Yield, content and nutrient uptake by winter wheat and spring barley in response to applications of digestate, cattle slurry and NPK mineral fertilizers

Digestate represents an alternative source of nutrients for crops in sustainable agriculture. We aimed to evaluate the effects of digestate fertilization on grain (GY) and straw yield (SY) and nutrient content and uptake in winter wheat (WW) and spring barley (SB). The study duration was from 2012 to 2016, with the following crop rotation: WW/WW/SB/WW. Every year, the same fertilizers were applied to each respective plot: control, digestate, digestate + straw, cattle slurry and mineral NPK fertilizer. Significantly higher GY and SY were noted after fertilizer application each year compared to the non-fertilized control. The average effect of the fertilizers on GY of WW was control < NPK <= digestate + straw <= cattle slurry <= digestate. Fertilizer application also increased N, S, Na, Zn and Fe content in the grains, especially when digestate was used as fertilizer. However, in non-fertilized plants (control), only the K content increased in the grains, although the uptake of K is positively correlated with GY. Our results show that digestate can be used not only as a replacement for cattle slurry but also as an alternative fertilizer, which, under certain soil conditions, is more effective than NPK fertilizer.