A major challenge of the Sustainable Development Goals linked to Agriculture, Food Security, and Nutrition, under the current global crop production paradigm, is that increasing crop yields often have negative environmental impacts. It is therefore urgent to develop and adopt optimal soil-improving cropping systems (SICS) that can allow us to decouple these system parameters. Soil salinization is a major environmental hazard that limits agricultural potential and is closely linked to agricultural mismanagement and water resources overexploitation, especially in arid climates. Here we review literature seeking to ameliorate the negative effect of soil salinization on crop productivity and conduct a global meta-analysis of 128 paired soil quality and yield observations from 30 studies. In this regard, we compared the effectivity of different SICS that aim to cope with soil salinization across 11 countries, in order to reveal those that are the most promising. The analysis shows that besides case-specific optimization of irrigation and drainage management, combinations of soil amendments, conditioners, and residue management can contribute to significant reductions of soil salinity while significantly increasing crop yields. These results highlight that conservation agriculture can also achieve the higher yields required for upscaling and sustaining crop production.

Information about the behavior and temporal evolution of heavy metals in agricultural soils is limited, particularly about greenhouse soils on semiarid lands, indeed it nonexistent. Western Almería (Southern Spain) is a semiarid land where some 30,000 ha are occupied by greenhouses with high productivity. As these greenhouses are fundamental to the socioeconomic development of this area, they should be maintained and well conserved. However, there are indications that long‐term intensive agriculture with considerable agrochemicals use can deteriorate soil quality, which in turn, would reduce productivity and food quality. This study was conducted to investigate soil contamination and the temporal trends of heavy metal concentrations in greenhouse soils of western Almería. Contamination level, availability, and sources of metals were evaluated by the extractable fraction percentage, by indices zinc equivalent, geoaccumulation, enrichment factor and pollution load, and by a correlation analysis between soil properties and metal contents. The results showed that the total contents of Cd, Cu, Ni, and Pb, and the available concentration of Cd, Cu, Pb, and Zn, were significantly higher than background levels. Temporal patterns indicated that these elements accumulate in greenhouse soils. After more than 20 years of intensive agriculture, the available concentration of elements, and contamination, had clearly increased.

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Soil is a fundamental resource, subject to severe and quick degradation processes because of the pressure of human activities, particularly in many regions of the Mediterranean where agriculture is an important economic activity. It has been proven that the use of sustainable soil management practices can potentially give rise to the creation of a carbon sink, an increase of soil organic matter content, the maintenance of crop productivity and a reduction in erosion. Despite the existence of scientific evidence about the benefits generated by the use of sustainable practices on soil, many farmers are reluctant to adopt them. The objective of this study is to identify and give a hierarchical structure to the factors that condition the adoption of sustainable practices in the management of agricultural soil. The case of olive tree cultivation in Southeast Spain has been studied, using a participatory qualitative methodology. The results show a series of seven principal barriers (information, costs, risk aversion, characteristics of the farm and sustainable practices, macro factors, and cultural barriers) and five facilitators (technology, farmer training, awareness, incentives, and social pressure) for the adoption of the proposed sustainable agricultural practices. The principal political and legislative actions proposed to increase the adoption of sustainable agricultural practices include: administrative control, fostering environmental awareness, technical knowledge, and on-farm demonstrations; and, on the economic and financial level, incorporation of both general incentives and subsidizing specific costs. This study contributes to the development and discussion of intervention proposals that are designed to stimulate the implementation of sustainable practices in agricultural soil management.

The short-term responses of soil quality indicators are important for assessing the effects of new management practices and addressing threats to crop yields in greenhouses. The aim of this study was to assess, during three consecutive cropping seasons, the effect of a sustainable management package (CRTMP)—which includes the on-site reuse of greenhouse crop residues and tillage—in comparison with conventional management, based on fertigation only (CMP), on certain biochemical soil quality indicators and crop yields. CRTMP significantly increased (p < 0.05) the values of total organic carbon (TOC), particulate organic carbon (POC), light fraction (LF), water soluble organic carbon (WSOC), and dehydrogenase (DH) and β-glucosidase (GL) activities at a depth of 0–15 cm, as well as the mean concentration of nitrates in the soil solution. In addition, a significant Pearson’s correlation (p < 0.01) found between the indicators suggested a balanced improvement of soil biological activity and nutritional soil state. Nonetheless, the significant (p < 0.05) increases in the mean concentration of chlorides in the soil solution and electrical conductivity (p < 0.05) increased the risk of salinization, which may have affected the concentration of nitrates in the petiole sap and total production in CRTMP, which were significantly lower than in CMP. Nevertheless, the proportion of premium product was significantly higher in CRTMP, while the proportion of non-commercial production decreased.

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Field experiments were conducted to evaluate the effect of a long-term (10 years) organic management on a greenhouse soil compared with the same soil under intensive conventional management. Soils of each greenhouse have an artificial sequence of layers: 0-10 cm depth of sand mulch with a dominant particle size of 0.5 mm-2.0 mm, and between 10 and 40 cm depth of loamy sandy soil layer with moderate infiltration as crop substrate. During the last 10 years, organic greenhouse received manure equivalent up to 170 kg N ha 71 year 71 (over 5600 kg ha 71 year 71 of manure of 3% N) mixed with crop substrate at 10 cm depth, while conventionally managed greenhouse received no organic amendments during this time. Water and nutrients were supplied to both greenhouses by drip irrigation, as required for crops. Crop rotation was similar in both greenhouses. An experimental plot (90 m 2 ) was established in each greenhouse and nine soil samples were taken near the drippers. Organic management diminished pH and bulk density and, as a consequence, improved infiltration, but reduced the water retention capacity. Total organic carbon, total nitrogen and cation exchange capacity were augmented by comparison with conventional management.

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