Agricultural management practices – directly or indirectly – influence soil properties.
Fertilization rates and crop rotation can strongly affect soil pH, soil nutrient supply and soil organic matter content due to the changes of microbial processes. The objective of this study was to compare the effects of different fertilization d...oses in monoculture and tri-culture of maize (monoculture: only maize grown since 1983, tri-culture: it is a three-year crop rotation system: pea – winter wheat – maize) on selected soil characteristics. The long-term fertilization experiments were set up in 1983 in Eastern Hungary. These experiments are situated west of Debrecen in Hajdúság loess region, on calcareous chernozem (according to WRB: Chernozems).
The test plant was maize (Zea mays L.). One-one pilot blocks were selected from monoculture and tri-culture of the long-term experiments. The observed soil samples were taken in the 30th year of the experiment, in 2013. The doses of NPK fertilizers increased parallel together, so the effects of N-, P- and K-fertilizers cannot be separated.
With the increasing fertilizer doses, the soil pH has decreased in both crop production systems and, in parallel, the hydrolytic acidity has significantly increased. A close negative correlation was proved between the pHH2O, pHKCl and hydrolytic acidity. An increased nutrient content in soil was recorded in every NPK treatment and the available phosphorus and nitrate content increased in higher proportion than that of potassium. Of the measured parameters of C-and N-cycles, fertilization has mostly had a positive effect on the microbial activity of soils. Besides the effects of fertilizer doses, correlation were looked for between soil microbiological properties. Evaluating the ratios among the measured parameters (organic carbon and microbial biomass carbon, OC/MBC ratio; carbon-dioxide and microbial biomass carbon; CO2/MBC proportion), the fertilization rate seems to be favoured by the increase of amounts of organic compounds
In the long term fertilization experiment of the University of Debrecen, Centre for Agricultural and Applied Economic Science(CAAEC) (Debrecen Látókép), the effects of a 25-year-long fertilization were examined in terms of some chemical and microbiological properties of soil. With the growing doses of fertilizers, the available nutrient cont...ent of soil increased. At the same time the pH significantly decreased, while the hidden acidity increased. Moreover, the ratio between the soil bacteria and microscopic fungi, and the occurrence of microbes also changed. The number of sensitive physiological bacteria groups decreased dramatically. These changes indicate the reactions of living organisms; they correspond to the „resistance stage” of stress effects, but in the case of nitrifying bacteria, they reach the „exhaustion stage”.
In a pot experiment, we have studied the effect of bentonite and zeolite in different dosages [control; 5; 10; 15; 20 g kg-1] on acidic (pHH2O=5.65) humus sandy soil. The experiment was set up in 2007 and 2008 in the greenhouse of the UD CASE Department of Agrochemistry and Soil Science. As a test plant, perennial ryegrass... (Lolium perenne L.) was used.
In laboratory examinations, pH(H2O), pH(KCl), hidrolytic acidity, nitrate-N content, readily available phosphorus and potassium content were determined. Among soil microbial parameters, the total number of bacteria, the cellulose-decomposing bacteria, the carbon-dioxide production, the microbial biomass-C content of soil, and the saccharase enzyme activity were measured. In the experiment the biomass of the test plant was determined.
The effect of bentonite and zeolite in different dosages can be summarized as follows:
− The pH increased under the effect of low dosages. With the increasing of the pH the hydrolytic acidity - at the bentonite treatments significantly – decreased.
− Regarding the readily available nutrient content of the soil, low and medium dosages proved to be effective. High dosages of bentonite treatments reduced the nitrate-N content, the readily available phosphorus, and potassium content of soil, by zeolite treatments the high dosages reduced the nitrate-N content of soil.
− Regarding the measured soil microbial parameters in both treatments low and medium dosages proved to be also effective, but the high dosages didn’t cause decreasing at the total number of bacteria, and by zeolite treatments the biomass-C content of soil.
− Also the bentonite and zeolite treatments enlarged the biomass of the test plant. We experienced significant increasing by bentonite treatments by the effect of medium and high dosages, while in zeolite treatments only the high dosage caused significantly increasing in plant biomass. The largest dosages decrease the plant biomass.
− Under the statistical analysis we found many medium and tight correlation between the studied parameters.