Study on some soil quality changes obtained from long-term experiments

Agricultural practice often causes soil structure degradation and as a result it leads to changes in soil fertility and quality. The aim of this study was to compare soil aggregate stability (SAS) and soil or ganic matter (OM) quantity and quality in different systems of soil management. Three adjoining longterm experiments established on Chernozem were chosen; they were all set up in different years with different crop rotations and comparable fertilization treatments: control (without fertilization); NPK; ma nure; NPK + manure; N + manure; OM and NPK + OM. SAS was statistically significantly lower in the trial with the highest proportion of cereals in the crop rotation. Differences among the fertilization treatments were noticeable, but not significant; the lowest SAS was observed at treatments with the mineral NPK fer tilization. Significant correlation was found out between SAS and C/N ratio ( R = –0.571; P < 0.05) and between SAS and soil pH (R = 0.30; P < 0.05). Further, the individual trials differed in soil pH. A significant positive influence of the treatment NPK + manure was observed in the content of hot water-extractable car bon (C hwl ) and total soil organic carbon and nitrogen. The significant correlation between the 3000–2800/cm peak area of fourier transform infrared (FTIR) spectra and labile organic compounds in soil (C hwl ) was confirmed.