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Plant/Animal Production
Crop production - nitrogen fixation
This material addresses aspects of the following syllabus outcome:
H2.1 describes the inputs, processes and interactions of plant production systems.
The work presented in the following section contributes towards achieving the following syllabus content areas:
- plant production systems
- the processes of respiration and photosynthesis and net assimilation rate
- microbes and invertebrates
- the role of microbes and invertebrates in the decomposition of organic matter and the fixing of atmospheric nitrogen via their association with legumes
- analyse and interpret agricultural data
Source: NSW Board of Studies Agriculture Syllabus
A variety of legumes are grown in agriculture. Some legumes are grown as a direct food supply for both animals and humans while others are grown as fodder crops, adding organic matter and valuable soil nitrogen. All legumes have the ability to fix soil nitrogen, making atmospheric nitrogen available for plant use. This ability makes them invaluable in sustainable agricultural production systems.
This work requires you to use your knowledge of nitrogen fixation and photosynthesis and how they effect the growth of some legume species. It also gives you a chance to practice your graphing skills.
You should examine the table below and answer the questions after the table.
The levels of nitrogen fixation occurring on-farm with different crops.
| Species | Crop management | Amounts of nitrogen fixed (kg N/ha) |
|---|---|---|
| Chickpea | no irrigation | 25 |
| Faba bean | no irrigation | 70 |
| Faba bean | partial irrigation | 106 |
| Lupin | no irrigation | 220 |
| Soybean | fully irrigated | 180 |
Source: Farming Ahead with the Knodinin Group. January 1998
Questions
- Draw and label a graph showing the amounts of nitrogen fixed for each of the species presented in the table.
- From the table and graph that you have drawn, determine which species fixed the greatest amount of nitrogen?
- Compare the amount of nitrogen fixed for non-irrigated Faba beans with partially irrigated Faba beans.
- Can you suggest any reason for the answer to question 3?
- Describe the process that occurs in legumes resulting in the fixation of nitrogen.
- Describe why legumes are a useful plant to be used in crop rotations.
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