Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Nitrogen Management for Organic Strawberry Production
Update
Mark Gaskell, Farm AdvisorUC Cooperative Extension- San Luis Obispo
Overview
• Nitrogen is critical limiting factor
• Certified organic N more costly, uncertain
• N mineralization determines nitrate availability
• Different materials with varying availability
• Field management also critical- nitrate moves with water
http://www.ams.usda.gov/AMSv1.0/nop
http://www.omri.org/
0 4 1412 6 10 8 18 16 2 20
.
Mineralization of Pre-plant Applied Compost
Time
Rate
of N
Min
eral
izatio
n or
abs
orpt
ion
Week
0 4 1412
6 10 8 18 16 2 20
Time
Week
.
Mineralization of Pre-plant Applied Compost
Rate
of N
Min
eral
izatio
n or
abs
orpt
ion Plant N Demand
0 4 1412
6 10 8 18 16 2 20
SouthernDistricts
Northern
Districts
Time
Week
. . ..
Periodic injections needed – weekly?
Mineralization of Pre-plant Applied Compost
Rate
of N
Min
eral
izatio
n or
abs
orpt
ion
Plant N Demand
Source- Tim Hartz, UC-Davis
Source- Tim Hartz, UC-Davis
Some materials relatively high in available N in greenhouse
0
20
40
60
80
100
120St
raw
berr
y N
Acc
umul
atio
n(lb
N/A
)Strawberry Nitrogen Accumulation
Plant N
Plant plus Fruit N
0
10
20
30
40
50
60R
esid
ual S
oil N
itrat
e-N
(ppm
)
Sample Date (2007/8)
True Organic
Neptunes Harvest
Phytamin 434
0
10
20
30
40
50
60S
oil R
esid
ual N
itrat
e-N
(ppm
)
Sample Date (2007 / 2008)
6.8 kg N /week
13.6 kg N / week
20.4 kg N /week
0
10
20
30
40
50
60
Res
idua
l Soi
l Nitr
ate-
N (p
pm)
Sample Date (2007/8)
True Organic
Neptunes Harvest
Phytamin 434
0
10
20
30
40
50
60
Res
idua
l Soi
l Nitr
ate-
N (p
pm)
Sample Date (2007 / 2008)
125 lb N Preplant
2.5 lb N /week
IllustrativeSeasonal Soil N in Conventional Field
Illustrative Seasonal Soil N in Organic Field
N uptake rate VS Timing of N availability
• Total N uptake important
• Strawberries? Early vegetative development?
• Sets stage for plant branch number, size
• Can have big effect on yield
0
10
20
30
40
50
60S
oil R
esid
ual N
itrat
e-N
(ppm
)
Sample Date (2007 / 2008)
6.8 kg N /week
13.6 kg N / week
20.4 kg N /week
0
10
20
30
40
50
60
70
Sampling Date
Weekly Soil Nitrate-N following varying rates ofpreplant and weekly injected organic N
10-3
10-6
0
10
20
30
40
50
60
()
Sampling Date
Weekly Soil Nitrate-N following varying rates ofpreplant and weekly injected organic N
0-3
5-3
10-3
Organic Fruit Yields?
• Typically half of conventional yields
• Rarely different among treatments• Preplant compost rates• in-season injection materials?• In-season injection rates
Are we applying N early enough and managing injections to assure N is available?
0
500
1000
1500
2000
2500
3000
3500
4000To
tal F
ruit
Yiel
d (K
g / h
a)
True OrganicNeptune'sPhytamin 434
2008 Season
Summary
• N fertilization is challenging in organic production
• Low OM soils more difficult and costly
• Materials vary in cost, N availability
• Mineralization determines nitrate availability
• Lower N compared to conventional- management can be critical - interaction with water management?
Acknowledgements
• Cachuma Resource Conservation District
Kate Dixon, Julie Fallon, Claire Wineman,Misael Sanchez, Kevin Peterson, Adriana Morales,
Tom Lockhart
• Dave Peck, Manzanita Farms / Well Pict- Santa Maria
• CalPoly San Luis Obispo – Soil Science Dept
• USDA – Section 2501 Program