Επίδραση τεχνητών μεταβολών των εδαφικών συνθηκών στις εδαφικές διεργασίες και στη φυτική παραγωγή

Abstract

The interest for the negative environmental effects of modern agricultural practices led to the adoption of agricultural practices friendly to the environment. The organic cultivation constitutes an alternative system of production, which includes the fundamental sustainable agriculture and has positive effects on the environment. Concerning the fact that the organic cultivation leads to the long-term amelioration of soil quality, the present thesis investigates improved soil quality practices that would lead to the increase of crop production and to the solution of environmental problems. Particularly, this thesis aims to study the changes in soil quality by the response of biochemical parameters after the application of disinfection and cultivation treatments. The study was conducted in Prespa region and was cultivated with the leguminous Phaseolus vulgaris L within an area of 3000 m2 where a field plot experiment was set consisting of 18 plots (10 x 10 m each one) with same endogenous characteristics and microclimatic conditions. Five samplings took place as well as a sampling of plant biomass. All samplings were done during the life circle of bean and all plots receiving different treatments were randomly interspersed. The first treatment was the disinfection. The chemical disinfection was done with the chemical product metam sodium and the biological disinfection was done with a mixture of organic additives. After the disinfection the next treatment that took place was the fertilization, where three plots from each disinfection type were cultivated organically receiving cow manure and the other three were cultivated conventionally. In the plots of organic cultivation hand weeding was applied while in the conventionally cultivated surfaces the herbicide paraquat was applied. The thesis consists of four chapters and the content is presented in brevity in the following paragraphs. In the first chapter the effect of disinfection on the soil biochemical parameters was investigated one month after the application. Six replicate plots were ΠΕΡΙΛΗΨΕΙ? 9 disinfected with metam sodium, six with a mixture of organic additives whereas the rest six received no disinfectants and were used as control. Soil samples were collected following a randomized complete design involving three genuine replicate samples at each plot (3 treatments x 6 replicate plots x 3 replicate samples). According to the results, the disinfection did not influence the organic C, the organic N and the enzyme activity of asparaginase and glutaminase. However, as concerns the other parameters, they were altered by this treatment. Thus, the biological disinfection decreased microbial C and increased the concentration of N in the soil while the chemical disinfection decreased the activity of urease and acid phosphatase, the microbial N and the concentration of P. Consequently, the chemical disinfection affected negatively the functionality of soil system while the biological disinfection ensured an increase in concentrations of available N and P and enzyme activity. The second chapter refers to the interaction effect of the disinfection with the cultivation type νn the soil parameters. Soil samples were collected in three different sampling times (June, August and October) and every sampling represented different stage of the bean crop. Also, samples of plant biomass were received during September, in the stage of harvest. The aims of this study were a) to compare soil properties between the two production systems (conventional and transitional organic) b) to explore the long-term effect of disinfection on soil quality c) to explore whether the effect of disinfectants on soil quality parameters is strengthened or reversed by the addition of chemical or organic fertilizer and d) to investigate how the interaction of disinfection and fertilization is differentiated along the crop development of Phaseolus vulgaris on the soil quality and on the plant biomass respectively. Disinfection, three months after its application, seemed to exert a long-term influence on glutaminase, microbial carbon and nitrogen by reducing its activity principally in ΠΕΡΙΛΗΨΕΙ? 10 chemically disinfected plots. Consequently, disinfection did not cause sterilisation of soil, however inhibited for a long time the microbial activity