The valorisation of vegetal waste as a source of crop nutrients constitutes a circular strategy to improve the sustainability of intensive horticultural production systems. The main goal of this study was to evaluate the effects of organic amendments derived from vegetal residues on the yield and quality of tomato. The following fertilisation treatments were carried out: fresh vegetal residues (4 kg m⁻¹), compost (3 kg m⁻¹), and vermicompost at two different doses (3 and 9 kg m⁻¹), all derived from previous tomato crop vegetal residues, an organic treatment with goat manure (3 kg m⁻¹), and a control mineral fertigation treatment. The highest yield was obtained with conventional mineral fertigation management, followed by vermicompost treatments at two different doses (3 and 9 kg m⁻¹), with no statistical differences. The organic treatments with fresh crop residues, compost and goat manure resulted in lower yield. Regarding quality parameters, the lycopene content was higher in the mineral fertilisation and vermicompost at 3 kg m⁻¹ treatment, while the other antioxidants measured were more concentrated in tomatoes fertilised with vermicompost treatment at 9 kg m⁻¹ and goat manure. The plant nutrient management with vermicompost is the best circular solution, as it allows to reintegrate the residues generated in previous crop cycles into the soil, obtaining a yield equal to chemical input management and tomatoes with high nutritional quality.

Saffron is traditionally cultivated in soil as a semi-perennial crop, although the feasibility of crop production is today constrained in Europe due to both agronomic and socioeconomic factors. Accordingly, interest has been increasing concerning its possible cultivation within protected environments through adoption of soilless cultivation technologies. The aim of the present study was to optimize nutrient solution features in the soilless cultivation of saffron corms. The trial was conducted in a greenhouse at Almeria University. Saffron was grown in 15-L pots filled with perlite. Three fertigation treatments were used, obtained by a linear increase of all nutrients of one standard in order to reach an electrical conductivity (EC) of 2.0 (control, EC_2.0), 2.5 (EC_2.5) and 3.0 (EC_3.0) dS·m⁻¹. Measurements included determinations of shoot length, corm yield, as well as nutrient uptake from the nutrient solution and concentrations within plant tissues. The nutrient solution with the highest EC (EC_3.0) allowed obtaining three to five times more corms above 25-mm diameter. The increasing EC had a significant effect on the increase of macronutrient uptake, except for NO₃⁻ and NH₄⁺ and resulted in a general increase of nutrient concentrations in tissues, such as corms and roots. Both macronutrient uptake and accumulation in plant tissues were highest under EC_3.0. Nutrient uptake was significantly correlated with production of larger corms due to higher horizontal diameter.

Plant nutrient deficiencies can reduce crop development and yields and can be especially problematic in high-yielding intensive crop production systems and when organic materials are used as the only source of nutrients. Aqueous extracts used in organic agriculture, such as compost – or vermicompost-tea, often have deficiencies in macro-nutrients and ionic imbalances. However, when organic materials are used as fertilisers, they are often applied in combination with plant growth promoting bacteria (PGPB), which can improve the availability of the nutrients. In this study, PGPB were used as a tool to facilitate the nutrition of horticultural crops without using synthetic fertilisers. Three bacterial species (Azotobacter vinelandii (AV), Bacillus megaterium (BM) and Frateuria aurantia (FA)) were tested as (i) inoculated to an aqueous vermicompost extract and (ii) applied directly by fertigation to the growing medium in two tomato production cycles. The results showed that it was possible to obtain a balanced nutrient solution, with adequate concentrations of the main nutrient ions, from an aqueous and aerated solution made from vermicompost, without the addition of PGPB. In the second trial, the inoculation with PGPB to the growing substrate for tomatoes fertigated with vermicompost tea, resulted in significant increases in the yield and quality of the tomato fruit, increased nutrient assimilation by the plants and increased enzymatic activity in the growing substrate.

Microorganisms are only effective when adequate conditions for their survival and development are provided. Among the factors that influence its effectiveness includes the type of soil or culture substrate, which works as an energy source reserve. Therefore, a tomato and a melon crop were established in different cycles to assess the effect of the physicochemical properties of organic substrates based on coconut fibre and vermicompost in three proportions, 0:100, 40:60 and 60:40 (% v:v), on the microbial activity in the rhizosphere when the bacteria Azotobacter vinelandii, Bacillus megaterium and Frateuria aurantia were applied. Concentrations of NO₃⁻, H₂PO₄⁻, K⁺ and Ca₂⁺ in the petiole cellular extract (PCE) were quantified at 60, 90 and 120 days after transplantation (DAT) for tomato and 45 and 65 DAT for melon. We analysed dehydrogenase activity (DHA), acid phosphatase activity (FTA) and β-glucosidase activity (β-GLU). In order to maintain optimal volumetric moisture for the survival of microorganisms, automatic control was used to manage the irrigation frequency between 22%–28%. The results showed that physicochemical substrate properties, by incorporating 40% vermicompost into the coconut fibre mixture, increased enzymatic activity. Plants that were inoculated with Azotobacter vinelandii and Frateuria aurantia showed an improvement in NO₃⁻ and K⁺ assimilation achieving highest yields.

For some years now, part of society has been demanding the implementation of circular economy models and so the use of organic matter as a source of nutrients is once again taking center stage. In this scenario, the aim of this work was to implement an integrated management model for a farm and to study the influence on a celery crop of organic amendments (animal and vegetable) obtained on the farm, as opposed to inorganic fertilization. This influence was evaluated for the yield and the nutritional, organoleptic, and sanitary quality of the resulting crops. The yield and size of the marketable parts of the celery plants were greater with the inorganic treatment; however, the nutritional and sanitary quality was better in the organic treatments, while the chromatic attributes, as well as the total P and Ca, were not affected by the different fertilization treatments applied. It is therefore concluded that the organic management model is environmentally and economically sustainable.

Background: Organic soilless production in containers requires substrates with appropriate physicochemical and biological properties to ensure that production is sustainable and profitable for several production cycles. The main objective of this study was to comprehensively evaluate these properties in three different mixtures of organic substrates (vermicompost [V] and coconut fibers [CF] in ratios 20V80CF, 40V60CF, 60V40CF) for four horticultural crop production cycles (PCs) using vermicompost tea (VT) as the main source of nutrients.Results: Readily available water (25%) in the control treatment (20V80CF) was below the recommended limit, and dry bulk density (>450 g/L) surpassed the recommended limit in the 60V40CF treatment (p < 0.05). In terms of chemical properties, cations and anions in the saturated media extract decreased significantly to values below established optimal conditions. Furthermore, the substrates presented high enzymatic activity in successive production cycles (p < 0.05), including dehydrogenase (350–400 μg TFF g⁻¹), acid phosphatase (4,700 μg p‐nitrophenol g⁻¹ soil hr⁻¹), and β‐glucosidase (1,200 μg p‐nitrophenol g⁻¹ soil hr⁻¹) activity during transformation from organic matter to inorganic compounds.Conclusion: The 40V60CF treatment presents adequate physicochemical and biological characteristics for reuse for more than four growing cycles when organic supplements are administered.