Xem 1-3 trên 3 kết quả Nitrate uptake
  • A ‘textbook’ plant typically comprises about 85% water and 13.5% carbohy- drates. The remaining fraction contains at least 14 mineral elements, without which plants would be unable to complete their life cycles. These essential mineral elements include six macronutrients – N, K, P, S, Mg and Ca – which are present in relatively large amounts in plant tissues (mg g−1 of dry tissue), and several micronutrients, including Fe and Zn, which are present in smaller amounts (µg g−1 of dry tissue).

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  • In most agricultural settings, commercial fertilizer provides only one source of N used for crop production. Animal manure, biological N fixation, mineralization from soil organic N, and deposition of N from the atmosphere can also contribute to soil fertility and surface water contamination. Because there are multiple sources and sinks of N in the soil, the relationship between N fertilizer application rate and nitrogen loss in drainage water is not always consistent across locations and across studies.

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  • If the soil becomes saturated, oxygen may become scarce and in anoxic conditions, denitrifying bacteria may convert the nitrate to nitrogen gases (NO, N2O, and N2). Nitrogen converted to these gases becomes unavailable for plant uptake or for surface water contamination. Additionally, saturated soil during the growing season is harmful to many crops like maize that cannot tolerate low oxygen concentrations in the root zone for more than a few days.

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