{"type": "FeatureCollection", "features": [{"id": "10.1016/j.agee.2005.10.020", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:15:31Z", "type": "Journal Article", "created": "2006-01-11", "title": "Soil Acidification Without Ph Drop Under Intensive Cropping Systems In Northeast Thailand", "description": "Light textured sandy soils occupy significant areas of Northeast Thailand and are characterized as being acidic to depth with a low inherent fertility. These soils form the basis of agricultural production systems on which significant numbers of people depend upon for livelihoods. The objectives of this study were to investigate soil acidification following the introduction of Stylosanthes in cropping systems of a tropical semi-arid region. Most soils in Northeast Thailand are sandy and acidic (pH 4.0 in CaCl2) with high rate of drainage. Soil acidification was studied over a 6-year period on plots that had been treated either with or without lime additions under different cropping patterns. In the initial first 3 years, a rotation of maize and cowpea was compared to a bare soil treatment where no vegetation was allowed to establish. During the following 3 years, a rotation of maize and Stylosanthes was compared to a continuous Stylosanthes hamata (stylo) treatment. Total soil acidification was calculated from measured pH changes and pH buffer capacity. Acidification due to root system activity was estimated from the above ground biomass production and its ash alkalinity. In the limed systems, soil pH decrease was well correlated with the ash alkalinity of the crop and its removal from the plot. Acidification was highest in the bare soil (6.3 kmol H+ ha(-1) year(-1)), due to leaching of applied N fertilizers. The cowpea-maize rotations did not increase significantly the rate of acid addition (7.6 kmol H+ ha(-1) year(-1)), since the crop residues were returned to the plot. The introduction of stylo in the cropping system resulted in a lower net acidification rate when it was cultivated in rotation with maize (1.3 kmol H+ ha(-1) year(-1)), due to the lower rate of leaching. In contrast, continuous cultivation of stylo triggered accelerated acidification (7.2 kmol H+ ha(-1) year(-1)), as a result of the large quantities of biomass with high ash alkalinity being removed from the plot. In the no-lime system, the pH of the soil profile remained stable at pH 4.0 regardless of the cropping system, even though the acidification rates were quite similar to those in the limed treatments. This would suggest that the soil was strongly buffered at pH 4.0. XRD patterns showed that kaolinite, the main clay mineral, was more disordered and less crystalline in the surface horizons than at depth. It is suggested that the dissolution of kaolinite is responsible for the buffering of soil pH at 4.0. From the dissolution equation of kaolinite, it is expected that the amount of aluminium in the topsoil would increase along with the release silica that would accelerate cementation processes between soil particles resulting in further degradation. (c) 2005 Elsevier B.V. All rights reserved.", "keywords": ["550", "SANDY SOILS", "buffering capacity", "01 natural sciences", "630", "soil degradation", "acidification", "[SDV.EE]Life Sciences [q-bio]/Ecology", "sandy soils", "BUFFERING CAPACITY", "0105 earth and related environmental sciences", "2. Zero hunger", "kaolinite", "SOL SABLEUX", "cropping systems", "04 agricultural and veterinary sciences", "Stylosanthes", "KAOLINITE", "15. Life on land", "6. Clean water", "[SDV.EE] Life Sciences [q-bio]/Ecology", " environment", "ASH ALKALINITY", "0401 agriculture", " forestry", " and fisheries", "environment", "ash alkalinity", "STYLOSANTHES", "ACIDIFICATION"]}, "links": [{"href": "https://doi.org/10.1016/j.agee.2005.10.020"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Agriculture%2C%20Ecosystems%20%26amp%3B%20Environment", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.agee.2005.10.020", "name": "item", "description": "10.1016/j.agee.2005.10.020", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.agee.2005.10.020"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2006-06-01T00:00:00Z"}}, {"id": "10.1016/j.geoderma.2007.11.019", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:16:38Z", "type": "Journal Article", "created": "2008-01-18", "title": "Soil Acidification And Carbon Storage In Fertilized Pastures Of Northeast Thailand", "description": "Abstract   Light textured soils are often characterized as acid to depth that results in low productivity levels. In an effort to address this constraint a four year study was undertaken that evaluated the productivity of Gamba grass (Andropogon gayanus) and Stylosanthes (Stylosanthes guianensis) (Stylo) to grow on these soils. In addition, Gamba grass treatments received either no nitrogen fertilizer (Gamba) or a total 287\u00a0kg N ha\u2212\u00a01 as either KNO3 (Gamba NO3) or (NH4)2SO4 (Gamba NH4). Average annual dry matter production levels for the Gamba, Gamba NO3 and Gamba NH4 were 11.9, 22.5, and 26.6\u00a0t ha\u2212\u00a01 whilst that of the Stylo treatment was 6.9\u00a0t ha\u2212\u00a01. However, the net annual acid addition rates associated with the export of biomass ranged from 5.1\u201313.3\u00a0kmol H+ ha\u2212\u00a01 yr\u2212\u00a01. Rapid acidification of the soil profile was observed to depths\u00a0>\u00a0110\u00a0cm in all treatments regardless of the tempering influence of nitrate based fertilizers. Soil organic carbon levels over the study period showed a 6 fold increase at >\u00a030\u00a0cm from the initial values, suggesting significant carbon sequestration. Whilst the study demonstrates the positive impact of a grass or legume ley in producing forage for livestock in a cut and carry system under rainfed conditions in Northeast Thailand, along with positive contributions to soil organic carbon sequestration, a precautionary approach should be adopted. Significant accelerated soil acidification has occurred to depths\u00a0>\u00a0110\u00a0cm that brings into question the sustainability of these systems on these soil types.", "keywords": ["2. Zero hunger", "carbon", "soil texture", "04 agricultural and veterinary sciences", "15. Life on land", "pastures", "6. Clean water", "acidification", "nitrogen fertilizers", "soil properties", "feeds", "stylosanthes guianensis", "0401 agriculture", " forestry", " and fisheries", "sandy soils", "andropogon gayanus"], "contacts": [{"organization": "Noble, A.D., Suzuki, S., Soda, Wannipa, Ruaysoongnern, Sawaeng, Berthelsen, S.,", "roles": ["creator"]}]}, "links": [{"href": "https://doi.org/10.1016/j.geoderma.2007.11.019"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Geoderma", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1016/j.geoderma.2007.11.019", "name": "item", "description": "10.1016/j.geoderma.2007.11.019", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1016/j.geoderma.2007.11.019"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2008-03-01T00:00:00Z"}}, {"id": "10.1038/371236a0", "type": "Feature", "geometry": null, "properties": {"updated": "2026-04-13T16:18:08Z", "type": "Journal Article", "created": "2003-08-12", "title": "Carbon Storage By Introduced Deep-Rooted Grasses In The South American Savannas", "description": "ESTIMATES of the global carbon dioxide balance have identified a substantial 'missing sink' of 0.4\u20134.3 Gt per year1. It has been suggested that much of this may reside in the terrestrial biosphere2. Here we present an analysis of the carbon stored by pastures based on deep-rooted grasses which have been introduced in the South American savannas. Although the deep-rooted grasses were chosen principally for agricultural reasons3, we find that they also sequester significant amounts of organic carbon deep in the soil. If our study sites are representative of similar pastures throughout South America, this process could account for the sequestration of 100\u2013507 Mt carbon per year\u2014a substantial part of the 'missing sink'. Thus, although some land-use changes4 (such as burning tropical rainforests) contribute to the atmospheric CO2 burden, we conclude that the introduced pastures studied here help to offset the effect of anthropogenic CO2emissions.", "keywords": ["2. Zero hunger", "carb\u00f3n", "carbon", "arachis pintoi", "root systems", "04 agricultural and veterinary sciences", "15. Life on land", "feed crops", "01 natural sciences", "sistema radicular", "brachiaria humidicola", "savannas", "13. Climate action", "0401 agriculture", " forestry", " and fisheries", "andropogon gayanus", "sabanas", "stylosanthes", "0105 earth and related environmental sciences"]}, "links": [{"href": "https://doi.org/10.1038/371236a0"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Nature", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.1038/371236a0", "name": "item", "description": "10.1038/371236a0", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.1038/371236a0"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "1994-09-01T00:00:00Z"}}], "links": [{"rel": "self", "type": "application/geo+json", "title": "This document as GeoJSON", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Stylosanthes&f=json", "hreflang": "en-US"}, {"rel": "alternate", "type": "text/html", "title": "This document as HTML", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Stylosanthes&f=html", "hreflang": "en-US"}, {"rel": "collection", "type": "application/json", "title": "Collection URL", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main", "hreflang": "en-US"}, {"type": "application/geo+json", "rel": "first", "title": "items (first)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Stylosanthes&", "hreflang": "en-US"}, {"rel": "last", "type": "application/geo+json", "title": "items (last)", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items?keywords=Stylosanthes&offset=3", "hreflang": "en-US"}], "numberMatched": 3, "numberReturned": 3, "distributedFeatures": [], "timeStamp": "2026-04-15T10:39:33.513516Z"}