Physical Properties of Soils Affected by the Use of Agricultural Waste

This chapter provided an overview of the physical properties of soils and their importance on the mobility of water and nutrients and the development of a vegetation cover. It also gives some examples of why the use of agricultural residues can affect positively soil physical properties. The incorporation of agricultural wastes can be a sustainable practice to improve soil characteristics, favoring a model of zero waste in agricultural production and allowing better management of soils. We review and analyze the effect of the use as amendments of different agricultural residues, on physical properties of the soil (e.g., bulk density, porosity, and saturated hydraulic conductivity), especially related to the movement of water in the soil

Land recycling, food security and Technosols

The world population will grow up to 9.8 billion by 2050. The intensification in urban growth will occur on all continents and in all sizes of cities, especially in developing countries, experiencing a greater rising in urban agglomerations of 300,000 to 500,000 people, those of 500,000 to 1 million and those of 1 to 5 million, by 2035. In this way, the demand of soil to host human activities (land take) will increase, mainly affecting soils with greater agricultural potential close to cities, at the same time as the need for food will increase. Land rehabilitation can contribute to human food security, to enhance ecosystem services and, if made by waste Technosols, those are viable as substrate for urban agroforestry systems.Although the references for brownfield reclamation for urban agriculture,adding constructed Technosols and de-sealed soils can recover its ecosystem functions even food supply services and would be the solution in urban areas

The Use of Composted Municipal Solid Waste under the Concept of Circular Economy and as a Source of Plant Nutrients and Pollutants

The European Union (EU) is one of the major producers of municipal solid wastes and has a common policy based on circular economy to reuse the wastes. However, there are differences between countries and the methods for disposal and treatments. Municipal solid waste (MSW) can be composted and recycled as a source of plant nutrients and improves soil properties. This chapter analyzed the production in the EU and the effects on plant nutrients and environmental pollutants when MSW is added to the soil. The origin of the waste and the compost-like output (CLO) derived is important to determine the expectative of nutrient availability and other possible risks. MSW is so heterogeneous, but after a good pretreatment, an organic-rich matter mix can be composted giving a stabilized organic matter. The addition of the CLO to the soils can improve the nutrient status and favor the bioavailability of nutrients (macronutrients and micronutrients). In general, an increment of N and P was found in the soils. Moreover, important micronutrient availability (Fe, Mn, Cu, and Zn) has been described. However, the presence of pollutants and their mobility should be considered as an environmental risk

Aggregate Recycling in Construction: Analysis of the Gaps between the Chilean and Spanish Realities

This study conducts a comparative analysis between Chilean and Spanish reality in regard to the recycling of aggregates and their reuse in road works and urban roads. The current situation of both countries was reviewed through different sources of information such as technical and legal regulation, projects and executed works, to then validate them in Chile by way of interviews to various professionals in the field of urban and interurban road construction, as well as others belonging to government bodies. Spain has extensive experience on this issue, as it has a culture of recycling and reusing aggregates that has produced excellent results, a situation which was taken into account to compare it to Chile’s reality. The conclusion is that currently, in Chile, although the existence of recycled aggregate use is known, this is not the case on a technical level for professionals in the sector. It lacks a specific government body that is in charge of this issue and does not have appropriate infrastructure for its treatment. The materials with a promising future within the construction sector are the production of crushed granular bases and the creation of low-resistance concretes, which cannot be used, as laws that regulate them are still being drafted

Empleo de filtro verde construido con residuos para reducir el contenido en fósforo en aguas de riego

El aumento de la población mundial conllevará un aumento de la demanda de alimentos y del consumo de agua de calidad para el riego de los cultivos. Por lo que será necesario aumentar la tasa de reutilización del agua de riego en las zonas que afronten escasez hídrica. De tal forma, para asegurar la calidad del agua de riego, la concentración de nutrientes es un aspecto a controlar. Entre ellos, el fósforo, es un nutriente esencial para los cultivos, pero su presencia en exceso en los ecosistemas acuáticos está asociada con procesos de eutrofización. Las soluciones basadas en la naturaleza, como los filtros verdes o humedales artificiales, están siendo implantados con éxito para la depuración de aguas que contienen altas concentraciones de nutrientes. En este trabajo se presentan prototipos de biorreactores anaerobios utilizando como material filtrante residuos (grava y poda de rama de almendro) y con flujo de circulación del agua tanto en horizontal como en vertical, para reducir la concentración de ortofosfato disuelto en aguas de riego. Tras analizar las aguas de riego tratadas se consigue una reducción significativa de la concentración de ortofosfato disuelto en los biorreactores de grava horizontal (92%) y vertical (81%) y en el biorreactor vertical de grava con poda de almendro (59%).Dirección General del Agua de la Conselleria de Agricultura, Desarrollo Rural, Emergencia Climática y Transición Ecológica

The Lixiviation of Metals When Amending Agricultural Soil of the Mediterranean Basin with Biosolids: Trials in Leaching Columns

An appropriate handling and use of urban and agricultural biosolids on soils are the best means to protect them from erosion, prevent the loss of nutrients due to runoff and washing, and preserve and restore soil productivity. Heavy metal concentrations in biosolids are one of the decisive factors when using this type of waste on soil, due to potentially being harmful to crops and reaching the human food chain. There is a clear need to study the incidence of these metals in agricultural practices in Mediterranean soils. Research for this article was performed as a controlled study using leaching columns. Three treatments were performed by applying different amounts of biosolids (T50: 50,000 kg ha−1, T90: 90,000 kg ha−1, T130: 130,000 kg ha−1), as well as a blank test or control treatment (T0). The presence of macronutrients (K, Na, Ca and Mg), micronutrients (Fe, Cu, Mn and Zn) and three contaminating heavy metals (Cr, Cd and Ni) in lixiviated water was analyzed. Relevant amounts of metals in the wash water were not found. This indicates that, under the watering conditions used, the contaminants and micronutrients analyzed are not a relevant source of water contamination on a common calcareous soil of the Mediterranean Basin

Soluble Elements Released from Organic Wastes to Increase Available Nutrients for Soil and Crops

Member States of the European Union must ban burning arable stubble by 2023 and improve the recycling of organic waste into fertilizers and organic farming practices by 2030. The current lack of nutrients from soils and crops leads to food insecurity, human malnutrition and diseases. Consequently, innovative solutions are required, as technosols are constructed by waste. The objective of this paper is to educate on the nutrients that some pruning residues can provide. This work characterizes elemental composition, nutrients soluble fraction and physical and chemical properties of the following organic wastes: almond tree pruning, commercial peat substrate, olive tree pruning, pine needle, date palm leaf pruning, sewage sludge compost and vine pruning. The results show significant differences between macro (Na, K, Ca, Mg) and micronutrient (Fe, Mn, Cu, Zn) content and their solubility. Sewage sludge compost, olive pruning and pine needle are the three residues with the highest presence of nutrients in their elemental composition. Nevertheless, if a farmer applies pruning residues as a nutritional supplement for crops, it will be key to finding the short-term soluble nutrient rate and synchronizing the nutritional requirement curve of a plant’s life cycle with its nutrient release. Consequently, organic waste (without composting treatment) obtains higher solubility rates, being date palm leaf residue the one with the greatest value. The solubility index of organic wastes can be significant in providing short-term nutrients to crops. Hence, our results can help in choosing the proper waste to enhance plant nutrient supply, mainly K, Ca, Mg and Na for crop nutrition, to ensure efficient biofertilization

Trace Metal Content and Availability of Essential Metals in Agricultural Soils of Alicante (Spain)

This article analysed the presence of trace metals (essential elements and pollutants) and soil properties in rural abandoned soils of a Mediterranean region. The soil properties determined were texture, pH, equivalent calcium carbonate, soil organic matter, availability of micronutrients (Fe, Mn, Cu, and Zn), and acid microwave digestion extraction to measure the trace metals considered as main pollutants (Cu, Zn, Cd, Cr, Ni, and Pb). Descriptive statistics and correlations were used to determine the relations among these parameters. pH, soil organic carbon (SOC), and clay were the main properties that controlled the availability of essential metals. pH was the main factor related to these metals in these calcareous soils. However, SOC, which can be incremented by adding organic fertilizers for soil rehabilitation as a sustainable practice, played an important role. Mean values of the metal composition in soils (Cu, Zn, Cd, Cr, Ni, and Pb) obtained in this study were similar to values reported for other areas in the Mediterranean basin