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Plant nutrition is the study of the chemical elements and compounds necessary for plant growth and reproduction, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element is part of some essential plant constituent or metabolite .
Carbon-to-nitrogen ratios indicate the degree of nitrogen limitation of plants and other organisms. They can identify whether molecules found in the sediment under study come from land-based or algal plants. [1] Further, they can distinguish between different land-based plants, depending on the type of photosynthesis they undergo.
Nitrogen is the most critical element obtained by plants from the soil, to the exception of moist tropical forests where phosphorus is the limiting soil nutrient, [36] and nitrogen deficiency often limits plant growth. [37] Plants can use nitrogen as either the ammonium cation (NH 4 +) or the anion nitrate (NO 3 −).
The spaces between the solid soil particles, if they do not contain water, are filled with air. The primary soil gases are nitrogen, carbon dioxide and oxygen. [2] Oxygen is critical because it allows for respiration of both plant roots and soil organisms. Other natural soil gases include nitric oxide, nitrous oxide, methane, and ammonia. [3]
The main nitrogen-based straight fertilizer is ammonia (NH 3) ammonium (NH 4 +) or its solutions, including: Ammonium nitrate (NH 4 NO 3) with 34-35% nitrogen is also widely used. Urea (CO(NH 2) 2), with 45-46% nitrogen, another popular source of nitrogen, having the advantage that it is solid and non-explosive, unlike ammonia and ammonium nitrate.
Plant-mediated methane flux through plant aerenchyma, shown here, can contribute 30–100% of the total methane flux from wetlands with emergent vegetation. [39] Plant aerenchyma refers to the vessel-like transport tubes within the tissues of certain kinds of plants. Plants with aerenchyma possess porous tissue that allows for direct travel of ...
Composting is most efficient with a carbon-to-nitrogen ratio of about 25:1. [10] Hot composting focuses on retaining heat to increase the decomposition rate, thus producing compost more quickly. Rapid composting is favored by having a carbon-to-nitrogen ratio of about 30 carbon units or less. Above 30, the substrate is nitrogen starved.
In plants with bacterial symbionts, which fix atmospheric nitrogen, the energetic cost to the plant to acquire one molecule of NH 3 from atmospheric N 2 is 2.36 CO 2. [13] It is essential that plants uptake nitrogen from the soil or rely on symbionts to fix it from the atmosphere to assure growth, reproduction and long-term survival.