Detection of cropland field parcels from Landsat imagery

Graesser, Jordan; Ramankutty, Navin

doi:10.1016/j.rse.2017.08.027

Cited by 100 publications

(50 citation statements)

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“…We examined the scale of cropland expansion in sub-Andean South America (figure S2 is available online at stacks.iop.org/ERL/13/084021/mmedia) from 1990 to 2014, in 5 year intervals. Each time period was centered on a 1.5 year season from 1 January of the first year to 1 August of the second year (e.g., 1 January 1990 to 1 August 1991) [32]. The two-year combinations for each time period were 1990/1991, 1995/1996, 2000/2001, 2005/2006, 2010/2011, and 2014/2015.…”

Section: Study Area and Timeframementioning

confidence: 99%

“…The methods to process Landsat imagery and extract cropland field parcels consisted of image normalization, temporal compositing of spectral indices, extraction of land cover objects (i.e., groups of pixels), per pixel (30 m) estimates of cropland, forestland, and other broad land cover classes, and the intersection of segmented land cover objects with the pixel-level cropland estimates. A simplified overview of the procedure to produce individual field parcels is described below (see [32] for details).…”

Section: Landsat Processing and Field Extractionmentioning

confidence: 99%

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Increasing expansion of large-scale crop production onto deforested land in sub-Andean South America

Graesser

Ramankutty

Coomes

2018

Environ. Res. Lett.

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A combination of high commodity crop prices, rising global food demand, and technological advances has transformed the scale of global crop production. Farming in South America is a prime example, where large-scale cash crops, such as soy, have transformed the land use dynamics at the forest frontier. We evaluate this transformation in sub-Andean South America by estimating crop and forest cover and detecting individual cropland field parcels using Landsat imagery in 5 year intervals over a 24 year period. From 1990 to 2014, cropland expansion onto deforested land was increasingly driven by large fields (>50 ha), whose contribution increased from 32% to 48% (+16% increase), while the contribution of smaller fields (<20 ha) declined from 36% to 26% (−10% decrease). This shift toward large-scale farming replacing cleared land across the region has important implications for food security and biodiversity conservation. Policy efforts will need to target different actors and transcend national borders in order to tackle the changing nature of South American deforestation.

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Section: Study Area and Timeframementioning

confidence: 99%

Section: Landsat Processing and Field Extractionmentioning

confidence: 99%

Increasing expansion of large-scale crop production onto deforested land in sub-Andean South America

Graesser

Ramankutty

Coomes

2018

Environ. Res. Lett.

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“…Both of these studies are part of a larger debate on the role of farm size in global food security (Meyfroidt, 2017), where farm size is related to field size (Graesser & Ramankutty, 2017). For example, an overall farm size may not change due to lack of capacity for expansion but a farmer may increase their existing field sizes.…”

Section: Introductionmentioning

confidence: 99%

“…Although the general patterns of field size were captured globally, there were numerous artifacts from the interpolation method when viewing the map in more detail, and limitations were recognized at a national level, for example, underestimation of small fields in Argentina (Graesser & Ramankutty, 2017). Hence, there was a clear need to improve this map with a much denser sample and apply a more appropriate interpolation algorithm.…”

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confidence: 99%

“…For example, Yan and Roy (2016) developed an automated crop field extraction method which they applied to 30 m Web Enabled Landsat data (WELD) time series to produce a wall-to-wall field size map for the contiguous USA (Yan & Roy, 2016). Graesser and Ramankutty (2017) developed a semi-automated approach involving edge extraction and adaptive thresholding to produce a field size map for five countries in South America. Although the results from both studies were good, that is, accuracies of >84%, both of these studies are limited in geographical coverage and concern areas where field sizes are large with a relatively precise geometry (square or round) in comparison with fields in other parts of the world.…”

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confidence: 99%

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Estimating the global distribution of field size using crowdsourcing

Lesiv

Bayas

See

et al. 2018

Global Change Biology

121

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There is an increasing evidence that smallholder farms contribute substantially to food production globally, yet spatially explicit data on agricultural field sizes are currently lacking. Automated field size delineation using remote sensing or the estimation of average farm size at subnational level using census data are two approaches that have been used. However, both have limitations, for example, automatic field size delineation using remote sensing has not yet been implemented at a global scale while the spatial resolution is very coarse when using census data. This paper demonstrates a unique approach to quantifying and mapping agricultural field size globally using crowdsourcing. A campaign was run in June 2017, where participants were asked to visually interpret very high resolution satellite imagery from Google Maps and Bing using the Geo‐Wiki application. During the campaign, participants collected field size data for 130 K unique locations around the globe. Using this sample, we have produced the most accurate global field size map to date and estimated the percentage of different field sizes, ranging from very small to very large, in agricultural areas at global, continental, and national levels. The results show that smallholder farms occupy up to 40% of agricultural areas globally, which means that, potentially, there are many more smallholder farms in comparison with the two different current global estimates of 12% and 24%. The global field size map and the crowdsourced data set are openly available and can be used for integrated assessment modeling, comparative studies of agricultural dynamics across different contexts, for training and validation of remote sensing field size delineation, and potential contributions to the Sustainable Development Goal of Ending hunger, achieve food security and improved nutrition and promote sustainable agriculture.

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Contribution of small‐scale farmers to global food security: a meta‐analysis

et al. 2022

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In this study, the impacts of small‐scale farmers on food security enhancement were estimated in three dimensions of food availability, food access and food utilization. In the current study, a systematic review and meta‐analysis have been performed to synthesize results from 75 original articles. It includes the pooling of data that quantitatively investigate whether or not causal links characterized in the original articles remain valid across a broader scope of the literature. The findings show that farmers who are small‐scale in natural/physical capital would lead to higher median food production and agricultural productivity, compared with small‐scale farmers in financial capital, at about 19% and 15%, respectively. Meta‐regression results indicate that small‐scale farmers in natural/physical capital have significantly positive effects on the average agricultural productivity, food income and biofortification. By contrast, farmers who are small‐scale in financial capital have negative effects on food security. The influential role of these small‐scale farmers should also be considered since food insecurity leads to socio‐economic implications. Therefore, it is recommended to cultivate higher value crops, to participate in various income‐generating activities such as fisheries and forestry, and to pay agricultural credits. The effect of the size of small‐scale farmers on global food security is very useful for policymakers to plan for a world without hunger. © 2022 Society of Chemical Industry.

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Detection of cropland field parcels from Landsat imagery

Abstract: Role of the funding source: The funding source had no involvement in the research.

Cited by 100 publications

References 54 publications

Increasing expansion of large-scale crop production onto deforested land in sub-Andean South America

Increasing expansion of large-scale crop production onto deforested land in sub-Andean South America

Estimating the global distribution of field size using crowdsourcing

Contribution of small‐scale farmers to global food security: a meta‐analysis

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