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If soil iron concentration is high, in spite of this it can become unavailable for absorption if soil pH is higher than 6.5. [1] Excess of elements such as manganese in the soil can interfere with plant iron uptake triggering iron deficiency. [2] Iron is needed to produce chlorophyll, hence its deficiency causes chlorosis.
Upwelling recycles iron and causes higher deep water iron concentrations. On average there is 0.07±0.04 nmol Fe kg −1 at the surface (<200 m) and 0.76±0.25 nmol Fe kg −1 at depth (>500 m). [21] Therefore, upwelling zones contain more iron than other areas of the surface oceans. Soluble iron in ferrous form is bioavailable for utilization ...
soil type and structure. For example, sandy soil holds little water while clay soils have high water-retention rates; the amount of water used by the plants/crops; how much nitrate is already present in the soil. [3] The level of nitrous oxide (N 2 O) in the Earth's atmosphere is increasing at a rate of 0.2 to 0.3% annually.
The human-caused changes to the water cycle will increase hydrologic variability and therefore have a profound impact on the water sector and investment decisions. [9] They will affect water availability ( water resources ), water supply , water demand , water security and water allocation at regional, basin, and local levels.
Chlorosis is typically caused when leaves do not have enough nutrients to synthesise all the chlorophyll they need. It can be brought about by a combination of factors including: a specific mineral deficiency in the soil, such as iron, [3] magnesium or zinc [4] deficient nitrogen and/or proteins [4]
where water tables are shallow, the irrigation applications are reduced. As a result, the soil is no longer leached and soil salinity problems develop; stagnant water tables at the soil surface are known to increase the incidence of water-borne diseases like malaria, filariasis, yellow fever, dengue, and schistosomiasis (Bilharzia) in many ...
Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure. [45] The amount of water present in the soil before the precipitation also plays an important role, because it sets limits on the amount of water that can ...
Soil erosion is the main factor for soil degradation and is due to several mechanisms: water erosion, wind erosion, chemical degradation and physical degradation. Erosion can be influenced by human activity. For example, roads which increase impermeable surfaces lead to streaming and ground loss.