Nitrogen and Sulfur Availability in Digestates from Anaerobic Co-digestion of Cover Crops, Straw and Cattle Manure

Abstract

Anaerobic digestion (AD) has the potential to enhance the availability of nitrogen (N) from green manures; however, part of the sulfur (S) is lost with the biogas. In this study, the N and S availabilities from untreated and digested cover crop (CC) and straw mixtures were measured after application to soil in the laboratory. In addition, a microplot experiment was carried out to assess the N availability in a spring barley crop. A CC consisting of red clover (Trifolium pratense L.) and chicory (Cichorium intybus L.) was harvested and ensiled with barley straw (Hordeum vulgare L.) at different ratios (1:0, 10:1 and 3:1). The silages were either digested alone or co-digested with cattle manure (CM) in continuously fed anaerobic reactors. Six months after soil application, the net inorganic N release was − 7%, 15% and 25% of total N for untreated CC:straw ratios of 3:1, 10:1 and 1:0, respectively. AD significantly increased the net inorganic N release of these plant materials to 5%, 26% and 38% (mono-digestion) and 40%, 41% and 43% (co-digestion with CM). Results from the laboratory experiment corroborated the field experiment in which AD significantly increased the nitrogen fertiliser replacement value (NFRV) of the CC:straw from 19 to 41% of total N applied. Gaseous loss of S up to 30% was observed during AD while the total N content remained unchanged. Sulfate from untreated CC:straw and digestates was immobilised soon after application to soil, resulting in low availability of inorganic S. Digestion of CC and straw significantly reduced N immobilisation but clearly did not contribute to inorganic S supply.

Treatment of Cattle Manure by Anaerobic Co-Digestion with Food Waste and Pig Manure: Methane Yield and Synergistic Effect

“…This difference is likely due to the fact that CM mixed with bedding material stays on the floor of pens generally for six months or longer before being treated by composting in Korea, unlike in many European countries and the United States where wet raw manure is usually scraped out. The unique characteristics of the CM rich in the lignocellulosic matter are also reflected in its significantly higher TS content (31.0%) and C/N ratio (24.3) than those reported for CM in other countries (TS, 8.0–22.2%; C/N ratio, 9.0–17.2) [ 22 , 26 , 27 , 28 , 29 , 30 , 31 ]. Too low moisture content leads to reduced fluidity and biodegradability, thereby causing difficulties in the digester operation, and co-digestion with high-moisture substrates is a simple solution to this problem [ 32 ].…”

Liquid Anaerobic Digestate as Sole Nutrient Source in Soilless Horticulture—Or Spiked With Mineral Nutrients for Improved Plant Growth

“…The reactor feedstock in this study consisted of 21% protein-rich slaughterhouse waste and relatively protein-rich pig- and cattle manure and organic household waste. However, due to S losses during anaerobic digestion caused by H 2 S volatilization and/or iron sulfide precipitation, feedstock with a relatively high S content can still result in a digestate with an N:S ratio that is too high to meet the needs of crops in soilless systems ( Massé et al, 2007 ; Peu et al, 2011 ; Wahid et al, 2018 ; Fontaine et al, 2020 ). The S content may also be decreased by volatilization during storage and handling, as digestate can contain potentially volatile S compounds not precipitated with the added Fe ( Möller and Müller, 2012 ).…”

“…Anaerobic digestion has also been shown to decrease the sulfur (S) content of the feedstock through emissions of hydrogen sulfide (H 2 S) and other volatile S-containing compounds ( Massé et al, 2007 ; Peu et al, 2011 ; Wahid et al, 2018 ; Fontaine et al, 2020 ). Hydrogen sulfide has corrosive properties and must be removed from the biogas stream using one of the varieties of techniques available ( Moestedt et al, 2013 ).…”

Acidified Animal Manure Products Combined with a Nitrification Inhibitor Can Serve as a Starter Fertilizer for Maize

“…The addition of H 2 SO 4 has furthermore been shown to be beneficial for plant Sulphur (S) supply, but may on the long run lead to excess amounts of S added to soil [37]. This may, however, be less problematic for materials derived from anaerobic digestion, as a large part of the S contained in the input material is lost during the digestion process [38]. Although the use of nitrification inhibitors is promoted as a measure to reduce adverse environmental effects of nitrate leaching and N 2 O emissions [39], recent studies on their ecotoxicology under field conditions are rare.…”