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Bruce Linquist
January 26 and 27, 2017
Nutrient management in California rice
systems
Outline
• 2016 Rice Yield Contest
• Variety usage survey
• Boosting yields and maintaining efficiency
– Assessing need for top-dress N applications
– K fertility
– Do temperatures affect yields? If so, what can we do about it?
– Time of planting
Yield Contest
• 2015 Pilot study – Butte County
• 2016 Sacramento Valley
• Minimum of 3 ac from a 10 ac plot
• Yield: 14% moisture minus dockage
1
4 3
2
1
43
2
Yield Contest Winners2016
Joe Richter115.0 cwt/acM-205
Josh Sheppard122.5 cwt/acM-105
Steve Willey119.4 cwt/acM-206
Rice Yield Contest: what have we learned?• Yields have ranged from 108.4 to 126.9 cwt/ac
• Commercial varieties have good yield potential
• High yields does not reduce quality– Head:63-68
– Total 69-72
• High yields were achieved with solid management practices– Total N applied across fields ranged from 162-180
Rice Yield Contest
• Bruce Linquist
• January 19 and 20, 2016
California variety usage
• Questions are for growers or PCAs
• Grower
– Base questions on primary region and practice (conventional vs organic)
• PCA
– Base questions on one grower you work with
– Use growers primary region and practice
– Preferably not a grower in the room
Top-dress N applications: Is it necessary?
• Leaf-color chart
• SPAD meter
• Evaluating the potential for using NDVI (Normalized Difference Vegetation Index)
N uptake at PI vs yield
• Requires 125 lb N in crop at PI to achieve maximum yield
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0 50 100 150 200 250
Gra
in Y
ield
(lb
s/ac
re)
N Uptake at PI (lbs N/acre)
RES 2016
Davis 2016
RES 2015
Arbuckle 2015
NDVI vs N uptake at PI
• NDVI of 0.76 is a good indication of 125 lb N/ac N uptake
0
50
100
150
200
250
300
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
N U
pta
ke a
t P
I (lb
s N
/acr
e)
NDVI
RES 2016
Davis 2016
RES 2015
Arbuckle 2015
29 Sites
When do top-dress N applications increase yields?
• 2016 research
• 5 preplant N rates
– 0 to 200 lb/ac
• 3 top-dress N rates
– 0, 22 and 44 lb N/ac
Yield response to top-dress N applications
• Confirms that 125 lbN/ac at PI is adequate
• Adding N when N uptake is below 125 lb/ac increases yields
• Adding N when N uptake is above 125 lb/ac decreases yield
-4000
-3000
-2000
-1000
0
1000
2000
3000
0 25 50 75 100 125 150 175
Ch
nag
e in
Gra
in Y
ield
wit
h T
op
dre
ss
(lb
s/ac
re)
N Uptake at PI (lbs N/acre)
RES 2016 22 lbs/acre topdress
44 lbs/acre topdress
-3000
-2000
-1000
0
1000
2000
3000
0 25 50 75 100 125 150 175
Ch
ange
in G
rain
Yie
ld w
ith
To
pd
ress
(l
bs/
acre
s)
N Uptake at PI (lbs N/acre)
Davis 2016 22 lbs/acre topdress
44 lbs/acre topdress
Top-dress N applications: Field trials
• Research will be continued
• Look at accessing N deficiencies with drone
Potassium
Flag leaf K vs. soil K
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
0 100 200 300 400
Flag
leaf
K c
on
cen
trat
ion
(%
)
Soil K (ppm)
60 120
24%50%
K fixation
• Some soils low in extractable K also fix K
• Soils tend to be on eastern and southern Sacramento Valley
Cold stress during booting had greatest effect on yields
(1000 lb/ac)
What does this mean for management?
• Cold stress during booting results in blanking
• Cold stress starts when night time temperatures drop below 56 degrees.
• Low temperatures occur in all regions of the valley but more in south
• Use suitable varieties for the region
– M-206 is a good variety for cold areas
• Raise water in field to cover emerging panicle.
Optimal planting times
• Planting time determined– Temperature– Time to work the seedbed
• From May to mid June planting dates the earlierthe better.
• Effect is significant but not large– May 1 vs May 30 about 6
sacks (20 lb/ac/day reduction)
Website• Website overview
– Meetings, news, newsletters, blogs, presentations, reports, contacts, yield contest, guidelines
http://rice.ucanr.edu/
CIMIS Station map
2 new stationsBiggsWilliams
1 station removedColusa
Thank you
