OR/15/030 Appendix 1

Nicole Archer, Barry Rawlins, Stephen Grebby, Ben Marchant and Bridget Emmett. 2015. Identify the opportunities provided by developments in earth observation and remote sensing for national scale monitoring of soil quality. British Geological Survey Internal Report, OR/15/030.

Published literature search criteria

The Excel spreadsheet of criteria used in the Web of Science search engine to search for published articles related to remote sensing of physical soil properties is summarised in Table 1. The number of ‘hits’ are the published references found by each search. The references found for the Search terms shown as grey rows, were downloaded to Endnote to create a database of 3663 published references. If the search terms provided more than 1000 ‘hits’, this was considered too many ‘hits’ and the search was run again using more defined search criteria

Table 1 Excel spreadsheet showing the number of references found using 43 different search criteria (shown as ‘fields’).

SEARCH' 'ID	Field' '1	Field' '2	Field' '3	Field' '4	Hits
1 Soil AND remote sensing AND			organic carbon		184
2 Soil AND remote sensing AND			geochemistry		22
3	Soil AND	remote sensing AND	physical OR	bulk density	51594
4 Soil AND remote sensing AND			bulk density		39
5 Soil AND remote sensing AND			soil depth		518
6 Soil AND satellite AND			organic carbon		143
7 Soil AND satellite AND			geochemistry		6
8	Soil AND	satellite AND	physical OR	bulk density	51594
9 Soil AND satellite AND			soil depth		418
10 Soil AND satellite			bulk density		20
11 Soil AND airborne AND			organic carbon		130
12 Soil AND airborne AND			geochemistry		53
13	Soil AND	airborne AND	physical OR	bulk density	51594
14 Soil AND airborne AND			bulk density		10
15 Soil AND airborne AND			soil depth		158
16 Soil AND hyperspectral AND			organic carbon		55
17 Soil AND hyperspectral AND			geochemistry		4
18	Soil AND	hyperspectral AND	physical OR	bulk density	51664
19 Soil AND hyperspectral AND			bulk density		2
20 Soil AND hyperspectral AND			soil depth		59
21 Soil AND LiDAR AND			organic carbon		10
22 Soil AND LiDAR AND			geochemistry		1
23	Soil AND	LiDAR AND	physical OR	bulk density	51616
24 Soil AND LiDAR AND			bulk density		3
25 Soil AND LiDAR AND			soil depth		50
26 Soil AND Radar AND			organic carbon		26
27 Soil AND Radar AND			geochemistry		8
28	Soil AND	Radar AND	physical OR	bulk density	51858
29 Soil AND Radar AND			bulk density		24
30 Soil AND Radar AND			soil depth		488
31 Soil AND Thermal AND			organic carbon		539
32 Soil AND Thermal imagery AND			organic carbon		7
33 Soil AND Thermal imagery					239
34 Soil AND Thermal AND			geochemistry		2
35	Soil AND	Thermal AND	physical OR	bulk density	51615
36 Soil AND Thermal AND			bulk density		1
37 Soil AND Thermal AND			soil depth		19
38 Soil AND Microwave			organic carbon		57
39 Soil AND Microwave			geochemistry		5
40	Soil AND	Microwave	physical OR	bulk density	51804
41 Soil AND Microwave			bulk density		22
42 Soil AND Microwave			soil depth		318
43 Soil AND Unmanned Aerial Vehicle					23
TOTAL HITS USED FOR LITERATURE REVIEW					3663

The Excel spreadsheet showing the number of hits for two Web searches and 1 Blog search is summarised in Table 2. The overall number of references considered to be of relevance was 44.

Table 2 Excel spreadsheet showing the number of hits for two Web searches and one Blog search using different search criteria (shown as ‘fields’).

SEARCH' 'ID	Field' '1	Field' '2	Field' '2	Field' '4	Search' 'tool	Hits	Number' 'of' 'pages' 'searched	Number' 'of' 'useful references
1	Remote sensing	soil	physical	properties	Web	2,180,000	10	39
2	Remote sensing	soil	monitoring		Web	4,110,000	10	1
3	Remote sensing	soil	physical	properties	Blog	8,910	10	4
TOTAL USEFUL REFERENCES								44