Soil structure stability and distribution of carbon in water-stable aggregates in different tilled and fertilized haplic luvisol

Abstract

The influence of tillage and fertilization on soil structure stability and the distribution of carbon in water-stable aggregates of loamy Haplic Luvisol were studied. Soil samples from the locality of Dolna Malanta (experimental station of SUA Nitra) were collected (in 2007-2009) from a depth of 0-0.2 m in two tillage variants: (1. conventional tillage, 2. minimal tillage) and three treatments of fertilization: (1. without fertilization, 2. crop residues and NPK fertilizers, 3. NPK fertilizers). The minimal tillage system has a positive effect on both the aggregation processes and sequestration of carbon in size fractions of water-stable aggregates, as well as ploughing of crop residues together with NPK fertilizers. On the other hand, application of only NPK fertilizers had a negative effect on SOM content. Under the minimal tillage system and in treatment with crop residues together with NPK fertilizers, what has been observed is a statistically significant increase in the total organic carbon contents by increasing size fractions of water-stable aggregates. Organic carbon did not influence the aggregation processes with dependence on tillage systems. Under conventional tillage as well as in treatment with ploughing crop residues with NPK fertilizers, a very important effect on aggregation had bivalent cations Ca2+ and Mg2+.