Macro Elements in Soil

The biogeochemical fluxes and exposure pathways of various macro- and microelements are different from those shown for Tropical Rain Forest ecosystems. The chemical composition of leaves of tree species in Mangrove Forest ecosystems is connected with higher content of Mg, Cl and S-SO4- and lesser content of K and Si as compared to the leaves of trees from Tropical Rain Forest ecosystems. The content of A1 is 3-4 times higher than that of Si and this can be related to the values of hydrogenic accumulation of these elements in soils (Figure 3). 

Of the various elements that are ktiown to be essential for the proper growth and reproduction of plants, Nitrogen, Phosphorus and Potassium are required in relatively large amounts and so are known as major elements or macro-nutrients. A deficiency of one or more of these elements in soil may limit the growth of a particular plant or crop and may thus decrease soil fertility. 

The second characteristic feature of Forest Ecosystem soils is the accumulation of macro-nutrients in the litter with sharp decreasing to the download horizon. However, the trace elements show the opposite trend and the concentration of micro-nutrients is gradually increasing up to the soil forming rocks. 

Abiotic toxic damage and accumulation of metals and nonmetals in wild and cultivated plants may result from natural geochemical loads in the soil (Kovalskij 1977) caused by macro, trace and ultratrace elements in water used for irrigation, in natural volcanoes and anthropogenic industrial pollution of the atmosphere. Water, aerosols, and dust contain a variety of aluminum, arsenic, cad-... 

The macro, trace, and ultratrace element contents of shooting wheat, rye in blossom, field red clover in bud and meadow red clover in blossom provide good information about the bioavailability of the elements in the soil (Anke 2003, Angelow 1994, Arnhold 1989, Anke etal. 1998, Griin 1984). Wheat, rye and red clover in the defined stages of development are generally suitable as indicator plants of cultivated soils. 

The concentration of the essential macro element potassium in plants is varied by the amount of plant-available potassium in the soil, plant age, species, and plant parts. 

Various forms of macro- and microelements differ in their ability to migrate and redistribute among the soil profile. The elements contained in clastic minerals are practically immobile. The elements, bound to finely dispersed clay minerals, are either co-transported with clay particles, or are involved in sorption-desorption processes. Part of the elements are found in concretions and also in very thin coating films of hydrated iron oxides some elements make a part of specially edaphic organic compounds. 

Of the seven macro mineral elements required by dairy cattle, five can be considered fertilizer elements (potassium, calcium, phosphorus, magnesium, and sulfur), but sodium and chloride are both toxic lo plants at high concentrations and present practical problems in areas with saline soils. High salt intakes have also been shown lo increase udder edema in heifers. Because of the importance of chloride in nutrition and mclabolisni. research is needed to define the chloride requirements of lactating cows and clarify mineral relationships, especially between chloride and potassium plus sodium-... 

First, it is interesting to note that a deficiency or excess of one element does not directly induce a particular symptom in cultivated or wild plants. In this respect, it is necessary to examine the macro, trace and ultratrace element transfer from the different polluted and unpolluted soils into the plant. Indicator plants must be easy to identify, grown worldwide, and indicate the mineral transfer to the food chain. On cultivated soils in many parts of the world, these conditions are met by wheat Triticum sativum), rye Secale cereale), and red clover Trifolium pratense sativum) of the field and meadow varieties (TrifoUum pratense spontaneum). The green plants were harvested when the rye was in blossom, the wheat shooting, the field red clover in bud, and the meadow red clover in blossom. 

The magmatic and sedimentary rocks contain highly different amounts of macro, trace and ultratrace elements, which after weathering of the rocks become components of the soil and of the soil waters. During weathering, the elements are released from the primary minerals and usually also fixed by organic matter. Thus, most of the macro, trace and ultratrace element contents are controlled by conditions of soil formation and the initial contents in the parent rocks. 

The phytotoxic actions of rubidium mostly affect the transportation of substances in the xylan (Zornoza and Carpona 1996). In order to prevent excessive amounts of rubidium in plant tissues, these authors proposed an increase in the content of potassium, manganese and boron in the soil solution, because of the known antagonism of these elements towards rubidium. Young, growing plants or parts of plants are extremely rubidium-rich and accumulate this element like most other macro, trace and ultratrace elements (Angelow 1994, Wyttenbach et al. 1995). The toxicity of rubidium in plants is low, and essentially unknown. 

Macro- and microcomponents of inorganic character in the soil are frequently directly related to the composition of underlying rocks. The determination of macro- or microcomponents of the soil serves as a basis of one method among the various approaches to a biochemical survey for the investigation of pollutants, microelements in the soil are of the main importance, being important for the nutrition and health of plants as well as animals. The character of the main elements is determined by their occurrence in the soil profile as whole, whereas their distribution inside of the soil profile is governed by their mobility together with other factors, such as the climate [2]. 

The pure soil sample is a quarter size of the other two S-RM samples, it is tested under 100 kPa, 200 kPa and 300 kPa confining pressure in the biaxial numerical simulation to verify the selection of soil particles calculation parameters in the discrete element model are corresponding with the macro-mechanical parameters of soil. The internal friction angle and cohesion force can be calculated through the three experiments. 

---