Water is crucial for enduring horticultural productivity, but high water-use requirements and declining water supplies with the changing climate challenge economic viability, environmental sustainability, and social justice. While the scholarly literature pertaining to water management in horticulture abounds, knowledge of practices and technologies that optimize water use is scarce. Here, we review the scientific literature relating to water requirements for horticulture crops, impacts on water resources, and opportunities for improving water- and transpiration-use efficiency. We find that water requirements of horticultural crops vary widely, depending on crop type, development stage, and agroecological region, but investigations hitherto have primarily been superficial. Expansion of the horticulture sector has depleted and polluted water resources via overextraction and agrochemical contamination, but the extent and significance of such issues are not well quantified. We contend that innovative management practices and irrigation technologies can improve tactical water management and mitigate environmental impacts. Nature-based solutions in horticulture—mulching, organic amendments, hydrogels, and the like—alleviate irrigation needs, but information relating to their effectiveness across production systems and agroecological regions is limited. Novel and recycled water sources (e.g., treated wastewater, desalination) would seem promising avenues for reducing dependence on natural water resources, but such sources have detrimental environmental and human health trade-offs if not well managed. Irrigation practices including partial root-zone drying and regulated deficit irrigation evoke remarkable improvements in water use efficiency, but require significant experience for efficient implementation. More advanced applications, including IoT and AI (e.g., sensors, big data, data analytics, digital twins), have demonstrable potential in supporting smart irrigation (focused on scheduling) and precision irrigation (improving spatial distribution). While adoption of technologies and practices that improve sustainability is increasing, their application within the horticultural industry as a whole remains in its infancy. Further research, development, and extension is called for to enable successful adaptation to climate change, sustainably intensify food security, and align with other Sustainable Development Goals.

Drought is a natural hazard occurring with increasing frequency due to climate change. Drought events reduce soil water content and also soil organic carbon (SOC) content, with negative impacts on crop development and food security. This study investigates the impact of drought on SOC dynamics in agricultural systems and the influence of water availability and farm management practices in these impacts. The manuscript is a systematic review, based on Scopus database for scoping the literature on the topic. A total of 283 records were retrieved, but only 16 papers were relevant for the review. The main findings are: (1) water plays a key role in regulating SOC mineralization due to its impact on dynamics of soil microbial communities, necessitating further research on water management to mitigate carbon losses during drought; (2) different agricultural systems can have differing impacts on SOC under drought conditions depending on crop type (e.g. pastures are more resilient than arable systems) and farm management practices; and (3) SOC loss generally occurs after a drought event, regardless of farm management regime, but the contribution of drought to this loss requires further research. Best management practices, such as cover cropping and soil amendment, can minimize SOC losses, but further research is required to optimize these practices in counteracting the effect of drought. A better understanding of the effects of drought on SOC dynamics, and of short-term and long-term ways to mitigate these effects, is important to ensure soil health and crop productivity.

Crop-livestock integration plays a key role in the sustainability of organic agriculture systems, where the reduction of inputs is central to farms performance. The existing literature has focused on the general dynamics of crop-livestock systems without exploring the specificities of each animal species. Egg production significantly contributes to the world food market and it is expected to continue due to its versatility. At the same time, consumption of organic products has increased in recent years, due to enhanced consumers’ awareness. This work reviews the complex web of relationships between various elements of organic agriculture systems with integrated laying hens. The major findings about the integration of laying hens with crops in organic systems are as follows: 1) contributes to the reduction of inputs (less feed and fertilizers) and a diversified production; 2) supports ecosystem services shaping the landscape toward biodiversity and contributing to a healthier environment; and 3) improves farmers’ livelihood, especially in developing countries. Its benefits will be increased by using mobile systems to ensure a better distribution of manure and in synchronization with canopy cover species, such as fruit and forest trees. However, more research is needed to find further contributions to this system sustainability.

Cynodon dactylon (L.) Pers. is one of the worst agricultural weeds and invasive species in the world, being widely established in many countries. Despite its impact on agriculture and the growing awareness of authorities and consumers about the consequences of synthetic herbicides, alternative control methods for this weed have been poorly reviewed. A systematic review of the literature published over the last 50 years was used to assess the most studied control methods of C. dactylon (excluding synthetic herbicides) and to summarize the trends and knowledge gaps. The major findings are as follows: (1) the number of publications that studied alternative methods to synthetic chemical control in C. dactylon management has been increasing exponentially since 1972; (2) most of the studies were made under controlled conditions (57%) and lack observations under real production conditions; (3) most of the field experiments were carried out in Asia (42%), under temperate subtropical and arid climates; (4) the publication of articles studying allelopathy stands out significantly (50% of the papers found), with two species from the Poaceae family, rice (Oryza sativa L.) and sorghum (Sorghum bicolor (L.) Moench), showing very high allelopathic inhibitory effects (often above 80%), especially under open field conditions; and (5) preventive soil tillage is the most studied treatment among indirect weed control treatments, and although there is a high risk of propagation, the results indicate that tillage can significantly contribute to control C. dactylon, when compared to no-tillage treatments. Further research is needed to optimize treatments and methods so that they can be applied by farmers under real production conditions.

Crop–livestock integration fosters a holistic view of the agricultural system, which is nowadays particularly relevant due to the rising environmental concerns. Laying hens can contribute to improvement of soil chemical properties, but their effects in soil fertility are not fully known. This study aimed to evaluate the effects of grazing laying hens on soil fertility. To meet this goal, we assessed the effects of indigenous laying hens in 22 soil parameters, including chemical, physical, and microbiological parameters, in two farms from the central region of Portugal: an organic horticultural field (A) and a conventional orchard (B). At farm A, the animals grazed during the dry period for 84 continuous days, at a density of 4 m² per hen. At farm B, the animals grazed during the wet period, at a density of 3.50 m² per hen, in two periods (34 + 33 days), with a 50 day break period in between grazing. The hens contributed to an increase in the extractable macronutrients phosphorus (P₂O₅) and potassium (K₂O), mineral nitrogen (NH₄⁺-N and NO₃⁻-N), and exchangeable bases calcium (Ca²⁺) and magnesium (Mg²⁺) in both farms, making these central parameters to consider in their grazing management. At farm A, where soil disturbance is higher, the grazing did not affect soil moisture retention but positively affected soil dry bulk density and contributed to an increase in total aerobic bacteria and nitrogen-fixing bacteria abundances. At farm B, where the hens’ presence led to the understory eradication, soil moisture retention, total aerobic bacteria, nitrogen-fixing bacteria, and fungi abundances were negatively affected, while soil dry bulk density was unaffected. These results show that hens can significantly contribute to improve soil fertility, but more research is needed regarding their grazing management.

Although chickens can improve the chemical properties of soil through the deposition of excreta, their effects on soil macrofauna are poorly known. This work assessed the effects of grazing indigenous laying hens on soil macrofauna of two agroecosystems in Portugal: an organic horticultural field and a conventional orchard. At the horticultural field, laying hens were used to control weeds and the results were compared with those of two other weed control treatments: mechanical (rototiller) and thermal (flame weeding). At the orchard, the effects of hens were compared to that of the orchard understory vegetation, as a control. Soil epigeic macrofauna was collected in both locations, and earthworms were only collected in the horticultural field. Relative to the other treatments, grazing in the horticultural field increased the density of earthworms in the medium term (ranging from 150 to 625 earthworms/m²), without harming the density and diversity of epigeic macrofauna. However, at the orchard, the grazed soils presented lower soil epigeic macrofauna diversity, as well as significantly lower density of spiders than the control (4.67 vs 8.67 individuals/sample, respectively). These results suggest that the grazing effects can be affected by several factors, including the type of agroecosystem and farm management. Further research is required to optimize grazing management in different farming systems, considering animal density and grazing duration, thus ensuring the best contributions of chickens to soil fertility.