Search Results (51)

Precision application of fertiliser nutrients based on soil-available nutrients is a vital means of increasing castor (Ricinus communis L.) productivity. Fertiliser application based on the targeted yield model under inorganic fertilisers alone and Integrated Plant Nutrition System (IPNS) differ from the blanket recommendation practices. Field experiments were conducted in two locations to validate the Soil Test Crop Response (STCR) targeted yield model developed for hybrid castor on non-calcareous Alfisol. The main objective was to determine the effect of inorganic fertilisers and organic manures on microbial populations, enzyme dynamics in soil, and productivity of castor. Experimental field data revealed that combined application of inorganic fertilisers along with 12.5 t ha⁻¹ farmyard manure increased the soil microbial population and enzyme activity in the rhizosphere soils of castor. Castor responded positively with an increase in highest targeted yield level. The highest yield of 2726 and 2695 kg ha⁻¹ were attained in the treatment T₈ (STCR-IPNS −2.75 t ha⁻¹) in both locations, and Treatment T₅ (STCR-NPK alone −2.75 t ha⁻¹) was on par with T₈. The IPNS treatments showed higher percent achievement than the NPK treatments alone. Root length and dry matter production increased significantly with the application of a higher dose of fertiliser along with farmyard manure. Root dry matter production significantly contributed towards the castor seed yield. More soil-beneficial microorganisms and enzyme dynamics were observed in the IPNS treatment. Full article

The transformation of natural ecosystems into agroecosystems due to changes in land use/land cover (LULC) has been shown to significantly affect soil characterization and classification. The impact of LULC on soil taxonomy was assessed in a primary forest located in central–eastern Honduras, which had been deforested approximately forty years prior to the study. Morphological, physical, and physicochemical analyses were performed by describing 10 representative profiles, applying the Soil Taxonomy (ST) and World Reference Base for Soil Resources (WRB) nomenclatures. LULC resulted in physical degradation in agricultural areas, as evidenced by lighter-colored horizons (P02), reduced granular structure (P01, P02, P05), higher bulk densities (≤1.73 Mg m⁻³), and surface crusting (P02, P05); this phenomenon was also observed in pastures (P06–P09). SOC loss was 62% in croplands, 47–53% in agroforestry systems (P03) and fruit tree plantations (P04), and 25% in pastures. All profiles exhibited pH values between 6.5 and 8.4 and complete base saturation (BS), except for P08 and P09, which had pH values below 5.5, high levels of Al³⁺, and reduced BS (50–60%). Mollic epipedons and variability in the endopedons were also observed. According to the ST of the System of Soil Classification (SSC), the soils were classified as Mollisols, Entisols, Vertisols, and Alfisols; and as Phaeozems, Fluvisols, Gleysols, Anthrosols, Gypsisols, and Plinthosols by the WRB. We advocate for the inclusion of Anthropogenic Soils as a distinct Order within Soil Taxonomy (ST). The implementation of sustainable agricultural practices, in conjunction with the formulation of regulatory frameworks governing land use based on capacity and suitability, is imperative, particularly within the context of fragile tropical systems. Full article

The present study applied a GIS-based methodology for assessing soil diversity in a protected mountain area of Italy. Using QGIS, morphological (i.e., altitude and slope), lithological, climatic, and land use layers were intersected to delineate 16 land units (LUs), each representing relatively homogeneous conditions for soil formation, according to Jenny’s equation. To obtain the soil map units, a total of 112 soil profiles were analyzed, including 79 from previous studies and 33 that were newly excavated during 2023–2024 to fill gaps in underrepresented LU types. Most soils were classified as Inceptisols/Cambisols, occurring in both Dystric and Eutric variants, mainly in relation to lithology (i.e., arenaceous or pelitic facies). Alfisols, Umbrisols, and hydromorphic soils were also identified. The physicochemical properties showed marked variability among LUs, with sand content ranging from 39 to 798 g kg⁻¹, pH from 4.4 to 7.9, and organic carbon content from 1.6 to 6.1%. This LU-based framework allowed efficient field sampling, if compared to grid-based surveys, while retaining information on fine-scale pedodiversity. No quantitative accuracy assessment (e.g., boundary precision, internal homogeneity metrics) was conducted, even if the spatial coherence of the delineated LUs was supported by the distribution of soil profiles, which provided empirical validation of the LU framework. Full article

The exponential increase in global plastic production, reaching over 380 million tons in recent years, has exacerbated environmental problems, particularly in agriculture. Agricultural residues, such as hazel (Corylus avellana L.) pruning and plastic wastes, are underutilized resources that can be transformed via pyrolysis into biochar. This study focuses on copyrolyzed biochar produced from hazel biomass and polyethylene and aims to evaluate its effect on the water retention properties of degraded Alfisol. Van Genuchten’s hydrological model was used to analyze parameters such as rapid drainage pores, plant-available water pores, and air capacity (AC) under varying particle sizes (small and large) and application rates (1% and 5% w/w). The results revealed that fine particles at higher doses (5%), especially in P-5%-large and P-5%-small, considerably improved plant-available water retention, particularly within micropores and mesopores. Microstructural modifications induced during pyrolysis enhanced the water retention capabilities of biochar copyrolyzed with plastic. However, its effects on AC and pore connectivity warrant further investigation to assess long-term soil functionality. By integrating waste valorization with improved agricultural practices, this study underscores the potential of biochar copyrolyzed with plastic as an amendment for degraded soil. However, the long-term stability of this amendment requires further study. Full article

The main problem with the conventional plastics presently used is that they are too slow to degrade, and thus, accumulate in the natural environment. This situation occurs on farmlands because low-density polyethylene (LDPE) is widely used in agriculture. Different authors propose employing biodegradable plastics (bioplastics) to solve this problem, and the most studied and promising candidates are poly(hydroxybutyrate) acid (PHB) and poly(lactic) acid (PLA). This work centers on the short-term evaluation of the biodegradability of the three above-mentioned plastic materials in soil type Mediterranean Alfisol and the effect of adding organic amendment (cow manure; CM) on their biodegradation. Two experiments were run for each plastic material: one without this organic amendment and the other by adding CM. Their biodegradation was determined by the procedure described in Standard ISO 17556. The results confirm that PHB is a highly biodegradable polymer, whereas the biodegradability of PLA and LDPE is poor. Using CM did not facilitate plastic polymer biodegradation in our soil. The nature and properties of soil can significantly impact plastics biodegradation. Bioplastics are still not the panacea to solve the plastics pollution problem, so other management options must be considered, such as prevention, reduction, and/or reuse in situ. Full article

Irish potato (Solanum tuberosum) is a critical crop for food security and economic growth in Tsangano and Angónia Districts, Central Mozambique. Challenges like inconsistent yields and variable quality are often linked to suboptimal soil conditions, which limit production. This study aimed to classify and evaluate the suitability of soils for potato cultivation in Tete Province, where detailed soil assessments remain limited. Four pedons—TSA-P01 and TSA-P02 in Tsangano and ANGO-P01 and ANGO-P02 in Angónia—were examined for bulk density, texture, pH, organic carbon, and nutrient content using a combination of pedological methods and laboratory soil analysis. To determine each site’s potential for growing Irish potatoes, these factors were compared to predetermined land suitability standards. The pedons were very deep (>150 cm) and had textures ranging from sandy clay loam to sandy loam. TSA-P02 had the lowest bulk density (0.78 Mg m⁻³) and the highest available water capacity (182.0 mm m⁻¹). The soil pH ranged from 5.6 to 7.9, indicating neutral to slightly acidic conditions. Nutrient analysis revealed low total nitrogen (0.12–0.22%), varying soil organic carbon (0.16–2.73%), and cation exchange capacity (10.1–11.33 cmol⁽⁺⁾ kg⁻¹). Pedons TSA-P01, ANGO-P1, and ANGO-P02 were characterized by eluviation and illuviation as dominant pedogenic processes, while in pedon TSA-P02, shrinking and swelling were the dominant pedogenic processes. Weathering indices identified ANGO-P01 as most highly weathered, while TSA-P02 was least weathered and had better fertility indicators. According to USDA Taxonomy, the soils were classified as Ultisols, Vertisols, and Alfisols, corresponding to Acrisols, Alisols, Vertisols, and Luvisols in the WRB for Soil Resources. All studied soils were marginally suitable for potato production (S3f) due to dominant fertility constraints, but with varying minor limitations in climate, topography, and soil physical properties. The findings hence recommended targeted soil fertility management to enhance productivity and sustainability in potato cultivation. Full article

Soil salinity affects crop growth and production, especially in arid and semi-arid regions of the world. The interactions between salt ions and soil particles vary depending on soil texture, mineralogy, and ion composition. The relationship between soil ions and particles and the effects of this interaction on crop plants remains underexplored. This study evaluated the plant water relations, growth, and yield of cowpea (Vigna unguiculata) as affected by the salinity of the irrigation water in two different soil types with varying weathering levels and contrasting mineralogies. The treatments consisted of six salinity levels based on the electrical conductivity (EC) of the irrigation water (0, 1.5, 3, 4, 5, 6.0, or 9 dS m⁻¹) and were tested in Ultisol (well-weathered soil) and Alfisol (less-weathered soil). The experiment was conducted over 80 days with 4 repetitions. The results showed that the plant salinity tolerance, growth, and yield in response to salinity varied depending on the soil type. Irrigation with saline water exceeding an EC of 3 dS m⁻¹ completely halted cowpea production in Ultisol, whereas in Alfisol, production ceased at an EC above 6 dS m⁻¹. Although it accumulates more salts under saline irrigation, Alfisol promotes better cowpea growth and yield than Ultisol. Full article

Peanut yield and quality are often threatened by soil degradation under continuous cropping. Biochar has been known to improve the soil microbial community and plant resistance. However, studies on its functions to reduce soil degradation losses and improve the peanut yield are limited. A field peanut experiment was conducted in an Alfisol soil and biochar was applied at a rate of 20 t ha⁻¹ in 2022. The biochar was prepared from woodchip (WB) and maize straw (MB) feedstocks alone, as well as with co-composted biochar of the same feedstocks with pig manure labeled as WBSC and MBSC amendment, respectively. The conventional organic manure was applied as a control treatment (OM). All plots were base-fertilized with a mineral compound fertilizer of N-P₂O₅-K₂O (16-16-16, %) at 600 kg ha⁻¹. Topsoil (20 cm) and plant samples were collected at the time of peanut harvest. Soil quality, enzyme function, peanut growth traits, microbial abundance, and community composition were analyzed. Compared to OM, peanut yields increased by 22%, 23%, and 18% under WB, WBSC, and MBSC, respectively. The content of oleic acid increased by 4–5%, while the content of linoleic acid decreased by 7–9%, respectively, under biochar–compost treatments. However, biochar amendment alone showed non-significant changes in these fatty acids. The soil extracellular enzyme activity increased by 3.7–5.5% with biochar amendments and 6.4–10.1% with biochar–compost application. The enzyme activity ratio of hydrolase to non-hydrolase, of C cycling to N cycling, and of P cycling increased by 11.4–15.9%, 20.9–33.8%, and 14.7–23.5% under biochar amendments and by 20.5–25.0%, 17.4–39.0%, and 23.5–32.3% under biochar–compost, respectively. Overall, crop residue biochar enhanced peanut yield and quality by improving soil aggregation, enzyme functionality, and fungal community in line with the soil nutrient supply. Full article

Our study aimed to assess the impact of sprinkler irrigation on the activity of selected soil enzymes in terms of nitrogen metabolism and oxidation–reduction processes in soil with different doses of inorganic nitrogen fertilizers. An Alfisol was sampled from an experimental field of spring barley within the University Research Center in the central part of Poland, namely the village of Mochełek with a moderate transitory climate, during the growing seasons of 2015–2017. The soil resistance (RS) was derived to recognize the resistance enzymes during drought. In the maturity phase, nitrate reductase activity was 18% higher in irrigated soil and the activities of other enzymes were higher than in the non-irrigated plots by 25% for dehydrogenase, 22% for peroxidase, 33% for catalase, and 17% for urease. The development phase in the barley influenced nitrate reductase activity. Enzymatic activities changed throughout the research years. During the maturity stage, a lower ammonium nitrogen content in the soil resulted from a higher spring barley uptake due to drought stress. Irrigation probably contributed to increased leaching of nitrate in the soil. The highest index of resilience was found in the soil catalase activity. Full article

The United Nations (UN) Land Degradation Neutrality (LDN) evaluation stresses the need to account for different types of land degradation (LD) as part of the UN Sustainable Development Goal (SDG 15: Life on Land) and UN Convention to Combat Desertification (UNCCD). For example, one of the indicators, 15.3.1 Proportion of land that is degraded over total land area, can be differentiated between different types of LD (e.g., urban development, agriculture, barren) when considering land use and land cover (LULC) change analysis. This study demonstrates that it is important to consider not only the overall anthropogenic LD status and trend over time, but also the type of LD to confirm LDN. This study’s innovation is that it leverages remote-sensing-based LULC change analysis to evaluate LDN by different types of LD using the state of Ohio (OH) as a case study. Almost 67% of land in OH experienced anthropogenic LD primarily due to agriculture (81%). All six soil orders were subject to various degrees of anthropogenic LD: Mollisols (88%), Alfisols (70%), Histosols (58%), Entisols (55%), Inceptisols (43%), and Ultisols (22%). All land developments in OH can be linked to damages from LD, with 10,116.3 km² developed, resulting in midpoint losses of 1.4 × 10¹¹ kg of total soil carbon (TSC) and a midpoint social cost of carbon dioxide emissions (SC-CO₂) of $24B (where B = billion = 10⁹, USD). Overall, the anthropogenic LD trend between 2001 and 2016 indicated LDN, however, during the same time, there was a six percent increase in developed area (577.6 km²), which represents a consumptive land conversion that likely caused the midpoint loss of 8.4 × 10⁹ kg of TSC and a corresponding midpoint of $1.4B in SC-CO₂. New developments occurred adjacent to current urban areas, near the capital city of Columbus, and other cities (e.g., Dayton, Cleveland). Developments negated OH’s overall LDN because of multiple types of damages: soil C loss, associated “realized” soil C social costs (SC-CO₂), and loss of soil C sequestration potential. The state of OH has very limited potential land (1.2% of the total state area) for nature-based solutions (NBS) to compensate for the damages, which extend beyond the state’s boundaries because of the greenhouse gas emissions (GHG). Full article

Although crop residue returns are extensively practiced in agriculture, large uncertainties remain about greenhouse gas (GHG) emissions and global warming potential (GWP) responses to residue return (RR) rates under different residue placements and nutrient supplements. We conducted a laboratory mesocosm experiment in Alfisol in central India to investigate the responses of soil GHG emissions (CO₂, N₂O, and CH₄) and the global warming potential to four wheat RR rates (R0: no residue; R5: 5 Mg/ha; R10: 10 Mg/ha; R15: 15 Mg/ha) and two placements (surface [Rsur] and incorporated [Rinc]) under three nutrient supplement levels (NSLs) (NS0: no nutrients, NS1: nutrients (N and P) added to balance the stoichiometry of C:N:P to achieve 30% humification in RR at 5 t/ha, NS2: 3 × NS1). The results demonstrated a significant (p < 0.05) interaction effect of RR × NSL × residue placement on N₂O emission. However, CH₄ and GWP responses to the RR rate were independent of NSL. N₂O fluxes ranged from −2.3 µg N₂O-N kg⁻¹ soil (R5 NS0 Rsur) to 43.8 µg N₂O-N kg⁻¹ soil (R10 NS2 Rinc). A non-linear quadratic model yielded the best fit for N₂O emissions with RR rate (R² ranging from 0.55 to 0.99) in all NSLs and residue placements. Co-applying wheat residue at 10 and 15 Mg/ha at NS1 reduced CH₄ and N₂O emissions (cf. R0 at NS1). However, increasing NSLs in NS2 reduced the nutrient stoichiometry to < 12:1 (C:N) and < 50:1 (C:P), which increased N₂O emissions in all RR rates (cf. R0) across all residue placements. Averaged across nutrient levels and residue placements, the order of the effects of RR rates on CH₄ emissions (µg C kg⁻¹ soil) was R10 (5.5) > R5 (3.8) > R15 (2.6) > R0 (1.6). Our results demonstrated a significant linear response of total GWP to RR rates R15 > R10 > R5 > R0, ranging from 201.4 to 1563.6 mg CO₂ eq kg⁻¹ soil. In conclusion, quadratic/linear responses of GHGs to RR rates underscore the need to optimize RR rates with nutrient supplements and residue placement to reduce GHG emissions and GWP while ensuring optimal soil health and crop productivity. Full article

The concept of soil quality (SQ) is defined as the soil's capacity to function, which is commonly assessed at the field scale. Soil quality is composed of inherent (soil suitability) and dynamic (soil health, SH) SQ, which can also be analyzed using geospatial tools as a SQ continuum (SQC). This study proposes an innovative spatiotemporal analysis of SQ degradation and emissions from land developments using the state of Iowa (IA) in the United States of America (USA) as a case study. The SQ degradation was linked to anthropogenic soil (SD) and land degradation (LD) in the state. More than 88% of land in IA experienced anthropogenic LD primarily due to agriculture (93%). All six soil orders were subject to various degrees of anthropogenic LD: Entisols (75%), Inceptisols (94%), Histosols (59%), Alfisols (79%), Mollisols (93%), and Vertisols (98%). Soil and LD have primarily increased between 2001 and 2016. In addition to agricultural LD, there was also SD/LD caused by an increase in developments often through urbanization. All land developments in IA can be linked to damages to SQ, with 8385.9 km² of developed area, causing midpoint total soil carbon (TSC) losses of 1.7 × 10¹¹ kg of C and an associated midpoint of social cost of carbon dioxide emissions (SC-CO₂) of $28.8B (where B = billion = 10⁹, USD). More recently developed land area (398.5 km²) between 2001 and 2016 likely caused the midpoint loss of 8.0 × 10⁹ kg of C and a corresponding midpoint of $1.3B in SC-CO₂. New developments are often located near urban areas, for example, near the capital city of Des Moines, and other cities (Sioux City, Dubuque). Results of this study reveal several different kinds of SQ damage from developments: loss of potential for future C sequestration in soils, soil C loss, and “realized” soil C social costs (SC-CO₂). The state of IA has very limited potential land (2.0% of the total state area) for nature-based solutions (NBS) to compensate for SD and LD. The results of this study can be used to support pending soil health-related legislation in IA and monitoring towards achieving the Sustainable Development Goals (SDGs) developed by the United Nations (UN) by providing a landscape-level perspective on LD to focus field-level initiatives to reduce soil loss and improve SQ. Future technological innovations will provide higher spatial and temporal remote sensing data that can be fused with field-level direct sensing to track SH and SQ changes. Full article

Soil makes important contributions to the United Nations (UN) Land Degradation Neutrality (LDN) concept and targets; however, currently, soil is not integrated into measurable information (e.g., indicators, metrics) to monitor land degradation (LD) patterns and trends. This study examines the role of soil in LDN in the UN Convention to Combat Desertification (UNCCD), and UN Sustainable Development Goal (SDG 15: Life on Land). This study is specifically focused on the LDN and biodiversity loss as they relate to an indicator 15.3.1 Proportion of land that is degraded over total land area. Tracking of LD status can be improved by using detailed soils databases combined with satellite-derived land cover maps. This study has applied these newly improved methods to quantify and map the anthropogenic LD status and trends in the contiguous United States of America (USA), as well as to identify potential land areas for nature-based solutions (NBS) to compensate for LD. Anthropogenic LD in 2016 in the contiguous USA affected over two million square kilometers, about one-third of the country’s total area, with high variability by state. Between 2001 and 2016, LD in the USA showed an overall increase of 1.5%, with some states exhibiting increases in degraded land while other states had overall improvements to their land. All ten soil orders present in the contiguous USA have been anthropogenically degraded, with Mollisols, Alfisols, and Vertisols having the highest LD levels. Compensating for LD requires a variety of strategies and measures (e.g., NBS), which often require additional land. In 2016, the potential land area for NBS was over two million square kilometers, an area approximately equal to that of degraded land. Some of the states that have high proportions of land available for potential NBS are dominated by soils (Aridisols) typical of deserts and therefore may have less promise for NBS. The variability of LD needs to be evaluated at finer spatial scales for realistic LDN analysis. Full article

The sequestration of soil organic carbon (SOC) through mineral protection is an important approach to mitigating climate change. However, the effect of mineral composition on SOC stability is unclear at regional scales. In this study, we investigated the relationship between mineralogy and SOC in Alfisol and Mollisol from southern and northern regions of China. We analyzed soil at two layers for its SOC fractions, mineralogical characteristics and functional groups. It was found that the majority of SOC was stored as mineral-associated organic C (MAOC), which had higher δ¹³C values and narrower C/N ratios compared to particulate organic C. In Mollisol, the proportion of MAOC and the abundance of aromatic C were higher than that in Alfisol, while polysaccharide C was lower. Compared to Alfisol, Mollisol was dominated by illite, and had significantly (p < 0.05) lower iron (Fe) and aluminum (Al) sesquioxides contents. The SOC content was positively correlated with illite in Mollisol, and with Fe and Al sesquioxides in Alfisol. The random forest model identified sesquioxides as the most important determinant of SOC accumulation (36%), followed by SOC fractions (18%) and functional groups (18%). In summary, our study suggests that SOC protection through mineralogy depends more on the composition of the host minerals, and not just on the clay content, and aromatic C is also important in the stabilization of SOC. Full article

Purple soil is a type of global soil that is referred to by various names in different countries, which makes it difficult to understand, utilize, and ameliorate purple soil internationally. Soil Taxonomy (ST) and the World Reference Base for Soil Resources (WRB) are the most widely used soil classification systems in the world. The aim of this study was to clarify the classification of purple soil in ST and the WRB and to establish a reference between different classification systems of purple soil. Therefore, based on the current principles and methods of the ST and WRB systems, 18 typical purple soil profiles in the eastern Sichuan Basin were identified, retrieved, and classified. Then, the soil units of the WRB were compared with those of ST and the Chinese Soil Taxonomy (CST). The results revealed that the 18 typical purple soil profiles could be classified into three soil orders, four soil group orders, and seven soil subgroups in ST and four reference soil groups (RSGs) in the WRB; each profile had its own unique principal and supplementary qualifier combinations within the soil units. It was found that when compared with the ST system, the WRB and CST systems had stronger abilities to distinguish purple soil. In addition, the WRB system was able to more comprehensively consider soil characteristics such as soil layer thickness, ferric horizon, soil color, texture mutations, and carbonate through qualifiers. However, the CST system added diagnostic characteristics, such as the lithologic characteristics of purplish sandstones and shales and the ferric properties and alic properties at the soil group and subgroup levels, which enhanced the differentiation ability of the purple soil at the subgroup level. Full article