Is soil an appropriate dumping ground for our wastes?

Managing food waste is key to tackling climate change

��������� � �� ���������� Biologically treated organic waste can be recycled back to agriculture and forestry for use on land. The organic waste products considered are processed (composted or anaerobically digested) or unprocessed organic waste from households, gardens, commerce and industry. Agricultural production waste and manure from conventional and organic animal production systems (cattle, pig, poultry slurry) are also used on land, but are not included in this chapter. The use of household wastes in agriculture is not widespread (but is increasing due to urban recycling programs) and most of the regulation in this field arises from the application of wastewater treatment sludges to agricultural land. Organic wastes can also be beneficially used in urban areas, provided they have been processed is some way, e.g. through composting. Waste composts may be used for soil manufacturing, improvement of degraded urban soils, for soil improvement in parks, gardens and recreational areas, and for revegetation of disturbed soils, e.g. roadways, embankments, etc. These applications are described in Chapter 9.9. From a historical perspective, land application of waste is as old as agriculture. The Chinese have used human and household waste as a fertilizer for thousands of years. In the beginning of the twentieth century, land application of sludge and waste in Europe and the United States was common. In those times the benefits of the waste were appreciated, and local farmers were glad to use waste or residuals to improve crop yields. However, as soon as concentrated and highly effective sources of plant nutrients became available and affordable in the form of chemical fertilizers, in many situations waste was seen as a disposal problem rather than a resource.

GroundwaterVolume 17, Issue 6 p. 608-608 REPLY TO the preceding Discussion by Ronald W. Crites and Sherwood C. Reed of “Land Application of Waste – An Accident Waiting to Happen” Charles C. Johnson Jr., Charles C. Johnson Jr.Search for more papers by this author Charles C. Johnson Jr., Charles C. Johnson Jr.Search for more papers by this author First published: November 1979 https://doi.org/10.1111/j.1745-6584.1979.tb03363.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume17, Issue6November 1979Pages 608-608 RelatedInformation

Organic matter is an indispensable element of soil. Its quantity and quality affect its properties, e.g., structure, buffering, sorption capacity, air–water relations, and thermal properties. The purpose of the research was to assess greenhouse gas (GHG) emissions in soybean cultivation, fertilized with biochar from various crops. Two experimental factors were included: the dose of biochar and the type of biochar used as per raw material used in its production. The adopted functional unit was 1 ton of soybeans. To reach the adopted goal, a strict field experiment was carried out. The total amount of GHG emitted by the cultivation was calculated according to the ISO 14040 and ISO 14044 standards. The system boundaries included: GHG emissions from fertilizers and seeds used, GHG emissions related to biochar production, emissions related to fossil fuel combustion, and emissions related to the decomposition of crop residues and soil organic matter and the decomposition of biochar. The results of the research indicate a significant potential of biochar to reduce GHG emissions in agricultural production. From the environmental and production perspective, the addition of biochar at 60 Mg ha−1 is the most advantageous. A further increase in the addition of biochar was related to a decrease in plant yield and an increase in GHG emissions per functional unit of the product. The use of biochar in soybean cultivation resulted in a 25% reduction in GHG emissions compared to the object without the biochar addition. The amount of GHG emissions for soybeans ranged from 846.9 to 1260.1 kg of CO2/Mg. The use of biochar from forest biomass resulted in a higher yield, 12% on average, compared to sunflower husk biochar. The introduction of biochar to soils can be an effective improvement in the economic and environmental efficiency of plant production, as it increases the use of nutrients by the plant and intensifies carbon sequestration in soils.

Biochar, compost and biochar-compost: effects on crop performance, soil quality and greenhouse gas emissions in tropical agricultural soils

Life cycle assessment of sludge anaerobic digestion combined with land application treatment route: Greenhouse gas emission and reduction potential

Metal sorption on soils as affected by the dissolved organic matter in sewage sludge and the relative calculation of sewage sludge application

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Recently, there has been increased concern about the presence of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARG), in treated domestic wastewaters, animal manures and municipal biosolids. The concern is whether these additional sources of ARB contribute to antibiotic resistance levels in the environment, that is, "environmental antibiotic resistance." ARB and ARG occur naturally in soil and water, and it remains unclear whether the introduction of ARB in liquid and solid municipal and animal wastes via land application have any significant impact on the background levels of antibiotic resistance in the environment, and whether they affect human exposure to ARB. In this current review, we examine and re-evaluate the incidence of ARB and ARG resulting from land application activities, and offer a new perspective on the threat of antibiotic resistance to public health via exposure from nonclinical environmental sources. Based on inputs of ARBs and ARGs from land application, their fate in soil due to soil microbial ecology principles, and background indigenous levels of ARBs and ARGs already present in soil, we conclude that while antibiotic resistance levels in soil are increased temporally by land application of wastes, their persistence is not guaranteed and is in fact variable, and often contradictory based on application site. Furthermore, the application of wastes may not produce the most direct impact of ARGs and ARB on public health. Further investigation is still warranted in agriculture and public health, including continued scrutiny of antibiotic use in both sectors.

Direct green waste land application: How to reduce its impacts on greenhouse gas and volatile organic compound emissions?

Pristine boreal peatlands store vast reserves of terrestrial carbon and have a net cooling impact on climate in the long term. Peatland drainage increases CO2 and N2O emissions and decreases CH4 emissions, leading to a net warming impact on climate. For example, cultivated peatlands can have high greenhouse gas (GHG) emissions per area and are therefore attractive targets for national aims to reduce GHG emissions. Raising water table depth (WTD) level can decrease the climate-warming impact. However, as drainage changes peat properties, the WTD elevation may lead to additional leaching of e.g. redox-sensitive phosphorus (P), which often restricts primary production in freshwaters. To support environmentally sound climate actions, we aimed to study the simultaneous impacts of different WTD conditions on GHG emissions and P leaching in variably managed peatlands.Our study sites include cultivated peatland plots with different peat thicknesses, peatland forest, abandoned peat field, and pristine peatland. The chemical potential for P retention in different soil depths was studied using chemical extractions of soil. The GHG emissions in field conditions were studied with year-round GHG emission inventories, which were conducted with chamber methods in snow-free conditions and otherwise with the snow-gradient method. Besides the effect of WTD, also the effects of vegetation and several environmental variables were considered. The simultaneous effects of different WTD conditions (saturation, slowly lowering WTD, quick fluctuations) on GHG emissions and P leaching were studied using intact soil profiles with a column experiment in controlled conditions.Our results help to find the best water management solutions considering both GHG emissions and P leaching. This knowledge is especially important in countries with large areas of drained peatlands and attempts to lower both GHG emissions and nutrient leaching. Sometimes land use changes may be unavoidable, and our studies with different land use options also support decision-making in these situations.

Organic soil amendments such as biochar and compost are thought to improve soil development, but it is unclear whether they affect nutrient leaching and greenhouse gas emissions. Using mesocosms, we investigated the effects of biochar and compost on nutrient leaching and greenhouse gas emissions across varying hydrologic regimes. Increased biochar decreased nutrient leaching and greenhouse gas emissions: the highest application rate (10% wt/wt) decreased cumulative phosphate leaching by 63% (SE 1.4), ammonium leaching by 65% (SE 0.8) and nitrate leaching by 92% (SE 0.3). Likewise, 10% biochar application decreased cumulative methane emissions by 92% (SE 3.7), carbon dioxide emissions by 48% (SE 7.0), and nitrous oxide emissions by 89% (SE 4.1). Biochar effects varied with hydrology for each greenhouse gas: stronger reductions in methane and nitrous oxide emissions were observed under waterlogged conditions, whereas stronger reductions in carbon dioxide emissions were observed at field capacity. In contrast with biochar, compost was the largest contributor to nutrient leaching and greenhouse gas emissions. These results suggest that biochar is most effective in soils with episodic flooding and drying rather than continuous flooding, and that compost should be avoided. We conclude that biochar can promote desirable functions simultaneously in restored wetland soils.

As global warming intensifies, the soil environment in middle to high latitudes will undergo more extensive and frequent freeze–thaw cycles (FTCs), which will significantly affect the carbon and nitrogen cycles of soil ecosystems and aggravate greenhouse gas (GHG) emissions. Biochar can increase soil organic carbon storage and mitigate climate change. To effectively control GHG emissions, soil supplemented with biochar at different application rates (0%, 2%, 4% and 6% [w/w]) under different numbers of FTCs (0, 3, 6, 9, and 12) was selected as the research object. The soil GHG emission characteristics in different experimental treatments and their relationships with soil physical and chemical properties were determined. Our results showed that N 2 O and CO 2 emissions were promoted during FTCs, with values of 3.13–50.37 and 16.22–135.50 μg m −2 h −1 , respectively. The order of N 2 O and CO 2 emissions with respect to biochar application rate was as follows: 2% > 0% > 4% > 6%. CH 4 emissions were negative during FTCs, varying from −1.62 to −10.59 μg m −2 h −1 , and negative CH 4 emissions were promoted by biochar. Correlation analysis showed that N 2 O, CO 2 and CH 4 emissions were significantly correlated with pH, soil moisture and soil organic matter (SOM), total nitrogen (TN) and –N contents ( p < .01). The conceptual path model demonstrated that GHG emissions were significantly influenced by FTCs, moisture, SOM and biochar application rate. Our results indicate that the effects of FTCs on GHG emissions were greater than those of biochar application. Biochar application rates of 4% or 6% should be considered in the future to reduce soil GHG emissions in the black soil region of Northeast China. Our results can help provide a theoretical basis and effective strategy to reduce soil GHG emissions during FTCs in seasonally frozen regions.

DISCUSSION OF “Land Application of Waste – An Accident Waiting to Happen,” by Charles C. Johnson, Jr., January‐February 1979 issue, v. 17, no. 1, pp. 69‐72

Land application of treated waste water can provide unique opportunities, not only for a final high level of waste‐water treatment but for reuse of nutrients as well. Recent laws passed by Congress have made it necessary to consider land treatment when planning and designing new waste‐water treatment facilities. The three types of land treatment commonly used are (1) irrigation, (2) overland flow, and (3) rapid infiltration. Selection of the most appropriate type of land treatment for a specific site is based on several considerations, including soil conditions, geology, topography, proximity to surface and subsurface water, and climate. Ensuring the protection of ground water is essential when siting or designing a land treatment system. Ground water is an important natural resource, having considerable impact on human life and well‐being as well as high economic value. Safeguarding this important resource from contamination includes careful site selection, appropriate pretreatment of waste water prior to its application, and a program of regularly scheduled monitoring to ensure that the waste water is being properly renovated for safe release to the environment. Utilization of municipal sludge on land for agricultural production is encouraged by federal law, as is land treatment of waste water. Sludge contains concentrated wastes, and there are practical limitations on the levels of heavy metals, salts, and toxic substances in sludges applied to agricultural lands. Sludge is generally stabilized before being applied, to destroy pathogens, and reduce weight, volume and odor. Several case studies of successful land treatment systems presently in operation are presented to demonstrate the viability of the land treatment concept.