Transcript Efforts to Improve N Use Efficiency of Corn in Arkansas

Efforts to Improve N Use Efficiency of Corn in Arkansas
Highlights of Research in Progress
Morteza Mozaffari
Soil Testing and Research Laboratory, Marianna
Acknowledgement
Research was funded by Arkansas Corn and
Grain Sorghum Promotion Board
Presentation outline
• Backgrounds Information
• Presidedress soil nitrate test (PSNT)
• Using chlorophyll meters
Mississippi Delta Region of Arkansas (MDRA)
MS River Delta Region of Arkansas
• Soils: predominantly alluvial
• Topography: relatively flat land
• One of the oldest row crop production regions
Corn Production in Arkansas
800
600
400
200
0
99
00
01
02
03
YEAR
04
05
06
07
Urea Price
800
$670
600
400
$395
$295
200
0
03
07
YEAR
08
Current AR corn N fertility recommendations
Yield Goal
Silt and sandy
loams
- bu/acre -
---------------- lb N /acre ---------------------
Clay loam and clay soil
125
150
230
150
185
280
175
220
330
> 200
255
330
Long-term sustainability of corn production
Profit margin
Protect water quality
Presentation outline
• Backgrounds Information
• Presidedress soil nitrate test (PSNT)
• Using a chlorophyll meter
The PSNT idea
• Apply a small amount of N (30-40 lb/acre) at planting
•
Collect a soil sample from 0-12” depth at 6-8-leaf stage
• Use the PSNT result as a guide to identify and apply the
optimum N rate
Objectives
For irrigated corn production in MRDRA
• Evaluate the effect of sidedress N-fertilizer rate on
corn grain yield
• Assess the suitability of PSNT for improving corn
N fertility management
• 21 replicated
field experiments
Research
Approach
– Production fields and AES sites across the MRDRA
– 04-07
• Experimental Design:
– Randomized complete block with 4-5 replications
– Five or six N rates
• Total N rates: 0-300 lb N/acre
– Year 1 and 2: 0, 50, 100, 150, 200, and 300 lb N/acre
– Year 3: 0, 60, 120, 180, 240 300 lb N/acre
• Cultural Practices:
– AES Sites: Cooperative Extension Service recommendations
– Commercial sites: Growers’ Practices
Nitrogen fertilizer application schedule
Total N rate
Pre-plant
At 6-8 leaf
-------------------------- lb N /acre ----------------------0
0
0
60
30
30
120
30
90
180
30
150
240
30
210
300
30
270
Research Approach
• Important dates:
– planted: 17 March to 4 June
– sidedress N date: 4 May to 6 June (6-8 leaf stage)
– harvest: 10 Aug to Sep 18
• Soil sampling and analysis:
– pre plant, top 6”, six cores/replication
– measured NO3-N, pH, texture, Mehlich-3 nutrients
– PSNT samples 6-8 leaf (before 2nd N application)
– zero to 12’’, six cores, 0 N plots
– measured NO3-N by ISE
Data Analysis
• Analysis of Variance:
–
–
to evaluate the effect of N rate on grain yield
sites were analyzed separately
• Calculated Relative Yield as:
– (check plot yield/highest plot yield) X 100
Results and Discussion
Properties of soil samples collected from the 0-6” depth before planting
Range Soil pH
NO3-N
SOM
Sand
Silt
Clay
Soil texture
-- ppm --- -------------------- % --------------------Min.
5.6
3
1.2
2
21
13
sandy loam
Max.
7.5
85
3.2
57
74
57
clay
Summary of the Results
• PSNT (mg/kg):
•
•
•
•
4-36: all sites
4-10: 12 sites
10-20: 5 sites
> 20: 4 sites
• Grain yield:
–
Significant N response: 20 sites, P≤0.0003
– Zero N treatments: 9-192 (bu/acre)
– Highest N rate: 140-223 (bu/acre)
– State average: 131-146 (bu/acre)
• Agronomic Optimum N rate:
– 150-250 (lb/acre)
Correlation between PSNT and relative yield of the check plot
(All 21 sites)
Relative yield (%)
100
80
60
40
y = 1.95x + 20.2
R2 = 0.53, P =0.0003
20
0
0
10
20
PSNT (ppm)
30
40
Correlation between PSNT and relative yield of the check plot
(sandy loam and silt loam sites, 16 sites)
Relative yield (%)
100
80
60
40
y = 2.06x + 21.4
R2 = 0.62, P =0.0003
20
0
0
10
20
PSNT (ppm)
30
40
Conclusions of PSNT Study
In irrigated corn production in MRDRA
• Sidedress application of N significantly increased corn grain
yield in 20 of the 21 sites
• Agronomic Optimum N rate was 150-250 lb/acre
• Presidedress soil nitrate test shows great promise for
improving corn N fertility management
Presentation outline
• Backgrounds Information
• Presidedress soil nitrate test
• Using a chlorophyll meter
Basic Idea
•
Establish a well fertilized N reference strip in your field
•
Collect chlorophyll meter reading from plants in area you may
want to fertilize
•
Collect chlorophyll meter reading from your reference strip
•
Calculate relative chlorophyll meter value (RCM)
CM reading from are you want to fertilize
RCM =
CM reading from the reference area
34.6
RCM =
= 0.59
58.0
Research Approach
• 5 replicated field experiments
– Production fields and AES sites across the MRDRA
– 07
• Experimental Design:
– Randomized complete block with 4-5 replications
• N fertilizer management:
– Five N rates 0, 60, 120, 180, 240 300 lb N/acre
– Split N application: preplant and four leaf stage
• Cultural Practices:
•
– AES Sites: Cooperative Extension Service recommendations
– Commercial sites: Growers’ Practices
Research Approach
• Important dates:
– planted: 4 April to May 5
– harvest: 15 Aug to Sep 17
• Soil sampling and analysis:
– pre plant, top 6”, six cores/replication
– measured NO3-N, pH, texture, Mehlich-3 nutrients
•
Leaf and CM data collection:
– 9-12 leaf stage
Data Analysis
• Analysis of Variance:
–
to evaluate the effect of N rate on grain yield, leaf N,
and CM
– sites were analyzed separately
• Calculated Relative Yield and Relative CM
Results and Discussion
Properties of soil samples collected from the 0-6” depth before planting
Range Soil pH
NO3-N
SOM
Sand
Silt
Clay
Soil texture
-- ppm --- -------------------- % --------------------Min.
5.6
10
1.1
2
12
11
sandy loam
Max.
7.5
53
2.9
75
72
39
silty clay
loam
Summary of the Results
• Grain yield:
–
Significant N response: all sites, P≤0.0044
– Zero N treatments: 31-178 (bu/acre)
– Highest N rate: 131-233 (bu/acre)
– State average: 148 (bu/acre)
Relative yield (%)
Correlation between RCM and relative yield at five sites
1.20
y = 2.01x - 1.07
r2 = 0.77, P =0.001
0.80
0.40
0.00
0.5
0.6
0.7
0.8
0.9
PSNT (ppm)
1.0
1.1
Concluding Remarks
• PSNT and CM are promising tools for Improving N
use efficiency in Arkansas
• Additional work is underway