Dynamika mineralizacji, nitryfikacji oraz przyswajalności mikroelementów w glebie inkubowanej z kompostem i ze słomą

Praca prezentuje wyniki z doświadczenia inkubacyjnego założonego na glebie lekkiej z dodatkiem kompostu i słomy, trwającego 180 dni. Celem jest ocena tempa mineralizacji wprowadzonych substancji organicznych do gleby i ich wpływ na ilości mikroelementów przyswajalnych dla roślin. Podczas trwania inkubacji systematycznie monitorowano ilości wydzielanego CO₂, zmiany ilościowe węgla organicznego, azotu ogólnego, mineralnego (N-NH₄ i N-NO₃) oraz mikroelementów w formach przyswajalnych dla roślin. Na podstawie uzyskanych danych wyznaczono współczynnik mineralizacji C (WMC) oraz indeks nitryfikacji (NI). Stwierdzono, że powyższe parametry w wyraźny sposób określały różnice w dynamice rozkładu słomy oraz kompostu, przy czym słoma była podatniejsza na przemiany. Ilości mikroelementów przyswajalnych dla roślin podczas inkubacji gleby z zastosowanymi substancjami organicznymi wzrosły w nieznacznym stopniu. Najwięcej wyekstrahowano Cu i Zn z gleby z dodatkiem słomy.

The decline of soil organic matter, as a consequence of the application of intense soil cultivation practice, has been identified as one of the most important threats to soil quality. To reverse these impacts, application of organic substances has been employed. Organic substances as straw and sewage sludge compost increase the input carbon and nutrients, for example micronutrients. Therefore an incubation experiment lasting 180 days was carried out to evaluate the effect of the addition of two sources of organic C: wheat straw and sewage sludge compost to light soil on CO₂ evolved, carbon mineralization, nitrification process and availability of nutrients (Cu, Zn, Mn, Fe). The compost and straw were dosed into the soil at the rate equivalent to 30 (I object) and 6 t DM per ha (II object) respectively. Soil samples were mixed with compost and straw and placed in plastic pots in three replications for each object. The decomposition rate was determined by trapping the evolving CO₂ in NaOH. The nitrification index was defines as the relation between nitrate –N and N mineral. The C mineralization coefficient was described as the relation between evolved CO₂ and TOC. Moreover the microelements (Cu, Mn, Zn and Fe) available to plants were extracted by 1 M HCl. To perform these analysis soil samples were collected after 1, 3, 7, 10, 14, 21, 35, 56, 84, 120, 150 and 180 days of incubation. The addition compost and straw increased amounts of CO₂ evolved and C mineralization. During incubation process the changes of the values of nitrification index were comparable for investigated soils but significant higher in condition of straw applied. Also the rate of C mineralization was higher in soil amended with straw. Application of compost and straw to soil increased content of microelements, and this was more sharply indicated at the soil fertilized with compost. Straw mineralization was fast process and caused the higher amounts of Cu and Zn. Mineralization of composts undergone very slowly and at the end of incubation influenced increase content of Cu and Zn. Moreover high significant linear correlation was found between evolved CO₂, C mineralization coefficient and available amounts of microelements extracted from the soil fertilized with straw.