Fertility of the Soil, Economic, the soil’s ability to yield farm produce, resulting from man’s improvements in its composition and in his farming methods. It is closely linked with natural fertility, i. e. the total of the soil’s physical, chemical and biological properties determined by nature. A rise in the economic fertility of the soil results in bigger harvests and an increased output per hectare of land. It is determined by the character of the dominant system of production. Marx wrote that "fertility is not so natural a quality as might be thought; it is closely bound up with the social relations of the time" (K. Marx, F. Engels, Collected Works, Vol. 6, p. 204). Capitalist relations of production are responsible for the predatory use of land. The capitalist tenant is interested in investment that yields quick returns. Under capitalism, the criterion of economic fertility is profit. Economically fertile land is taken as that which yields average profit and rent; and at the stage of imperialism—- monopoly profit. Public ownership of land creates the objective conditions for the scientifically-based utilisation of land on the scale of the entire economy, and the steady growth of agricultural production. The agrarian policy of the Communist Party of the Soviet Union is aimed at the rational use of the land, its increased fertility, and greater yield from each hectare. This presupposes that each farmer has to be encouraged to treat the land with consideration and care. Today the main factor of increasing soil fertility is the running of agriculture on the basis of scientific and technical progress and modern know-how. However, the machinery, fertilisers and other means of production provided to collective and state farms yield the adequate economic effect only when combined with highly effective, rational farming techniques and a broad complex of agronomic, zootechnical and organisational economic measures applied in conformity with the conditions of the given farm. Rational farming specifically involves specialisation, the introduction of new machines and technological methods, the use of chemicals and land improvement, and the use of new grades of agricultural crops. An important link in the farming system is crop rotation, which determines the composition, ratio and sequence of various crops, with consideration of the farm’s soil, climatic and economic conditions. All these factors are closely linked and must be used in their entirety. For instance, the use of chemicals requires planting those crops that can guarantee higher yields with increased amounts of fertiliser. Machinery is needed to spread fertilisers. In making use of the achievements of scientific and technical progress, it is also important to evaluate the long-term consequences of the novelties used, their influence on the quality of the products, on soil condition and on the environment.