Overview

The environmental indicator for land use efficiency is intended to inform understanding of the sustainability of productivity and is very closely tied to crop yields, which are key to achieving an economically sustainable farming operation. In addition, cropland in the U.S. today covers about 19 percent of land area and encompasses the most suitable agricultural regions of the country. Trends over time in land cover change are explored in Part Two of this report; the land resource base in the U.S. and globally has largely brought under cultivation the most productive lands. Thus, expanding agriculture onto previously uncultivated land may bring less productive lands into cultivation, requiring greater resource use to produce marketable yields. Land expansion for agriculture would also come at the expense of land currently valued for habitat and for other ecosystem services. Maintaining and improving yields on existing cropland are critical both to maintaining economic sustainability and to producing other sustainability outcomes.

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SECTION 1:

RESULTS

© Steve Werblow

Results for the Land Use Indicator for the ten crops are illustrated and described in the figures below. Land Use is presented in the amount of land required to produce a unit of production for the given crop. This indicator is primarily impacted by trends in crop. Additional information can be seen in the methods below and in the crop specific sections of the report. 

The trends described below are the result of many different environmental, social, and policy drivers and represent innumerable individual producer decisions regarding management. Our intention is to provide an overview of how these forces and decisions, in aggregate, have influenced the resource use efficiency of U.S. commodity agriculture over the long term. Where the data that were used in the indicator calculations can explain changes over time, some interpretation is provided. However, we do not attempt a thorough, geographically specific interpretation that would be needed to fully understand some of these trends or provide a robust statistical assessment. Thus, while linear trend lines are provided to illustrate whether there is a consistent directional change over time, this should not be considered a measure of the statistical significance of trends.

Land Use Indicator by Crop

SECTION 2:

METHODOLOGY

The primary Land Use indicator considered here is the amount of land required to produce a unit of production (e.g., acre/bu.), and is the inverse of standard crop yield calculations. In addition, for each crop we report on the trends in total area planted and total production, and in Part Two we further consider trends in land cover change and the spatial distribution of agricultural land throughout the study period. The Land Use indicator follows the same methodology as the Land Use metric result from the Fieldprint Calculator. 

Annual yield per planted acre for each crop considered was downloaded from the USDA NASS Quickstats database [36], along with planted area and total production at the national scale. As indicated earlier, the annual crop yields were adjusted using a five-year moving average in order to reduce the impact of any one-year event on yields. The annual number provided by USDA is based on state and country crop yields aggregated according to standard USDA statistical sampling and procedures [36]. For some crops, the regions where they are grown in the U.S. are geographically small and relatively homogeneous (e.g., barley, peanuts), and thus even the national-level indicators are influenced by regional climate events. 

This indicator is calculated using a simple algorithm, where the one data variable (crop yield) is known with a high degree of accuracy. Thus the uncertainty level for this indicator is low.