. average yield. Clearly then, there is much that can be done to increase yield in many parts of the world.
Corn is a thirsty crop compared to others and less frequent rains has negatively impacted yields around the globe but is felt most in dryer parts of the world. Aquifers are being drained to irrigate corn to maintain and boost yield, an unsustainable practice if the aquifers are not being recharged. In the U.S. alone 5.6 cubic miles of irrigation water is withdrawn each year to keep yields high. In an increasing water constrained world, water usage needs to be carefully managed.
On the other hand, too much water can also be problematic for maize growers. The increase in heavy rains brought on by climate change can lead to flooded fields which can delay planting, reduce quality and/or quantity of yield and lead to increased disease pressure requiring yet more chemicals to fend of bugs, bacteria and fungi.
Fertilizer usage for maize production is rampant, costly and damaging to the environment. More than 5.6M tons of chemical nitrogen and nearly another million in organic N in the form of manure is spread, sprayed, injected or otherwise applied to maize fields in the U.S. every year. (Foley 2013) Often that N is washed away after heavy rains leading to increasingly severe eutrophication in local and not so local waterways. As one example, the Gulf of Mexico has been hard hit by excessive N used by corn farmers in the mid-west. It has also been found to leach into groundwater supplies leading to potential health issues. (Garcia et al 2017)
While many profess the best solution is specially engineered seed that grow maize that can withstand multiple biotic and abiotic threats (e.g. drought, waterlogging, increased heat and various diseases), a better solution may lie in restoring the underlying soils that are in many cases are exhausted resulting in low fertility and poor nutrient management capabilities. These factors often lead farmers to use ever more chemical fertilizers which are costly and environmentally damaging. Some farmers are coming to the realization that this is downward spiral and are instead seeking out ways to increase soil fertility and resiliency using more natural methods. Biochar represents one of the ways that farmers can begin to restore soils, but it offers several other potential benefits as well which are discussed in this report.