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  2. δ15N - Wikipedia

    en.wikipedia.org/wiki/Δ15N

    The difference is whether the relative abundance is with respect to all the nitrogen, i.e. 14 N plus 15 N, or just to 14 N. Since the atmosphere is 99.6337% 14 N and 0.3663% 15 N, a is 0.003663 in the former case and 0.003663/0.996337 = 0.003676 in the latter.

  3. Nitrogen-15 tracing - Wikipedia

    en.wikipedia.org/wiki/Nitrogen-15_tracing

    Nitrogen-15 (15 N) tracing is a technique to study the nitrogen cycle using the heavier, stable nitrogen isotope 15 N.Despite the different weights, 15 N is involved in the same chemical reactions as the more abundant 14 N and is therefore used to trace and quantify conversions of one nitrogen compound to another.

  4. Kjeldahl method - Wikipedia

    en.wikipedia.org/wiki/Kjeldahl_method

    Total Kjeldahl nitrogen or TKN is the sum of nitrogen bound in organic substances, nitrogen in ammonia (NH 3-N) and in ammonium (NH 4 +-N) in the chemical analysis of soil, water, or waste water (e.g. sewage treatment plant effluent).

  5. Plant growth analysis - Wikipedia

    en.wikipedia.org/wiki/Plant_growth_analysis

    where N is total plant organic Nitrogen, PNC is the plant organic nitrogen concentration, and NP, the nitrogen productivity, the increase in biomass per unit organic N present. [9] Another way to break down RGR is to consider biomass increase from the perspective of a nutrient (element) and its uptake rate by the roots.

  6. Leaf Color Chart - Wikipedia

    en.wikipedia.org/wiki/Leaf_Color_Chart

    The Leaf Color Chart (LCC) is a diagnostic tool used to determine the nitrogen level in rice plants relative to the shade of green of the plant's leaves. It is a ruler-shaped strip containing at least four panels of color, ranging from yellowish green to dark green.

  7. Soil test - Wikipedia

    en.wikipedia.org/wiki/Soil_test

    In agriculture, a soil test commonly refers to the analysis of a soil sample to determine nutrient content, composition, and other characteristics such as the acidity or pH level. A soil test can determine fertility , or the expected growth potential of the soil which indicates nutrient deficiencies, potential toxicities from excessive ...

  8. Plant nutrients in soil - Wikipedia

    en.wikipedia.org/wiki/Plant_nutrients_in_soil

    Bacteria may on average add 25 pounds (11 kg) nitrogen per acre, and in an unfertilised field, this is the most important source of usable nitrogen. In a soil with 5% organic matter perhaps 2 to 5% of that is released to the soil by such decomposition. It occurs fastest in warm, moist, well aerated soil. [55] The mineralisation of 3% of the ...

  9. Universal Soil Loss Equation - Wikipedia

    en.wikipedia.org/wiki/Universal_Soil_Loss_Equation

    The Universal Soil Loss Equation (USLE) is a widely used mathematical model that describes soil erosion processes. [1]Erosion models play critical roles in soil and water resource conservation and nonpoint source pollution assessments, including: sediment load assessment and inventory, conservation planning and design for sediment control, and for the advancement of scientific understanding.