Soil Fertility and Fertilizers

Samuel L. Tisdale
- President (Retired), The Sulphur Institute
- Formerly Professor of Soils at North Carolina State University
Werner L. Nelson
- Senior Vice President, Potash & Phosphate Institute
- Formerly Professor of Agronomy at North Carolina State University
James D. Beaton
- Northwest Director, Potash & Phosphate Institute
- Formerly Instructor of Soils at the University of British Columbia
Publisher: Macmillan Publishing Company, New York; Collier Macmillan Publishers, London

Food is a fundamental necessity for human survival, historically procured through hunting and gathering.
The evolution of agriculture is crucial for sustaining the growing population, which reached approximately 4 billion in 1975 and is expected to stabilize at 11 billion by 2075.
Agricultural practices and their efficiency have allowed developed countries to be self-sufficient, though underdeveloped regions still suffer from starvation.

The anticipated increase in global population necessitates significant increases in food production.
Cultivated land may only expand by 20%, underscoring the essential role of fertilizers in intensifying agricultural output.

Ancient Cultivation:
- Transition from nomadic lifestyles to settled agricultural communities; cultivation likely began several thousand years before Christ.
- Key civilizations, such as Mesopotamia, are noted for early agricultural advances, with records dating back to 2500 B.C.

Writings indicate extraordinary yields, such as barley harvests documented at 86 to 300-fold returns based on seed units planted.
Greek historian Herodotus (c. 5th century B.C.) noted high agricultural yields due to advanced irrigation systems and fertile soils in Mesopotamia.

Continuous cropping led to soil fertility exhaustion; therefore, manuring using animal and vegetable waste was adopted.
Mythological references (Augeas's stables) highlight the early understanding of nutrient replenishment in soils.
Theophrastus (c. 372-287 B.C.): Suggested practices of manuring and highlighted the relationship between plant nutrient needs and water use.

Theophrastus classified manures based on richness, emphasizing human excrement at the top and various animal manures thereafter.
Romans and later writers, such as Virgil, noted the usage of sewage and ashes to enhance soil fertility.

The effects of soil texture and structure on plant growth were acknowledged; color of soil was mistakenly linked to fertility.
Tools for determining soil types and their impacts, like bulk density assessments, were developed by early practitioners.

Emerging philosophy during the 16th-18th centuries: Francis Bacon suggested that water was the primary plant nutrient.
Jan Baptiste van Helmont conducted foundational experiments proposing that water was the sole nutrient based on a willow planting.
The conceptual understanding of plant nutrition evolved, with figures like Robert Boyle and Jethro Tull introducing experimental methods leading to practical agricultural tools (like the seed drill).

Scientists like Jean Baptiste Boussingault and Justus von Liebig shaped modern agricultural chemistry.
Liebig's principles highlighted the importance of CO₂, nutrients for plant growth, and controlling nutrient availability through fertilization (Law of the Minimum).
- His observations indicated that crop yields were dependent on the least available nutrient, controlling the overall fertility outcomes of soil.

Establishment of experiment stations in the 19th century helped formalize agricultural science; notable contributions from figures like Lawes and Gilbert in understanding soil dynamics and fertilizer efficacy.

Advancements in crop yield through improved fertilizers, irrigation systems, and hybrid crops starting in the 20th century.
Shift towards conservation tillage leading to better resource management and potential increased yields.
Introduction of technologies such as remote sensing for improved agricultural practices and nutrient management.

As global populations rise, the need to enhance agricultural productivity remains critical, driving ongoing research and technological advancements.
The interplay between advances in agricultural science and practical application will shape future methods for soil fertility enhancement and crop yield optimization.