The article shows the results of studying the influence of soil moisture, cellulose-decomposing activity of microorganisms and the amount of nutrients on the productivity of barley in crop rotations and monocrops in Orenburg region. The purpose of the experiment is to identify the effect of moisture, cellulosolytic activity of soil and macronutrients (nitrates, phosphorus, potassium) on increase of barley productivity in crop rotations and during its continuous growing. The following research methods are used: field, thermostatic-weight, application-weight, ionometric and method of Machigin. In average for 2002-2021 studies, it is observed that the yield of fodder and energy units of barley increases up to 2.10, 1.63 and 1.24, 0.96 t/ha on a fertilized background of nutrition in the second and fourth variants of the experiment. The yield of feed units increases due to the use of productive moisture by the plant during the growing season in the mount of 32.3, 32.2 mm nitrates - 4.20, 1.91 mg, phosphorus - 1.76, 0.50 and potassium - 2.47, 1.01 mg/100 g of soil with cellulose-destroying activity of microorganisms - 7.93 and 10.37%. For other variants of the experiment, various indicators of the studied factors and barley productivity are registered. The influence of moisture, activity of microorganisms, nutrients on increase of barley productivity due to influence of millet and peas in crop rotations after the application of mineral fertilizers was revealed. The dependence of the yield of energy fodder units of barley in a crop rotation with millet on the content of used nitrates in the arable soil layer has been established. The results of the study are of great importance for agronomy in the steppe zone of the Southern Urals.