Lecture
THE ORIGINS OF AGROCHEMISTRY
From the earliest steps of ancient agriculture, its central problem was the search for ways to maintain and restore the fertility of cultivated lands and to conduct more rational land use. According to archaeological research, the cultivation of agricultural crops began approximately 10-12 thousand years ago. With the emergence of agriculture, the history of human development changed qualitatively. Man gradually began to move away from natural sources of subsistence toward the production of food, toward the cultivation of agricultural plants. Farming experience gradually accumulated and was passed down from generation to generation, from father to son. In forested areas, people moved to a slash-and-burn system of agriculture. This already required knowledge of an entire system of technological practices, such as: selecting a plot of forest, clearing it, burning it, mixing the ash with the soil, and loosening and working the soil with appropriate implements. The importance of ash as a source of soil fertility and plant nutrition grew. Agriculture itself was viewed as a unity of factors: soil, water, fire, forest, metal. As for irrigated agriculture, in the giant river valleys of the Nile, Tigris, Euphrates, and Indus, controlled irrigation of the land already existed several millennia before our time, and it became the principal function of the state formations that arose there. The Egyptians understood well that the flooding of fields during the Nile's floods performed a threefold task: it moistened the fields, fertilized them with river silt, about whose fertility legends were composed, and carried away the salts that had accumulated on the soil surface during the dry period. In the time of the first pharaohs of Egypt, a cadastre of lands appeared, based on their fertility and productivity.
The historical origins of ancient irrigation in Central Asia developed in parallel with Egypt and Mesopotamia, that is, before the 2nd millennium BC. The soils of the Amu Darya delta are heavy and were not distinguished by high fertility, so Khorezm farmers learned early to sand-dress them and to fertilize them with various wastes. Archaeological monuments in northern India show that the cradle of Indian agriculture appeared in the 3rd-2nd millennium BC, first in the north of the country, after which its center shifted to the more fertile alluvial plains, where a fallow (shifting) system of agriculture arose early, and later artificial irrigation as well. Eastern China is also one of the most ancient centers of agriculture. Here, long before our era (4,000 years BC), a great deal of knowledge about agriculture had been accumulated, and the government, guided by annual observations of field work, prescribed to the people the timing of ploughing, fertilizing, and methods of sowing, and so on. The first specialized agronomic, biological, and geographical writings that have survived to our time, in which much is said about the land-soil, its properties, and fertility, go back to the ancient Greeks, who already knew of differences between soils and methods of working them within rain-fed agriculture of the Mediterranean type. In the literary works of the ancient Greek philosopher and scholar Aristotle (384-322 BC), the most significant information on the peculiarities of agronomy and plant nutrition is set out. He noted the stages of nature: the inorganic world, plant, animal, man. Aristotle believed that plants need four elements: air, water, earth, and fire. The outstanding researcher of the plant world in Ancient Greece, Theophrastus (c. 372-287 BC), in his work "Enquiry into Plants," noted on which soils which crops are best sown, how to maintain soil fertility, and the role of manure, and so on. In natural science, he, on a par with his teacher Aristotle, played an important role in the development of the study of plants and soil. Theophrastus's work "Enquiry into Plants" is considered the foremost of the earliest botanical and agronomic writings. Greek agronomy was the successor to that of the ancient East, and the agricultural knowledge of the Romans developed under the influence of Greek culture and science. Before the 2nd century BC, no literary works of agronomic content have been found among the Romans.
On various questions of agriculture, a rich legacy for their time was left by ancient Roman scholars and writers: Cato, Varro, Pliny, and Columella. All of them engaged in agriculture, since they considered this occupation the most useful and worthy of a free citizen. They left behind many works on questions of agronomy. Marcus Porcius Cato the Elder (234-149 BC) was a statesman and writer. The book "On Rural Affairs" and the treatise "On Agriculture" have come down to us, in which practical advice on various branches of farming is collected: on working the soil, cultivating vineyards and olive orchards, on meadow husbandry and livestock breeding. He made an attempt to classify soils by their suitability for growing various cultivated plants, gave practical advice on the proper storage and timing of hauling manure to the fields, recommendations on growing lupine, vetch, and beans for green manure, and on the best times for mowing grasses for hay, namely before the seeds begin to ripen. Cato wrote that to work a field well means to plough it well and to manure it well. If a farm lacked enough manure, he recommended using straw, chaff, oak leaves, and tall grass as bedding for sheep, that is, increasing the amount of organic fertilizer through composting. Cato considered agriculture the foundation of the Roman state, and the labor of the farmer the purest, most reliable, and free of envy. He treated farmers with respect, writing of them as the most courageous of people and admirable soldiers. Marcus Terentius Varro (116-27 BC) was a writer and encyclopedic scholar. He successfully summarized the material accumulated over the century after Cato. His work "On Agriculture" has survived in its entirety to our time. Varro attached great importance to a scientific approach in resolving questions of agriculture. He proposed carefully studying the soils of individual districts, advising that wheat be sown on richer soils and beans on poorer ones. Varro also wrote about green manure, recommending that lupine be grown and ploughed under for this purpose. Varro wrote his work on the basis of literary sources and conversations with knowledgeable people, yet he was the first to assert the independence of agriculture as a science and noted that agriculture is a necessary and great science. In characterizing soils, Varro made wide use of the writings of Theophrastus and gave a classification of the soils of Italy. He was an active
supporter of applying manure to the soil and was the first to put forward the idea of a union between agriculture and livestock breeding. For Varro, concern for the fertility of the soil was the most important task of agriculture. This concern also underlay his idea of the necessity of establishing crop rotations. At the beginning of our era, Roman science reached its ultimate heights. In this connection, one cannot fail to mention the works of the famous Roman scholar and writer Gaius Plinius Secundus, Pliny the Elder (23-79 AD), one of the last Roman authors to write on questions of agriculture. His "Natural History," consisting of 37 books, was a kind of encyclopedia. Over the following centuries, this enormous work, which had demanded of its author great energy, diligence, and exceptional erudition, served as a reference work for a whole range of branches of knowledge, agriculture among them. Pliny held that the fertility of soils declines, and that this cannot be compensated for by even the most costly methods of working it. In essence, this is an early version of the law of diminishing soil fertility, whose underlying cause was slave labor, whose productivity fell owing to the slaves' lack of interest in good soil cultivation and in raising fertility. The philosophical justification for Pliny's views was the teaching of Seneca and Marcus Aurelius on the exhaustion of the earth as an inexorable but natural process. Pliny died tragically during the eruption of Vesuvius in 79 AD, wishing to observe this natural phenomenon more closely. Lucius Junius Moderatus Columella (1st century AD) was an outstanding representative of ancient agronomy, a Roman writer and agronomist. He argued against the views of Pliny and other authors. His work "On Agriculture" consists of 12 books and is a genuine agricultural encyclopedia. Polemicizing with the proponents of the doctrine of declining soil fertility, Columella maintained that a reasonable person would not allow the land to be driven to such a degree of fatigue and exhaustion that it would cease to provide people with sustenance as generously as before. The earth cannot grow old if it is helped with manure as food for restoring the strength it has lost. Columella urged that agriculture be conducted on a scientific basis, that experimentation be introduced into agriculture, and that agricultural knowledge be widely disseminated by introducing public courses on these branches of science. In his works, Columella devoted much attention to the description and use of various kinds of fertilizers: manure, the preparation
of various kinds of composts, the application of ash, the cultivation of lupine for green manure. Columella proposed a classification of fertilizers: manure, mineral fertilizer, green manure, compost, and fertilizing "earth with earth." Green manure, in his opinion, "has the power of the best manure." As for fertilizing with earth, he refers to the improvement of sandy soils with clay, and of clay soils with sand. From the first century of our era, the development of science was practically halted, and the works of ancient thinkers on agronomy and natural science were forgotten, and only after 1000 years did people begin to return to the authors of the ancient world, especially to Aristotle and Columella.
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