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Garden with Insight Kurtz-Fernhout Software
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Garden with Insight v1.0 Help: Plant daily N group

N optimal concentration today: The optimal (best) elemental nitrogen concentration for this plant today, from an S curve derived from three 'N optimal fraction' parameters. The plant will attempt to obtain enough nitrate to reach this concentration from the soil layers it has roots in.

N demand for optimal growth today: Plant demand for nitrate considering only the plant's optimal N concentration at the current heat unit index as per the 'N optimal fraction' parameters for this plant, which are used to generate an S curve of optimal N concentration vs. heat unit index.

Ratio of N uptake over demand today: The ratio of nitrogen actually taken up by the plant today to the optimal (best) amount of N uptake today. Used in calculation of N growth constraint factor.

N demand today: Plant demand for nitrate from each soil layer considering the plant's current optimal N concentration, the plant's water uptake today (which limits nutrient uptake), and nitrate availability in the layer, but not considering competition with other plants.

N fixation today: Atmospheric N2 fixed to plant-usable N by symbiosis between legumes and bacteria in root nodules. Decreased by very young or old plant, inadequate soil water, and high nitrate levels. All fixed N is taken up immediately by the plants that fix it.

N supply today: The amount of nitrate N that would be available to this plant if it were the only plant in the soil patch. Considers plant root depth, root biomass distribution, and water uptake. Does not consider plant competition, which affects final uptake.

N uptake today: The amount of nitrate N actually taken up by this plant today, considering root biomass distribution over the soil layers, water uptake (which limits nutrient uptake), and competition between plants in the same soil patch.

N growth constraint today: Constraint from 0 (worst) to 1 (best) on above-ground plant growth due to inadequate nitrogen uptake. Based on the ratio of lifetime actual N uptake to optimal N uptake and modified by an S curve that determines the plant's tolerance of N and P stress.

N in live plant biomass: The total amount of elemental nitrogen in the living parts of the plant.

N in standing dead biomass: The amount of elemental nitrogen in standing dead biomass for this plant, or biomass that has died but has not yet fallen to the soil. This N is leached to the top soil layer (and enters fresh organic N) when it rains and when the soil is mixed.

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Updated: March 10, 1999. Questions/comments on site to
Copyright © 1998, 1999 Paul D. Fernhout & Cynthia F. Kurtz.