Crop yield

**Measurement:**
– Units for measuring crop yield: kilograms per hectare or bushels per acre
– Long-term cereal yields in the UK: 500kg/ha in Medieval times, 2000kg/ha in the Industrial Revolution, 8000kg/ha in the Green Revolution
– Technological advances increase crop yield and reduce ecological footprint
– Yield vs. agricultural productivity distinction
– Importance of considering total inputs for accurate productivity measurement

**Seed multiplication ratio:**
– Seed multiplication ratio definition: ratio of seed investment to yield
– Example: 1:3 ratio means 3 grains harvested for each seeded grain
– Historical seed ratios in Europe: 1:2.5 in 9th century, improved to 1:14 with crop rotation
– Factors affecting seed multiplication ratio variability
– Recent recommendations by the Indian Council of Agricultural Research

**Law of physiological relations:**
– Alexander Mitscherlich’s study of crop yields in 1909
– Articulation of the law of physiological relations
– Comparison to Liebig’s Law of the Minimum and Frederick Blackman’s limiting factors
– Explanation of the logarithmic function between yield and plant food constituents
– Review of the relation by Hans Schneeberger in 2009

**See also:**
– Agriculture and Agronomy portal
– Actual Production History
– Agricultural productivity
– Grain yield monitor
– Green Revolution

**References:**
– Max Roser and Hannah Ritchie, Yields and Land Use in Agriculture, 2016
– Paul V. Preckel, Thomas W. Hertel, Channing Arndt, and Alejandro Nin on productivity measures
– Richard Pipes on Russia under the Old Regime
– J.A. Bornewasser on the history of the Netherlands
– Mitscherlich, E. A. on the Law of Minimums and diminishing soil yields