Development of a Response Index for Corn
description
Transcript of Development of a Response Index for Corn
![Page 1: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/1.jpg)
Development of a Response Index for Corn
Development of a Response Index for Corn
Robert Mullen
Ohio State University
Robert Mullen
Ohio State University
![Page 2: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/2.jpg)
Response IndexResponse Index
• RI first proposed by Johnson and Raun, 2003 (inverse of sufficiency index)
• RI = Yield of N Rich / Yield of Check (0N)– Direct measure of N response
• RI first proposed by Johnson and Raun, 2003 (inverse of sufficiency index)
• RI = Yield of N Rich / Yield of Check (0N)– Direct measure of N response
![Page 3: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/3.jpg)
Response IndexResponse Index
• Can we reliably predict the response to applied N during the growing season?
• Environmentally and economically important– Less N subject to denitrification, leaching, and
runoff– Produce more with less inputs
• Is the relationship stable at different stages of growth?
• Can we reliably predict the response to applied N during the growing season?
• Environmentally and economically important– Less N subject to denitrification, leaching, and
runoff– Produce more with less inputs
• Is the relationship stable at different stages of growth?
![Page 4: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/4.jpg)
Response IndexResponse Index
• In-season estimates of RI were used to identify RI at harvest for winter wheat
• In-season estimates of RI were used to identify RI at harvest for winter wheat
y = 0.99x - 0.01
r2 = 0.65
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4
RI-NDVI
RI-
Har
vest
y = 0.99x - 0.01
r2 = 0.65
0
0.5
1
1.5
2
2.5
3
3.5
4
0 1 2 3 4
RI-NDVI
RI-
Har
vest
![Page 5: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/5.jpg)
Response IndexResponse Index
• Would RI for corn work as well?
• Can RI be identified at early stages of growth (< V8)?
• Would RI for corn work as well?
• Can RI be identified at early stages of growth (< V8)?
![Page 6: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/6.jpg)
Response IndexResponse Index
• Varvel et al., 1997– Used SPAD meters to identify N response at
various stages of growth• V6 – R3
• Relationship has been established between GNDVI and SPAD meter reading (Shanahan et al., 2003)
• Varvel et al., 1997– Used SPAD meters to identify N response at
various stages of growth• V6 – R3
• Relationship has been established between GNDVI and SPAD meter reading (Shanahan et al., 2003)
![Page 7: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/7.jpg)
Can RI work for corn?Can RI work for corn?
• Varvel data shows that pseudo-RI can be determined at various stages of growth– Very little data for some stages of growth– Lack of response at most locations (especially
where corn followed soybeans)
• Varvel data shows that pseudo-RI can be determined at various stages of growth– Very little data for some stages of growth– Lack of response at most locations (especially
where corn followed soybeans)
![Page 8: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/8.jpg)
Can RI be estimated at early stages of growth?
Can RI be estimated at early stages of growth?
• Red NDVI determined significant difference between N rate at V4
• Red NDVI determined significant difference between N rate at V4
N rate RNDVI RNDVI
0 0.209 0.204
60 0.234 0.249
120 0.247 0.239
180 0.263 0.244
Linear P=0.0149 P=0.0319
![Page 9: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/9.jpg)
Can RI be estimated at early stages of growth?
Can RI be estimated at early stages of growth?
• Green and red NDVI determined differences between treatments at V6
• Green and red NDVI determined differences between treatments at V6
N rate RNDVI GNDVI
0 0.531 0.437
60 0.654 0.530
120 0.664 0.546
180 0.678 0.540
Linear P=0.0001 P=0.0001
![Page 10: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/10.jpg)
DiscussionDiscussion
• Practicality of N rich strip– Production scale agriculture without
sophisticated sensors– Answer N loss questions and helps make N
application decisions
• Practicality of N rich strip– Production scale agriculture without
sophisticated sensors– Answer N loss questions and helps make N
application decisions
![Page 11: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/11.jpg)
DiscussionDiscussion
• The earlier, the better– Determination of RI early in the season would
be better• Lack of high-clearance application equipment• Increase in application window
• The earlier, the better– Determination of RI early in the season would
be better• Lack of high-clearance application equipment• Increase in application window
![Page 12: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/12.jpg)
Conclusions?Conclusions?
• Continue research to identify relationship between RI-NDVI and RI-Harvest for corn.
• “Calibrate” RI at various growth stages with N application rates if yield cannot be predicted accurately (this will be difficult).
• Encourage use of N rich strips in production fields to answer simple N application questions.
• Continue research to identify relationship between RI-NDVI and RI-Harvest for corn.
• “Calibrate” RI at various growth stages with N application rates if yield cannot be predicted accurately (this will be difficult).
• Encourage use of N rich strips in production fields to answer simple N application questions.
![Page 13: Development of a Response Index for Corn](https://reader036.fdocuments.us/reader036/viewer/2022062803/5681474b550346895db48eae/html5/thumbnails/13.jpg)
Questions?Questions?