What is the agricultural importance of loess?
The agricultural importance of loess. Abstract. Loess soils are among the most fertile in the world, principally because the abundance of silt particles ensures a good supply of plant-available water, good soil aeration, extensive penetration by plant roots, and easy cultivation and seedbed production.
Why is loess soil so fertile?
Loess soils are among the most fertile in the world, principally because the abundance of silt particles ensures a good supply of plant-available water, good soil aeration, extensive penetration by plant roots, and easy cultivation and seedbed production.
What are the characteristics of loess soil?
Loess often develops into extremely fertile agricultural soil. It is full of minerals and drains water very well. It is easily tilled, or broken up, for planting seeds. Loess usually erode s very slowly—Chinese farmers have been working the loess around the Yellow River for more than a thousand years.
Is loess easily tilled?
It is easily tilled, or broken up, for planting seeds. Loess usually erodes very slowly—Chinese farmers have been working the loess around the Yellow River for more than a thou sand years. The Yellow River gets its name from the yellow loess suspended in the water.
Why are loess deposits so difficult to identify?
Because they have been weathered (decalcified), disturbed, mixed with other deposits beneath and extensively redistributed either by solifluction during the later episodes of the Devensian cold stage or by slopewash and streams during the Holocene, British loess deposits are often quite difficult to identify in the field, and soil analyses such as particle size distribution and mineralogy are necessary to confirm their presence Catt, 1978, Catt and Staines, 1982, Catt et al., 1971, Catt et al., 1974. In areas where other pre-Holocene surface deposits are virtually silt-free, the presence of quite small amounts of loess (10%) in soil horizons can be confirmed by analyses at ? (?log 2 mm) or even coarser size intervals Avery et al., 1959, Harrod et al., 1974. Similarly the coarse silt (16–60 μm) fraction of the Late Devensian loess in southern and eastern England contains a characteristic mineral suite, which can be used to identify a loess component in mixed soil or sediment horizons Catt et al., 1971, Catt et al., 1974, Gibbard et al., 1987, Recio Espejo et al., 1992, to distinguish the Devensian from older loess components (Avery et al., 1982) or to distinguish the loess from silt derived from other sources such as weathered Palaeozoic shales (Catt and Staines, 1982).
How does climate affect soil nitrogen?
Early American work on loess soils showed the importance of climate in determining the amounts of topsoil organic matter under natural grassland and therefore the natural reserves of soil nitrogen, which occurs mainly in the organic matter. In the virgin (uncultivated) prairie soils of the Midwest, Alway and McDole (1916), Russell and McRuer (1927), Jenny and Leonard (1934) and Gillam (1939) found that topsoil organic matter and total nitrogen content increase eastwards as mean annual rainfall increases. This was because where the soil was wetter, there was greater growth of prairie grass and more plant residues were incorporated into the soil. However, temperature is also important in determining the amount of organic matter, as the warmer the soil the faster is the organic matter mineralised. By incorporating data on mean annual temperature, Jenny (1941) was therefore able to construct a three-dimensional “nitrogen-climate surface” for the prairie loess soils of the Great Plains (Fig. 1). In this figure, precipitation is replaced by the NS Quotient of Meyer (1926), which is rainfall (mm) divided by the absolute saturation deficit of air (mm Hg). This allows for water lost by evaporation, which does not contribute to plant growth and thus to incorporation of organic nitrogen into the soil. Fig. 1 shows that at constant temperature, soil nitrogen increases logarithmically with NS Quotient, though the rate is greater at lower temperatures. At a constant NS Quotient nitrogen decreases exponentially as temperature increases, and the rate of decrease is greater where more water enters the soil. These relationships apply to the nitrogen contents of loess soils that have reached equilibrium over several millenia under prairie grassland, but once such soils come under cultivation their organic nitrogen content decreases because of accelerated mineralisation.
What is the most fertile soil?
Throughout the world, soils derived from loess have long been regarded as among the most fertile. However, the exact meaning of this description is unclear. Soil fertility depends on a range of physical and chemical properties that are determined by present climatic and biological factors, past climatic and geomorphological history and recent human activities as well as by the nature of the soil parent material. One must also distinguish between natural (inherent) soil fertility sustained without use of fertilisers, organic manures, irrigation or special cultivation techniques and fertility that depends on one or more of these treatments. At low levels of soil and crop management, as in prehistoric periods or present-day underdeveloped regions, differences in inherent fertility have maximum effect on plant growth and crop yields. As management improves, differences in growth and yield between soil types become smaller and may even disappear. However, in conditions of uniformly high levels of management, productivity differences between soil types often re-emerge, sometimes because of the same inherent soil factors as influenced fertility under low or zero management. Statements and opinions concerning the high fertility of loess-derived soils may refer to any of these three stages, though it is likely that most reflect the success of primitive, low-management agriculture in early centres of civilisation, such as northern China, eastern and central Europe.
Why is loess soil so fertile?
Loess soils are among the most fertile in the world, principally because the abundance of silt particles ensures a good supply of plant-available water, good soil aeration, extensive penetration by plant roots, and easy cultivation and seedbed production. Also micaceous minerals in the silt and clay fractions provide an adequate supply …
Where is the Loess soil experiment?
One of the oldest field experiments on a loess soil (chernozem) in Europe is the Static Fertilization Experiment at Bad Lauchstädt in Germany (Körschens and Müller, 1993). This was started in 1902 in one of the driest areas of Germany (mean annual rainfall 489 mm), and has a range of fertiliser treatments with and without farmyard manure as well as a nil (untreated) plot. Over the last 90 years, yields of winter wheat grown continuously have increased on all plots, including the nil plot, principally because of better cultivars, more advanced plant protection and increased deposition of nitrogen compounds from the atmosphere. Over the decade 1983–1992, the yields on the nil plot were 43–94% of the yearly maxima obtained with any fertiliser/manure treatment (Table 2). By comparison, in the Broadbalk Experiment at Rothamsted (UK), where the soil is derived from a much thinner loess layer over Clay-with-flints (Catt, 1969), the yields of the nil plots in continuous wheat were only 8–26% of the maxima obtained with fertilisers or manure in the same years (1983–1992) (Table 2). Most of the year-to-year variation in yield at Bad Lauchstädt is related to seasonal rainfall, and Körschens and Müller (1993) suggested that the large yields of the nil plot compared with those of other soils result from (a) deeper root penetration (2+ m) leading to more efficient use of water and available nutrients, and (b) weaker tillering without fertiliser, which gives more efficient utilisation of water in periods of drought.
What is the loss of fertility in Illinois?
In Illinois, Hopkins and Pettit (1908) also noted loss of fertility through accelerated decomposition (mineralisation) of organic matter resulting from continual cultivation of loess soils. They showed that the darker-coloured, more organic soil, usually formed in a thin layer of loess overlying various glacial deposits, had much larger natural reserves of plant-available nitrogen and slightly more available phosphorus than other soils in Illinois, including the less organic, degraded “yellow” soils on thick loess deposits. As a result the yields of unfertilised wheat in field experiments were 59–154% greater on the organic loess soils than on “tight clay” soils and 11–77% greater than on the “yellow” loess soils.
What are the effects of dust on soil?
Further possible beneficial effects of dust deposited on soils other than those in thick loess are improved potassium, magnesium, calcium and micronutrient contents Tiessen et al., 1991, Drees et al., 1993. For example, in a sequence of soils with increasing rates of loessial dust deposition onto greywacke-derived river gravels in New Zealand, both plant uptake of potassium (Hay et al., 1976) and amounts of available micronutrients (Fe, Mn, Zn, Cu and Co) (Haynes and Swift, 1984) were increased by increasing amounts of dust. Similarly, the modern dust from China and Mongolia, which is deposited on parts of Japan at rates equivalent to 3.6–7.1 mm/1000 years, increases soil potassium contents (Inoue and Naruse, 1987) mainly because it contains micas and other layer-silicate clay minerals (Mizota et al., 1992). However, the natural potassium-supplying power of loess soils decreases with increasing rainfall Wells and Riecken, 1969, Hay et al., 1976, because exchangeable K and interlayer K in layer silicates are easily removed by leaching. Potassium-containing feldspars are often abundant in the silt fraction of loess, but are very resistant in most environments and provide almost no plant-available or leachable K.
What is the layer of fine mineral rich material called?
Vocabulary. In some parts of the world, windblown dust and silt blanket the land. This layer of fine, mineral -rich material is called loess. Loess is mostly created by wind, but can also be formed by glacier s. When glaciers grind rocks to a fine powder, loess can form.
What causes dust to settle in the desert?
On the far side of the desert, moisture in the air causes the particles and dust to settle on the ground. There, grass and the roots of other plants trap the dust and hold it to the ground. More dust slowly accumulates, and loess is formed. Loess often develops into extremely fertile agricultural soil.
How thick is loess?
Loess ranges in thickness from a few centimeters to more than 91 meters (300 feet). Unlike other soil s, loess is pale and loosely packed. It crumbles easily; in fact, the word “loess” comes from the German word for “loose.”. Loess is soft enough to carve, but strong enough to stand as sturdy walls.
What are the particles that wind blows across the Gobi?
For example, as wind blows across the Gobi, a desert in Asia, it picks up and carries fine particle s. These particles include sand crystal s made of quartz or mica. It may also contain organic material, such as the dusty remains of skeleton s from desert animals.
What is a natural substance composed of solid mineral matter?
natural substance composed of solid mineral matter. part of a plant that secures it in the soil, obtains water and nutrients, and often stores food made by leaves. small, loose grains of disintegrated rocks. solid material transported and deposited by water, ice, and wind.
What is solid material transported and deposited by?
solid material transported and deposited by water, ice, and wind.
What is an inorganic material?
inorganic material that has a characteristic chemical composition and specific crystal structure.
How does biochar affect soil?
There is sparse peer-reviewed literature on the biochar effects on the thermal properties of soils although they play an important role in the soil energy balance and resulting temperature distribution. The objective of this study was to quantify the effect of biochar from wood off cuts on the thermal conductivity, heat capacity, thermal diffusivity, albedo, water content, and bulk density of loess soil under grassland (G) and fallow (F) in the temperate climate of Poland. The biochar at an amount of 0, 10, 20, and 30 Mg ha?1 was incorporated to a depth of 0–15 cm under F and remained on the surface under G. All field measurements were done on 24 occasions from spring to autumn in 2013–2014. Additional laboratory measurements of the thermal properties in water saturated (Wet) and dry (Dry) states. Incorporation of biochar under the F led to reduced soil bulk density and particle density from 1.18–1.20 Mg m?3 and 2.48–2.55 Mg m?3 under F0 and F10 to 1.00 Mg m?3 and 2.20 Mg m?3 under F30, respectively. The field measured average water contents were greater under F while the minimum ones were lower in biochar-amended than control soil without biochar. In general, the average thermal conductivity and thermal diffusivity and values of thermal conductivity at the saturation and dry state under F in general decreased with the increasing biochar application rate. After biochar addition, the albedo decreased with the increasing biochar application rate and was considerably greater under F than G. After rain, there was substantial reduction of the albedo under F in contrast to G, where it was increased. Changes in the soil thermal properties in response to biochar application were most pronounced under F and those in albedo under G. Irrespective of the biochar application rate, the average thermal conductivity and water content were greater under G than F. The daily soil temperature amplitude in biochar amended plots decreased under G and increased under F. The use of the statistical-physical model showed that the rate of the increase in the thermal conductivity and thermal diffusivity with increasing soil water content was greater in soil with greater rather than lower bulk density. The relatively wide range of variations suggests that biochar application can be an important factor in regulation of the thermal soil properties and albedo as well as climate change.
What is the most used herbicide in agriculture?
Glyphosate is the most used herbicide in agricultural lands worldwide, with more than 825 000 tons sold globally in 2014. Such great use is mostly a result of the introduction of glyphosate-resistant (GR) crops in 1996 by Monsanto company. Loess soils, on the other hand, are amongst the most productive and fertile soils and, consequently, are intensively used for agriculture and to grow GR crops. Consequently, they are heavily subject to the application of glyphosate-based herbicides every year. Despite being the most used pesticide worldwide, the environmental fate of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) is still not well understood. Therefore, this PhD thesis aims at better understanding the environmental fate of glyphosate and AMPA in the loess soil environment. Special focus is given to: 1) the decay kinetics of glyphosate and the formation and decay kinetics of AMPA; and 2) the off-site transport of glyphosate and AMPA associated to the particle-bound phase, as a result of wind and water erosion. These processes were studied under laboratory and field conditions. The field study was performed in agribusiness fields of the loess Pampas of Argentina. The results of this PhD thesis have shown that: 1) the decay of glyphosate and AMPA in loess soils is mostly a microbiological process and is fastest under warm and moist soil conditions and slowest under cold and dry soil conditions; 2) AMPA persists longer in loess soil than glyphosate, and tends to accumulate; 3) the type of decay kinetics followed by glyphosate in loess soils is mostly temperature dependent, but abrupt soil moisture changes from dry to moist also play a role; 4) glyphosate degradation into AMPA was extremely variable (5-100%) amongst different temperature conditions and between laboratory and field conditions; 5) glyphosate and AMPA contents are highest in eroded soil particles <10 µm (PM10) and, consequently, their long-range off-site transport risk with wind erosion (dust) is very high: 6) during water erosion events, the particle-bound transport of glyphosate and AMPA is as or even more important than the water-dissolved transport; and 7) the risk of deposition of glyphosate and AMPA into off-target downslope fields during water erosion events can be considerable. It is concluded that repeated glyphosate applications, particularly under dry soil conditions, increase the risk of accumulation of glyphosate and AMPA in loess soils and, consequently, of on-site soil pollution and off-site transport with wind and water erosion.
What are the most fertile soils in the Balkan Peninsula?
The loess in the Danubian plain is rich of nutrients and there is situated the south border of so called ―corn belt of Europe‖, where are the most fertile soils of Balkan Peninsula. There are five main typical soil types spread over loess - Chernozems, Phaeozems, Kastanozems, Regosols and Calcisols. There is also a big diversity in the content of basic nutrient elements – it varies between low and high content of organic carbon and mobile forms of nitrogen, phosphorous and potassium. As a whole there is shortage of phosphorus in all soil types. Soils over loess are characterized by a surface layer that is rich in organic matter, minerals and nutrients with abundant natural grass vegetation and high fertility soil types such as Chernozems, Phaeozems and Kastanozems. Eroded and shallow soils such as Regosols and Calcisols have low quantities of major nutrient elements as mobile nitrogen, phosphorus, and total organic matter, consequently their fertility is low.
Why is loess soil so fertile?
The loess soils are among the most fertile in the world, principally because the abundance of plant-available water, good soil aeration, adequate supply of nutrients, extensive penetration by plant roots, and easy cultivation and seedbed production. However, loess soils often contain little clay, resulting structural instability …
Where are the loess deposits located?
In the Rhône Valley, a north-south oriented Cenozoic rift in southeast France, thick Pleistocene loess deposits have been recognized since the beginning of the last century. These loess records, which are disconnected from the North European Loess Belt (NELB), are of significant interest to document the evolution of perimediterranean landscapes and environments during the Last Glacial. To overcome the poor precision of available aeolian distribution maps, aeolian deposits were mapped using the topsoil textural database provided by the Land Use and Cover Area frame Statistical Survey project (LUCAS). The grain-size distribution of aeolian sand and loess was first determined using 116 samples taken from surveyed outcrops. Then, the areas showing a similar grain-size composition were extracted from the LUCAS rasters. The resulting map reproduces the conventional maps correctly but suggests a more significant extension of loess, in better agreement with the known distribution of outcrops. The map shows that the distinctive morphology of the valley dominantly controls the distribution of aeolian deposits. The deflation-related landforms, i.e., yardangs, closed depressions (pans), and desert pavements, are widespread south of narrowings of the Rhône Valley between latitudes 44°N and 45°N. They indicate palaeowinds blowing from the north/northwest. Aeolian sand, loessic sand, sandy loess, and loess deposits successively spread on both sides of the Rhône River. The loess is characterized by a coarse texture (main mode around 60 μm), strong local thickness (>5 m), limited extension, and abundant bioturbation. This preservation results from the persistence of a shrub vegetal cover during the coldest and driest phases of the Last Glacial that allowed for trapping the saltating and suspended particles close to the alluvial sources.
Where are rills found?
Rills are commonly found on sloping farm fields in both the loess and the purple soil regions of China . A comparative study on rill erosion between the two soils is important to increase research knowledge and exchange application experiences. Rill erosion processes of loess and purple soils were determined through laboratory experiments with the volume replacement method. Water was used to refill the eroded rill segments to compute eroded volume before sediment concentration distribution along the rill was computed using the soil bulk density, flow rate, and water flow duration. The experimental loess soil materials were from the Loess Plateau and purple soil from the southwestern part of China, Chongqing City. A laboratory experimental platform was used to construct flumes to simulate rills with 12.0m length, 0.1m width, and 0.3m depth. Soil materials were filled into the flumes at a bulk density of 1.2gcm-3 to a depth of 20cm to form rills for experiments on five slope gradients (5°, 10°, 15°, 20°, and 25°) and three flow rates (2, 4, and 8L/min). After each experimental run under the given slope gradient and flow rate, the rill segments from the upper slope between 0-0.5, 0.5-1, 1-2, 2-3,.., 7-8, 8-10, and 10-12m were lined with plastic sheets before be re-filled with water to determine sediment concentration after the eroded volumes was measured. Rill erosion differed between the two soils. As purple soil started to erode at a higher erosive force than loess soil, it possibly exhibits higher resistance to water erosion. The subsequent erosion process in the eroding purple rill was similar to that in the loess rill. However, the total erosion in the eroding loess rill was more than that in the eroding purple rill. The maximum sediment concentration transported by the eroding purple rills was significantly lower, approximately 55% of those transported by the loess rills under the same flow rate and slope gradient. Hence, less purple sediments can be transported compared with loess sediments. These findings were validated through comparison with existing studies. The results indicate that the research methods and experiences on rill erosion can be inter-exchanged between the loess and purple soils.
What are the most complete terrestrial archives of Quaternary climatic cyclicality?
Loess-palaeosol sequences represent the most complete terrestrial archives of Quaternary climatic cyclicality. Particle size and geochemistry are widely used proxy data in palaeoclimatologic analysis of loess-palaeosol sequences . The palaeoclimatologic signals hidden in the texture and chemical composition of the Czech loess-palaeosol sequences , which are part of the European loess belt, are modulated by temporal changes in the interplay of oceanic and continental macroclimates and by the diverse bedrock geology of the Bohemian Massif. Innovative tools of compositional data analysis, including log-ratio transformation and scalar-on-function regression, can substantially enhance the information value of large granulometric and geochemical datasets, when compared to classical statistics of raw data. Particle size distribution and bulk-rock geochemistry of 389 and 542 samples, respectively, from four Czech loess-palaeosol sequence sections representing the last glacial-interglacial cycle were analysed in this study. Centered log-ratio transformation was applied to the key elemental proxies and their spatial (between sections) and stratigraphic (within section) distribution. Centered log-ratio transformed densities of key elements were then plotted against particle size distribution to assess the particle size control on element concentrations. Nearly all loess-palaeosol sequence samples exhibit a bimodal particle size distribution with medium/coarse silt and coarse clay fraction representing the main modes. The dominant silt fraction is completely allogenic. The clay component is partly allogenic, transported by high altitudes air stream, and partly authigenic (neoformed in situ by pedogenic processes). However there is only a minor variation in particle size between the sections, the centered log-ratio transformed density functions reveal that the particle size control on the distribution of major and trace elements is highly site-specific. The provenance signal is recorded especially in coarser-grained fractions transported for a short distance from the source area by near-surface wind. The proportion of the authigenic clay fraction, the alteration of feldspars, micas and low alkali contents indicated by high Rb/K ratio and high values of Rb/Sr and Sr/Ca ratios, which indicate the intensity of carbonate leaching, reflect the intensity of chemical weathering, which is highest in the podzols. Precipitation rates were likely the main microclimatic factor that controlled the compositional differences. The loess-palaeosol sequences in areas with higher present-day annual precipitation show higher contents of clay minerals, higher degree of loessification (cementation) and subsequent pedogenic changes.
What is the feature of the Loess Plateau?
Feature/ Turning desert to fertile farmland on the Loess Plateau. Feature/. Turning desert to fertile farmland on the Loess Plateau. Soil is not just dirt but a living system with many important functions. Degraded soils impact on food production, erosion, and more, affecting the lives of people around the world.
Why is it important to have resilient soil?
Building resilience in healthy and restored soils is essential to help them retain functions in a world of global environmental change , in which disturbances, such as drought and flooding, are expected. “The fundamental idea of resilience is how the system can respond to a shock,” says Johan Six, an agroecologist at the Swiss Federal Institute of Technology (ETH Zurich). “A shock causes a disturbance, but a healthy and resilient soil will be able to recover, rather than deteriorate.”
Why is it important to build resilience in healthy soils?
Building resilience in healthy and restored soils is essential to help them retain functions in a world of global environmental change
What happened in the 7th century?
By the 7th century, the rich soils were feeding about one quarter of the Chinese population. But intense pressure on the land eroded the soil. By the 20th century, desertification had condemned the remaining population to poverty.
How does soil have resilience?
Building resilience in healthy soils means managing this complexity: from the chemical make-up of the soil that allows nutrients to circulate, and the presence of microbes and other organisms to break down organic matter, to how often the soil is disturbed by a plough or compressed by heavy machinery. The structure of the soils – which the soil experts sometimes refer to as soils physics – is also important, and centres around large and small clumps of soil that hold together. Six explains that in healthy soils, it is the way the clumps set in place that protects microbial populations and also traps carbon, nitrogen, and other nutrients.
Why is the soil in bad shape?
In 2015 a landmark report from the United Nations Food and Agriculture Organization (FAO) found that one third of the planet’s soils are in bad shape due to erosion, salinisation, chemical pollution, and more. 1. 1. UN FAO, 2015. Status of the World’s Soil Resources. PDF See all references.
How many people are affected by land degradation?
The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), which has released summaries of its soon-to-be-published 2018 comprehensive report, concludes that land degradation affects approximately 3.2 billion people around the world. Unsustainable agriculture expansion, urban expansion, and climate change are among the top causes. According to the IPBES findings, investing in avoiding degradation and restoring degraded land makes financial sense – the short-term gains from activities that lead to degradation are small in comparison to the value of what is lost in the degradation.