Final answer:
The significant discovery that increased food production and influenced human population growth in the early 1900s was synthetic fertilizer, which was instrumental in advancing the Green Revolution and increasing agricultural yield.
Step-by-step explanation:
Synthetic fertilizers played a transformative role in enhancing food production in the early 20th century. Their development allowed crops to grow larger and more bountiful without the need for traditionally nutrient-rich soils. The use of these fertilizers, combined with high-yield crop varieties, especially wheat and rice, fueled the Green Revolution. This agricultural innovation began in the 1940s and continued to influence farming practices throughout the subsequent decades, leading to significant increases in food production.
The Green Revolution was indeed a turning point in history, as it greatly increased the carrying capacity of the Earth for human life, averting the global famines that were feared in the late 1960s. It involved the use of advanced agricultural techniques such as improved crop varieties, extensive use of fertilizer, expansion of irrigation, and the adoption of machinery, substantially increasing the well-being and income of farmers around the world.