Water use of sugar beet and spring barley in different crop rotations and fertilisation systems in chernozem in Ukraine

The purpose of the research was to study the soil water content (SWC) and water use efficiency (WUE) of sugar beet ( Beta vulgaris L.) and its aftercrop spring barley ( Hordeum vulgare L.) under the influence of crop rotation, fertilisation system, and weather conditions. A long-term field experiment was established in the Central Forest Steppe zone of Ukraine. The experiment included the following six-field crop rotations: (i) cereal, fodder, and tilled, (ii) tilled, and (iii) cereal and tilled. In the experimental field, sugar beet fertilisation was mineral (N 100 P 90 K 90 ) and organic-mineral (40 t ha −1 cattle manure + N 100 P 90 K 90 ). Regardless of crop rotation, sugar beet plants used water more efficiently under mineral and organic-mineral fertilisation with the WUE reaching 67−76 m 3 t −1 , which is 2.1–2.5 times lower compared to zero fertilisation (control). The WUE of spring barley was 277–372 m 3 t −1 under residual effect of mineral and organic-mineral fertilisation and 428–458 m 3 t −1 under zero fertilisation of sugar beet. Fertilisers applied to sugar beet provided an additional 100–122 mm of SWC (0–150 cm soil layer) for its aftercrop spring barley, while with zero fertilisation the SWC was only 58–79 mm. It can be concluded that organic-mineral fertilisation applied to sugar beet is more effective compared to mineral fertilisation, as it provides a significant additional water reserve to the aftercrop spring barley.