Soil Water Classification – Briggs (1894): Laid the foundation for distinguishing types of soil water (gravitational, capillary, hygroscopic).

Moisture Holding Capacity – Hilgard (1896): Defined the soil's ability to retain water against gravity.

Capillary Potential – Buckingham (1907): Introduced the concept of capillary movement in unsaturated soils.

Moisture Equivalent – Briggs & McLane (1910): Defined water retained by soil after centrifugation, an early measure of available water.

Permanent Wilting Point (PWP) – Briggs & Shantz (1912): Identified the point where plants cannot recover turgidity.

Hygroscopic Coefficient – Alway (1913): Quantity of water retained by oven-dried soil under air-dry conditions.

Field Capacity (FC) – Israelsen & West (1922): Amount of water retained in soil after gravitational drainage.

Ultimate Wilting Point – Taylor et al. (1934): Refined PWP by linking it with plant physiology.

pF and Ratio Law – Schofield (1935): Developed logarithmic scale (pF) to express soil moisture tension.

Tensiometer (Irrometer) – Richards & Gardner (1936): Instrument to measure soil water tension in situ.

Gypsum Block/Electrical Resistance Method – Bouyoucos & Mick (1940): Used for estimating soil moisture.

Permanent Membrane Apparatus (PMA) – Richards (1941): Allowed measurement of water retention curves.

Parshall Flume – Parshall (1941): Instrument for measuring water flow in open channels.

Pressure Plate Apparatus (PPA) – Richards & Fireman (1941): Accurately determines soil moisture retention at high tensions.

Total Soil Moisture Stress (TSMS) – Wadleigh & Aiyer (1945): Combined capillary and osmotic potentials.

Available Water Concept – Veihmeyer & Hendrickson: Defined as the difference between field capacity and PWP.

Darcy’s Law – Henry Darcy: Fundamental law of water movement through saturated soils.

Potential Evapotranspiration (PET) – Thornthwaite (1948): Developed climatic formula for estimating PET.

Effective Rainfall Term – N. G. Dastane: Conceptualized rainfall contributing to crop water needs.

Modified Penman Method – Doorenbos & Pruitt (1977): Standard method for estimating ET.

Water Harvesting Term – Myors: Popularized the term in arid zone water management.

Water Expense Efficiency – Parihar et al. (1976): Defined as yield per unit of water used.

Irrigation Scheduling (Combination Approach) – Doorenbos & Kassam (1979): Integrated climatic and soil moisture indicators.

Surge Irrigation System – Stringham & Keller (1979): Developed method of intermittent water application for better infiltration.

Drip Irrigation – Simcha Blass (1964): Innovated controlled irrigation at plant root zone.

Residual Sodium Carbonate (RSC) – Eaton (1950): Defined index to evaluate irrigation water quality.

Leaching Requirement – Richards (1954): Defined water needed to prevent salt accumulation.

Soil-Plant-Atmosphere Continuum (SPAC) – Huber (1924): Introduced concept linking water movement from soil to atmosphere via plants.

Water Balance Concept – Thornthwaite: Developed method to estimate water surplus and deficit.

Evapotranspiration in Calculations – Thornthwaite: First to include ET in water balance studies.

Book: “Irrigation Agronomy” – N. G. Dastane: Standard reference for irrigation in crop science.

Book: “Irrigation Engineering” – A. M. Michael: Widely used textbook in irrigation engineering.