Potential effect of wetting agents added to agricultural sprays on the stability of soil aggregates

Abstract. The presented research deals with the issue of the potential effect of adjuvants/wetting agents (WA) added to the spray mixture for stability of soil aggregates (SAS) in agricultural soil. Nine localities were chosen in the Czech Republic. Each locality was mapped using soil pits (depth min. 1.4 m). A total of 54 mixed samples were collected from the topsoil horizon in the selected localities. The samples were exposed to the action of four different types of wetting agents (organosilicone wetting agent; methyl ester of rapeseed oil; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate). SAS was determined before and after the addition of WA. Average values of SAS across the sampling point exhibited a demonstrable trend: the SAS value of control sample (without WA application) was at all times higher than in samples with the addition of WA (organosilicone wetting agent; mixture of methyl ester palmitic and oleic acids; Isodecyl alcohol ethoxylate), on average by more than 15 %. If the measured SAS values are compared in terms of overall means, it is obvious that the control variant always exhibited the highest SAS value (44.04 %) and the variants with the application of WA showed always SAS values lower by min. 16 %. All soil samples were also analysed for basic soil parameters (glomalin, Cox, pH, Na, P, Ca, K, Mg) in order to determine their potential influence on SAS and a possible elimination of the negative impact of WA. In this respect, only a significant influence of Cox content on SAS was recorded, which positively correlated with SAS.