Cereal crops play a critical role in global food security, but their productivity is increasingly threatened by climate change. This study evaluates the feasibility of using PlanetScope satellite imagery and a UAV equipped with the MicaSense RedEdge multispectral imaging sensor in monitoring winter wheat under various fertilizer treatments in a Mediterranean climate. Eleven fertilizer treatments, including organic-mineral fertilizer (OMF) pellets, were tested. The results show that conventional inorganic fertilization provided the highest yield (8618 kg ha⁻¹), while yields from OMF showed a comparable performance to traditional fertilizers, indicating their potential for sustainable agriculture. PlanetScope data demonstrated moderate accuracy in predicting canopy cover (R² = 0.68), crop yield (R² = 0.54), and grain quality parameters such as protein content (R² = 0.49), starch (R² = 0.56), and hectoliter weight (R² = 0.51). However, its coarser resolution limited its ability to capture finer treatment-induced variability. MicaSense, despite its higher spatial resolution, performed poorly in predicting crop components, with R² values below 0.35 for yield and protein content. This study highlights the complementary use of remote sensing technologies to optimize wheat management and support climate-resilient agriculture through the integration of sustainable fertilization strategies.

The excessive use of synthetic fertilizers in agriculture has raised environmental concerns, prompting the search for sustainable alternatives, such as organic amendments. This study evaluated the agronomic performance, nutrient use efficiency and metabolomic profiles of lettuce (Lactuca sativa L. var. baby leaf) cultivated using synthetic and organic (olive mill waste-based compost pellets and sewage sludge) in a controlled pot experiment. The treatments included three doses of inorganic fertilizer and two organic fertilizers applied at equivalent nitrogen (N) rates, alongside an unfertilized control. Soil physicochemical properties, plant biomass, nutrient uptake and metabolite profiles, including amino acids, sugars and organic acids, were analyzed. Inorganic fertilization rapidly increased soil mineral N and phosphorus (P), enhancing leaf chlorophyll, canopy development and fresh biomass, and promoting the accumulation of reducing sugars (p < 0.05). However, it reduced amino acid and phenolic levels, indicating a metabolic shift towards growth at the expense of stress and antioxidant compounds. Sewage sludge increased soil organic matter and amino acid and sucrose accumulation, but also induced stress-related metabolites. Pelletized compost maintained an intermediate level of nutrient availability, preserved phenolic compounds and improved phosphorus use efficiency. This surpassed the results achieved with sewage sludge in terms of dry matter yield, despite limited short-term growth stimulation. These findings highlight the potential of integrating moderate mineral fertilization with pelletized compost to balance immediate productivity, nutrient efficiency and long-term soil and metabolic quality in lettuce cultivation.

The European Union (EU) advocates for a sustainable agricultural model with reduced synthetic fertiliser use. This study compares different high-P organo-mineral pellet fertilisers (OMFs) and their effects on crop yield. A trial was conducted under controlled conditions in ryegrass (Lollium perenne L.) pots with different organo-mineral fertilisation strategies at sowing with adjusted doses of P (120 kg P ha⁻¹) and N (200 kg N ha⁻¹). Pellets were developed from compost enriched with bone meal (OMF-BON), struvite (OMF-STR), and monoammonium phosphate (OMF-MAP). Conventional fertilisers (Complex15 and MAP) and alternative unpelletised/pelletised sources (STR and BON) were also tested. The experimental design included an unfertilised control (C), and treatments were carried out in triplicate (N = 24). Over 40 days, three cuttings (10, 25, and 40 days) were collected to determine fresh/dry biomass, nutrient content, and N, P, and K extraction efficiency. Soil labile parameters were influenced by the application of fertilisers especially OMF-MAP, OMF-STR, and MAP. MAP and STR yielded the highest nutrient extraction and biomass production, followed by their pelletised forms (OMF-MAP and OMF-STR). These results highlight the potential of pelletised organo-mineral fertilisers as sustainable alternatives to conventional sources.

In this study several phosphorus fertilizers were evaluated under controlled production conditions using Lactuca sativa var. baby leaf and a clay-loam soil of pH 6.5 as a plant–soil model system. Various inorganic (phosphate rock, monoammonium phosphate, struvite), organic (bone meal and bone meal pelletized with compost) and organomineral fertilizers (phosphate rock, monoammonium phosphate, struvite pelletized with compost) were compared. The soil properties, crop yield, morphological aspects and metabolomics of the plants were analyzed. After 45 days of the growing cycle, the organomineral fertilizers (OMFs) composed of compost and monoammonium phosphate (OMF₂(MAP+C)) or struvite (OMF₃(STR+C)) exhibited the best yield results: 101.37 g and 83.21 g, respectively. These treatments also exhibited the best phosphorus use efficiency (PUE) results: 7.40% and 8.33%, respectively. The yield of plants treated with MAP was 56.01 g, and its PUE was 5.33%. The yield of plants treated with STR was 62.10 g and the PUE was 4.67%. Accordingly, the development of OMFs with compost had a positive effect regarding MAP and STR fertilization. Lettuce fertilized with organic bone meal fertilizers had the lowest yield and nutrient use efficiency. The non-targeted metabolic study of green tissue revealed an overactivation of the TriCarboxylic Acids-TCA cycle and amino acid biosynthesis in plants fertilized with bone meal and phosphate rock treatments, likely as a plant stress response. The overall conclusion of this work is that the development of OMFs with compost is a good strategy to increase soil P availability and, accordingly, plant P uptake and %PUE.

Olive mill wastewater is a polluting residue generated from the olive oil industry and is one which constitutes an environmental concern in Mediterranean countries. Composting has been reported as a viable valorization alternative, as it reduces the volume and the phytotoxic characteristics of OMW. In this study, several composts derived from OMW were evaluated under controlled conditions over two growing season pot experiments using Lactuca sativa as a test crop. The analysis focused on soil quality changes, crop yield, and plant development. Additionally, potential phytotoxicity was also evaluated through a direct acute toxicity plant growth test. Application of OMW composts improved soil fertility indicators, including oxidizable carbon, Kjeldahl total nitrogen, Olsen phosphorous, and plant availability. Crop yields were comparable to those obtained with other organic amendments such as vermicompost and fresh cattle manure in both growing seasons and plant development (in terms of chlorophyll content and canopy cover) was not negatively affected. Nutrient uptake (NPK) was consistent during both growing seasons, with similar nitrogen use efficiency to that achieved in other organic treatments. Regarding the potential toxic effect, the OMW composts tested enhanced seed germination when mixed with coconut fiber at weight ratios below 29.2%. No half-maximal effective concentration (EC50) values were detected, even at 100% compost concentration, while half-maximal inhibitory concentration (LC50) values ranged between 65–75%. These results indicate that OMW composts can serve as an effective short-term source of plant-available nitrogen and a medium-term source of phosphorus, without risk of finding inhibitory or phytotoxic effects on crops.

The rapid growth of insect farming generates significant volumes of insect frass, a novel organic by-product. Utilizing frass-based organo-mineral fertilizers represents a sustainable alternative to synthetic fertilizers, yet long-term agronomic efficacy and residual effects require further field validation. This study evaluated pelletized organo-mineral formulations for conventional and organic agriculture, derived from Hermetia illucens and Tenebrio molitor frass. Eight field treatments were evaluated: an unfertilized control; an inorganic NPK fertilizer (150 kg N ha⁻¹); a biostabilized municipal solid waste compost at two nitrogen rates (150 and 300 kg N ha⁻¹); and two novel insect-frass-derived organo-mineral fertilizers (VHTI and VHTO) applied at a standard product dose (1000 kg ha⁻¹) and an N-equivalent dose (150 kg N ha⁻¹). Application of organo-mineral and organic treatments at the same nitrogen dose (150 kg N ha⁻¹) doubled cabbage yield compared to the unfertilized control and significantly outperformed the conventional inorganic treatment. These formulations demonstrated enhanced nitrogen and phosphorus use efficiencies, reflecting improved synchronization between nutrient release and crop demand. Furthermore, organo-mineral formulations significantly increased soil available phosphorus without adversely affecting key soil quality parameters. The Integrated Soil–Crop Response Index (ISCRI) confirmed a superior overall agroecosystem response for these treatments. These findings provide important theoretical insights into nutrient synchronization mechanisms in organo-mineral fertilizers, alongside practical applications for sustainable cabbage production. Consequently, frass-based pelletized fertilizers represent a highly sustainable, circular, and efficient alternative to optimize horticultural yield and nutrient use efficiency while enhancing soil health, ultimately supporting the valorization of insect farming by-products as viable substitutes for synthetic fertilizers.