In 2007-2010, a three-factor field experiment was conducted at the Experimental Station in Mydlniki near Kraków. The objective was to determine the impact of a tillage system and plant cover on soil losses of magnesium and calcium by water erosion depending on a slope gradient. The first factor in the experiment was a slope gradient (9% and 16%), the second one consisted of a tillage system (plough system and direct sowing system) and the third one comprised plant cover (horse beans, spring wheat, and winter rapeseed). The experimental plots were 22 m x 2 m in size. Modified Słupik bag catchers were placed at the bottom borderline of each plot for the purpose of catching the material washed down. The ICP-OES method was applied to determine the content of calcium and magnesium. Calcium and magnesium losses were calculated based on the content of these elements in the soil washed down and in the runoff water. Analysis of Variance (ANOVA) was performed to analyze the results statistically. The significance of mean differences among the objects was tested with the use of multiple comparisons procedures and a Tukey’s range test at α = 0.05 level of significance. The studies showed that losses of Ca ranged from 3.11 to 9.20 kg ∙ year-1 ∙ ha-1 and losses of Mg varied from 0.97 to 2.12 kg ∙ year-1 ∙ ha-1. The losses of Ca were about 25% higher from the plots situated on the slopes with the 16% gradient than on the slopes with the 9% gradient; the difference in the losses of Mg from the plots on both slopes was similar and equalled about 26%. Compared to the conventional plough system, direct sowing (the ploughless system) reduced the losses of Ca and Mg by 36% and 20%, respectively. Of all the plants analyzed, the value of winter rapeseed as a soil protection agent was the highest.

21.2.2016