Important Events in Soil–Water Relationship

S. No.	Scientific Contribution / Event	Associated Scientist(s) & Year
1	Classification of soil water	Briggs (1894)
2	Moisture holding capacity	Hilgard (1896)
3	Capillary potential	Buckingham (1907)
4	Moisture equivalent	Briggs & McLane (1910)
5	Permanent wilting point (PWP)	Briggs & Shantz (1912)
6	Hygroscopic coefficient	Alway (1913)
7	Field capacity (FC)	Israelsen & West (1922)
8	Ultimate wilting point	Taylor et al. (1934)
9	pF scale / Ratio law	Schofield (1935)
10	Tensiometer (Irrometer)	Richards & Gardner (1936)
11	Gypsum block / Electrical resistance method	Bouyoucos & Mick (1940)
12	Permanent Membrane Apparatus (PMA)	Richards (1941)
13	Parshall flume	Parshall (1941)
14	Pressure Plate Apparatus (PPA)	Richards & Fireman (1941)
15	Total Soil Moisture Stress (TSMS)	Wadleigh & Aiyer (1945)
16	Available water concept	Veihmeyer & Hendrickson
17	Darcy’s law	Henry Darcy
18	Potential Evapotranspiration (PET)	Thornthwaite (1948)
19	Term “Effective rainfall”	N. G. Dastane
20	Modified Penman method	Doorenbos & Pruitt (1977)
21	Term “Water harvesting”	Myers
22	Water use efficiency	Parihar et al. (1976)
23	Combination approach of irrigation scheduling	Doorenbos & Kassam (1979)
24	Surge irrigation system	Stringham & Keller (1979)
25	Drip irrigation system	Simcha Blass (1964)
26	Residual Sodium Carbonate (RSC)	Eaton (1950)
27	Leaching requirement	Richards (1954)
28	SPAC (Soil–Plant–Atmosphere Continuum) concept	Huber (1924)
29	Water balance concept	Thornthwaite
30	Evapotranspiration (ET) first used for calculation	Thornthwaite
31	Author of book “Irrigation Agronomy”	N. G. Dastane
32	Author of book “Irrigation Engineering”	A. M. Michael