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National policy styles and path-dependencies are affecting the abilities of Baltic Sea countries to deliver on their commitments under the Helsinki Convention. This article synthesizes evidence and insights from studies relating to the provisions on agricultural nutrient management, a main source of marine pollution. We contend that governments that are strongly concentrated vertically, while fragmented horizontally, lack capacity including with respect to informal institutions that can leverage implementation. As a stocktaking of institutional impediments to sustainable development, our analysis has wider relevance for other international agreements with Baltic Sea countries involved. [ABSTRACT FROM AUTHOR]

The evolution of environmental policy is increasingly driven by the emergence and interaction of policy concepts and the frameworks, knowledge, and ideas they employ. We argue that policy actors' creative use of policy concepts often leads to their combinatorial development. In this policy process, the concepts interact and shape each other's policy relevance and future development under the influence of ideas, knowledge, and political factors. We formulate this new research approach using ideational and policy process theories. In particular, we explicate internal and contextual combinatory elements that enable policy change resulting from mutual development of policy concepts. For an empirical demonstration, we analyze the conceptual innovation, rise, and ramifications of nutrient recycling as a new segment of Finnish environmental policy. [ABSTRACT FROM AUTHOR]

This study uses a new approach for the recycling of plant nutrients by co-digesting sewage sludge with fly ash from a wood combustion. Sewage sludge and fly ash both are enriched with nutrients of the wastewater resp. wood, which makes these products an enhanced source for recycled fertilizers. The effects of the ash addition to the anaerobic digestion are studied in several lab scale experiments including effects on the gas production and microbial activity. Following that, the fertilizing qualities of the digestate are evaluated by plant growth experiments. The results show that the fertilizing qualities of the digested sludge were improved by the ash addition. Next to this, gas production results show that the methane production was not affected by the ash addition, while the total gas release was reduced. The sulphur addition by the ash stimulated sulphate reducing bacteria. The sulphate reducing bacteria did not markedly inhibit the methanogens. [ABSTRACT FROM AUTHOR]

Aquaculture has grown rapidly to play a crucial economic and social role and meet the increasing global demand for seafood. As aquaculture intensifies, there is increasing pressure to find more sustainable practices that save resources and reduce waste. Major wastes and by-products from aquaculture were quantified across a full range of farming types. Key opportunities for wastewater treatment and by-product recovery include nutrient recycling through a combination of biofilters, bioaccumulation and multitrophic systems. To support a sustainable intensification of aquaculture, improvements in by-product harvesting, accumulation and processing methods require further investigation. Likewise, energy generated from by-products can potentially support intensified production through land-based recirculating aquaculture systems (RAS). Future challenges faced by the reuse of side streams include control of food safety and gaining consumer acceptance. Combined with increases in resource use efficiency across the aquaculture sector, from feeding methodologies to product storage, nutrient recycling can enable aquaculture to contribute sustainably toward the nutritional requirements of billions of people over the next century. [ABSTRACT FROM AUTHOR]

Residue management is one of the most difficult tasks in the modern-mechanized agriculture with the intensification of cropping systems, which leads to reduced sowing window between two crops and farmers prefer in-situ burning of crop residues. Therefore, the present study was conducted to assess the effect of zero tillage (ZT) based residue management on soil health parameters in maize (Zea mays L.)–chickpea (Cicer arietinum L.) rotation in black soils of central India. After 4 years of study, the soil bulk density was reduced by 3.0–10.2% and volumetric moisture content was improved by 10.2–19.3% at 0–10 cm soil depth in ZT with residue over conventional tillage (CT). The soil organic carbon and labile carbon were increased by 13.6–61.7% and 6.0–22.0%, respectively, at 0–10 cm soil depths. Similarly, ZT with residue increased the KMnO4-N, Olsen-P and NH4OAc-K, and total fungal and actinomycetes density in surface soil as compared to CT. Thus, our study advocates that ZT with residue retention (1.8–5.4 Mg ha–1 maize and 0.8–2.4 Mg ha–1 chickpea residue) should be implemented for sustainable soil health in Vertisols (Typic Haplustert) of central India and other similar agro-ecological systems. [ABSTRACT FROM AUTHOR]

Wastewater reuse from fertirrigation has become a new strategy for sustainable crop production, especially because there is a need to save fresh water. It can also reduce fertilizer costs and environmental pollution. This work aimed to evaluate the production of tomato and eggplant seedlings irrigated with wastewater reuse from fertirrigation. The experiment was carried out in a completely randomized design in a 2 × 4 factorial scheme with four replicates, where each replicate was represented by 25 seedlings. Treatments were represented by two crops (tomato and eggplant) and four concentrations of fertirrigation wastewater leachate (Treatment 1 (T1): 25%; Treatment 2 (T2): 50%; Treatment 3 (T3): 75% and Treatment 4 (T4): 100%). Seedlings were evaluated for the following parameters: number of leaves, seedling height, basal stem diameter, leaf area, total dry mass, and relative water content. With the exception of the basal stem diameter, eggplant seedlings were affected by leachate concentrations for all the other parameters evaluated, while tomato seedlings presented significant responses for all variables. It was observed that the use of concentrations between 50 and 75% of fertirrigation wastewater leachate can be a possible alternative to reduce the use of chemical fertilizers in the production of tomato and eggplant seedlings. [ABSTRACT FROM AUTHOR]

Integrating a combination of organic matter management (OMM) practices can increase soil fertility, biomass, and nutrient recycling, but evidence of this potential is limited. This study tested the impact of integrating a combination of OMM practices on soil fertility, biomass, and nutrient recycling on smallholder farms. Following a randomised complete block design, a four-season experiment was conducted in 2018-2019 on 10 farms. The treatments (T) included T1: cowpea-maize-bean-maize rotation; T2: cowpea-maize-bean-maize rotation + farmyard manure; T3: Faidherbia albida alleys + cowpea-maize-bean-maize rotation; T4: F. albida alleys + cowpea-maize-bean-maize rotation + farmyard manure; and T5 (control): maize monocrop with diammonium phosphate application at 50 kg/ha application rate. T1-T4 are the OMM practices. The maize in T2-T4 was undersown with Mucuna pruriens. Soil fertility parameters (i.e. pH, water holding capacity, nitrogen, phosphorus, and potassium), biomass, and nutrients in the biomass were determined. There were no differences in soil fertility parameters among all treatments (P > 0.05). From the second to the fourth season, biomass was consistently higher under T3 and T4 than in other treatments. Moreover, the nutrients in biomass were higher in T3 and T4 than in other treatments, an indicator that OMM practices with alley crops can increase nutrient recycling. [ABSTRACT FROM AUTHOR]