Can we improve the Nitrogen Use Efficiency in Maize Production?

Maize leaf area and N uptake at different plant densities and N rates

Ignacio A. CiampittiAGRY 596 – Professional Presentation

Purdue University - Department of AgronomySeptember 22, 2010

Introduction

Why NUE is important?

–Right N rate applied, both economically and environmentally important.

NUE, defined as the grain yield per unit of N available from the soil, including N fertilizer

Why Maize NUE is so low?

–Total loss of fertilizer N ranged from 20 to 50%, attributed to the combined effects of denitrification, volatilization and/or leaching.

Why N is important?• N uptake evolution follows the dry matter accumulation

Nitrogen in the Life of the Corn Plant100

80

60

40

20

0

Percen

t of to

tal N taken

up

by p

lant

N

Dry WeightSilking

Days after Planting (Mid-Season Corn Belt Hybrid)0 25 50 75 100 115

~100%

Highest Leaf Area

100

75

50

25

0

Per

cen

t o

f M

axim

um

Lea

f A

rea

~50%

Leaf Area

Nitrogen rate

Management factors

Plant density

Nitrogen rate

N uptake

NUE

Maize Yield

Environment

Understanding the leaf area and N uptake relationship

Presentation Question

Is the ratio of N uptake to leaf area constant when both are affected by plant density and N rate?

0.4 0.6 0.8 1.0

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Plant DensitySlice at V3 = 2

Nitr

ogen r

ate

Nitr

ogen

rat

e (k

g ha

-1)

Plant density (pl ha-1)54,000 79,000 104,000

0

165

33

0

Relationship

N uptake Leaf Area (g N/m2)

Optimum point??

Concluding remarks

•The strategy of the maize crop is to maintain the leaf area expansion even under N deficiency situations.

•The accumulation of N per unit of leaf area decreases as N rate decreases and plant density increases.

•The ratio of the N uptake to leaf area is not constant, and it varies with the N rate and plant density factors.

•More knowledge about maize physiology and N uptake dynamics will be needed to improve the NUE.

Thanks! Questions?