| Abstrakt: |
The positive effects of biochar on soil structure were demonstrated in many studies. Substantially less, even information on the interrelationships between Al, Fe forms and soil structure induced by biochar application as well as its re-application is still absent. Therefore the aims of this study were: (1.) to evaluate the changes in soil structure parameters affected by biochar application and its re-application in different rates (0, 10 and 20 t ha-1 ), (2.) to evaluate the effect of biochar application and re-application on the content of Al and Fe forms, (3.) to determine the relationships between Al and Fe forms and individual size fractions of water-stable aggregates. In 2014, the field experiment with biochar was established on experimental site of SUA in Nitra (Dolná Malanta) on a silty loam Halpic Luvisol. In 2018, re-application of biochar was done at the same rates as in 2014. In 2018, in spring and autumn the soil samples were collected. The results showed that the primary application of biochar and its re-application at the rate of 20 t ha-1 significantly increased the content of water-stable macro-aggregates (WSAma) by 19 and 13%, the mean weight diameter of water-stable aggregates by 46 and 46% and the stability index of water-stable aggregates by 19 and 13% and decreased the content of water-stable micro-aggregates (WSAmi) by 57 and 36%, respectively compared to the control. At the same time, the biochar re-application in higher rate significantly increased the content of total iron (Fet) and decreased the content of total aluminium (Alt) in comparison to the control. In addition, Fet positively correlated with WSAma (r = 0.615, P<0.001) and negatively with WSAmi (r = -0.615, P<0.001). Feo was in a positive relationship with WSAma (r = 0.475, P<0.01) and in a negative relationship with WSAmi (r = 0.476, P<0.01). On the other hand, Alo was in a significant negative correlation with WSAma (r = -0.567, P<0.01) and in a positive correlation with WSAmi (r = 0.566, P<0.01). All in all we concluded, that different rates, age of biochar, individual forms of Al and Fe can influence the soil structure in a very different ways. [ABSTRACT FROM AUTHOR] |
