Enhancing Sorghum Yield and Profitability through Sensor Based N Management Dave Mengel and Drew Tucker Department of Agronomy K-State.
Post on 14-Jan-2016
217 Views
Preview:
Transcript
Enhancing Sorghum Yield and Profitability through Sensor Based N
Management
Dave Mengel and Drew Tucker
Department of Agronomy
K-State
Situation: Risk
• Sorghum is the summer crop of choice where it is too dry to produce dryland corn.
• Yields vary widely from year to year due to weather, especially rainfall and temperature.– Using county level yield records, farmers
produce <50 bu/a sorghum 30% of the time in central Kansas and 40% of the time in western Kansas
Situation: N Management
• N fertilizer costs are significant, $20-40/a or more, depending on rate and source. This represents 10 to 20% of gross revenues.
• Optimum N rates vary from year to year.– Need varies due to changes in yield– Carryover varies dramatically from field to field– In-season N loss can be significant at times.– People refuse to use the profile N soil test
Long-term N Response Study Hutchinson KS
• Wheat-sorghum-soybean rotation. No-till– Sorghum yields averaged 72 bu/acre ‘91-’05– Range: 10-142
• <50, 3 years• 51-75, 5 years• 76-100, 4 years• >100, 3 years
Long-term N Response Study, Hutchinson KS
• Mean optimum N rate, 50 lbs N/acre– Range: 0-100
• 0, 4 years, 10 to 75 bu/a• 25, 2 years, 47 to 63 bu/a• 50, 3 years, 76 to 97 bu/a• 75, 2 years, 94 to 107 bu/a• 100, 4 years, 50 to 142 bu/a• 125, 0 years
The Big Question
• Can a N management strategy be developed to: – Reduce economic risk in bad years?– Take advantage of the potential of good years?– Fine-tune N needs in high yielding irrigated crops?– Reduce environmental risk in sensitive
environments?– Enhance profitability in the long run?
Our Approach
• Apply a base level of N to carry the crop through the first 40-50 days. 20 to 30 lbs/a
• Evaluate the crop at 35-45 days– If yield potential is low, soil moisture is limited
and outlook bleak……. punt– If moisture reserves and weather outlook are
good……., use sensor technology to estimate yield potential, and add appropriate N
The Devils in the Detail
• How good is your weather crystal ball?
• How early can we accurately estimate yield potential in sorghum?
• How early can we pick up differences in N levels between “normal” and “reference” strips?
• How late can N be applied and still be utilized and/or get a response?
More Details
• How do we need to apply late N?– And not damage the crop– And get the best response
• How much N must be put down early to maximize yield potential in good years?
• Can sensors be used to do this on the go?
Procedures 2006
• Locations: Manhattan, Belleville, Tribune, Hutch/Partridge
• No-till planted, surface plus profile N ST• Normal practices for weeds, bugs, fert etc• N treatments: 0 to 150 lbs N; pre, post/sd or
both.• Measure: leaf, stover and grain N, yield and
various sensor measurements using Greenseeker, Crop Circle and SPAD meter
Tribune
Belleville
Hutch
Manhattan
INSEY vs. Grain Sorghum Yield in 2006
y = 4.9019e156.22x
R2 = 0.5869
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
0 0.005 0.01 0.015 0.02 0.025 0.03
INSEY (NDVI/Days After Planting)
Yie
ld B
u/A
c
NDVI/GDD's vs. Grain Sorghum Yield in 2006
y = 4.4102e3804.4x
R2 = 0.6562
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012
NDVI/GDD's
Yie
ld B
u/A
c
NDVI vs. Grain Sorghum Yield in 2006
y = 0.8018e7.177x
R2 = 0.7745
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
180.0
200.0
0.3 0.4 0.5 0.6 0.7 0.8 0.9
NDVI at GS-3 (30-40 days post-plant)
Yie
ld B
u/A
c
Sufficiency Index vs. Relative Grain Sorghum Yield in 2006
y = 2.1715x - 126.64
R2 = 0.8695
0
20
40
60
80
100
120
0 20 40 60 80 100 120
Sufficiency Index
Rel
ativ
e Y
ield
%
Sufficiency Index vs. Change in Yield from Additional N in 2006
y = -1.4183x + 149.01
R2 = 0.7681
-10
0
10
20
30
40
50
60
70
50 60 70 80 90 100 110
Sufficiency Index
Yie
ld B
u/A
c
-20
-10
0
10
20
30
40
50
60
70
80
0.8 1 1.2 1.4 1.6 1.8
Relationship of Response Index and ∆ Yield in Sorghum in 2006
Response Index, NDVI reference/ NDVI unfertilized
∆G
rain
Yie
ld B
u/A
c∆Yld = 101.05 RI -91.95
R2= .73
Effect of time and method of N application on sorghum yield, 2006
0
20
40
60
80
100
120
Check 40 day SB 30 day SB 40 day Inject 30 day Inject
2007 Work
• Continuing work on sorghum, wheat and corn at multiple locations
• Plan on providing sensor based N rate calculators for wheat and sorghum this fall on our ST website (sorghum, developed by Drew and Bill Raun, is currently on the OSU/NUE site)
• Starting preliminary work on cotton and canola
GS-3 NDVI .60, check plot GS-3 NDVI .65, reference plot
GS-3 N Rec. 45 lbs/Ac
Questions?
top related