E.V. Titova, I.B. Sorokin
Station of Agrochemical Service “Tomskaya”, Tomsk, Beringa st., 12a
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Summary. The article summarized the investigation results on determination of efficiency of phosphorus fertilizers on different types of soils in the geographic network of experiments with mineral fertilizers during the period since 1965 to 1992. Tomsk region is located in the southern taiga zone of Western Siberia. Soils are represented by the genetic series: podzol, sod-podzol, grey forest, black soils (leached and podzolized). The content of mobile phosphorus in them decreases from black and grey forest soils of southern regions to grey forest, light grey forest and sod-podzol soils of northern regions of the region. According to the results of five stages of agrochemical survey the portion of arable lands with low provision with this element varied from 30.4 to 41.1 % on the average through the region and today it is 35.5 %. Herewith, for example, the value of this index in Bakchar district reaches 87.3 %, in Verkhneketsky, Kolpashevo, Parabel, Teguldet and Chainsky districts it is 74, 62, 83.1, 79.9 and 65.1 %, correspondingly. The level of provision of soils of the non-chernozem region of Western Siberia is evaluated according to the indices, based on the determination of mobile phosphorus from the method of Kirsanov in 0.2 n hydrochloric acid. This method of determination of this index is quite acceptable, but recommended for the agrochemical service indices on data of the given experiments do not match with the estimation of soil provision with mobile phosphates and efficiency of phosphorus fertilizers. They are deflated approximately 2 times. The new indices are developed; it is proposed to consider the soil provision with mobile phosphorus as low with P2O5 content at the level 0…100 mg/kg of soil, at the level 100…200 mg/kg – as middle, 200…300 mg/kg – as increased and more than 300 mg/kg – as high provision.
Keywords: genetic series of soil, labile phosphorus index, efficiency of fertilizers, crop capacity.