Soil-conservation effect of intercrops in silage maize

More than 50% of agricultural land is threatened by water erosion in the Czech Republic. With respect to soil erosion, maize (Zea mays L.) belongs to the most problematic crops; one of the possibilities to increase protection against erosion is intercropping. In this study, we attempted to find out the effects of individual intercrops and their mixtures (sown 4-6 weeks after sowing maize) or a mixed culture (maize plus lupine) on the soil losses and surface runoff in the period 2019-2021. The study was realised in a sugar beet growing region (Haplic Luvisol); a field rainfall simulator was used. From the used variants with Lolium perenne L., Trifolium repens L., Vicia villosa Roth, Lolium multiflorum Lam., Festuca arundinacea Schreb., Triticum aestivum L. or a mixture (Vicia villosa plus a Trifolium hybrid diploid), the variants with Lolium perenne, Lolium multiflorum, Vicia villosa or Vicia villosa plus the Trifolium hybrid diploid, established between the maize rows (hybrid maize, cultivar Walterinio) on May 27, were the most efficient in case of both the soil losses and runoff reductions in the year 2019. For example, Triticum aestivum between the maize rows mostly reduced the soil losses and the surface runoff was similar (or higher) compared with the control (maize without any intercrop). The variant with Trifolium repens had mostly higher (or similar) soil loss values (compared with the control); in this variant, the runoff was lower compared with the control. We proved our hypothesis with regards to the higher reduction in the soil losses than with the runoff in the variant with Lolium perenne. The results from the years 2020 (the used variants with Lolium multiflorum, Secale cereale L., Trifolium incarnatum L., Phacelia tanacetifolia Benth., Lolium multiflorum plus Trifolium incarnatum, Lolium multiflorum plus Vicia pannonica Crantz) and 2021 (the variants with Lolium multiflorum, Lolium multiflorum - early sowing, Secale cereale, Trifolium incarnatum, Phacelia tanacetifolia, Lolium multiflorum plus Trifolium incarnatum, a mixed culture = maize plus Lupinus albus L.) showed the variants with Trifolium incarnatum, the mixture (Lolium multiflorum plus Trifolium incarnatum), Phacelia tanacetifolia (in the year 2020) or the mixture (Lolium multiflorum plus Trifolium incarnatum) and a mixed culture (maize plus Lupinus albus) (2021) had the most positive effect - the soil loss and surface runoff values were lower when the maize was > 2 m compared with the maize < 1 m. The results obtained in the period 2019-2021 showed the grasses were the most efficient in decreasing the soil losses when the maize was < 1 m and when the maize was > 2 m with the used mixtures.