Use of organic materials on rice 7july 2010 bohol.ppt

organic production of rice

1. Organic fertilizers and rice

2. Organic farming and organic fertilizers
are not the same
Organic farming is a form of agriculture that
deliberately follows a set of management
practices
Organic fertilizer is fertilizer derived from
animal or plant materials

3. What is organic fertilizer?
•Crop residues
–Stubble and straw
•Locally available materials
–Farmyard manure
–Plant biomass
–Green manures
–Compost
•Commercially available fertilizers
–Produced from plant and/or animal
byproducts
–Microbial amendments
Materials derived from plants or animals

4. Why apply organic materials?
1.Improve soil physical and chemical properties
Water-holding capacity
Soil structure
Nutrient-holding capacity
2.Provide a source of plant-available nutrients
Alternative to mineral fertilizers
3.Enhance biological processes

5. What organic material to apply?
1.Improve soil physical and chemical properties
Added OM should be retained for long period
Large amount of slow decomposing organic material
High C/N ratio desirable
Surface mulching/no tillage can be desirable
2.Provide a source of plant-available nutrients
Added OM should rapidly release nutrients
Large amount of fast decomposing organic material
Best materials are high in nutrients & disappear rapidly
Low C/N ratio desirable

6. Where to apply organic material?
Lowland riceUpland crop
Tillage of aerated soilTillage of flooded soil

7. Land preparation and flooding for
lowland rice affects soil
Soil structure and
aeration
Important for crop
production
Destroyed by land
preparation
Soil microorganismsAerobes Anaerobes
Mineral matter
Organic matter
Water
Air
Soil with upland
crop
Lowland rice
soil
Soil is about 50% pore
space (air and water) and
50% particles (mineral and
organic matter

8. Benefit of organicUpland crop Lowland rice
1. Improve soil physical
and chemical
properties
*** Important
Requires slow
decomposing material
2. Provide a source of
plant-available
nutrients
** Potentially important
Requires fast
decomposing, nutrient-
rich material
3. Enhance biological
processes
** Potentially important
Must overcome a limit to
crop growth
Role and importance of added
organic materials depend upon crop

9. Benefit of organicUpland crop Lowland rice
1. Improve soil physical
and chemical
properties
*** Important
Requires slow
decomposing material
Limited importance
Normally not serious
constraint for rice
2. Provide a source of
plant-available
nutrients
** Potentially important
Requires fast
decomposing, nutrient-
rich material
** Potentially important
Requires fast
decomposing, nutrient-rich
material
3. Enhance biological
processes
** Potentially important
Must overcome a limit to
crop growth
* Lesser importance
Normally less serious
constraint for rice
Requires anaerobes
Role and importance of added
organic materials depend upon crop

10. Benefit of organicUpland crop Lowland rice
1. Improve soil physical
and chemical
properties

2. Provide a source of
plant-available
nutrients


3. Enhance biological
processes

Importance of added organic materials
for upland crop and lowland rice

11. Organic materials must decompose in
order to supply nutrients to crops
NH
4
+
NO
3
-
HPO
4
2-

H
2PO
4
-
K
+
SO
4
2-
Ca
2+
Mg
2+
mineralization
(microbial activity)
Organic
materials
urea NPK
Mineral fertilizers

12. Plants take up nutrients in the same
form from organic and mineral
fertilizers
Nutrient Forms absorbed by plant
Nitrogen (N) NH
4
+
, NO
3
-
ammonium,
nitrate,
Phosphorus (P) HPO
4
2-
, H
2
PO
4
-
phosphate
Potassium (K) K
+
potassium ion
Sulfur (S) SO
4
2-
sulfate
Calcium (Ca) Ca
2+
Magnesium (Mg) Mg
2+

13. Can nutrients solely from organic
sources supply the requirements of a
rice crop to attain high yield?

14. Example of lowland rice:
Specific conditions:
Yield: 6 t/ha at 14%
moisture
Soil P: high-medium
Soil K: high-medium
Rice stubbles retained
Can organic materials match crop
needs for added nutrient?
Need for nutrient estimated with
Nutrient Manager for Rice
Nutrient requirement (kg ha
-1
)
0
20
40
60
80
100
120
N P
2
O
5
K
2
O
110
kg/ha
28
kg/ha
32
kg/ha

15. How much nutrient can the organic source
provide?
Suppose a rice farmer return rice straw materials to his rice field
at a rate of 3 t/ha with analysis of 0.65% N, 0.10% P
2
O
5
, and
1.40% K
2
O
0
20
40
60
80
100
120
19.5 kg/ha
3 kg/ha
42 kg/ha
110 kg/ha
28 kg/ha
32 kg/ha
Deficit by 25 kg/ha
Deficit by 90.5 kg/ha
Excess by 10 kg/ha
N P
2
O
5
K
2
O
N
u
t
r
ie
n
t
r
e
q
u
ir
e
m
e
n
t
(
k
g
h
a
-
1
)

16. How much nutrient can the organic source
provide?
Suppose a rice farmer applies an organic material to his rice field
at a rate of 2 t/ha with analysis of 2% N, 1% P
2O
5, and 2% K
2O
0
20
40
60
80
100
120
40 kg/ha
20 kg/ha
40 kg/ha
110 kg/ha
28 kg/ha
32 kg/ha
Deficit by 8 kg/ha
Deficit by 70 kg/ha
Excess by 8 kg/ha
N P
2
O
5
K
2
O
N
u
t
r
ie
n
t
r
e
q
u
ir
e
m
e
n
t
(
k
g
h
a
-
1
)

17. How much nutrient can the organic source
provide?
Suppose a rice farmer applies an organic material to his rice field at
a rate of 5 t/ha with analysis of 2% N, 2% P
2
O
5
, and 2% K
2
O
N
u
t
r
ie
n
t
r
e
q
u
ir
e
m
e
n
t
(
k
g
h
a
-
1
)
0
20
40
60
80
100
120
N P
2
O
5
K
2
O
78 % more
212 % more
9% less

18. To meet the requirement of 100kg N/ ha
we need this amount of materials:
UREA
(46%N)
Poultry
manure
(2%N)
Cattle
manure
(1%N)
Compost
(0.5%N)
217 kg 5,000 kg10,000 kg20,000 kg

19. Nutrients available from composted straw
Nutrient% in
straw
Amount per ton of
composted straw
(kg/ton)
N 0.65 6
P
2
O
5
0.10 1.9
K
2
O 1.40 15.6
Source: Fairhurst et al. 2007. Rice: A Practical Guide to Nutrient Management

20. Distribution of nutrient benefits
from organic sources
•First 10 kg N/ha is subtracted from the
recommended N at early application
•The remaining N is subtracted from the
recommended N at panicle initiation

21. What are the disadvantages (problems) of
organic material?
•Organic material can be bulky, with high handling and
transport costs
•Organic manures are sometimes more expensive than
inorganic fertilizers per unit of nutrient.
•It is not always available.
•It must be applied at the beginning of the crop, so early
applications may not meet later crop demand for nutrients.
•Organic material can smell bad.

22. Why use microbial amendments?
1)Hasten decomposition of organic materials
Increase availability of added nutrient
Does not increase total amount of added nutrient
2)Increase availability of nutrient in soil
Enable plant to better extract nutrient in soil
Does not increase total amount of nutrient
3)Increase supply of N
Symbiotic N
2 fixation
Associative N
2
fixation – aerobic organism
4)Improve crop health
Little or no benefit of added aerobes in lowland rice
Careful agronomic and economic evaluation &
quality control are required!

23. •All aboveground crop residue removed
Long-term continuous cropping experiment
(LTCCE) at IRRI
•Started in 1963
•3 rice crops per
year
•Crop in 2010
early wet
season: 139
•The most
intensively
cropped
experimental site
in Asia

24. •4 N rates, from 0 to high
•All plots receive sufficient P, K, and Zn
•No organic fertilizer applied
Long-term continuous cropping experiment
(LTCCE) at IRRI
•Started in 1963
•3 rice crops per
year
•Crop in 2010
early wet
season: 139
•The most
intensively
cropped
experimental site
in Asia

25. 20

22

24

26

28

1983 1998
Total soil C (g kg
-1
)

b

a
Organic materials are not essential to maintain
soil organic matter (C) and soil N supply in
lowland rice
Pampolino et al., Soil Sci. Soc. Am. J. (2008)
1983
20

21

22

23

24

1998

Anaerobic N mineralization (mg N kg
-1
day
-1
)

a
a
LTCCE at IRRI, 0-20 cm, avg. of 3 N-fertilized treatments,
continuous rice

26. Addition of organic material does not
guarantee no loss of soil organic matter for
upland crop
Incorporated
crop residue
did not prevent
loss of soil C in
rice-maize
a
a
b
a
15
17
19
21
23
25
Rice-rice
Total soil C (t/ha)
1993
a
a
b
a
Rice-maize
2006 20061993
R. Buresh, IRRI
Long-term experiment at IRRI

27. •25 LTE in Asia (7 rice-rice, 18 rice-wheat)
•Application of either manure or straw did not improve
grain yield trends
•Manure or straw may be profitable when (i) available
& affordable and (ii) used as a complement to a
recommended dose of inorganic NPK

28. Summary
•There are not enough organic nutrient sources to feed
this world
•Benefits of organic materials for soil physical and
chemical properties are greater for upland crops than
for lowland rice
•Incorporation of crop residue or manure is not
essential for many productive lowland rice soils
•Organic materials and crop residues seldom increase
lowland rice yield compared to fertilizer BMP
•Use organic fertilizer when it is economical, as a
complement to mineral fertilizers

29. Practical considerations for organic
fertilizers
•Land, water, energy and time are required to produce
organic materials
•Nutrients from organic sources are not “free”
•Nutrient content can vary widely among materials and
batches of a material
•Often do not supply enough N
•May not give short-term benefit on yield
•Must have the same product stewardship regulations as
mineral fertilizers: accurate display of nutrient content,
quality control, proper usage
•Subsidies may distort markets