Land Area Experiments
Land is a key element of farmer wealth, a critical input in farm production, and an essential variable for analyzing agricultural input use and productivity measures. Although often overlooked by analysts, the quality of land area measurement can have non-trivial implications for agricultural statistics, economics, and policy analysis. Different means of measuring agricultural land area can lead to different conclusions when assessing key issues such as land inequality or the relationship between farm size and productivity.
In an effort to thoroughly understand the variation in measurement method outcomes and the associated systematic biases, the LSMS team, with support from UK Aid, has prioritized land area measurement in its methodological research agenda. Methodological validation experiments have been conducted in Ethiopia, Tanzania, and Nigeria to test the three most common methods for farm area measurement: compass and rope (CR) measurement, farmer self-reported estimates (SR), and measurement by handheld GPS devices.
Ethiopia Land and Soil Experimental Research (LASER)
In an effort to improve the quality of agricultural data, particularly with respect to land area and soil fertility measurements, the LSMS team collaborated with the Central Statistical Agency of Ethiopia and the World Agroforestry Center (ICRAF) to execute the Land and Soil Experimental Research (LASER) study in Ethiopia. The LASER study aimed to test the methodological options in measuring land area and soil fertility and subsequently assess the feasibility of implementing each method in large household survey operations. Methods tested for land area measurement include traversing (or compass and rope), handheld GPS unit, and farmer estimation. Plot-level soil samples were collected and analyzed at ICRAF’s Soil-Plant Spectral Diagnostics Laboratory using conventional and spectral techniques. Additionally, a series of subjective questions were asked of the farmer to allow for comparison of subjective and objective measurements of soil fertility. Crop-cutting was conducted on pure stand maize fields.
LASER was implemented across three administrative zones of the Oromia region in Ethiopia. In total, 1018 households were interviewed, with nearly 1800 agricultural fields selected for objective land area and soil fertility measurement.
Land Measurement Bias and Its Empirical Implications: Evidence from a Validation Exercise. Andrew Dillon, Sydney Gourlay, Kevin McGee and Gbemisola Oseni. Policy Research Working Paper 7597. March 2016.
Missing(ness) in Action: Selectivity Bias in GPS-Based Land Area Measurements. Talip Kilic, Alberto Zezza, Calogero Carletto, and Sara Savastano. Policy Research Working Paper 6490. June 2013.
From Guesstimates to GPStimates: Land Area Measurement and Implications for Agricultural Analysis. Calogero Carletto, Sydney Gourlay, and Paul Winters. Policy Research Working Paper 6550. July 2013.