Anaerobically Digested Cattle Manure Supplied More Nitrogen with Less Phosphorus Accumulation than Undigested Manure

Abstract

Solid beef cattle manure is a good anaerobic digestion feedstock for methane production, but more research is needed to determine how co-products of the anaerobically digested manure may be used in crop production, while limiting the risk of nutrient loss to the environment. Over four growing seasons, we measured the N and P supplied to barley (Hordeum vulgare L.) forage test crops from (i) anaerobically digested solid beef cattle manure (digestate), (ii) separated solids from the digestate (separated solids), (iii) pelletized separated solids (pellets), and (iv) undigested solid beef cattle manure (manure) that were applied to target 1× (260 kg N ha -1 ) and 2× (520 kg N ha -1 ) the recommended N rates. Non-amended soil was the control. Digestate led to 31 to 50% greater barley forage yield than the other amendments. Th e apparent N recovery from digestate (19%) was much greater than pellets (2%) and about double that of the separated solids (9%) and cattle manure (10%). Th e barley N uptake derived from digestate was 41%, which was signifi cantly greater than manure (22%), separated solids (17%), and pellets (2%). Digestate increased P uptake, while signifi cantly reducing soil-test P accumulation compared with the other coproducts and cattle manure when applied at N-based rates. Our results confi rmed that management practices for solid beef cattle feedlot manure may be used for separated solids, but not digestate. Pelletized separated solids may be an eff ective slow release fertilizer, while also supplying C, but determination of its nutrient release patterns is required.

Short-term nitrogen dynamics in a soil amended with anaerobic digestate

“…Anaerobic digestion of agricultural residues may be considered ecologically sound (Insam et al 2015), but the variation in digestate N concentrations and decomposition of digestate's organic N leads to uncertainties in recommendation rates for agricultural use. Previous studies on digestate N dynamics demonstrated the need for determination of digestate N release pattern and rate (i.e., potentially mineralizable N parameters) for more efficient management of this product in cropping systems (Thomas et al 2017).…”

Economic Analysis of Pellet Production in Co-Digestion Biogas Plants

“…On the basis of the results, after drying the fermentation residue is suitable for use as nutrient replenishment, and without loss of yield to replace fertilizers and liquid cow manure. Thomas et al (2017) investigated not only organic fertilizer, matured fermentation liquid, and solid separated matter, but also supplemented this with the already pelletized fermentation residue, during which the effects of the individual fertilizer pulp on autumn barley were measured for four years. On the basis of their results, during the fermentation and processing, the material undergoes substantial internal changes in content until it becomes pellet.…”

“…Nitrogen absorption was the lowest in the case of pellets, at only 2%, while it was highest in the matured fermentation liquid, at 41%. In addition, it was argued that pellet from fermented sludge could be an effective, but slow-release nutrient source, while also providing carbon replenishment [56].…”

“…The composition of organic fertilization pellet was calculated on the data of Thomas et al (2017) [56], Ross et al (2018) [57], Kratzeisen et al (2010) [54] and Haggard et al (2005) [60]. Since the nitrogen content significantly reduces during drying, we considered only its phosphorus-(0.8%) and potassium-content (1.5%) for pricing.…”

Optimising Anaerobic Digestion of Manure Resources at a Regional Level

“…The amount of digestate and the fertilising effect is assumed to be approximately the same as for manure [44,45]. It was also assumed that there is no need to invest in new spreading equipment.…”