Effect of biochar application on the content of nutrients (Ca, Fe, K, Mg, Na, P) and amino acids in subsequently growing spinach and mustard

The objective of this study was to assess the effect of biochar on growth and metabolism of spinach (Spinacia oleracea L.) and mustard (Sinapis alba L.) planted in crop rotation: spinach (spring)-mustard-spinach (autumn). The impact of biochar soil application (5% per mass of soil) on the availability of Ca, Fe, K, Mg, Na and P to plants as well as the content of free proline and total amino acids contents were evaluated at degraded Chernozem soil. The results showed that biochar soil addition significantly increased spinach growth by 102% and 353% in spring and autumn, respectively. Biochar limited plant content of Ca, Mg and Na, however K content increased in all plants. Inconsistent effect was determined for Fe and P content in plants biomass. Total content of free amino acids was higher in plants harvested at amended treatments, except autumn spinach. Biochar increased proline content in all plants in comparison to control. The highest increase was obtained in mustard – by 186%. The results showed a more sensitive reaction of mustard to biochar application than spinach.