The transferring and management of water and nutrients, and the mechanism of productivity in rice paddy ecosystem

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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

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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 high-efficiency and
  sustainable agriculture in central hilly area in
  the country by researching the important
  problems, and promoting the development and
  constructing of agro-ecology and resource
  management.

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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.

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1. Change of rice planting systems in rice paddy
ecosystems
The rice planting area have increased since
1950s, and it decreased after 1970s Area of
middle-rice have induced since 1950s, by the
early of 1970s it is up to the lowest. That of
early and late rice have increased since 1950s,
by the early of 1970s it is up to the
largest Single cropping rice have been changed
double cropping rice
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2. Change trend of rice total yield near 50 years
in Hunan province
Less rice yield increase was observed before
1960s, then the yield increased rapidly, by the
early of 1980s it was up to the highest The
yield of middle rice have decreased since 1950s,
by the early of 1970s it was up to the lowest,
however, that of early and late rice indicated
the increased trend.
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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 1960s, 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.
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4. Change of fertilizer application amount near
50 years in Hunan province
The amount of fertilizer application was much
less before 1960s, Since the early of 1960s,
the rapid increase of fertilizer have
observed The ratio of N, P, K was inadaptable,
NPK is 1 0.2 0.1
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5. The relationship of between fertilizer
application and total rice grain yield
By the 1960s, the less increment of rice yield
was observed due to fertilizer was applied too
less, from the early of 1960s to the middle of
1980s, the rice yield increased with increased
fertilizer applied, then that was at steady state
while the quantity of fertilizer was increased
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6. The relationship of between rice grain yield
of unit area and fertilizer application quantity
The change trend of the rice yield of unit area
was the same as total rice yield.
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Fertilization Models with Double Cropping Rice
System
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7. Change of rice grain yield under fertilizer
application
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 .
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8. Rice yield benefit under different
fertilization model
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.
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9. Rice yield benefit under different
fertilization models
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.
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The Relationship of Rice Productivity and water
Irrigation Models
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10.The annual variation of irrigation effect in
the growth of double-crop rice (19891998, 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.
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11. The cumulative effect of colony
photosynthesis in rice booting in the different
water management(in 2000)
Seasonal drought influents production of double
cropping rice in the region , net photosynthesis
was decreased under less water
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12. The relationship of plant transpiration
rate and leaf porous conductance
Considerably correction was found between plant
transpiration rate and leaf porous conductance
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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

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• Thank you very much!