Water infiltration and soil structure related to organic matter and its stratification with depth

2002 ◽  
Vol 66 (2) ◽  
pp. 197-205 ◽  
Author(s):  
A.J Franzluebbers
Author(s):  
Vito Ferro ◽  
Vincenzo Bagarello

Field plots are often used to obtain experimental data (soil loss values corresponding to different climate, soil, topographic, crop, and management conditions) for predicting and evaluating soil erosion and sediment yield. Plots are used to study physical phenomena affecting soil detachment and transport, and their sizes are determined according to the experimental objectives and the type of data to be obtained. Studies on interrill erosion due to rainfall impact and overland flow need small plot width (2–3 m) and length (< 10 m), while studies on rill erosion require plot lengths greater than 6–13 m. Sites must be selected to represent the range of uniform slopes prevailing in the farming area under consideration. Plots equipped to study interrill and rill erosion, like those used for developing the Universal Soil Loss Equation (USLE), measure erosion from the top of a slope where runoff begins; they must be wide enough to minimize the edge or border effects and long enough to develop downslope rills. Experimental stations generally include bounded runoff plots of known rea, slope steepness, slope length, and soil type, from which both runoff and soil loss can be monitored. Once the boundaries defining the plot area are fixed, a collecting equipment must be used to catch the plot runoff. A conveyance system (H-flume or pipe) carries total runoff to a unit sampling the sediment and a storage system, such as a sequence of tanks, in which sediments are accumulated. Simple methods have been developed for estimating the mean sediment concentration of all runoff stored in a tank by using the vertical concentration profile measured on a side of the tank. When a large number of plots are equipped, the sampling of suspension and consequent oven-drying in the laboratory are highly time-consuming. For this purpose, a sampler that can extract a column of suspension, extending from the free surface to the bottom of the tank, can be used. For large plots, or where runoff volumes are high, a divisor that splits the flow into equal parts and passes one part in a storage tank as a sample can be used. Examples of these devices include the Geib multislot divisor and the Coshocton wheel. Specific equipment and procedures must be employed to detect the soil removed by rill and gully erosion. Because most of the soil organic matter is found close to the soil surface, erosion significantly decreases soil organic matter content. Several studies have demonstrated that the soil removed by erosion is 1.3–5 times richer in organic matter than the remaining soil. Soil organic matter facilitates the formation of soil aggregates, increases soil porosity, and improves soil structure, facilitating water infiltration. The removal of organic matter content can influence soil infiltration, soil structure, and soil erodibility.


2021 ◽  
Author(s):  
Alla Yurova ◽  
Valery Kiryushin ◽  
Anna Yudina

&lt;p&gt;The key for implementation of sustainable development goals in land management is in multifunctional paradigm of landscape usage. A lot of scientific efforts were done since 1980s (e.g. Kiryushin, 2019) to develop a landscape-adaptive system which is in essence addressing&lt;/p&gt;&lt;p&gt;1) spatial distribution of plant varieties and farm operations adapted to topographical and lithological landscape features 2) temporal tuning of crop phenology to regional and even local weather conditions. This system proved especially useful in increasing the yield and yet reducing pollution level in experimental settings. However, there were no boost of implementation in the country of origin-Russia- due to number of reasons, social and economical included. The rapid growth of carbon tax and carbon market provides a new window of opportunity for landscape adaptive agriculture, but only in case documented benefit for carbon sequestration could be shown. Here we present theoretical proof of concept based on integrated critical zone model, 1D-ICZ (Giannakis et al, 2017), that couples computational modules for soil organic matter dynamics, soil aggregation and structure dynamics, bioturbation, plant productivity and nutrient uptake, water flow, solute speciation and transport, and mineral weathering kinetics. The model was applied to study C sequestration soil function along the regional natural soil moisture and temperature gradient. Calibration was done for three soil types (Retisols, Phaeozems, Chernozems) of increasing moisture deficits representing the well-drained landscape shoulder positions with an automorphic regime and hydromorphic footslope positions. The scenario simulation included the change in relative frequency of weather condition with low and extremely low, but also high end extremely high precipitation (from IPCC set of climate models). The model explicitly couples water infiltration storage and supply to soil structure and pedotransfer functions varying with meteorological conditions. This interaction allowed to select the current soil configuration and usage or structural and biogeochemical change in each soil and each scenario that are presumably most beneficial for C sequestration. The role of climate variables was maximum for automorphic regime and decreased with the decreasing distance to ground water. The soil textural, structural, and chemical properties on opposite played the major role on footslope positions. Accordingly, optimal land management option that promote corresponding soil structure, organic matter input and soil climate is proposed and discussed in balance with other soil functions.&lt;/p&gt;


Author(s):  
Robert F. Keefer

Erosion can be controlled by four main means, that is, improving soil structure, covering soil with plants, covering soil with mulch, and using special structures. Soil structure is related to the soil tilth, or physical condition of a soil, with respect to ease of tillage or workability as shown by the fitness of a soil as a seedbed and the ease of root penetration. Other terms relating to soil structure improvement are soil aggregation and the formation of aggregates. Aggregates form when a cementing substance is present in a soil. The most important cementing substances in soil are soil polysaccharides and soil polyuronides produced as by-products from microorganisms during decomposition of organic matter. Other less important cementing substances in soil include clays, Ca, and Fe. Formation of aggregates results in improved water infiltration with reduction in erosion. Decomposition of organic matter in soils can be shown as an equation: . . . Plant and animal remains + O2 + soil microorganisms → CO2 + H2O + elements + humus + synthates + energy . . . The decomposition process has the following features: . . . 1. Oxygen is required; thus soil aeration is important. Anytime a soil is stirred or mixed by cultivation, spading, plowing, some organic matter decomposition occurs. 2. Readily available decomposable organic material is required for the microbes to work on. Green organic material, such as grass clippings, is an excellent substrate. 3. Many different types of soil microorganisms are involved in this process. Decomposition is more rapid in soils at pH 7 (neutral). 4. A product of organic decomposition is humus. Humus has many desirable features that improve a soil for plant growth. 5. Plant or animal remains are not effective in soil aggregation until they begin to decompose. 6. The more rapid the decomposition, the greater effect of soil aggregation. . . . Microbial synthates consist of polymers called “polysaccharides” and “polyuronides.” A polymer is a long-chain compound made up of single monomer units hooked together acting as a unit. The term “poly” means “many” and “saccharide” means “sugar.”


2020 ◽  
Author(s):  
Evelin Pihlap ◽  
Franziska Bucka ◽  
Tiia Haberstok ◽  
Emily Scholes ◽  
Tabea Klör ◽  
...  

&lt;p&gt;Soil structure and soil organic matter (SOM) are closely linked characteristics describing the status of development of a soil. Their interactions affect various physical, chemical and biological soil properties and functions like water holding capacity, water infiltration, composition of the carbon pool and microbial activity. Rehabilitated soils from post mining fields are considered to have poor soil structure, low nutrient content and microbial activity. Besides disturbed soil properties, in Australia soil rehabilitation success is also influenced by climatic conditions like high evaporation rate which affects rebuilding of soil system functions. Although there are several studies looking into the development of soil properties post rehabilitation in temperate climates, the intertwined development of soil structure and quality and quantity of SOM during soil formation under water stressed environment is not clear until now.&lt;/p&gt;&lt;p&gt;In this study we used a space-for-time chronosequence approach in the rehabilitated open-cast mines at Yallourn Mine (Victoria, Australia) to elucidate the development of soil structure and soil organic matter after rehabilitation in a water limited environment. We selected five different fields with different rehabilitation ages (40, 22, 11, 4 and 3 years) and two mature soils that are used as grazing land. In each field we sampled 6 independent locations with stainless steel cylinders (100 cm&lt;sup&gt;3&lt;/sup&gt;) at two depths of 0-4 cm and 10-14 cm. &amp;#160;All samples were analysed for bulk density, organic carbon (OC) and total nitrogen (TN) concentration. Selected samples were wet sieved into four aggregate size classes of &lt;63 &amp;#181;m, 63-200 &amp;#181;m, 200-630 &amp;#181;m and &gt;630 &amp;#181;m. For detecting OC contribution to aggregate formation, OC and TN was measured from each aggregate size fraction. This system is temporarily highly dynamic and shows different developments for bulk density and SOM stocks, which had an effect on the structure of the microbial communities. Along the space-for-time chronosequence we can observe soil structure formation with ageing and a build-up of a OM, which has a positive effect on recovering soil functionality.&lt;/p&gt;


1986 ◽  
Vol 66 (2) ◽  
pp. 273-285 ◽  
Author(s):  
J. F. DORMAAR ◽  
C. W. LINDWALL ◽  
G. C. KOZUB

A field was artificially eroded by levelling in 1957 and then continuously cropped to barley for 7 yr. Subsequently, a wheat-fallow experiment was conducted from 1965 to 1979 to determine the effects of four fertilizer treatments and green manure (yellow sweet clover) on restoring the productivity to soil that had been "eroded" to various depths. After 22 yr and 14 crops, the productivity of the land from which soil was removed has been improved but not fully restored. Although green manuring with yellow sweet clover improved soil structure, wheat yields were not improved because of competition for soil moisture and poorer in-crop weed control in this part of the rotation. The addition of 45 kg N plus 90 kg P2O5 per hectare in each crop year to sites from which 8–10, 10–20, or 46 + cm of soil had been removed resulted in yield increases of 18, 46, and 70%, respectively, over the unfertilized check of each treatment; the average yields were 104, 91, and 70%, respectively, of the undisturbed, unfertilized (check) treatment. On "erosion" treatments where only 8–10 cm of soil were removed, 45 kg N plus 22 kg P2O5 per hectare were sufficient to restore the productivity. Precipitation apparently had a greater effect than fertilizer application on wheat yields. The loss of organic matter and associated soil structure characteristics seemed to be critical factors contributing to yield losses associated with soil erosion. These results show that it is more practical to use management practices that prevent soil erosion than to adopt the practices required to restore eroded soil. Key words: Soil erosion, topsoil loss, water-stable aggregates, soil organic matter, green manure, precipitation


2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Johann G. Zaller ◽  
Maureen Weber ◽  
Michael Maderthaner ◽  
Edith Gruber ◽  
Eszter Takács ◽  
...  

Abstract Background Glyphosate-based herbicides (GBHs) are among the most often used pesticides. The hundreds of GBHs used worldwide consist of the active ingredient (AI) glyphosate in form of different salts, possibly other AIs, and various mostly undisclosed co-formulants. Pesticide risk assessments are commonly performed using single AIs or GBHs at standard soil conditions without vegetation. In a greenhouse experiment, we established a weed population with common amaranth (Amaranthus retroflexus) to examine the effects of three GBHs (Roundup LB Plus, Roundup PowerFlex, Touchdown Quattro) and their corresponding AIs (salts of glyphosate isopropylammonium, potassium, diammonium) on the activity and physiological biomarkers (glutathione S-transferase, GST; acetylcholine esterase, AChE) of an ecologically relevant earthworm species (Lumbricus terrestris). GBHs and AIs were applied at recommended doses; hand weeding served as control. Experiments were established with two soil types differing in organic matter content (SOM; 3.0% vs. 4.1%) and other properties. Results Earthworm activity (casting and movement activity) decreased after application of glyphosate formulations or active ingredients compared to hand weeding. We found no consistent pattern that formulations had either higher or lower effects on earthworm activity than their active ingredients; rather, differences were substance-specific. Earthworm activity was little affected by soil organic matter levels. Biomarkers remained unaffected by weed control types; GST but not AChE was decreased under high SOM. Water infiltration after a simulated heavy rainfall was interactively affected by weed control types and SOM. Leachate amount was higher after application of formulations than active ingredients and was higher under low SOM. Glyphosate concentrations in soil and leachate were strongly affected by application of formulations or active ingredients and varied with SOM (significant weed control type x SOM interaction). Conclusions We found that both commercial formulations and pure active ingredients can influence earthworms with consequences on important soil functions. Glyphosate products showed increased, reduced or similar effects than pure glyphosate on particular soil functions; soil properties can substantially alter this. Especially at lower SOM, heavy rainfalls could lead to more glyphosate leaching into water bodies. A full disclosure of co-formulants would be necessary to further decipher their specific contributions to these inconsistent effects.


1996 ◽  
Vol 25 (3) ◽  
pp. 151-156 ◽  
Author(s):  
Charles L.A. Asadu

An comparison of soilmanagement techniques In the different irrigation zones of Lower Anambra Irrigation Project (LAIP) In eastern Nigeria showed that heavy use of machinery led to Increases In bulk density and decreases In field water Infiltration rate. The relative proportion of clay In the irrigated fields Increased as a result of Irrigation, suggesting that mobilized clay from uncemented main and distribution canals Is carried and deposited In the rice fields. Both Irrigation and the use of machinery have had substantial negative effects on soli nutrient levels, and there is a danger of this process continuing. Soli management for sustainable production in the area should centre on applying organic matter in combination with inorganic fertilizers, monitoring the soli properties on yearly basis before the cropping season for fertilizer and lime recommendations, and varying the depth of tillage to Increase or maintain the effective soli depth.


2007 ◽  
Vol 28 (3) ◽  
pp. 104 ◽  
Author(s):  
Margaret M Roper ◽  
Vadakattu V S R Gupta

Soils are much more than a porous medium for supporting plant growth. Soils are living, because they contain a wide range of microorganisms including bacteria, fungi, algae, protozoa, nematodes and other fauna including microarthropods, macroarthropods, termites and earthworms. All play a crucial role in the biological function of soils including decomposition of organic matter, nutrient transformations, biological control, development of soil structure to mention a few. Until recently the complexity of life in the soil has been difficult to unravel, but new DNA and biochemical tools are providing insights into its phenotypic and functional diversity and capability, and should drive the development of managements that nurture biodiversity and ecosystem function.


2021 ◽  
Author(s):  
Hans-Jörg Vogel ◽  
Mar­ia Balseiro-Romero ◽  
Philippe C. Baveye ◽  
Alexandra Kravchenko ◽  
Wilfred Otten ◽  
...  

&lt;p&gt;Soil structure, lately referred to as the ''architecture'' is a key to explain and understand all soil functions. The development of sophisticated imaging techniques over the last decades has led to significant progress in the description of this architecture and in particular of the geometry of the hierarchically-branched pore space in which transport of water, gases, solutes and particles occurs and where myriads of organisms live. Moreover, there are sophisticated tools available today to also visualize the spatial structure of the solid phase including mineral grains and organic matter. Hence, we do have access to virtually all components of soil architecture.&lt;/p&gt;&lt;p&gt;Unfortunately, it has so far proven very challenging to study the dynamics of soil architecture over time, which is of critical importance for soil as habitat and the turnover of organic matter. Several largely conflicting theories have been proposed to account for this dynamics, especially the formation of aggregates. We review these theories, and we propose a conceptual approach to reconcile them based on a consistent interpretation of experimental observations and by integrating known physical and biogeochemical processes. A key conclusion is that rather than concentrating on aggregate formation in the sense of how particles and organic matter reorganize to form aggregates as distinct functional units we should focus on biophysical processes that produce a porous, heterogeneous organo-mineral soil matrix that breaks into fragments of different size and stability when exposed to mechanical stress.&amp;#160; The unified vision we propose for soil architecture and the mechanisms that determine its temporal evolution, should pave the way towards a better understanding of soil processes and functions.&lt;/p&gt;


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