Sivalingam Kts

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The second option required crop rotation and prevented continuous cultivation of staple grain crops, be it rice or wheat. As the demand for staple grains grew with an expanding (and urbanizing) population, it became clear that farmers would not be able to meet future food needs without new, synthetic sources of “fixed” nitrogen—that is, nitrogen available in forms that can be tapped by growing crops.
Numbers Don't Lie: 71 Things You Need to Know About the World
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