scholarly journals Trends and Variability in U.S. Corn Yields Over the Twentieth Century

2005 ◽  
Vol 9 (1) ◽  
pp. 1-29 ◽  
Author(s):  
Christopher J. Kucharik ◽  
Navin Ramankutty
Keyword(s):  
Twentieth Century ◽  
Growth Rates ◽  
The United States ◽  
Yield Variability ◽  
Corn Belt ◽  
Corn Yield ◽  
County Level ◽  
Agricultural Revolution ◽  
Decadal Scale ◽  
The U.S

Abstract The United States is currently responsible for 40%–45% of the world’s corn supply and 70% of total global exports [the U.S. Department of Agriculture–National Agricultural Statistics Service (USDA–NASS)]. Therefore, analyses of the spatial and temporal patterns of historical U.S. corn yields might provide insight into future crop-production potential and food security. In this study, county-level maize yield data from 1910 to 2001 were used to characterize the spatial heterogeneity of yield growth rates and interannual yield variability across the U.S. Corn Belt. Widespread decadal-scale changes in corn yield variability and yield growth rates have occurred since the 1930s across the Corn Belt, but the response has varied substantially with geographic location. Northern portions of the Great Plains have experienced consistently high interannual corn yield variability, averaging 30%–40% relative to the mean. Increasing usage of irrigation in Nebraska, Kansas, and Texas, since the 1950s, has helped boost yields by 75%–90% over rain-fed corn, creating a yield gap of 2–4 T ha−1 between irrigated and nonirrigated corn that could potentially be exploited in other regions. Furthermore, irrigation has reduced interannual variability by a factor of 3 in these same regions. A small region from eastern Iowa into northern Illinois and southern Wisconsin has experienced minimal interannual yield variability, averaging only 6%–10% relative to mean yields. This paper shows that the choice of time period used for statistical analysis impacted conclusions drawn about twentieth-century trends in corn yield variability. Widespread increases in yield variability were apparent from 1950 onward, but were not significant over the entire 1930–2001 period. There is also evidence that yield variability decreased from the early 1990s to 2001. Corn yield growth rates peaked at an annual-average rate of 3%–5% in the 1960s (124.5 kg ha−1 yr−1), but have steadily declined to a relative rate of 0.78% yr−1 (49.2 kg ha−1 yr−1) during the 1990s. A general inverse relationship between increasing corn yield and decreasing yield growth rates was noted after county-level yields reached 4 T ha−1, suggesting that widespread, significant increases in corn yield are not likely to take place in the future, particularly on irrigated land, without a second agricultural revolution.

scholarly journals Machine Learning-Based Modeling of Spatio-Temporally Varying Responses of Rainfed Corn Yield to Climate, Soil, and Management in the U.S. Corn Belt

2021 ◽  
Vol 4 ◽  
Author(s):  
Tianfang Xu ◽  
Kaiyu Guan ◽  
Bin Peng ◽  
Shiqi Wei ◽  
Lei Zhao
Keyword(s):  
Machine Learning ◽  
Organic Matter ◽  
Random Forest ◽  
Planting Date ◽  
Yield Variability ◽  
Corn Belt ◽  
Corn Yield ◽  
Water Capacity ◽  
Available Water Capacity ◽  
The U.S

Better understanding the variabilities in crop yield and production is critical to assessing the vulnerability and resilience of food production systems. Both environmental (climatic and edaphic) conditions and management factors affect the variabilities of crop yield. In this study, we conducted a comprehensive data-driven analysis in the U.S. Corn Belt to understand and model how rainfed corn yield is affected by climate variability and extremes, soil properties (soil available water capacity, soil organic matter), and management practices (planting date and fertilizer applications). Exploratory data analyses revealed that corn yield responds non-linearly to temperature, while the negative vapor pressure deficit (VPD) effect on corn yield is monotonic and more prominent. Higher mean yield and inter-annual yield variability are found associated with high soil available water capacity, while lower inter-annual yield variability is associated with high soil organic matter (SOM). We also identified region-dependent relationships between planting date and yield and a strong correlation between planting date and the April weather condition (temperature and rainfall). Next, we built machine learning models using the random forest and LASSO algorithms, respectively, to predict corn yield with all climatic, soil properties, and management factors. The random forest model achieved a high prediction accuracy for annual yield at county level as early as in July (R2 = 0.781) and outperformed LASSO. The gained insights from this study lead to improved understanding of how corn yield responds to climate variability and projected change in the U.S. Corn Belt and globally.

scholarly journals Timing of social distancing policies and COVID-19 mortality: county-level evidence from the U.S.

2021 ◽  
Author(s):  
Catalina Amuedo-Dorantes ◽  
Neeraj Kaushal ◽  
Ashley N. Muchow
Keyword(s):  
New York ◽  
Political Ideology ◽  
Death Rate ◽  
The United States ◽  
County Level ◽  
Level Data ◽  
Level Information ◽  
Alternative Measures ◽  
The U.S ◽  
Pharmaceutical Interventions

AbstractUsing county-level data on COVID-19 mortality and infections, along with county-level information on the adoption of non-pharmaceutical interventions (NPIs), we examine how the speed of NPI adoption affected COVID-19 mortality in the United States. Our estimates suggest that adopting safer-at-home orders or non-essential business closures 1 day before infections double can curtail the COVID-19 death rate by 1.9%. This finding proves robust to alternative measures of NPI adoption speed, model specifications that control for testing, other NPIs, and mobility and across various samples (national, the Northeast, excluding New York, and excluding the Northeast). We also find that the adoption speed of NPIs is associated with lower infections and is unrelated to non-COVID deaths, suggesting these measures slowed contagion. Finally, NPI adoption speed appears to have been less effective in Republican counties, suggesting that political ideology might have compromised their efficacy.

Disproportionately Overrepresented: Women in Local Elected Offices

2018 ◽  
Vol 50 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Ethan M. Bernick ◽  
Brianne Heidbreder
Keyword(s):  
United States ◽  
Maximum Likelihood ◽  
Gender Norms ◽  
The United States ◽  
Census Bureau ◽  
National Association ◽  
County Level ◽  
Political Factors ◽  
Using Data ◽  
The U.S

This research examines the position of county clerk, where women are numerically disproportionately over-represented. Using data collected from the National Association of Counties and the U.S. Census Bureau, the models estimate the correlation between the county clerk’s sex and county-level demographic, social, and political factors with maximum likelihood logit estimates. This research suggests that while women are better represented in the office of county clerk across the United States, when compared to other elective offices, this representation may be because this office is not seen as attractive to men and its responsibilities fit within the construct of traditional gender norms.

scholarly journals INSTYTUCJONALNA I KOMPETENCYJNA EWOLUCJA BANKU CENTRALNEGO STANÓW ZJEDNOCZONYCH AMERYKI W XX WIEKU

2016 ◽  
Vol 10 (2) ◽  
pp. 275
Author(s):  
Wojciech Kwiatkowski
Keyword(s):  
Twentieth Century ◽  
Central Bank ◽  
Federal Reserve ◽  
The United States ◽  
Institutional Evolution ◽  
Federal Reserve System ◽  
Initial Shape ◽  
Treasury Department ◽  
Reserve System ◽  
The U.S

Institutional and Competence Evolution of the U.S. Central Bank in the Twentieth CenturySummary The article describes the initial shape of the U.S. central bank, i.e. the Federal Reserve System created under the federal act of 1913 as a “Federal Reserve”, as well as the reasons for its competence and institutional evolution mainly in the thirties of the twentieth century. The paper seeks to identify the consequences of the absence of statutory regulations – in many ways necessary for the proper functioning of the central bank in the United States as a confederation, which has become a major cause of the appropriation of powers by the representatives of the private sector at the central bank. In addition, by analyzing the agreement concluded by the representatives of the bank and the U.S. Treasury Department the article shows the consequences of the absence of constitutional guarantees for the central bank’s operational independence. The article also seeks to name and describe the laws passed in the twentieth century, which have contributed significantly to today’s field of competence of the Federal Reserve System and its present modus vivendi.

The Birth of Modern Transnational Bribery Law

2019 ◽  
pp. 31-40
Author(s):  
Kevin E. Davis
Keyword(s):  
United States ◽  
Twentieth Century ◽  
The United States ◽  
Historical Record ◽  
Foreign Corrupt Practices Act ◽  
Sarbanes Oxley ◽  
The U.S

This chapter traces the development of modern transnational bribery law in the United States. After a brief discussion of the U.S. Supreme Court’s decision in Oscanyan v. Arms Co., it traces the evolution of domestic anti-bribery law in the United States through the twentieth century. It then discusses the Watergate investigation and scandals involving companies such as Lockheed and United Brands that led to enactment of the U.S. Foreign Corrupt Practices Act of 1977. The historical record sheds light on the moral and economic motivations behind this landmark legislation. Subsequent amendments to the FCPA and related statutes, such as the Sarbanes-Oxley Act, are also discussed.

Shaping Knowledge about American Labor: External Advising at the U.S. Bureau of Labor Statistics in the Twentieth Century

2010 ◽  
Vol 23 (2) ◽  
pp. 187-220 ◽  
Author(s):  
Thomas A. Stapleford
Keyword(s):  
Twentieth Century ◽  
The United States ◽  
Social Scientists ◽  
Political Values ◽  
Construction Of Knowledge ◽  
Unemployment Compensation ◽  
Labor Statistics ◽  
Bureau Of Labor Statistics ◽  
The U.S ◽  
American Labor

ArgumentCreated in 1884, the U.S. Bureau of Labor Statistics (BLS) has been the major federal source for data in the United States on labor-related topics such as prices, unemployment, compensation, productivity, and family expenditures. This essay traces the development and transformation of formal and informal consulting relationships between the BLS and external groups (including academic social scientists, unions, businesses, and other government entities) over the twentieth century. Though such a history cannot, of course, provide a comprehensive analysis of how political values have shaped the construction of labor statistics during this period, I argue that it can nevertheless provide important insights into the political context for the construction of knowledge about American workers and their living and working conditions.

scholarly journals Gulf of Mexico Coastal County Resilience to Natural Hazards

2021 ◽  
Vol 32 ◽  
pp. 67-78
Author(s):  
Kevin Summers ◽  
Linda Harwell ◽  
Andrea Lamper ◽  
Courtney McMillon ◽  
Kyle Buck ◽  
...  
Keyword(s):  
United States ◽  
Gulf Of Mexico ◽  
Natural Hazards ◽  
Social Economic ◽  
Multiple Scales ◽  
The United States ◽  
County Level ◽  
Coastal County ◽  
County Scale ◽  
The U.S

Using a Cumulative Resilience Screening Index (CRSI) that was developed to represent resilience to natural hazards at multiple scales for the United States, the U.S. coastal counties of the Gulf of Mexico (GOM) region of the United States are compared for resilience for these types of natural hazards. The assessment compares the domains, indicators and metrics of CRSI, addressing environmental, economic and societal aspects of resilience to natural hazards at county scales. The index was applied at the county scale and aggregated to represent states and two regions of the U.S. GOM coastline. Assessments showed county—level resilience in all GOM counties was low, generally below the U.S. average. Comparisons showed higher levels of resilience in the western GOM region while select counties in Louisiana, Mississippi and Alabama exhibited the lowest resilience (<2.0) to natural hazards. Some coastal counties in Florida and Texas represented the highest levels of resilience seen along the GOM coast. Much of this increased resilience appears to be due to higher levels of governance and broader levels of social, economic and ecological services.

scholarly journals La educación bilingüe en los Estados Unidos: Programas, perspectivas, retos y lecciones

2020 ◽  
pp. 130
Author(s):  
David Nieto
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Bilingual Education ◽  
Critical Evaluation ◽  
Historical Analysis ◽  
The United States ◽  
Educational Programs ◽  
The Us ◽  
The U.S

The present paper engages in a historical analysis and interpretation of the policies that have contributed to develop bilingual education in the United States. Departing from the U.S. interpretation of bilingual education, this study examines each of the educational programs that have been implemented in the country since the twentieth century, its pedagogical underpinnings, and the critical evaluation of its outcomes. The paper concludes with an analysis of potential interpretations and lessons that the US case may have for other contexts.

Sign in / Sign up

Export Citation Format

Share Document