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This dissertation consists of three essays empirically investigating three important aspects of the U.S. agriculture: conservation, subsidy, and productivity. Each essay is conducted with the U.S. Census of Agriculture micro file data. Availability of cross-sectional and time variations of detailed individual farm production and demographic characteristics allows for uncovering heterogeneous relationships between farm production decisions and the corresponding aspects of U.S. agriculture.

The first essay examines an adverse effect of a cropland retirement policy. A cropland retirement policy contributes to the reduction of environmental externalities from agricultural production such as soil erosion, nutrient runoff and loss of wildlife habitat. On the other hand, participant's potential adverse behavior could undermine the environmental benefits of the policy. Several sources of such an unintended effect, known as ``slippage'', have been conceptually identified, but their empirical evidence has been scarce. This article tests one source of slippage caused by in-farm land substitution from noncropland to cropland as a result of farmland retirement in the U.S. Conservation Reserve Program (CRP). The causal relationship of CRP participation and subsequent slippage through in-farm land substitution is identified by employing farm fixed effects, time-varying county fixed effects, and selection-on-observables. These could eliminate effects of unobservables that are potentially correlated with both the program participation and subsequent farmland reallocation decisions. Overall, slippage seems evident and fairly robust among specifications. It is found that an average program participant converts 14% of noncropland to cropping activities after enrollment. Results further show that participants with a larger share of uncropped land contribute more to slippage, indicating that farms with the excess capacity of conversion are more flexible in the land allocation decision and thus likely to give rise to slippage. This suggests that additional restrictions on the rest of land use for participants and/or introduction of penalty points reflecting the share of noncropland in the current auction mechanism can hinder such a backward incentive offsetting the program benefits.

The second essay examines the distortionary effects of agricultural policy on farm productivity by examining the response of U.S. tobacco farmers' productivity to the quota buyout of 2004. We focus on the impact of distortionary policy, i.e., the tobacco quota, by decomposing aggregate productivity growth into the contribution of farm-level productivity growth and the contribution of reallocation of resources among tobacco growers. We find that the aggregate productivity of Kentucky tobacco farms grew 44% between 2002 and 2007. The elimination of quota rental costs and reallocation of resources, including entry and exit, accounted for most of the post-buyout productivity growth. It is also noted that the aggregate productivity of Kentucky tobacco farms vary across farm characteristics and locations. This highlights the importance of using highly disaggregated data to uncover the sources of aggregate productivity growth.

The third essay examines the relationship between farm size and productivity growth. In the past several decades, crop production in the U.S. has shifted to larger farms. During the same period, crop productivity has fairly improved. While these two events seem clearly associated, no studies have fully uncovered the link between them. Using farm-level longitudinal data from the Censuses of Agriculture from 1987-2007 enables us to decompose aggregate productivity growth (APG) by farm size, but also by farm entry/exit and by technology/reallocation. We have three main findings. First, productivity growth is clearly non-uniform among farm sizes. Between 1987 and 2007, virtually all of the aggregate productivity growth of crop farms came from farms with annual sales of more than $500,000. These farms account for only 8% of U.S. crop farms. A closer look at the APG contributions to productivity growth from surviving farms confirms the findings for all crop farms: the productivity of mid-size farms has barely increased, and the productivity of smaller farms has fallen. Finally, the relative importance of technical efficiency growth and resource reallocation varies over time. Technical efficiency growth seems to be a larger source of APG for large farms between 1987 and 1997, whereas reallocation across all sales classes contributes more to APG between 1997 and 2007. Overall, our finding provides the concrete evidence that farm consolidation has been strongly associated with the productivity growth of U.S. crop farms. Our finding that resource reallocation through farm consolidation is nontrivial for the APG of crop farms highlights the usefulness of farm-level panel data for studying structural changes and APG.