Caking Caliche (Lime-Pan)

C<ul style="display: flex;"><li style="flex:1">CAKING </li><li style="flex:1">CAPILLARITY </li></ul>Changing of a powder into a solid mass by heat, pressure, The tendency of a liquid to enter into the narrow pores within a porous body, due to the combination of the cohesive forces within the liquid (expressed in its surface tension) and the adhesive forces between the liquid and the solid (expressed in their contact angle). or water. CALICHE (LIME-PAN) Bibliography Introduction to Environmental Soil Physics. (First Edition). 2003. <a href="/goto?url=http://www.sciencedirect.com/" target="_blank">Elsevier Inc. Daniel Hillel (ed.) http://www.sciencedirect.com/ </a>science/book/9780123486554 (I)A zone near the surface, more or less cemented by secondary carbonates of Ca or Mg precipitated from the soil solution. It may occur as a soft thin soil horizon, as a hard thick bad, or as a surface layer exposed by erosion. (II) Alluvium cemented with NaNO3, NaCl and/or other soluble salts in the nitrate deposits of Chile and Peru. Cross-references Sorptivity of Soils Bibliography Glossary of Soil Science Terms. Soil Science Society of America. <a href="/goto?url=https://www.soils.org/publications/soils-glossary" target="_blank">2010. https://www.soils.org/publications/soils-glossary </a>CAPILLARY FRINGE The thin zone just above the water table that is still saturated, though under sub-atmospheric pressure (tension). The thickness of this zone (typically a few centimeters or decimeters) represents the suction of air entry for the particular soil. CANOPY STRUCTURE Plant canopy structure is the spatial arrangement of the above-ground organs of plants in a plant community. Bibliography Introduction to Environmental Soil Physics. (First Edition). 2003. <a href="/goto?url=http://www.sciencedirect.com/" target="_blank">Elsevier Inc. Daniel Hillel (ed.) http://www.sciencedirect.com/ </a>science/book/9780123486554 Bibliography Russel, G., Marshall, B., and Gordon Jarvis, P. 1990. Plant Canopies: Their Growth, Form and Function. Cambridge University Press. Cross-references Sorptivity of Soils Jan Gliński, Józef Horabik & Jerzy Lipiec (eds.), Encyclopedia of Agrophysics, DOI 10.1007/978-90-481-3585-1, #Springer Science+Business Media B.V. 2011 108 CARBON LOSSES UNDER DRYLAND CONDITIONS, TILLAGE EFFECTS substantially. Studies under different conditions are required to assess the broader of the greenhouse gas impacts of CT (Ventera et al., 2006). Tillage often increases short-term CO2 flux from the soil due to a rapid physical release of CO2 trapped in the soil air spaces (Bauer et al., 2006; Álvaro-Fuentes et al., 2008; Reicosky and Archer, 2007; López-Garrido et al., 2009). This rapid flux of CO2 is influenced by the tillage system and the amount of soil disturbance (Reicosky and Archer, 2007). Root and microbial activity together constitute soil respiration. Root and rhizosphere respiration can account for as little as 10% to greater than 90% of total “in situ” soil respiration depending on vegetation type and season of the year (Hanson et al., 2000). Nevertheless, only soil organic matter (SOM)-derived CO2 contributes to changes in atmospheric CO2 concentration. Long residence time of soil organic matter (SOM) results in very slow turnover rates relative to other less-recalcitrant respiratory substrates. This implies that SOM is the only C pool that can be a real, long-term sink for C in soils. Despite long residence times in steady state, if decomposition exceeds humification, the pool of C in SOM becomes a very large potential source of CO2 (Kuzyakov, 2006). CARBON LOSSES UNDER DRYLAND CONDITIONS, TILLAGE EFFECTS Félix Moreno, José M. Murillo, Engracia Madejón Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS-CSIC), Sevilla, Spain Definition CO2 emissions are mainly produced by inadequate soil tillage combined with intensive cropping systems and climatic conditions. Introduction Losses of soil organic carbon (SOC) are associated with reductions in soil productivity and with increases in CO2 emissions from soil to the atmosphere (Lal et al., 1989; Bauer et al., 2006; Ventera et al., 2006; Conant et al., 2007). Gas exchange between soils and the atmosphere may be an important contributing factor to global change due to release of greenhouse gases (Ball et al., 1999). Intensive agriculture frequently causes important losses of soil carbon. Conservation tillage (CT) agriculture (reduced tillage) has been promoted since approximately 1960 as a means to counteract all these constraints (Gajri et al., 2002). Moreover, CT improves soil quality and crop performance, especially under semiarid conditions (Moreno et al., 1997; Franzluebbers, 2004; Muñoz et al., 2007). Long-term adoption of conservation tillage (reduced and no tillage) in Mediterranean Spanish areas has proven to be an effective way to increase soil organic matter and, especially, to improve biochemical quality at the soil surface (Madejón et al., 2009). However, as the climatic conditions of the semiarid areas are an important limiting factor for the accumulation of organic carbon in the top Tillage effects on carbon losses Degradative effects of tillage on soil include rapid decline soil layers, the simple determination of total organic carof soil organic carbon due to mineralization rate increase bon (TOC) is not always the best indicator of the improve(Lal, 1993). This is particularly important under semiarid ment caused by conservation tillage. Under these conditions using conventional tillage in which moldboard conditions, it may be more interesting to study the stratifiplowing with soil inversion is the main operation (López- cation ratio of TOC calculated by the division of TOC Garrido et al., 2009). Moldboard plowing is one of the content at surface between TOC content at deeper layers most important factors increasing CO2 emissions by soil (Franzluebbers, 2002). This approach could also be microbial activity stimulation due to greater soil aeration applied to other variables related to soil biology, such as and breakdown of soil macroaggregates that conduces to MBC (microbial biomass carbon) and enzymatic activities a greater release of labile organic matter previously micro- (Madejón et al., 2009), which are normally significantly bial protected. There are studies that suggest that the correlated with TOC. Changes in soil biochemical propergreenhouse gases contribution of agriculture, such as ties with conservation tillage and in their stratification CO2, can be mitigated by widespread adoption of conser- ratios should provide practical tools to complement phys- <ul style="display: flex;"><li style="flex:1">vation tillage (Lal, 1997; Lal, 2000). </li><li style="flex:1">ical and chemical test and, thus, evaluate the effect of con- </li></ul>Conservation tillage (CT) is any tillage and planting servation tillage in dryland conditions. Despite some system that maintains at least 30% of the soil surface studies have reported similar or even greater TOC accucovered by residue after planting to reduce soil erosion mulation in the total profile (1 m and more) under convenby water. Where soil erosion by wind is a primary concern, tional tillage than under CT (Baker et al., 2007), the the system must maintain at least 1.1 Mg haÀ1 flat small improvements made by CT surface are very important grain residue equivalent on the surface during the critical for the soil functions. <ul style="display: flex;"><li style="flex:1">wind erosion period (Gajri et al., 2002). This system </li><li style="flex:1">These processes are very influenced by the local condi- </li></ul>reduces the number of operations and trips across the field, tions and management. Franzluebbers (2004) reported that and of course, avoids the soil inversion that buries most low benefit of no tillage on TOC storage could be <ul style="display: flex;"><li style="flex:1">crop residues into the soil. </li><li style="flex:1">expected in dry, cold regions, in which low precipitation </li></ul>The effectiveness of CT in mitigating the greenhouse would limit C fixation by plants and decomposition, even gas impact of individual agroecosystems could vary when crop residues are mixed with soil by tillage. CARBON LOSSES UNDER DRYLAND CONDITIONS, TILLAGE EFFECTS 109 Bauer, P. J., Frederick, J. R., Novak, J. M., and Hunt, P. G., 2006. Soil CO2 flux from a Norfolk loamy sand after 25 years of conventional and conservation tillage. Soil and Tillage Research, 90, 205–211. Conant, R. T., Easter, M., Paustian, K., Swan, A., and Williams, S., 2007. Impacts of periodic tillage on soil C stocks: a synthesis. Soil and Tillage Research, 95, 1–10. Franzluebbers, A. J., 2002. Soil organic matter stratification ratio as an indicator of soil quality. Soil and Tillage Research, 66, 95–106. Franzluebbers, A. J., 2004. Tillage and residue management effects on soil organic matter. In Magdoff, F., and Weil, R. R. (eds.), Soil Organic Matter in Sustainable Agriculture. Boca Raton: CRC Press, pp. 227–268. However, for most soils, the potential of carbon (C) sequestration upon conversion of plow tillage to no-tillage farming with the use of crop residue mulch and other recommended practices is 0.6–1.2 Pg C yearÀ1 (Lal, 2004). The important ecological and agronomic benefits that can derive from these practices could be limited not only by plowing but also by using crop residues for other purposes. Numerous competing uses of crop residues under arid and semiarid conditions (Bationo et al., 2007) can be a constraint for CT establishment (e.g., grazing and feed livestock). Biofuel production may be another destination (Lal and Pimentel, 2007). There is at present an imperious necessity of using cellulosic biomass instead Gajri, P. R., Arora, V. K., and Prihar, S. S., 2002. Tillage for Sustain- able Cropping. Lucknow: International Book Distributing. Hanson, P. J., Edwards, N. T., Garten, C. T., and Andrews, J. A., of crop grain for producing biofuel (mainly ethanol) and, currently, few sources are supposed to be available in suf- 2000. Separating root and soil microbial contributions to soil res- ficient quantity and quality to support development of an piration: a review of methods and observations. Biogeochemis- economically sized processing facility, except crop residues (Wilhelm et al., 2004). try, 48, 115–146. Kuzyakov, Y., 2006. Sources of CO2 efflux from soil and review of partitioning methods. Soil Biology and Biochemistry, 38, 425–448. Despite the suitability of CT to avoid C losses, this system may also has some drawbacks, such as the greater dependence of herbicides, higher level of residue management than conventional tillage, and it could not be adequate to all soils, climates, or crops. Moreover, the no-till system may lead to soil compaction. All these issues require experimentation in each particular scenario. However as a rule, CT does not cause yield losses when adequately established. Particularly, under arid and semiarid conditions in dry years, yields may be greater than under traditional tillage due to water savings resulting from conservation tillage. Lal, R., 1993. Tillage effects on soil degradation, soil resilience, soil quality and sustainability. Soil and Tillage research, 27, 1–8. Lal, R., 1997. Residue management, conservation tillage and soil restoration for mitigating the greenhouse effect. Soil and Tillage Research, 43, 81–107. Lal, R., 2000. Soil conservation and restoration to sequester carbon and mitigate the greenhouse effect. Third International Congress of the European Society for Soil Conservation (ESSC). Valencia (Spain): Key Notes, pp. 5–20. Lal, R., 2004. Soil carbon sequestration to mitigate climate change. Geoderma, 123, 1–22. Lal, R., and Pimentel, D., 2007. Biofuels from crop residues. Soil and Tillage Research, 93, 237–238. Conclusions Lal, R., Hall, G. F., and Miller, F. P., 1989. Soil degradation. I. basic principles. Land Degradation and Rehabilitation, 1, 51–69. López-Garrido, R., Díaz-Espejo, A., Madejón, E., Murillo, J. M., and Moreno, F., 2009. Carbon losses by tillage under semi-arid mediterranean rainfed agriculture (SW Spain). Spanish Journal of Agricultural Research, 7, 706–716. Madejón, E., Murillo, J. M., Moreno, F., López, M. V., Arrúe, J. L., Álvaro-Fuentes, J., and Cantero-Martínez, C., 2009. Effect of long-term conservation tillage on soil biochemical properties in Mediterranean Spanish areas. Soil and Tillage Research, 105, 55–62. Moreno, F., Pelegrín, F., Fernández, J. E., and Murillo, J. M., 1997. Soil physical properties, water depletion and crop development under traditional and conservation tillage in southern Spain. Soil and Tillage Research, 41, 25–42. Muñoz, A., López-Piñeiro, A., and Ramírez, M., 2007. Soil quality attributes of conservation management regimes in a semi-arid region of south western Spain. Soil and Tillage Research, 95, 255–265. Several studies have shown that the potential reduction for CO2 emission from the adoption of conservation tillage under dryland conditions could be substantial. However, further investigation should be necessary to validate, under different scenarios, the potential effect of soil to sequester carbon in these conditions. In any case, the adoption of conservation tillage, if adequately established, has a potential effect to increase organic carbon, and thus, soil quality especially at soil surface, essential for the soil functions. Bibliography Álvaro-Fuentes, J., López, M. V., Arrúe, J. L., and Cantero- Martínez, C., 2008. Management effects on soil carbon dioxide fluxes under semiarid Mediterranean conditions. Soil Science Society of America Journal, 72, 194–200. Baker, J. M., Ochsner, T., Venterea, R. T., and Griffis, T. J., 2007. Tillage and soil carbon sequestration – what do really know? Agriculture, Ecosystems and Environment, 118, 1–5. Ball, B. C., Scott, A., and Parker, J. P., 1999. Field N2O, CO2 and CH4 fluxes in relation to tillage, compaction and soil quality in Scotland. Soil and Tillage Research, 53, 29–39. Reicosky, D. C., and Archer, D. W., 2007. Moldboard plow tillage depth and short-term carbon dioxide release. Soil and Tillage Research, 94, 109–121. Ventera, R. T., Baker, J. M., Dolan, M. S., and Spokas, K. A., 2006. Carbon and nitrogen storage are greater under biennial tillage in a Minnesota corn-soybean rotation. Soil Science Society of America Journal, 70, 1752–1762. Wilhelm, W. W., Johnson, J. M. F., Hatfield, J. L., Voorhees, W. B., and Linden, D. R., 2004. Crop and soil productivity response to corn residue removal: a literature review. Agronomy Journal, 96, 1–17. Bationo, A., Kihara, J., Vanlauwe, B., Wasawa, B., and Kimetu, J., 2007. Soil organic carbon dynamics, functions and management in West African agro-ecosystems. Agricultural Systems, 94, 13–25. 110 CARBON NANOTUBE specific utilization. In the most cases, the utility value of cereals concerns using of grains to food production. Cross-references Biochemical Responses to Soil Management Practices Greenhouse Gases Sink in Soils Hydrophobicity of Soil Introduction Organic Matter, Effects on Soil Physical Properties and Processes Physical Protection of Organic Carbon in Soil Aggregates Stratification of Soil Porosity and Organic Matter Tillage, Impacts on Soil and Environment The assessment of cereal utility value is made from the beginning of the food processing. The utility value of cereal grain depends mainly on species and cultivar properties, climatic conditions, and agricultural treatments. Moreover, the storage conditions of the cereals, the preparing conditions for processing, and the manufacturing process, all have an influence on the utility values of cereals. CARBON NANOTUBE The utility values of cereal is widely more significant than the technological value. The cereal utility value does not indicate only the utility of cereal grain to foodstuff production, but also takes into consideration other uses of cereals (e.g., seed production, and utilization in pharmaceutical or chemical industry) However, the technological value of the cereal grains for food production is the most often determined. See Nanomaterials in Soil and Food Analysis CATCHMENT (CATCHMENT BASIN) See Water Reservoirs, Effects on Soil and Groundwater Methods of evaluation of cereal grains utility values CATION EXCHANGE CAPACITY The methods of evaluation of the utility values of cereals can be divided into two groups: indirect and direct methods. The most commonly used indirect methods are selected physical and chemical properties of grain, specialist technological indices (such as falling number or sedimentation value), and rheological properties of dough. The results obtained from these tests indirectly provide information about the utility value of cereal grains. Direct methods, on the other hand, are more suitable for examining the full characteristic of utility values of cereals; however, they are often time consuming and require more expensive equipment. These methods depend on processing grain or flour and imitated industry conditions. Subsequently, the quality of the product is evaluated. Examples of the direct methods are laboratory milling tests and laboratory baking tests. See Surface Properties and Related Phenomena in Soils and Plants CEMENTATION The process by which calcareous, siliceous, or ferruginous compounds tend to dissolve and then re-precipitate in certain horizons within the soil profile, thus binding the particles into a hardened mass. Bibliography Introduction to Environmental Soil Physics. (First Edition). 2003. <a href="/goto?url=http://www.sciencedirect.com/" target="_blank">Elsevier Inc. Daniel Hillel (ed.) http://www.sciencedirect.com/ </a>science/book/9780123486554 Indirect methods The basic assessment of the cereal grain includes such properties as appearance, smell, color, amount and the kind of impurities, the broken grains, and the presence of pests. A more detailed assessment includes the following physical properties of grains: density, test weight, 1,000 kernel weight, shape and size of grain, vitreousness (especially for wheat, rice, barley, and corn), mechanical properties (hardness, shear strength, rapture force and rapture energy, crushing strength, etc.) The research conducted on the endosperm structure (electron microscopy and X-ray methods) can also be used for the evaluation of the quality of cereals. Test weight (grain weight in a given volume) is the oldest and the most commonly used quality index of cereal grain. As a general rule, the higher Cross-references Ortstein, Physical Properties CEREALS, EVALUATION OF UTILITY VALUES Dariusz Dziki, Janusz Laskowski Department of Equipment Operation and Maintenance in the Food Industry, University of Life Sciences, Lublin, Poland Definition Utility values of cereals – feature or features of grains that the test weight, the better grain quality. Test weight is characterize the properties of kernels in the aspect of influenced by various factors, including fungal infection, CEREALS, EVALUATION OF UTILITY VALUES 111 insect damage, kernel shape and density, foreign mate- the utility value of wheat. The hardest wheat varieties are rials, broken and shriveled kernels, agronomic practice, commonly used for semolina, cuscus, or bulgur producand the climatic and weather conditions (Czarnecki and tion. Varieties having medium hardness are used as Evans, 1986). Tkachuk et al. (1990) have shown a main source for bread flour production, while soft wheat a positive correlation between wheat test weight and varieties are the good raw material for cookies or cakes wheat flour yield and bread-baking usefulness. The test flour production (Seibel, 1996). <ul style="display: flex;"><li style="flex:1">weight shows positive correlation with the grain density. </li><li style="flex:1">Grain hardness has the greatest influence on the milling </li></ul>The research of wheat grain density has revealed that the process. Particularly for wheat, this parameter should be type of grain significantly affects the mean density; taken into consideration both during wheat cleaning and healthy kernels averaged 1,280 kg mÀ3, sprout-damaged conditioning and during flour milling. The denser struckernels averaged 1,190 kg mÀ3, and scab-damaged ture of hard wheat endosperm does not allow tempering <ul style="display: flex;"><li style="flex:1">kernels averaged 1,080 kg mÀ3 (Martin et al., 1998). </li><li style="flex:1">water to be absorbed by hard wheat at a rate faster than that </li></ul>Thousand kernel weight (TKW) is used by wheat for soft wheat, and therefore, the time of tempering is lonbreeders and flour millers as a complement to test weight ger for hard wheat. In general, hard wheat cultivars are to better describe cereal kernel composition and potential tempered to about 16–16.5% moisture whereas soft wheat flour extraction. Generally, grain with a higher TKW can cultivars are tempered to 15–15.5% (wet basis) (Fang and be expected to have a greater potential flour yield. The parameter that is commonly used for the evaluation Campbell, 2003). The endosperm of hard wheat during grinding tends to of utility values of wheat, barley, rice, and corn is grind down to the coarser particles referred to as semolina vitreousness. Vitreousness indicates natural kernel trans- whereas soft varieties give more flour particles directly. lucence, which is a means of description of kernel appear- The bran layer of hard wheat is usually more susceptible ance. Vitreous kernels have a translucent, glassy to grinding than the bran layer of soft wheat. It is found appearance, as opposed to mealy kernels, which have that hard wheat kernels grind better during the reduction a light, opaque appearance. Vitreous grains are usually stage than soft kernels, and bran includes little endosperm harder and denser, and have higher protein content than (Gąsiorowski et al., 1999). <ul style="display: flex;"><li style="flex:1">mealy grains. Vitreousness is usually described by </li><li style="flex:1">The flour particle size distribution also depends on the </li></ul>a visual assessment of grain cross section. This parameter wheat grain hardness. Testing of the total percentage of has a significant influence on the milling process (grain flour with particle size of less than 50 mm shows considercleaning and tempering, passage and total flour extraction, able differences between soft wheat and hard wheat. <ul style="display: flex;"><li style="flex:1">and semolina yield). </li><li style="flex:1">Approximately 50% of total flour produced from soft </li></ul>The size and shape of grains are often useful parame- wheat is smaller than 50 mm whereas it is only 25% in hard ters to evaluate the cereal utility value. The larger and wheat. In fact, hard wheat cultivars display single-mode more spherical grains are characterized by higher yield particle size distribution whereas soft wheat cultivars have and endosperm. Small grain screenings are often sepa- bimodal distribution with the first mode at about 25 mm rated to form sound grains and can be used as a feed com- (Haddad et al., 1999). Moreover, the flour obtained from ponent. Also, small grains have a higher level of hard wheat is easy to sieve whereas soft wheat flour microbiological contamination. Gaines et al. (1997) eval- particles tend to stick to other surfaces and to other uated the influence of kernel size on soft wheat quality. It flour particles, causing sifting problems. <ul style="display: flex;"><li style="flex:1">was found that besides kernel size, kernel shriveling </li><li style="flex:1">Several tests are available for the determination of </li></ul>should also be taken into consideration. Shriveling cereal grain hardness. These methods often rely on the greatly reduced the test weight and decreased the amount classic method commonly used for constructional mateof flour produced during milling. Compared to sound ker- rials (e.g., the Vickers or Brinnel hardness test). However, nels, shriveled kernels had greater flour protein content, the most practical application for the evaluation of the utiland increased flour ash and kernel softness. Small, non- ity value of cereals includes tests that indirectly express shriveled kernels had slightly better baking quality than grain hardness. Especially for wheat, several methods of large non-shriveled kernels. In addition to the above men- grain hardness determination have been proposed, such tioned parameters, the kernel size uniformity is very as wheat hardness index (WHI), particle size index important to the wheat milling industry, especially in such (PSI), pearling resistance index (PRI), and a modern processing as cleaning, conditioning, debranning, or method called single kernel characterization system grinding. Kernel size and shape can be precisely (SKCS). This system is especially useful for a rapid analdescribed using Digital Image Analysis (DIA). This ysis of cereal grain physical properties (Grundas, 2004). method can be used for the evaluation of milling proper- The SKCS instrument analyzes 300 kernels individually ties of cereals (flour or semolina yield) (Berman et al., and determines kernel weight by load cell, kernel diameter <ul style="display: flex;"><li style="flex:1">1996; Novaro et al., 2001). </li><li style="flex:1">and moisture content by electrical current, and kernel </li></ul>The mechanical properties of cereals play a significant hardness (HI) by pressure force. A number of researchers role in the evaluation of quality of cereals, especially the have shown the usefulness of SKCS for the evaluation of grain hardness, which is often evaluated. This parameter wheat utility value, especially milling value. This instruis one of the most important indices in the evaluation of ment can be used to evaluate the time of tempering wheat

Caking Caliche (Lime-Pan)

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