Enzyme dynamics in contaminated paddy soils under different cropping patterns (NE Italy) uri icon

abstract

  • Four rice plots with different rotation systems were investigated before rice planting and during the phenological cycle in a paddy soil from the Veneto region, Italy; sampling of soils (0-15 cm) was carried out four times during growing season (three replicates). A total of 48 samples were air dried, for some chemical (soil pH, electrical conductivity, soil organic carbon, extractable P), physical (particle size distribution), and biochemical measurements (enzymatic assays and extraction of soil DNA). Moreover, the total concentration of trace and macro- and microelements were measured for assessing element levels and possible contamination of soils.
  • Soil enzyme activities are sensitive indicators of soil quality reflecting effects of land management. This study aims to monitor the effects of four crop rotation systems (rice-rice-rice: R-R-R, soya-rice-rice: S-R-R, fallow-rice: F-R and pea-soya-rice: P-S-R) on the activities of six important soil enzymes involved in C, N, P, and S cycling and soil properties during rice growth.
  • The obtained results suggest that the activity of most enzymes decreases in the different experimental conditions with the following order: drained soil > late waterlogging > early waterlogging > moist soil. However, the response of enzymes to waterlogging differed with the chemical element and the cropping pattern. The best rotation system for chitinase, leucine aminopeptidase, and beta-glucosidase activity (C and N cycles) was R-R-R, while for arylsulfatase, alkaline, and acid phosphatase activities (S and P cycles), it was the S-R-R.
  • The results demonstrated that compared with field moist soil, drained soil conditions resulted in a significant increase (P < 0.05) of beta-glucosidase, arylsulfatase, alkaline and acid phosphomonoesterase, leucine aminopeptidase, and chitinase activities in almost all rotations. The results obtained point to a land with high soil contamination by Li and TI. Moreover, soil DNA was negatively correlated to soil TI stress (r = - 0.41, p E, 0.01). The P-S-R rotation had the highest TI concentration in April and it is likely to be responsible for the lowest enzyme activities in the field-moist condition.The total concentrations of most studied elements (Al, As, Be, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, Sn, Sr, V, Zn) in the soil samples fell within the natural geochemical background concentration levels.

publication date

  • 2018
  • 2018
  • 2018