The Impact of Drought on Maize Production in Iowa
Introduction
Cereal crops, including maize, are the most important food source for human consumption , and as global population increases, crop production must increase [1]. The United States (USA) holds the title of the world’s largest maize producer and exporter, with Iowa being the top maize-producing state for the past two decades (as seen in Figure 1). However, in 2022, Iowa experienced a drop in maize production. According to U.S. Department of Agriculture, the decline in Iowa corn production, from 2.54 billion bushels in 2021 to 2.48 billion bushels in 2022, was largely attributed to drought [2].
Climate change is causing worldwide climate shifts, including increasing drought like conditions int the Midwest [3]. Therefore, it is a significant concern for agricultural production, especially in the Iowa, where maize is a crucial crop [2]. To maintain maize yields, farmers will need to implement a range of adaptation strategies, with the choice of strategy dependent on how the local to regional climate is predicted to evolve. As a result, it is essential to investigate the impact of drought on maize production in Iowa and consequently the effect on corn prices. The repercussions of reduced maize production can be extensive, including rising food costs, which can disproportionately affect low-income families.
Methodology
The objective of this report is to assess the historical impact of drought on maize production and prices in Iowa, and to evaluate the potential impact of future droughts on maize production in the region.
To achieve this, the study utilized two climate variables – average annual temperature and precipitation - as they are the most significant factors affecting maize yield variability. Increasing temperature will shorten the length of time to maturity, while brief spikes in temperature can affect metabolic processes, leading to reduced carbon assimilation, and cause declines in pollination and grain set [4,5]. In addition, low rainfall can lead to moisture stress in the plant as soil moisture decreases [6]. Therefore, the trends in annual temperature and precipitation over the past 30 years were analyzed to understand how corn production would be impacted in climatic conditions.
The study also considered drought as a crucial factor affecting maize production in Iowa. The Palmer Drought Severity Index (PDSI) and Palmer Z Index were used to measure drought. The Palmer Z Index measured short-term drought on a monthly scale, while the PDSI attempted to measure the duration and intensity of the long-term drought-inducing circulation patterns [7]. The PDSI is a standardized index based on a simplified soil water balance and estimates relative soil moisture conditions. The magnitude of both indices indicates the severity of the departure from normal conditions [8]. So, a value > 0 represents wet conditions, while a value < 0 represents an drought [8].
A linear regression was run between temperature and the PDSI index, and the PDSI index and maize production to analyze the correlation. A model was developed to predict how future increases in temperature could change production, and different climate scenarios were tested.
Finally, the study observed the historical trend between price and changes in production in Iowa to understand how price would be affected by changes in maize production.
Climatic Conditions In Iowa
Iowa’s climate, which is characterized as humid with mostly loam and silty clay loam soils, plays a crucial role in the production of maize [9]. Therefore, an analysis was conducted to examine trends in annual average temperature, annual precipitation, PDSI (Palmer Drought Severity Index), and Palmer Z Index over the past 30 years in relation to climate change.
The analysis revealed that the annual average temperature has been steadily increasing over the past three decades, as shown in Figure 2. Furthermore, there has been a particularly rapid increase since 1996. Although annual precipitation did increase from 1990 to 2013, it experienced a sharp decline around 2014 (as seen in Figure 3).
Warning: package 'plotly' was built under R version 4.2.3The above trends are consistent with the drought indices, which indicate that Iowa has experienced increasingly severe drought conditions over the past 30 years. While short-term droughts have been relatively frequent (as illustrated in Figure 4), there has been an increase in long-term droughts since 2000 (as shown in Figure 5).These findings suggest that climate change is having a significant impact on Iowa’s climate.
Correlation Between Annual Temperature, Drought, and Maize Production
An analysis was conducted to evaluate the relationship between annual temperature, drought, and maize production. The study found that there was a negative correlation between annual temperature and the Palmer Drought Severity Index (PDSI), indicating that as temperature increases, the PDSI value decreases, which suggests dry conditions. Conversely, as temperature decreases, the PDSI value increases, indicating wetter conditions.
Furthermore, a positive correlation was observed between the PDSI and maize production, suggesting that as the PDSI value increases (indicating wetter conditions), maize production also increases. It is worth noting that the optimal maize production occurs when the PDSI value ranges between 0 to 3.
Climate Scenario Analysis
A linear regression model was developed to predict the impact of changes in temperature on maize production, based on the observed correlations between annual temperature, drought, and maize production. Four different scenarios were analyzed, where changes in production were plotted from 2023-2030 with temperature changes of 0.1°F, 0.5°F, 1°F, and 1.5°F.
According to the Annual 2022 Global Climate Report by the National Oceanic and Atmospheric Administration, North America’s yearly temperature has increased at an average rate of 0.13°C (0.23°F) since 1910. However, the rate of increase has been twice as high (0.27°C / 0.49°F) since 1981. Therefore, the 0.5°F scenario represents the current situation.
Figure 8 shows that maize production is expected to decline under all scenarios in the next eight years if temperatures continue to rise. However, the extent of the decline in production varies greatly among the different scenarios. The production output among the four scenarios shows a significant year-on-year change. Although the production levels in 2023 are similar across all four scenarios, there is a notable decrease in production output among the scenarios by 2030.
Iowa Maize Production and Maize Price in the U.S
Figure 10 illustrates that as the corn price increases, there is a corresponding increase in the percentage change of production. This can be explained by the fact that increased production results in larger opening stocks for the following year, causing prices to drop [10]. Conversely, a consistent decrease in maize production due to drought will result in relatively small beginning stocks, causing prices to rapidly surge. Additionally, this will lead to a reduction in exports and an increase in costs related to domestic feed, residual, and fuel ethanol usage [11].
Thus, a consistent decrease in maize production due to drought or other factors can have adverse effects on the economy. This can lead to an increase in food prices, as corn is a primary ingredient in many foods, including livestock feed, cereals, and sweeteners. The increased costs of corn can also impact the price of meat and dairy products, which can lead to inflation and a decrease in consumer purchasing power. The increase in corn prices can also impact other industries, such as the fuel industry. Ethanol, which is made from corn, is blended with gasoline to create a biofuel. A decrease in corn production can lead to a decrease in ethanol production, which can lead to higher fuel prices and a decrease in demand for ethanol-related products.
Furthermore, changes in corn production can impact international trade. The U.S can witness a decline in revenue due to decrease in maize exports. On the other hand, countries that import corn may face higher prices, which can also negatively impact their economies.
Conclusion
In conclusion, the increasing frequency and severity of droughts caused by climate change pose a significant threat to maize production in Iowa, which could result in rising food prices that disproportionately affect low-income families. The study analyzed the historical trends in temperature, precipitation, and drought indices over the past 30 years and found a negative correlation between temperature and drought severity, as well as a positive correlation between drought severity and maize production. A linear regression model was developed to predict the impact of changes in temperature on maize production, which showed that even small increases in temperature could lead to significant decreases in production and thus leading to increase in corn prices. Such changes in corn production and prices can have a significant impact on the economy. While an increase in corn production can have positive effects, a consistent decrease in production can lead to higher food prices, inflation, and a decrease in demand for corn-related products. Therefore, it is essential to carefully monitor and manage changes in corn production to ensure a stable and sustainable economy.
References
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