Fertilization with Magnesium- and Sulfur-Supplemented Digestate Increases the Yield and Quality of Kohlrabi

Abstract

The vegetation pot experiment with kohlrabi (Moravia variety) was established in 2014 and 2015. The experiment included four treatments of fertilization: (1) untreated control, (2) digestate, (3) digestate + Mg + S, and (4) digestate + S. Treatments 2–4 were fertilized with the same N dose. Differences between the years were recorded in all parameters. Compared with the variant with digestate (100%), the kohlrabi yield of the unfertilized variant was demonstrably lower in both years (33.1% and 46.9%). Digestate enriched with the fertilizer containing Mg + S (treatment 3) demonstrably increased the yield of kohlrabi by 10.2% and 15.7% compared with pure digestate (treatment 2). Digestate enriched with the fertilizer containing elementary S (treatment 4) demonstrably increased the yield of kohlrabi (by 7.4%) only in 2015 compared with pure digestate (treatment 2). Except for the year 2015, there were no yield differences between variants 3 and 4. In both years, the lowest content of nitrates in kohlrabi was observed in the unfertilized control (135 and 163 mg NO3−/kgFM, respectively). Following the application of digestate (treatment 2), the content of nitrates (mg NO3−/kgFM) increased to 327 in 2014 and to 509 in 2015. The addition of fertilizers with Mg + S as well as fertilizer with elementary S to the digestate (treatment 3 and 4) significantly reduced the content of nitrates to 295–301 mg NO3−/kgFM (2014) and to 449–468 mg NO3−/kgFM (2015). The content of ascorbic acid did not statistically differ among the four treatments in the two years (268–281 and 311–329 mg/kgFM in 2014 and 2015, respectively). Digestate supplemented with Mg + S (magnesium sulfate) or only with elementary S can be recommended for kohlrabi fertilization prior to the planting in order to reduce dangerous accumulations of nitrates in kohlrabi.

In Vitro Growth and Regeneration of Brassica oleracea var. gongylodes: A Decade of Research

“…Being more favorable in taste than most other brassicas and comprising a large variety of functional compounds, it is not surprising that kohlrabi has been recently receiving more and more attention both as food and feed [3]. In this context, the number of studies on ex vitro grown kohlrabi has increased, including studies on the metabolism of phenolic compounds and glucosinolates [8,12], their antioxidant and antimicrobial potential [13], biosynthesis of anthocyanin [14,15], effects of plant growth regulators and various means of biofortification on growth, yield, and quality traits of kohlrabi [16][17][18], as well as reports on transcriptomic [19,20] and hormonomic [21] analysis of stem tuber formation.…”

Effect of Mycotoxins in Silage on Biogas Production

“…It is also necessary to realize that silage AD gives rise not only to biogas but also to fermentation residues in the form of digestate, which can be contaminated by mycotoxins too [28]. Additionally, when digestate is used as fertilizer, it is necessary to investigate its influence on the quality of food and feed products not only in terms of nutritional value [29], but also in terms of soil properties [30,31], as well as the possible contamination of the environment with mycotoxins [32]. This study presents a novel combined evaluation of the content of mycotoxins in the contaminated silage, their effect on biogas and methane production, and the degradation of mycotoxins during the AD process (monitored as the residual content of mycotoxins in the digestate).…”

“…It is also necessary to realize that silage AD gives rise not only to biogas but also to fermentation residues in the form of digestate, which can be contaminated by mycotoxins too [28]. Additionally, when digestate is used as fertilizer, it is necessary to investigate its influence on the quality of food and feed products not only in terms of nutritional value [29], but also in terms of soil properties [30,31], as well as the possible contamination of the environment with mycotoxins [32].…”

Protection and Modeling in the Use of S, Ca, and Mg Alternatives for Long-Term Sustainable Fertilization Systems

“…All elements have essential roles in the crop life cycle, and macroelements mainly play plastic, constitutive, and qualitative roles while trace elements have mainly enzymatic and catalytic roles in plant metabolism [4,5,[13][14][15][16].…”

“…The effect of S + Mg is more pronounced and significant, even in relation to the N and K nutrients, in the form of fertilizing applications of these complexes in diversified assortments [13] (Table 11).…”