After the decline of Rome there was little contribution to the development of agriculture. In the beginning of seventeenth century J.B.Van Helmont (1577-2644) conducted the first quantitative experiment to unravel the mystery of plant growth. However,human ingenuity kept on searching for the principle of vegetation and gave the concept of ‘saltpeter’ (J.R.Glauber, 1604- 1668) and organic material or ‘humus’ (Francis Home, 1775) nourishment of plants.
Ultimately with the march of the caravan of science, the foundations of modern chemistry were laid and the essentials of plant growth started taking shape.
Justus Von Liebig (1803-1873), a German organic chemist, fathers of agricultural chemistry, presented in 1840, his historic book on “Organic Chemistry in the applications to agriculture and Physiology” before the British Association for the Advancement of Science. He made the following statements:
i) Most of the carbon in plants comes from the carbon dioxide of the atmosphere.
ii) Hydrogen and oxygen come from water.
iii) The alkaline metals are needed for the neutralization of acids formed by plants as a result of their metabolic activities.
iv) Phosphates are necessary for seed formation.
v) Plants absorb everything indiscriminately from the soil but excrete from the roots those materials that are nonessential.
After the Second Ward War technical experts began to focus on making the fertilizer products more easy to use by the farmer. Some outstanding developments, which took place were granulation of fertilizers and introduction of compound fertilizers. During the past 40 years, much headway has been made toward understanding soil fertility problems. Scientists all over the world have made the contributions.