Acta Univ. Agric. Silvic. Mendelianae Brun. 2012, 60(1), 91-96 | DOI: 10.11118/actaun201260010091

Digestate is equal or a better alternative to mineral fertilization of kohlrabi

Tomáš Lošák¹, Ludmila Musilová¹, Andrea Zatloukalová¹, Monika Szostková¹, Jaroslav Hlušek¹, Jiří Fryč², Tomáš Vítěz², Martin Haitl², Eduardo von Bennewitz³, Anna Martensson⁴

¹ Ústav agrochemie, půdoznalství, mikrobiologie a výživy rostlin, Mendelova univerzita v Brně, Zemědělská 1, 613 00 Brno, Česká republika

² Ústav zemědělské, potravinářské a environmentální techniky, Mendelova univerzita v Brně, Zemědělská 1, 613 00 Brno, Česká republika

³ Department of Agronomy, Universidad Católica del Maule, Casilla 7-D, Curicó, Chile

⁴ Department of Soil and Environment, Swedish University of Agricultural Sciences, Ulls väg 17, Ultuna, SE 756 51 Uppsala, Sweden

In a one-year vegetation pot experiment, we compared the effect of digestate from a biogas station and mineral fertilisers on yield and quality parameters of kohlrabi, variety Segura F1. Four treatments were used in the trial: 1) untreated control, 2) urea, 3) digestate, 4) urea, triple super phosphate, KCl, MgSO₄. The N dose was the same in treatments 2-4, 1.5 g N/pot. In treatment 4 the P, K and Mg doses corresponded to those supplied in the digestate treatment (3).
The weight of single kohlrabi bulbs in the unfertilised control was significantly lower (36.2%) than in the urea treatment (100%) and the other fertilised treatments. After application of digestate (treatment 3) and mineral fertilisers (treatment 4), the weight of single bulbs significantly increased by 36.2 and 33.6%, respectively, compared with the urea treatment (2). The content of ascorbic acid did not differ between the fertilised treatments (282-301 mg/kg), but was significantly lower than in the unfertilised control (334 mg/kg). There were significant differences between all fertilised treatments (2, 3, 4) in bulb nitrate content (745, 187, 462 mg NO₃^-/kg fresh matter, respectively). After digestate application the content decreased significantly, to 187 mg NO₃^-/kg fresh matter. The soil N_min content after harvest varied between 4.19-5.79 mg/kg in all fertilised treatments and the N-NH₄⁺ form prevailed over N-NO₃^- only in the digestate treatment (3.45/2.34 mg/kg). We recommend the use of digestate to kohlrabi as it results in comparable or better yield and qualitative parameters of kohlrabi compared with mineral fertilizers.

Keywords: ascorbic acid, mineral fertilizers, mineral nitrogen, nitrate, yields, urea

Grants and funding:

This study was financed by the Internal Grant Agency of the Faculty of Agronomy MENDELU in Brno No. TP 9/2011 and by the Research plan No. MSM6215648905 'Biological and technological aspects of sustainability of controlled ecosystems and their adaptability to climate change', which is financed by the Ministry of Education, Youth and Sports of the Czech Republic.

Received: October 31, 2011; Prepublished online: October 5, 2013; Published: October 9, 2013  Show citation