Development of agronomic thought and principles of soil fertilization in the Middle Ages

In the first two centuries of the new era, the slave-owning mode of production in the Roman Empire reached its peak. However, subsequently, numerous slave uprisings, internal struggles for power among the nobility, and the onslaught of northern barbarians (Germanic tribes) led to the fall of the Roman Empire in the 5th century.

Feudalism replaced the slave-owning system, and the Middle Ages replaced the Ancient World. Under these conditions, the development of agronomic science stalled, and the achievements of Roman farmers and agronomists were forgotten for a long time. Agricultural technology declined to the level of the Germanic and Slavic tribes, which were at a lower stage of cultural development than the Greeks and Romans.

All "science" was then concentrated in monasteries. Therefore, the authors of agronomic literature were usually church figures. Their writings mostly repeated what the Romans had written many centuries ago, and only individual thoughts and recommendations could claim novelty. They are interesting, however, in that they reflect the level of agronomic thought of that time. The most prominent of these authors was the German Albertus Magnus (Albert von Bollstädt, 1193–1280) – a Dominican monk who created a significant work for that time, "On Plants". His pen also belongs to the works: "On Alchemy", "On Metals and Minerals".

Here are a few original statements by Albertus Magnus on various issues of agriculture: "Food... is not some simple element; it is necessary that the plant food be complex." With this, the author seeks to emphasize the idea that plants need various nutrients. Let us note that the ancient agronomists did not have such a clear understanding of this issue.

Regarding the degree of organic matter decomposition most suitable for plant nutrition, Albert writes: "And since a plant does not have a belly, but uses the soil instead of a belly, it is important that rotting food be located in the soil around the plants, then its moisture be drawn by the roots, and they feed on it."

"Thus, after the distribution of fertilizer is generally established, it is necessary that it (be) closer to the path of decomposition than to have already turned to ash: when turned to ash, it has already been reduced by natural heat to earthen dust, and this in no way is suitable as food for anything living... Therefore, fertilizer that is neither too young nor already turned to ash by age is required; growers consider it best when it has lain for a year, or three-quarters of a year. For young (fertilizer) still hides moisture within itself; old (fertilizer), on the other hand, has lost it entirely, while that which exudes moisture is in a state of giving its humidity as food."

Another agronomic work of the Middle Ages worthy of attention is the book by the Italian Pietro de' Crescenzi (1230–1309) "On the Benefits of Agriculture", written in 1305. The treatise contains many references to Cato, Varro, Columella, Palladius, and agronomic writers of the Middle Ages. The merit of the book lies in the abundance of theoretical and practical material and in its clear presentation. That is why it remained one of the best European works on agriculture for a long time.

In the 8th century, a number of agricultural treatises also appeared in England. The most significant of them is "Husbandry", written by Walter of Henley. Henley's work is characterized by clearer recommendations than those of other authors regarding the use of straw: "Do not sell straw and do not remove it from the field unless you need it to roof houses; if you remove it, you will lose more than you gain." The scholar recommended plowing it in. Not knowing about the chemical composition of manure, or about the volatilization of such an important element as nitrogen from it, Henley correctly approached the idea of preserving nutrients in manure: "When both manure and soil are harrowed together, the soil will support the manure and it will not be as depleted as it would be without being mixed with it" (we also say that manure scattered across a field should be incorporated as soon as possible to avoid losses of the nitrogen it contains). "If you put manure on lifted fallow, it will be turned under the soil during the second plowing, and during the plowing for sowing it will be thrown to the surface mixed with the soil. If, however, you put manure on fallow after the second plowing, then during the plowing for sowing it will be turned under the soil and mixed poorly with the soil, which is very disadvantageous."

Evidence of medieval Russian culture can be found in the remarkable written monuments of those times that have survived to this day. Among them, the oldest collections of Kievan Rus, known as the "Izborniks of Svyatoslav" (1073; 1076), deserve attention. Among a number of church writings and information on grammar, logic, poetics, and others, they contain valuable descriptions of soils, plants, and their properties. They show that even in those times, our ancestors were well aware of the importance of soil fertility for growing crops. It is from the Middle Ages that aphoristic sayings have come down to us: "Without father manure (i.e., manure) do not expect bread from mother earth", "Haul manure, don't be lazy, even if you don't pray to God", "Put manure around the vines", "You hauled manure to the field, and brought back a cart of bread", "You keep plowing the same strip, you don't let it lie fallow, you don't add manure — that's how you exhausted it, it won't produce", "Where there is an extra clod of manure, there is an extra loaf of bread", "Good soil accepts manure once and remembers it for nine years", "Get your grandfather's manure, and sheaves will fall from the cart", "Before Ilyin's Day (August 2) there is a pood of honey in the hay, after Ilyin — a pood of manure", "Earth is ash upon ash", "The earth loves manure, and a horse loves oats", "Manure is added so that more grain is produced, and emmer is sown so that it is useful to people", "We will haul the manure, and we will bring the grain", "On new land they sow grain, on old land they haul manure", "Do not throw ash on the road, but carry it to the vegetable garden bit by bit", "From Fedor's Day (June 21) the manuring season begins (i.e., hauling manure to fallow)".

The problem of soil exhaustion and yield instability has been known to farmers since ancient times. As early as the Early Middle Ages (6th–8th centuries), Slavic tribes were actively developing arable farming, extending it from the south to the northern lands. However, the lack of a systematic return of nutrients to the soil quickly led to a decline in soil fertility.

How soil exhaustion influenced state borders

The development of agriculture and migration in search of fertile plots went hand in hand with the key stages of statehood development:

• 9th–12th centuries — East Slavic tribes united into Kievan Rus', expanding areas for ploughing;
• Late 15th century — the Russian state was formed with Moscow at its head.

Chronicles confirm that it was the plough, not the sword, that moved the borders of the state forward. Peasants moved east and north not for the sake of conquest, but because of the critical exhaustion of old fields. Searching for untouched virgin land remained the only way available at that time to restore grain production volumes.