The usability of digestate in organic farming

Clements, Lily; Salter, Andrew M.; Banks, C.J.; Poppy, Guy M.

doi:10.2166/wst.2012.389

Cited by 15 publications

(6 citation statements)

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“…The available data show an interaction with the specific experimental setup. In cropped fields, very often, no or minor differences in soil biological activity were measured in comparison to application of undigested feedstocks (Allan et al 2003;Schauss et al 2006;TerhoevenUrselmans et al 2009;Clements et al 2012;Walsh et al 2012b;Bachmann et al 2014), whereas in an experimental setup carried out on fallow land, the differences between undigested and digested manures were very often significant (Friedel et al 1996;Ernst et al 2008;Terhoeven-Urselmans et al 2009). Simultaneously, the influence of anaerobic digestion on soil microbial activity is also mediated by the used feedstock (Johansen et al 2013).…”

Section: Effects Of Anaerobic Digestion On Soil Properties and Soil Bmentioning

confidence: 99%

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

Möller¹

2015

Agron. Sustain. Dev.

220

135

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Sustainability in agriculture means the inclusion of several aspects, as sustainable agriculture systems must not compromise not only their ability to satisfy future needs by undermining soil fertility and the natural resource base but also sustainable agriculture has had to address a range of other issues including energy use, efficient use, and recycling of nutrients, the effects on adjacent ecosystems including the effects on water bodies and climate change. Organic manures are an important factor to keep the soil fertility level of soils. However, their management is often related to large emissions. In this context, anaerobic digestion is-similarly to composting-a treatment option for stabilization of biogenic wastes leading to a residual product called digestates, enabling the sanitation and the recycling and use as fertilizer. It is also a means to obtain energy from wastes as well as from dedicated energy crops. Therefore, anaerobic digestion potentially addresses several aspects of agricultural sustainability. This review discusses the current state of knowledge on the effects of anaerobic digestion on organic compounds in digestates and the most important processes influencing N emissions in the field, as well as the possible longterm effects on soil microbial biomass and soil fertility. The main findings are that (1) the direct effects of anaerobic digestion on long-term sustainability in terms of soil fertility and environmental impact at the field level are of minor relevance. (2) The most relevant effects of anaerobic digestion on soil fertility as well as on N emissions will be expected from indirect effects related to cropping system changes such as changes in crop rotation, crop acreage, cover cropping, and total amounts of organic manures including digestates. Furthermore, (3) the remaining organic fraction after anaerobic digestion is much more recalcitrant than the input feedstocks leading to a stabilization of the organic matter and a lower organic matter degradation rate after field application, enabling a similar reproduction of the soil organic matter as obtained by direct application of the feedstock or by composting of the feedstock. (4) Regarding emissions, the main direct effect of anaerobic digestion on a farm level is the influence on gaseous emissions during manure or digestate treatment and handling, whereas the direct effects of anaerobic digestion on a field level on emissions (NH 3 − and N 2 O − emissions, NO 3 -leaching) are negligible or at least ambiguous. (5) The main direct effects of anaerobic digestion on the field level are short-term effects on soil microbial activity and changes in the soil microbial community. Therefore, in terms of the effects on agricultural sustainability, potential cropping system-based changes induced by introduction of biogas plants are probably much more relevant for the overall performance and sustainability of the cropping system than the direct effects triggered by application of digestates in comparison to the undigested feedstock...

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Section: Effects Of Anaerobic Digestion On Soil Properties and Soil Bmentioning

confidence: 99%

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

Möller¹

2015

Agron. Sustain. Dev.

220

135

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“…Other research undertaken to date has not reported any adverse effects of digestate on earthworm populations. For example, Clements, Salter, Banks, and Poppy (2012) measured earthworm numbers following applications of cattle slurry and manure‐based digestate in comparison with an untreated control on earthworm populations in ley grassland. Six weeks after application, there were no differences in earthworm numbers between any of the treatments.…”

Section: Discussionmentioning

confidence: 99%

The effect of field application of food‐based anaerobic digestate on earthworm populations

Rollett

Scullion

Nicholson

et al. 2020

Soil Use and Management

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In general, farming systems that provide the greatest organic matter returns to the soil support the highest earthworm populations and typically the application of organic materials will increase earthworm numbers because of an abundance of food.There has been limited work on the effects of digestate applications on earthworm populations with most focus on the short-term effects of digestate from manure or crop-based feedstocks, not from food wastes. To address this gap in current knowledge, the objective of this study was to assess the impact of repeated food-based digestate applications on earthworm populations/biomass in both the short term (c. 6 months after digestate application) and longer term (2 years later) in comparison with other commonly used inputs (manufactured nitrogen-N fertilizer, compost and livestock manures). This multi-site field experiment has shown that the application of food-based digestate at application rates above current good practice can have a short-term, negative impact on earthworm numbers under certain conditions. Six months after the final digestate addition, earthworm numbers were 32%-60% lower than following the additions of other organic materials at four of the seven sites investigated. A combination of high ammonium/low organic matter loadings and soil compaction most likely explained the observed effects.

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“…Studies observing plant response to biogas slurry, e.g., [28,[44][45][46][47] or (composted) biochar e.g., [33,[48][49][50][51][52][53][54][55], have often revealed positive results in terms of stimulated crop productivity. Furthermore, co-composting of source-separated human faeces has also been empirically studied, cf.…”

Section: Intersectional Resource Management For Subsistence Fertilizementioning

confidence: 99%

Recycling Improves Soil Fertility Management in Smallholdings in Tanzania

Krause

Rotter

2018

Agriculture

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Abstract:Residues from bioenergy and ecological sanitation (EcoSan) can be utilized to sustain soil fertility and productivity. With regard to certain cooking and sanitation technologies used in smallholder households (hh), we systematically analyzed how utilization of the respective potentials to recover residues for farming affects (i) soil nutrient balances, (ii) the potential for subsistence production of composts, and (iii) environmental emissions. On the example of an intercropping farming system in Karagwe, Tanzania, we studied specific farming practices including (1) current practices of using standard compost only; (2) a combination of using biogas slurry, urine, and standard compost; (3) a combination of using so-called "CaSa-compost" (containing biochar and sanitized human excreta, Project "Carbonization and Sanitation"), urine, and standard compost. The system analysis combines a soil nutrient balance (SNB) with material flow analysis (MFA). Currently, nitrogen (N) and phosphorus (P) are depleted by −54 ± 3 and −8 ± 1 kg·ha −1 ·year −1 , respectively. Our analysis shows, however, a clear potential to reduce depletion rates of N, and to reverse the SNB of P, to bring about a positive outcome. Composts and biogas slurry supply sufficient P to crops, while urine effectively supplements N. By using resources recovered from cooking and sanitation, sufficient compost for subsistence farming may be produced. Human excreta contribute especially to total N and total P in CaSa-compost, whilst biochar recovered from cooking with microgasifier stoves adds to total carbon (C) and total P. We conclude that the combined recycling of household residues from cooking and from sanitation, and CaSa-compost in particular, is especially suitable for sustainable soil management, as it mitigates existing P-deficiency and soil acidity, and also restores soil organic matter.

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The usability of digestate in organic farming

Cited by 15 publications

References 0 publications

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

The effect of field application of food‐based anaerobic digestate on earthworm populations

Recycling Improves Soil Fertility Management in Smallholdings in Tanzania

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