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This study was conducted to evaluate the effect of compost produced with agricultural residues and oat-based biochar, iron oxide and halloysite nanoparticles as additives of the process of composting on soil chemical properties, nutrient status and growth of ryegrass Lolium perenne L. For this, a 90-day mesocosm experiment was carried out under greenhouse conditions. Bare soil and a basal fertilization treatment were compared to soils amended with nonadditive compost (NA compost), compost supplied with oat-based biochar (Bioch compost), iron oxide nanoparticles (Fe compost), and halloysite nanoparticles (Ha compost). Compost supplied with nanoparticles and biochar combined were also considered. The incorporation of compost with or without additives increased the content of total C and N in soil, with N diminishing (total and mineral forms) and C/N modifications after 90 days. The addition of compost and co-composted treatments also increased the total contents of main nutrients such as Ca, K, P and S. Furthermore, the supply of additives into composting did not increase the concentration of trace toxic elements. At the end of the experiment, plant biomass increased by the addition of the different organic amendments, with the highest shoot biomass in soils amended with compost supplied with nanoparticles. These results suggest that the addition of compost based on agricultural residues with additives such as halloysite or biochar improves chemical properties and nutritional status of soil that favor and increase plant growth of Lollium perenne stablished in soils from the Mediterranean Region.

In Andisols of Southern Chile, crop yield is mainly limited by P fixation and aluminum phytotoxicity (Al3+), but scarce information in these soils is known in rotations, including wheat after Andean crops. It is very relevant to the knowledge of suchcrops’ root architecture to improve productivity through a greater absorption capacity of water, nutrients, and tolerance to biotic and abiotic stresses. The objective of this work was to evaluate root architecture at early phenological stages of Andean crops in an acidic Andisol from Southern Chile. During the 2019/2020 season, a field trial was established using four non-mycorrhizal cultures: buckwheat (Fagopyrum esculentum L.), amaranth (Amaranthus spp.), lupine (Lupinus albus L.), and quinoa (Chenopodium quinoa L.), and compared with oats (Avena sativa L.) a mycorrhizal culture. During the growth period, four plant and soil amplings were carried out, evaluating phenological stages, root architecture, together with soil pH and P-availability. During the first half of the vegetative cycle, the growth of the crops was continuous but drastically reduced at the end development cycle due to the prevailing drought during the summer months. These climatic conditions affected quinoa and lupine growth showing high sensitivity to water stress. In general, all crops showed good root architecture, suggesting a more efficient P mobilization. A greater root length was obtained in buckwheat, while a better adaptation capacity to the environmental conditions was observed in quinoa. It is concluded that through suitable agronomic management by incorporating quinoa or amaranth as pre-crops of wheat in a rotation, the P-availability for the next crop could be increased by reducing the application of chemical fertilizers., En Andisoles del sur de Chile, el rendimiento de los cultivos está principalmente limitado por fijación de fósforo (P) y fitotoxicidad por aluminio (Al3+), existieron escasos antecedentes sobre rotaciones con trigo que incluyan cultivos andinos. Resulta relevante el conocimiento de la arquitectura radical en estos cultivos con el fin de mejorar su productividad, al otorgar una mayor capacidad de absorción de agua, nutrientes y tolerancia a estreses bióticos y abióticos. El objetivo del trabajo fue evaluar la arquitectura radical en estadios tempranos de desarrollo de cultivos andinos establecidos en un Andisol del sur de Chile en condiciones de campo. Durante la temporada 2019/2020 se estableció un ensayo en campo utilizando cuatro cultivos: alforfón (Fagopyrum esculentum L.), amaranto (Amaranthus spp.), lupino (Lupinus albus L.) y quínoa (Chenopodium quinoa L.), todos no micorrizables, y como comparación se usó avena (Avena sativa L.), un cultivo micorrizable. En el periodo de crecimiento se realizaron cuatro muestreos de plantas y suelo registrando estadios fenológicos y evaluando arquitectura de raíces, pH del suelo y P disponible. En la primera mitad del ciclo vegetativo, el crecimiento de los cultivos fue continuo y se redujo drásticamente al final del ciclo de desarrollo, por la sequía imperante durante los meses de verano. Estas condiciones climáticas afectaron a quínoa y lupino, los cuales mostraron alta sensibilidad al estrés hídrico. En general, en todos los cultivos se observó una buena arquitectura radical, lo que sugiere una movilización de P en forma más eficiente. Mayor longitud radical se obtuvo en el alforfón, mientras que mejor capacidad de adaptación al medio se observó en quínoa. Se concluye que, mediante un adecuado manejo agronómico al incorporar quínoa o amaranto como precultivos en rotación con trigo, se podría incrementar la disponibilidad de P para el cultivo siguiente reduciendo la aplicación de fertilizantes químicos

This study was conducted to evaluate the effect of compost produced with agricultural residues and oat-based biochar, iron oxide and halloysite nanoparticles as additives of the process of composting on soil chemical properties, nutrient status and growth of ryegrass Lolium perenne L. For this, a 90-day mesocosm experiment was carried out under greenhouse conditions. Bare soil and a basal fertilization treatment were compared to soils amended with nonadditive compost (NA compost), compost supplied with oat-based biochar (Bioch compost), iron oxide nanoparticles (Fe compost), and halloysite nanoparticles (Ha compost). Compost supplied with nanoparticles and biochar combined were also considered. The incorporation of compost with or without additives increased the content of total C and N in soil, with N diminishing (total and mineral forms) and C/N modifications after 90 days. The addition of compost and co-composted treatments also increased the total contents of main nutrients such as Ca, K, P and S. Furthermore, the supply of additives into composting did not increase the concentration of trace toxic elements. At the end of the experiment, plant biomass increased by the addition of the different organic amendments, with the highest shoot biomass in soils amended with compost supplied with nanoparticles. These results suggest that the addition of compost based on agricultural residues with additives such as halloysite or biochar improves chemical properties and nutritional status of soil that favor and increase plant growth of Lollium perenne stablished in soils from the Mediterranean Region.

This study aimed to examine how interactions at both plant genotype and arbuscular mycorrhizal fungus species levels affected the expression of root traits and the subsequent effect on plant nutrition and growth. We used two wheat cultivars with contrasting phosphorus (P) acquisition efficiencies (Tukan and Crac) and two arbuscular mycorrhizal (AM) fungi (Rhizophagus intraradices and Claroideoglomus claroideum). Plant growth, as well as morphological and architectural root traits, were highly dependent on the myco-symbiotic partner in the case of the less P-acquisition efficient cultivar Tukan, with mycorrhizal responses ranging from -45 to 54 % with respect to non-mycorrhizal plants. Meanwhile, these responses were between only -7 and 5 % in the P-acquisition efficient cultivar Crac. The AM fungal species produced contrasting mechanisms in the improvement of plant nutrition and root trait responses. Colonization by R. intraradices increased Ca accumulation, regardless of the cultivar, but reduced root growth on Tukan plants. On the other hand, C. claroideum increased P content in both cultivars, with a concomitant increase in root growth and diffusion-based nutrient acquisition by Tukan. Moreover, plants in symbiosis with R. intraradices showed greater organic acid concentration in their rhizosphere compared to C. claroideum-colonized plants, especially Tukan (24 and 35 % more citrate and oxalate, respectively). Our results suggest that the responses in plant-AM fungal interactions related to nutrient dynamics are highly influenced at the fungus level and also by intra-specific variations in root traits at the genotype level, while growth responses related to improved nutrition depend on plant intrinsic acquisition efficiency.

The utilization of additives is a strategy commonly used in composting operations to enhance the physicochemical properties and optimize the process. However, little is known about the impact of nanominerals, biochar and their combination during composting. The objective of this research was to evaluate the effects of iron oxide/halloysite nanominerals and oat hull-biochar as additives in the physicochemical properties of an aerobic composting process, the emission of greenhouse gases (GHG) and the composition of end-products. In order to analyze the biodegradability of composting end-products in grassland soils, an incubation experiment was also carried out. Wheat straw, lupine and beef manure were mixed (C/N: ~25) with iron oxide (Fe) or halloysite (Ha) nanoparticles (2% w/w), oat hull-biochar (B) (7% w/w) and their combination (BFe, BHa). pH, EC, C/N ratio, NH4-NO3 contents and the emission of CO2 and CH4 were analyzed. After 128 days of aerobic composting process, the end-products and their NaOH soluble fraction were characterized by using spectroscopic analysis that included E4/E6 ratio and solid state nuclear magnetic resonance (13CNMR). To analyze the biodegradability of produced compost in grassland soils, a respiration experiment (60 days) using Respicond Apparatus IV, combined with ¿13C isotopic analysis was conducted. A decrease of final C/N ratio was observed in all treatments that was lower in B treated compost. Nitrate concentration increased as composting progressed, and compost supplied with Ha showed the higher final content of NO3 (5800 mg kg-1) and NH4 (220 mg kg-1). The addition of B significantly decreased the mean emission of both CO2 (~400 g CO2 m2 d-1) and CH4 (~4.5 g CH4 m2 d-1). Nanominerals significantly decreased the final E4/E6 ratio (<6) and the addition of B increased the aromaticity (twice), the alkyl-C/O alkyl-C ratio and the hydrophobicity which are parameters associated to stabilized end-products. In soil, the incorporation of addi

Metallic oxides and clay minerals have gained increasing interest as additives of composting due to their influence in greenhouse gas emissions reduction and their effectivity in the stabilization of carbon both in compost and soils, leading to a cleaner compost production and potentially C sequestrant amendments. In this study, wheat straw (WS) was co-composted with iron oxide and allophanic soil and their influence on WS composting and composition of the end-products was evaluated. WS compost and their humic like-substances (HS) fraction were characterized by chemical and spectroscopic analyzes. After 126 days of process, the elemental composition showed slight differences of the N content for compost and HS, where the C/N atomic ratio tended to decrease relative to the initial material (WS; ~130). This trend was more pronounced in the HS from co-composted treatments (<30). The addition of inorganic materials increased the total acidity and phenolic-OH group contents (~15 and 14 mEq g−1 respectively, iron oxide treatment) relative to the treatment without inorganic additives. Nevertheless, the FTIR and solid-state 13CNMR spectroscopy barely support the wet chemical analysis and revealed a similar final composition between all the studied compost treatments. These results suggest that the incorporation of these materials as compost additives had no major effect on the spectroscopic features of the end-products, however, critical changes of the properties such as the extractability, functionality and composition of HS were revealed by traditional methods. In conclusion, the supply of metal oxides and clays could impact the aerobic composting of WS favorizing the stabilization of certain C pools and adsorptive properties of the end-products, that is of importance in production of amendments suitable for being used in degraded and contaminated soils. Nevertheless, under the experimental conditions of our research C stabilization apparently depends of other mechanisms