Water is an essential resource for food production, and agriculture consumes close to 69% of total freshwater use. Water shortage is becoming critical in arid and semiarid areas worldwide; therefore, it is vital to use water efficiently. The objective of this research was to evaluate the response of onion growth, plant water status, bulb yield, irrigation water use efficiency and bulb quality using three continued deficit strategies, applying 100, 75, and 50% of the irrigation water requirements during three seasons. The yield response factor was 0.71, indicating that in the analysed conditions the crop was tolerant to a water deficit. Compared to full irrigation, deficit irrigation with 75% of the irrigation water requirements resulted in a low yield and profit reduction for the growers (10.3% and 10.9%, respectively), but also important water savings (26.6%), improving both the irrigation water use efficiency and water use efficiency. However, onion exposure to severe water deficits at 50% of the irrigation water requirements drastically reduced plant growth and bulb yield and growers’ profits, although it did increase their soluble solid content. Irrigating at 75% of the irrigation water requirements could be an actionable strategy for onion production under water-limited conditions.

The use of microorganisms capable of promoting the growth and development of crops is generating interest at a global level as a sustainable technique in modern agriculture, especially in intensive farming systems, where the excessive use of synthetic fertilizers has led to environmental problems. The objective of this research was to evaluate the biofertilizing power of formulations enriched with plant growth-promoting bacteria (PGPB) (Azotobacter spp. to fix N and strains of Bacillus spp. to solubilize P and K not bioavailable for plants) to improve the fertility, quality, and productivity of a tomato crop and their potential use as an alternative to conventional fertilizers. Thus, NPK levels in soils, leaves, and fruits were evaluated; various parameters of fruit quality were measured; and an exhaustive analysis of the production and economic yields of the harvest was carried out. The results showed that the periodic supply of biofertilizers based on PGPB increased the harvest yield (20–32%) and favored the development of larger fruit sizes, which are economically more valuable, and the incomes increased even more than production (32–52%). The biofertilizers also demonstrated a positive effect on the solubilization of P and K in the soil, and the levels of P in leaves were also promoted. The capacity to mobilize the nutrients from soil to fruits was clearly favored when PGPB were inoculated periodically, and a reduction of up to 20% in synthetic fertilizers was accomplished (16, 34, and 23% increases for N, P, and K, respectively, against the treatment without PGPB and no fertigation reduction). Finally, the use of PGPB did not show appreciable differences regarding fruit quality parameters.

In Europe, food and agricultural waste amount to millions of tonnes annually. Effective management and valorisation of these residues result in environmental benefits and foster opportunities within the circular economy. Composting has emerged as a sustainable method to convert waste into fertiliser, enhancing soil fertility, water retention, and crop resilience against diseases. However, an adequate compost production process is vital to obtain a functional fertiliser. In this study, a controlled conditions self-produced compost from horticultural waste (C1) was compared against two other commercial composts, one of similar vegetable origin (C2) and another from chicken manure (C3). Physicochemical parameters and nutrient contents in the three compost types were analysed, and phytotoxicity and plant development tests were carried out on Lolium multiflorum Lam. seeds and Pistacia lentiscus L. seedlings. C1 presented fertility and germination parameters similar to C3 and showed the best seedling development. In contrast, C2 showed low levels of fertility, germination, and plant development because of impurities and possible substances inhibiting plant growth, suggesting inadequate compost formation processes. Finally, C3, although it presented germination data similar to C1, produced the worst results in the development of seedlings, probably because of high salinity values and low phosphorus content.