The recultivation of the sterile dumps implies certain changings in their properties. In order to emphasize this aspect we have researched the evolution of the main agrochemical features of the sterile dumps from Husnicioara under the influence of recultivation and fertilization using chemical and organic fertilizers within the 2002-2008 period. There were two monofactorial trials: the first one where there were applied different chemical fertilizers and the second one where there used the same chemical fertilizers on 25 t/ha manure background. Both experiments have been set up after block method, using three repetitions in complete randomised blocks.The experimental data have calculated using the analysis of variance (Fisher and t tests)and all variants have been distinctivelly significant. All variants have been compared with the not fertilized variant which has been taken as control. The chemical fertilizers doses: N40, N80, N120, N160, N160P80, N160P80K80. As nitrogen fertilizer there was used the urea, as phosphorus, the simple superfosfate and as potassium, KCl. After 7 years of corn-wheat crop-rotation there were noticed the following changings of the agrochemical features: The sterile dump reaction – was, in 2002, weak alkaline (pH=8.05-8.10) due to the nature of the sterile dump. The applying of large urea doses, of N120, N160 determines the decreasing of the pH value from 8.10 and 8.09 to 7.74 and 7.59, with 0.36-0.50 units without manure and 0.18 and, respectively, 0.25 units on 25 t/ha manure background. The evolution of the mobile phosphorus – in all no manure variants where there were applied no phosphorus fertilizers (the 1-5 variants) the concentration of mobile phosphorus from the sterile dump has decreased after 7 years in comparison with the initial concentration. Within the variants where there were applied phosphorus fertilizers, the final concentration of the mobile phosphorus was higher than the initial one (the 6, 7 variants), from 34.7 ppm P – 59.0 ppm P). Within the variants where manure was applied, the initial and final concentrations are almost equal excepting the case where over the manure background there were applied phosphorus fertilizers (simple superphosphate) and in these cases the soluble phosphorus concentration after 7 years of researching is higher than the initial concentration (34.9 ppm – 59.5 ppm P). The determination of the potassium content was performed after Egner-Riehm-Domingo method. The evolution of the mobile potassium – the mobile potassium from the sterile dump has decreased within all fertilized variants with simple nitrogen or nitrogen and phosphorus as well as with manure yet it increased with the potassium fertilized variants (59.1 – 113.0 ppm K). The evolution of the organic carbon content – the organic carbon content has recorded an increasing tendency only with the variants fertilized with manure (0.77 – 0.81%) yet with large nitrogen doses applied alone there even was recorded a decreasing, mainly because of leaching and lack of organic support of the sterile dumps. The paper deals with the first research on these type of sterile dump.

biological re cropping; sterile dumps; fertilizers

Presentation: oral