The transferring and management of water and nutrients, and the mechanism of productivity in rice paddy ecosystem
Weijun Zhou, Kelin Wang, Kairong Wang
Taoyuan Experimental Station of Agroecosystem Observation
Introduction• Taoyuan Station is located in hilly area of South China, is a compositive field
experimental station with function of located observation and research of agricultural ecosystem, demonstration of the model of high-efficiency utilization of resources and agricultural sustainable development. The station is subordinated to Institute of Subtropical Agriculture (IAS).
• In this area, it is rich in the resources of light, caloric, water and biology. The potential productivity of climate is very high, and the management of compositive agriculture is advanced too.
• This is a typical “valley agriculture” area and the structure of the agricultural production is unitary. Rice is a most important crop.
Its scientific aim is providing the decision-making basis and technique support
for the ecological and environmental constructing and the development of hig
h-efficiency and sustainable agriculture in central hilly area in the country by r
esearching the important problems, and promoting the development and cons
tructing of agro-ecology and resource management.
In rice paddy ecosystem, the researches have been focused on the following fields:
The recycle of the nutrients and the mechanism of the productivity in rice paddy ecosystem.
The transferring and management of water and optimization of the irrigation technique in rice paddy ecosystem.
The environmental response to the fertilization and its adjustment mechanism.
The ecological elements in high productivity cultivation of special rice(high quality rice, function rice, food rice).
The constitution of high productivity super-rice colony and its physiological index.
The fertility index system of high productivity and high quality rice.
1. Change of rice planting systems in rice paddy ecosystems
Fig. 1 Rice planting area near 50years in Hunan provinve
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
49 54 59 64 69 74 79 84 89 94 99Year
Plan
ting
area
(kha
)Total area Eary rice
Middle rice Late rice
The rice planting area have increased since 1950’s, and it decreased after 1970’s
Area of middle-rice have induced since 1950’s, by the early of 1970’s it is up to the lowest. That of early and late rice have increased since 1950’s, by the early of 1970’s it is up to the largest
Single cropping rice have been changed double cropping rice
2. Change trend of rice total yield near 50 years in Hunan province
Fig.2 Rice grain yield near 50 years in Hunan
0
500
1000
1500
2000
2500
3000
49 54 59 64 69 74 79 84 89 94 99Year
Gra
in y
ield
(100
0kt)
Total yield
Early rice
Middle rice
Late rice
Less rice yield increase was observed before 1960’s, then the yield increased rapidly, by the early of 1980’s it was up to the highest
The yield of middle rice have decreased since 1950’s, by the early of 1970’s it was up to the lowest, however, that of early and late rice indicated the increased trend.
Fig. 3 Change of rice grain of unit area near 50 years inHunan province
0
2000
4000
6000
8000
10000
12000
49 54 59 64 69 74 79 84 89 94 99Year
Gra
in y
ield
of
unit
ere
a (k
g/h
m2)
Annual average
Early rice
Middle rice
Late rice
3. Change trend of rice grain yield of unit area near 50 years in Hunan province
The rice yield of unit area showed the increase trend. Before the early of 1960’s, middle-rice was the important planting system, so the annual yield increased slowly and then the early and late rice became the main planting system, the annual yield increased rapidly.
4. Change of fertilizer application amount near 50 years in Hunan province
Fig.4 The amount of fertilizer application near 50years in Hunan province
0
20
40
60
80
100
120
49 54 59 64 69 74 79 84 89 94 99Year
Fer
tili
zer
amo
unt(
10
00
kt)
N
PK
The amount of fertilizer application was much less before 1960’s, Since the early of 1960’s, the rapid increase of fertilizer have observed
The ratio of N, P, K was inadaptable, N:P:K is 1: 0.2: 0.1
5. The relationship of between fertilizer application and total rice grain yield
Fig. 5 The change trend of both rice grain yield andfertilizer applition amount near 50years in Hunan
0
500
1000
1500
2000
2500
3000
49 52 57 64 73 78 80 84 88 92 96 98 00Year
Gra
in y
ield
(10
0kt)
0
20
40
60
80
100
120
140
160
180
200
Fert
ilize
r am
ount
(100
0kt)
Grain yield
Fertilizer amount
By the 1960’s, the less increment of rice yield was observed due to fertilizer was applied too less, from the early of 1960’s to the middle of 1980’s, the rice yield increased with increased fertilizer applied, then that was at steady state while the quantity of fertilizer was increased
6. The relationship of between rice grain yield of unit area and fertilizer application quantity
Fig. 6 Change trend of both rice grain yield of unit areaand fertilizer application amount
0
2000
4000
6000
8000
10000
12000
49 52 57 64 73 78 80 84 88 92 96 98 00Year
Grai
n yi
eld
of u
nit
area
(kg/
hm2)
0
20
40
60
80
100
120
140
160
180
200
Fert
ilize
r am
onut
(100
0kt)
Grain yield
Fertilizer amount
The change trend of the rice yield of unit area was the same as total rice yield.
Fertilization Models with Double Cropping Rice System
7. Change of rice grain yield under fertilizer application
Fig. 7 Rice grain yield under fertilizer application
0
2000
4000
6000
8000
10000
12000
90 91 92 93 94 95 96 97 98 99 00 01Year
Gra
in y
ield
(g/h
m2)
CK N NPK
The less yield-increase observed, no significant difference the relative no fertilization under only N application, while the rice yield was increased under N, P, K was incorporated .
8. Rice yield benefit under different fertilization model
Fig. 8 Rice grain yield under inorganic-organic fertilizerincorporation
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4000
8000
12000
16000
90 91 92 93 94 95 96 97 98 99 00 01Year
Gra
in y
ield
(kg/
hm2)
CK NPK C NPK+C F+1/ 2C
The rice yield increased under organic residue cycle, no considerably difference was observed between NPK incorporation, but based on organic residue cycle, the rice yield is the largest among all the fertilization models.
9. Rice yield benefit under different fertilization models
Annual yield kg/hm2 Net increment kg/hm2 Yield-increase rate % Treatments 90-93 94-97 98-01 90-93 94-97 98-01 90-93 94-97 98-01
CK 5877 5391 6608
C 8203 6938 9362 2326 1548 2754 39.6 28.7 41.7
N 7921 6275 6688 2044 884 80 34.8 16.4 1.2
N+C 9833 7883 9492 3956 2492 2884 67.3 46.2 43.7
NP 8783 7362 8617 2906 1971 2009 49.4 36.6 30.4
NP+C 9778 8379 9854 3901 2989 3247 66.4 55.4 49.1
NK 8472 6656 8717 2595 1265 2109 44.1 23.5 31.9
NPK 9262 7774 9305 3385 2384 2697 57.6 44.2 40.8
NPK+C 9965 8933 10425 4088 3542 3818 69.6 65.7 57.8
F+1/2C 9674 8521 9935 3797 3131 3328 64.6 58.1 50.4
Table 1 Rice yield benefit of different stage under different fertilization systems
The rice yield-increase rate was decreased under fertilizer application while it was increased under based on organic residue cycle, no fertilizer or NPK incorporation. Residual efficiency of organic residue was very important.
The Relationship of Rice Productivity and water Irrigation Models
10.The annual variation of irrigation effect in the growth of double-crop rice (1989~1998, in Taoyuan,Hunan)
The negative correlation was observed between the quantity of irrigation water and its production efficiency. More the quantity of irrigation, less its efficiency.
0
10
20
30
40
50
5 6 7 8 9 10 Month
Irrig
atio
n(10
0m3 /h
m2)
Bio
mas
s(10
0kg/
hm2)
0246810121416
Irrig
atio
n E
ffici
ency
(%
)
I r r i gat i on Bi omassEffi ci ency
11. The cumulative effect of colony photosynthesis in rice booting in the different water management(in 2000)
0
5
10
15
20
25
30
Water- l ogged Genernal l yRai n- watered
Net
phot
osyn
thes
is (
umol
/sec
)Ear l y r i ce Late r i ce
Seasonal drought influents production of double cropping rice in the region , net photosynthesis was decreased under less water
12. The relationship of plant transpiration rate and leaf porous
conductance
y = 1.0129x + 0.4385
R2 = 0.6392
0
1
2
3
4
5
0 1 2 3 4Leaf porous conductance(cm/s)
Tran
spira
tion
rate(
ug/s.
cm2)
Considerably correction was found between plant transpiration rate and leaf porous conductance
Conclusion
• Improved the composition of fertilizer input, adjusted the ratio of NPK fertilizer
• Reasonably applied the fertilizer according to the law of nutrient balance
• Enough using the organic residue resource, let organic residue in rice paddy system recycle and utilize
• Adjusted and saved the rainfall resource, reasonable irrigation according to the law of rice need, heightened the use efficiency
Thank you very much!