OPTIMAL DENSITY OF THE CHERNOZEM OF SOUTHERN ORENBURG URAL
Objective. Establishment of ranges of optimum density of southern medium-loamy carbonate Chernozem for the main agricultural crops cultivated in the Orenburg region. Materials and methods. The object of the study is the southern Chernozem of the Orenburg Urals. The research was conducted in a stationary experiment to study 16 systems of soil treatment in the Orenburg GAU. Soil density in layers 0-10, 10-20 and 20-30 cm was determined by the Dolgov drilling method (ring cutting method) using metal cylinders 10 cm high and 500 cm<sup>3</sup> in volume. Results. The interval of optimal values of soil density depends on the culture. The upper indicators for layers 10-20 and 20-30 cm are: for winter-1.21 and 1.24 g/cm<sup>3</sup>, spring early-1.23 and 1.24 g/cm<sup>3</sup> (1.27 g/cm<sup>3</sup>- for barley), corn 1.15 and 1.20 g/cm<sup>3</sup>, respectively. The lower values of the optimal density for all crops are the same and are in the range of 1.10-1.16 g/cm<sup>3</sup>. The calculated range of optimal density was 1.16-1.23...1.27 g/cm<sup>3</sup>, and coincided with the interval obtained by the empirical method. A close relationship was established between spring wheat yield and spring soil density in a layer of 10-20 cm (r = 0.660 in 1991, r = 0.496 in 1992 and r = 0.733 in 1993) and in a layer of 0-10 cm (r = 0.689; r = 0.485 and r = 0.842, respectively). Conclusion. Knowledge of the optimal density range for specific soils is essential in determining how to regulate it in accordance with the requirement of the culture.