Phosphorus (P) is essential for plant growth but is frequently limiting in tropical agroecosystems due to strong sorption and low availability. The adoption of cover crops (CCs) with high P uptake efficiency can enhance P cycling for cash crops, reducing fertilizer use and improving P-use efficiency. This study aimed to assess changes in soil P dynamics after adopting CCs under contrasting P sources in a sandy soil in dryland conditions in Brazil. The experiment was carried out in sandy loam soil over two maize-growing seasons under no-tillage. Treatments consisted of two P sources (single superphosphate – SSP, and rock phosphate – RP) and a control without P (Nil P), combined with six summer CC species (sunn hemp, spectabilis, pigeon pea, lablab, jack bean, and pearl millet) plus fallow. P uptake, P offtake, and soil P fractions were determined in both seasons. Cover crops increased PUE under both P sources. Under SSP, PUE increased significantly after lablab cultivation, reaching 58% compared to fallow. Under RP, all CCs promoted a significant increase in PUE, except for spectabilis. Most cover crops reduced system P balance relative to fallow, indicating greater P export by maize harvest. Sunn hemp was the most efficient CCs in P uptake, ~36 kg ha-1 of P from the soil on average across both growing seasons (36% higher than the average of other CCs). In the first season, CCs increased the labile P pool under Nil-P at 0–10 cm depth, especially with spectabilis, pigeon pea, sunn hemp, and pearl millet (~38% higher than fallow). However, this pool was depleted in the second season. Under P fertilization, labile and moderately labile P increased substantially, particularly with pearl millet under RP at 0–5 cm. Across seasons, CCs depleted non-labile P at 10–20 cm and accumulated it in the surface depth. Overall, CCs efficiently cycled P and improved maize PUE most consistently under RP, highlighting that CC selection can be used to increase the effectiveness of sparingly soluble P inputs in sandy, low-buffering dryland soils.

The Godavari River basin, a major rice —producing region, requires an accurate understanding of soil drainage to enhance crop productivity. Soil color-evaluated using the Munsell chart and converted to the CIE Lab system, acts as a reliable indicator of soil moisture, texture, and drainage. In this system, L* denotes lightness, a* redness, and b* yellowness. A drainage index was derived using Mahalanobis distance based on these color parameters. A total of forty-two soil profiles were opened from three landforms—fluvial, fluviomarine, and marine—using a 1:250,000-scale soil resource inventory. Fluvial soils exhibited clay to silty clay textures with Ap horizons (0–18 cm) and Bg horizons extending beyond 100 cm, indicating sustained alluvial deposition. Fluviomarine soils displayed stratified silty clay to silty clay loam and sand layers with subsoil effervescence, indicating carbonate accumulation under combined fluvial and marine influence. In contrast, marine soils showed lighter silt loam to sandy textures, reflecting slower pedogenesis. CIE Lab analysis showed marine soils are lighter (L* = 50.65) with higher b* values (23.76), while fluvial soils are darker (L* = 33.88) and more reddish-yellow (b* = 12.32). Fluviomarine soils exhibited the highest color variability, reflecting heterogeneous sediment mixing and fluctuating redox conditions. Drainage assessments showed moderate to poor subsoil drainage in fluvial and fluviomarine soils, which influenced root growth, water retention, and soil color. These results demonstrated strong relationships between soil color, texture, and drainage, emphasizing the need for site-specific management to optimize irrigation, fertility, and pedogenesis in the Godavari rice landscapes. • Marine soils have lighter, sandy horizons with slower pedogenesis, showing higher L* and b* values. • Soil color is a reliable and non-intrusive method for assessing soil health and fertility. • Soil color correlates strongly with soil drainage class.

This study was conducted to determine the impact of land use and livestock farming on riparian areas in the state of São Paulo, Brazil. A range of physical, hydraulic and chemical properties were measured in hydromorphic soils under four scenarios; namely: i) native vegetation (NV), ii) semi-extensive grazing (SEG, ~21 animal units ha −1 ) with 30 years of established practice; iii) intensive grazing with 20 years of established practice (IG20, ~24 animal units ha −1 ); and iv) intensive grazing after 1 year of being implemented (IG1, ~21 animal units ha −1 ). The replacement of native vegetation with pastures, regardless of the duration and type of management, resulted in significant changes in soil structure and soil functioning, due to increased bulk density and penetration resistance, and concurrent reductions in macroporosity and saturated hydraulic conductivity. The soil under long-term intensive management (IG20) showed less structural degradation, closely resembling the conditions observed in the native vegetation area (NV). By contrast, the soil under semi-extensive grazing (SEG) management exhibited significant damage to the soil structure, which affected all measured soil physical and hydraulic properties. Despite these negative impacts on soil structure, SEG exhibited higher levels of total carbon, total nitrogen, and total sulfur. The results suggested that the intensive management system (IG20) tended to maintain higher soil quality in riparian areas than the condition observed under native vegetation, although these differences cannot be exclusively ascribed to grazing.

In Quebec, Canada, field vegetable production largely occurs on cultivated organic soils of Montérégie. These soils become arable following extensive drainage of peatlands, which are highly fertile but vulnerable to subsidence, erosion, and organic matter mineralization. The latter causes carbon losses to the atmosphere through CO₂ emissions and can also lead to dissolved organic carbon leaching. This study quantified CO₂ emissions and identified governing edaphic and meteorological parameters to support the development of carbon compensation strategies for peatland managers. Easily measurable soil parameters were selected to provide farmers with potential proxies for routine soil analysis. Five commercial sites were selected based on their organic matter (OM) content: F1 (52.2 %), F2 (56.7 %), F3 (74.0 %), F4 (77.4 %), and F5 (91.3 %). All sites, except F3, were devoid of vegetation. Soil CO₂ emissions were measured using manual static chambers over one year (September 2021–September 2022) at bimonthly intervals. Gross annual carbon losses were 4.94 Mg C-CO₂ ha −1 yr −1 for F1, 5.47 for F2, 15.30 for F3, 7.62 for F4, and 3.20 for F5. Soil temperature, total microbiological activity (fluorescein diacetate hydrolysis), total nitrogen, and pH significantly and positively influenced CO₂ fluxes, while soil water content showed a negative correlation. Annual carbon losses were highly and exponentially correlated with total microbiological activity, underscoring its relevance as a biological indicator and promising proxy for CO₂ emissions. This study advances understanding of CO₂ emissions from cultivated organic soils and highlights the importance of targeted strategies to mitigate carbon losses and conserve these valuable peatland resources.