Humus balance as a key regulator of differential rent of peculiarly valuable agricultural land and an instrument to prevent its degradation

The modern development of the agricultural sector in the Russian Federation is impossible without ensuring the rational use and protection of land resources, which are an essential component of the country's natural and economic potential. In recent decades, the issue of agricultural land degradation, including particularly valuable areas with high fertility and significance for the country's food security, has become particularly relevant. Large-scale processes of erosion, pollution, salinization, compaction, and soil depletion lead to a decrease in agricultural productivity, a reduction in agricultural profitability, and a deterioration in the ecological state of agricultural landscapes. In this regard, the authors propose measures to prevent soil (land) degradation based on increasing humus in arable soils and ensuring its balance in the process of agricultural production. The formation of humus balance is proposed to be carried out on the basis of a scientifically based selection of crops in crop rotation, the application of the necessary agrotechnical methods of soil cultivation. In particular, without expanding the area under crops that produce humus-forming stubble, the authors propose using a reclamation crop rotation with barley as a green manure crop. Research conducted by the authors in the Voronezh region showed that the yield of oil radish is more than twice that of lupine, white mustard, and rye, and in favorable climatic conditions, it reaches 500-600 kg/ha in 75-80 days, while its seed yield is 10-18 kg/ha. The calculations presented by the authors show that the proposed reclamation crop rotation allows for the accumulation of + 6.04 t/ha of humus per year, compared to the conventional field crop rotation of – (– 0.51) t/ha. According to the authors' calculations, the costs of organizing and implementing a reclamation crop rotation with the introduction of a green manure crop into the crop rotation structure will amount to 22,500 rubles per year, while the restoration of degraded soils throughout the Voronezh region, where the humus content is low, will require 63,828 million rubles and 8 years of implementation of the authors' proposals. The paper also notes that the presence of humus and its quantity is not always a factor or indicator of the quality and/or demand for soil or land for agricultural production. The presence of pollutants in humus plays a negative role in increasing its quantity, so the costs of eliminating humus pollution should be assessed based on the loss in quality and production volumes on such land. In general, the balance of humus, when soil fertility is actively used for agricultural purposes, can act as a key regulator of differential rent and determine its cadastral assessment.