The work begins by examining the organic and inorganic constituents of plants, breaking down the essential elements such as carbon, hydrogen, nitrogen, oxygen, and various mineral substances. The author explores how plants derive their nourishment from the atmosphere and the soil, detailing the specific chemical forms in which elements like carbon and nitrogen must be presented for absorption. It closely evaluates the role of humus in soil fertility, refuting earlier notions of its direct absorption and establishing its role as a source of carbonic acid.
The text then delves into the proximate constituents of plants, classifying them into saccharine and amylaceous compounds, oily or fatty matters, and nitrogenous or albuminous constituents. The chemical relationships and transformations among these groups during germination and after-growth are thoroughly traced. A significant portion of the book is dedicated to the inorganic constituents found in plant ash, demonstrating their essential nature through scientific experiments and analyzing their variation across different plant organs and growth stages.
The later chapters investigate the soil, exploring its geological origins from the disintegration of crystalline and stratified rocks. The author details the chemical and physical characters of soils, the methods for analyzing their soluble and insoluble components, and their capacity to absorb ammonia and other valuable compounds. Various mechanical improvements of the soil, including draining, subsoil ploughing, and burning, are analyzed in relation to physical and chemical changes.
The final sections establish the general principles of manuring, comparing the utility of general and special manures, and detailing the composition and properties of farm-yard manure, liquid manure, and town sewage. The book concludes with exhaustive analyses of specific vegetable, animal, and mineral manures, evaluating their practical applications and economic value in farm management.
