Growth Performance, Biochemical Composition and Nutrient Recovery Ability of Twelve Microalgae Consortia Isolated from Various Local Organic Wastes Grown on Nano-Filtered Pig Slurry

This paper demonstrated the growth ability of twelve algae-microbial consortia (AC) isolated from organic wastes when a pig slurry-derived wastewater (NFP) was used as growth substrate in autotrophic cultivation. Nutrient recovery, biochemical composition, fatty acid and amino acid profiles of algae consortia were evaluated and compared. Three algae-microbial consortia, i.e., a Chlorella-dominated consortium (AC_1), a Tetradesmus and Synechocystis co-dominated consortium (AC_10), and a Chlorella and Tetradesmus co-dominated consortium (AC_12) were found to have the best growth rates (µ of 0.55 ± 0.04, 0.52 ± 0.06, and 0.58 ± 0.03 d−1, respectively), which made them good candidates for further applications. The ACs showed high carbohydrates and lipid contents but low contents of both proteins and essential amino acids, probably because of the low N concentration of NFP. AC_1 and AC_12 showed optimal ω6:ω3 ratios of 3.1 and 3.6, which make them interesting from a nutritional point of view.

Soil and Plant Responses to Phosphorus Inputs from Different Phytase-Associated Animal Diets

The over-supplementation of animal feeds with phosphorus (P) within livestock-production systems leads to high rates of P excretion and thus to high P loads and losses, which negatively impact the natural environment. The addition of phytase to pig and poultry diets can contribute to reducing P excretion; however, cascading effects of phytase on plant–soil systems remain poorly understood. Here, we addressed how three different diets containing various levels of exogenous phytase, i.e., (1) no-phytase, (2) phytase (250 FTU), and (3) superdose phytase (500 FTU) for pigs (Sus scrofa domesticus) and broilers (Gallus gallus domesticus) might affect P dynamics in two different plant–soil systems including comfrey (Symphytum ×uplandicum) and ryegrass (Lolium perenne). We found that differences in phytase supplementation significantly influenced total P content (%) of broiler litter and also pig slurry (although not significantly) as a result of dietary P content. P Use Efficiency (PUE) of comfrey and ryegrass plants was significantly higher under the intermediate ‘phytase’ dose (i.e., commercial dose of 250 FTU) when compared to ‘no-phytase’ and ‘superdose phytase’ associated with pig slurry additions. Soil P availability (i.e., water soluble P, WSP) in both comfrey and ryegrass mesocosms significantly decreased under the intermediate ‘phytase’ treatment following pig slurry additions. Dietary P content effects on P losses from soils (i.e., P leaching) were variable and driven by the type of organic amendment. Our study shows how commercial phytase levels together with higher dietary P contents in pig diets contributed to increase PUE and decrease WSP thus making the plant–soil system more P conservative (i.e., lower risks of P losses). Our evidence is that dietary effects on plant–soil P dynamics are driven by the availability of P forms (for plant uptake) in animal excretes and the type of organic amendment (pig vs. broiler) rather than plant species identity (comfrey vs. ryegrass).

Different pig slurry application methods modify the soil quality and increase the productivity of winter wheat (Triticum aestivum L.) Crop (Córdoba, Argentina) / Diferentes métodos de aplicação de dejectos líquidos de suínos modificam a qualidade do solo e aumentam a produtividade da cultura de trigo de inverno (Triticum aestivum L.) (Córdoba, Argentina)

Na Argentina, a aplicação superficial de dejecto líquido é a técnica mais utilizada, embora com alto risco de perdas de amônia. Essas emissões podem ser reduzidas por meio de diferentes métodos de aplicação, mas seus impactos no sistema solo-planta têm sido pouco explorados. Assim, este trabalho teve como objetivo avaliar os efeitos de diferentes métodos de aplicação de dejetos líquidos de suínos: dejetos acidificados (AS), dejetos incorporados (IS) e dejetos superficiais (SS) na qualidade do solo e a produtividade de uma cultura de trigo, em comparação com a fertilização mineral (MF) e controle (C). IS causou aumento nos valores de fosfatase ácida, enquanto SS apresentou os menores valores de quociente metabólico de todos os métodos e altos valores de hidrólise de diacetato de fluoresceína. Os tratamentos com dejecto líquido de suino e MF mostraram valores de pH significativamente mais baixos do que C. SS levou a um rápido aumento na concentração de NO3-, enquanto AS e IS mostraram valores de nitrificação mais lentos do que SS. Dependendo da disponibilidade de NO3-, a absorção de N e a biomassa aérea mostraram um comportamento semelhante. O rendimento do trigo aumentou até 57% com a aplicação de dejetos líquido de suínos, sem diferenças significativas entre os diferentes métodos de aplicação usados. No entanto, MF atingiu o valor de rendimento mais alto. Concluímos que a aplicação de dejetos líquido de suínos, principalmente na superfície, melhora a qualidade do solo e aumenta a produção de trigo.

Physical properties of a soil under a pig slurry application and organic matter activators

To investigate the effects of organic matter activators combined with a pig slurry on a soil’s physical properties, a field experiment was carried out in a monoculture of corn (2015–2017). Three pig slurry application variants complemented with the activators in question, i.e. with PRP SOL spread directly on the soil surface (SOL), with Z’fix added to the slurry during the pig housing (ZF) and with a combination of both PRP SOL and Z’fix (ZF_SOL), were compared with just the pig slurry (C) under an equal dose of nitrogen and a uniform growing technology. According to the results, a positive effect of the penetration resistance with the pig slurry and the activators of organic matter (Z’fix and PRP SOL) was not proven. The saturated hydraulic conductivity was demonstrably better achieved with the Z’fix activator, but PRP SOL activator also provided a certain improvement. The largest change in the unit draught was observed in the ZF_SOL application (20% increase). The results seem ambiguous; however, they give a good indication of the activators’ effect in practice. Nevertheless, the findings would certainly benefit from further verification.

Repeated Manure Application for Eleven Years Stimulates Enzymatic Activities and Improves Soil Attributes in a Typic Hapludalf

Animal manure may be a valuable resource for the development of agricultural sustainability. We proposed to verify the feasibility of applications of three types of animal manures to improve soil attributes and to sustain crop yields under intensive cropping and no-tillage systems. The field experiment was established in 2004 on Typic Hapludalf soil with pig slurry (PS), cattle slurry (CS), pig deep-litter (PL), mineral fertilizer (MF) and a non-fertilized treatment. From 2004 to 2015, were grown black oat, maize, forage turnip, black beans, and wheat. Soil samples were taken after winter 2014 and summer 2015, and submitted to chemical, physical, microbiological and biochemical analyses. Animal manures increased soil pH, but MF caused acidification of soil. The PL and CS applications reduced soil density, and increased total pore volume and hydraulic conductivity. Animal manures increased soil P fractions, total organic carbon, total nitrogen, stimulated soil respiration, and had higher activities of glucosidase and acid phosphatase. Wheat had its biggest dry matter and grain yields with MF, but maize grain yields with CS were higher than MF. All indicators pointed that application of animal manure converges to an interesting strategy to recycle nutrients at farmyard level and to contribute to global sustainability.

Coupling of Anaerobic Digestion and Struvite Precipitation in the Same Reactor: Effect of Zeolite and Bischofite as Mg2+ Source

The aim of this research was to assess the simultaneous effect of zeolite and bischofite on estruvite production in an anaerobic digester treating pig slurry as substrate. Three ratios (5:1, 6:1 and 7:1) of Mg-P were used for evaluating the effect of only bischofite on anaerobic digestion. For assessing the simultaneous effect of zeolite and bischofite on anaerobic digestion, three mass ratios of zeolite:bischofite (1, 5 and 10%) were used. As results, bischofite as Mg+2 source served to decrease the total phosphorous (TP) concentration in the anaerobic digestion of pig manure without affecting the maximum methane production rate or methane yield of the system. An average 82.5% TP removal was found in the reactors with bischofite during the first 5 days of digestion. Nevertheless, bischofite increased the lag-phase of the system. The simultaneous presence of zeolite and bischofite (1% ratio with respect to bischofite) caused a TP removal of 65.6% and increased the methane yield by up to 19.9% compared to a system without zeolite or bischofite. Thus, it is feasible to use bischofite and zeolite as enhancers for the simultaneous production of biogas and struvite inside an anaerobic digester treating piggery wastewater.