Besides well‐known effects of climate and parent material on silicate weathering the role of land use change as a driver in the global silicon cycle is not well known. Changes in vegetation cover have altered reservoirs of silicon and carbon in plants and soils. This has potential consequences for plant‐Si availability, agricultural yields, and coastal eutrophication, as Si is a beneficial element for many crop plants and an essential nutrient for diatom growth. We here examined the role of sustained and intensive land use and human disturbance on silicon (Si) pool distribution in soils with similar climatological and bulk mineralogical characteristics. We show that land use impacts both biogenic and nonbiogenic Si pools. While biogenic Si strongly decreases along the land use change gradient (from forest to croplands), pedogenic silica fractions (e.g. pedogenic clays) increase in topsoils with a long duration of cultivation and soil disturbance. Our results suggest that nonbiogenic Si pools might compensate for the loss of reactive biogenic silicon in temperate zones.

Recent research established a link between environmental alterations due to agriculture intensification, social damage and the loss of economic growth. Thus, the integration of environmental and social dimensions is key for economic development. In recent years, several frameworks have been proposed to assess the overall sustainability of farms. Nevertheless, the myriad of existing frameworks and the variety of indicators result in difficulties in selecting the most appropriate framework for study site application. This manuscript aims to: (i) understand the criteria to select appropriate frameworks and summarize the range of those being used to assess sustainability; (ii) identify the available frameworks to assess agricultural sustainability; and (iii) analyze the strengths, weaknesses and applicability of each framework. Six frameworks, namely SAFA, RISE, MASC, LADA, SMART and public goods (PG), were identified. Results show that SMART is the framework that considers, in a balanced way, the environmental, sociocultural and economic dimensions of sustainability, whereas others focused on the environmental (RISE), environmental and economic (PG) and sociocultural (SAFA) dimension. However, depending on the scale assessment, sector of application and the sustainability completeness intended, all frameworks are suitable for the assessment. We present a decision tree to help future users understand the best option for their objective.

The biogeochemical cycling of silicon (Si) along the land‐to‐ocean continuum is studied by a variety of research fields and for a variety of scientific reasons. However, there is an increasing need to refine the methodology and the underlying assumptions used to determine biogenic silica (BSi) concentrations. Recent evidence suggests that contributions of nonbiogenic sources of Si dissolving during alkaline extractions, not corrected by standard silicate mineral dissolution correction protocols, can be substantial. The ratio between dissolved Si and aluminum (Al) monitored continuously during the alkaline extraction can be used to infer the origin of the Si fractions present. In this study, we applied both a continuous analysis method (0.5 M NaOH) and a traditional 0.1 M Na₂CO₃ extraction to a wide array of samples: (1) terrestrial vegetation, (2) soils from forest, cropland and pasture, (3) lake sediments, (4) suspended particulate matter and sediments from rivers, (5) sediments from estuaries and salt marshes and (6) ocean sediments. Our results indicate that the 0.1 M Na₂CO₃ extraction protocol can overestimate the BSi content, by simultaneously dissolving Si fractions of nonbiogenic origin that may represent up to 100% of the Si traditionally considered as biogenic, hampering interpretation especially in some deeper soil horizons, rivers and coastal oceanic sediments. Moreover, although the term amorphous Si was coined to reflect a growing awareness of nonbiogenic phases we show it is actually inappropriate in samples where silicate minerals may account for a large part of the extracted Si even after linear mineral correction.

Silicon (Si) is a “quasi-essential” element, associated to stresses/limitations alleviation in crops. However, stressful situations are becoming the norm, due to climate change, human exhaustion of natural resources, land degradation and loss of soil biodiversity. In this context, Si becomes a critical element, capacitating crops to grow more and better with less. A total of 467 articles up to 2021 were selected, reporting 501 experiments (lab-oriented and field trials) resulting in 682 cases where different Si-based fertilizers were used to study crops/plants with agronomic value to evaluate its physiological and/or agronomic performance under a specific motivation. Results show that 63% of cases testing Si-fertilization show increase in productivity, while 13% refuted this observation and 24% did not evaluate plant growth. Crop physiological responses was registered in 42% of the cases and only 3% did not report any alteration, although 55% did not evaluate these indicators. Symptom alleviation, in cases where stresses/limitations were studied, was registered in 74% of the cases with a low number of negative outcomes (9%). Field trials where crop yield was measured after application of Si-fertilization show that 69% of different measurements (599) register a yield improvement ≥ 5%, while 18% of the measurements registered between 0 and 5% and only 14% reported yield loss. Si-fertilization is therefore and important factor to improve crop yield and capacitate crops with resilience to endure future limitations. Its inclusion in modern agriculture should be considered in larger scales to adapt crops to the current challenges of sustainable agriculture and food provision.