Monteiro, M.C.H.Carneiro, J.P.2022-01-122022-01-122021MONTEIRO, M.C.H.; CARNEIRO, J.P. (2022) - Use of digestate as organic amendment and source of nitrogen to vegetable crops. Appl. Sci. ISSN 2076-3417.12 (1).13 p.2076-3417http://hdl.handle.net/10400.11/7828Anaerobic digestion is a valuable process to use livestock effluents to produce green energy and a by-product called digestate with fertilising value. This work aimed at evaluating the fertilising value of the solid fraction (SF) of a digestate as an organic amendment and as a source of nitrogen to crops replacing mineral N. A field experiment was done with two consecutive vegetable crops. The treatments were: a control without fertilisation; Ni85 mineral fertilisation with 85 kg ha-1 of mineral N; fertiliser with digestate at an increasing nitrogen application rate (kg N ha-1): DG-N85, DG-N170, DG-N170+85, DG-N170+170; fertilisation with digestate together with Ni: DG-N85+Ni60, DG-N170+Ni60, DG-N170+Ni25. The results showed a soil organic amendment effect of the SF with a beneficial effect on SOM, soil pH and exchangeable bases. The SF was able to replace part of the mineral N fertilisation. The low mineralisation of the stable organic matter together with some immobilisation of mineral N from SF caused low N availability. The fertilisation planning should consider the SF ratio between the organic N (NO) and total N (TKN). Low NO:TKN ratios (~0.65) needed lower Ni addition to maintaining the biomass production similar to the mineral fertilisation.engAnaerobic digestionCircular economyGreen energyN use efficiencyShort carbon cyclejournal article10.3390/app12010248