Order

Subject area

Frequency

Centrality

Starting year

1

ENVIRONMENTAL SCIENCES & ECOLOGY

1429

0.06

1990

2

AGRICULTURE

1369

0.06

1990

3

ENVIRONMENTAL SCIENCES

1068

0.23

1990

4

SOIL SCIENCE

792

0.03

1990

5

PLANT SCIENCES

689

0.19

1990

6

ECOLOGY

519

0.26

1991

7

AGRONOMY

441

0.10

1990

8

WATER RESOURCES

334

0.11

1990

9

GEOLOGY

226

0.09

1991

10

GEOSCIENCES, MULTIDISCIPLINARY

221

0.09

1991

11

ENGINEERING

216

0.30

1992

12

AGRICULTURE, MULTIDISCIPLINARY

203

0.07

1990

13

FORESTRY

166

0.03

1991

14

ENGINEERING, ENVIRONMENTAL

146

0.03

1993

15

MICROBIOLOGY

141

0.07

1991