# Nlai: Leaf N distribution within canopies In nlraa: Non-linear regression for agricultural applications

## Description

Function used to describe leaf N distribution within canopies (Jonshon et al., 2010 AoB). This is equation 1.9 in Table S.1 in the paper referenced below.

## Usage

 `1` ```Nlai(lai, Yo, nb, kn, c) ```

## Arguments

 `lai` Cummulative leaf area index. Starting from the top. Should be zero right above the canopy. `Yo` Value of leaf N concentration at lai = 0 `nb` Minimum N for photosynthesis `kn` extinction coefficient `c` emprical paramater: when c=0 then the there is no decay (uniform distribution), when c=1 then the decay is exponential, when c>1 then the decay takes an inverse S shape

## Value

a numeric vector of length equal to the inputs

## Author(s)

Fernando E. Miguez

## References

Nonlinear Regression Models and Applications in Agricultural Research. Sotirios V. Archontoulis and Fernando E. Miguez. Agronomy Journal. doi: 10.2134/agronj2012.0506

## Examples

 ```1 2 3 4 5 6 7 8 9``` ```require(lattice) ## Set parameter values and plot the relationship lai <- seq(1, 8, 0.5) ans1 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=1) ans2 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=4) ans3 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=8) ans4 <- Nlai(lai, Yo=2, nb=0.4, kn=0.5, c=12) xyplot(ans1 + ans2 + ans3 + ans4~ lai, type="l", auto.key=TRUE, ylab = "N distribution", xlab = "LAI") ```

nlraa documentation built on May 2, 2019, 5 p.m.