Soil Systems

FTIR spectroscopy, attenuated total reflection (ATR), and diffuse reflectance (DRIFT) modalities, along with ICP–AES spectroscopy and correlation analysis, including two-dimensional correlation spectroscopy (2DCOS), were used for the detailed analysis of Kastanozem (chestnut) soils. Microaggregates (20–200 μm) and macroaggregates (200–1000 μm) of characteristic horizons of uncultivated (fallow) and cultivated (arable land) chestnut soils of the same origin were physically fractionated by wet sieving. The combination of these molecular and atomic spectroscopy techniques in combination with correlation analysis was able to find direct correlations between matrix-forming anions and soil organic matter (SOM) of Kastanozems. Humic substances were separated from the corresponding soil samples to reveal SOM contributions more explicitly. Microaggregates of the size fractions of 20–40 μm and 40–60 μm bore the most comprehensive information for both techniques used. Most significant differences between land-use Kastanozem samples were observed in topsoil horizons (arable P versus light-colored humic AJ horizon), and for the next pair of horizons along the profile xerometamorphic BMK horizon to structural metamorphic BM horizon. These differences included carbonate matrix and SOM amounts and composition. Topsoil arable land showed significantly smaller amounts of total organic carbon and a decrease in the share of long-chain hydrocarbons compared to fallow, which has a more distinctive character compared to similar land-use samples of Chernozem. An increase in carbonate contents with soil depth was found for both land-use samples, while the amounts and composition of the silicate matrix remained largely unchanged within the depth profile. The heterospectral 2DCOS comparison of FTIR (between horizons and land-use samples), ICP–AES (between land-use samples), and FTIR–AES (for the same sample) showed the possibility of a more reliable attribution of FTIR absorption bands and revealed the differences in the macro- and micro-aggregate elemental and SOM composition of Kastanozems.

The development of urban green infrastructures (UGI) is considered among the main nature-based solutions for climate mitigation in cities; however, the role of soils in the carbon (C) balance of UGI ecosystems remains largely overlooked. Urban green spaces are typically dominated by constructed Technosols, created by adding organic materials on top of former natural or agricultural subsoils. The combined effects of land-use history and current UGI management result in a high spatial variation of soil organic carbon (SOC) stocks and soil CO₂ emissions. Our study aimed to explore this variation for the case of Wageningen University campus. Developed on a former agricultural land, the campus area includes green spaces dominated by trees, shrubs, lawns, and herbs, with well-documented management practices for each vegetation type. Across the campus area (~32 ha), a random stratified topsoil sampling (n = 90) was conducted to map the spatial variation of topsoil (0–10 cm) SOC stocks. At the key sites (n = 8), representing different vegetation types and time of development (old, intermediate, and recent), SOC profile distribution was analyzed including SOC fractionation in surface and subsequent horizons, as well as the dynamics in soil CO₂ emissions, temperature, and moisture. Topsoil SOC contents on campus ranged from 1.1 to 5.5% (95% confidence interval). On average, SOC stocks under trees and shrubs were 10–15% higher than those under lawns and herbs. The highest CO₂ emissions were observed from soil under lawns and coincided with a high proportion of labile SOC fraction. Temporal dynamics in soil CO₂ emissions were mainly driven by soil temperature, with the strongest relation (R² = 0.71–0.88) observed for lawns. Extrapolating this relationship to the calendar year and across the campus area using high-resolution remote sensing data on surface temperatures resulted in a map of the CO₂ emissions/SOC stocks ratio, used as a spatial proxy for C turnover. Areas dominated by recent and intermediate lawns emerged as hotspots of rapid C turnover, highlighting important differences in the role of various UGI types in the C balance of urban green spaces.

Sorghum is a strategic crop for food, feed, and bioenergy. However, information on its cultivation area and agronomic profile in Indonesia remains limited. Therefore, this study aimed to identify, characterize, and evaluate sorghum cultivation in different agroecosystems and pedoagroclimatic settings in Indonesia. We surveyed published articles, newspapers, and other digital resources, collating a dataset that contained pedoagroclimatic characteristics. We then conducted a field survey to gather data on sorghum farming practices. The results show that sorghum is planted in 11 agroclimatic zones, mainly in D3, B1, and E4, and in seven soil types, mainly in Inceptisols, Mollisols, Vertisols, and Andisols. The cultivated varieties cover Bioguma 1, Bioguma 2, Bioguma 3, Numbu, Kawali, UPCA-S1, Suri 3 Agritan, Soper 9, and local varieties. Under smallholder farmers’ management, the average sorghum yield ranges from 3.6 to 7.5 Mg ha⁻¹. The 15–68% of the yield gap can be closed by implementing site-specific technologies, including high-yielding varieties and soil management. These findings provide a baseline for supporting efforts to increase sorghum production and develop robust sorghum cultivation technologies.