11) rotation of crops. The Columbia Encyclopedia, Sixth Edition. 2001
...rotation of crops, agricultural practice of varying the crops on a piece of land in a planned series, to save or increase the mineral or organic content of the soil,...
12) diseases of plants. The Columbia Encyclopedia, Sixth Edition. 2001
...about viruses. 3 ControlPlant diseases are controlled by methods of cultivation (e.g., crop rotation and the plowing under or burning of crop residue); by application...
13) wheat. The Columbia Encyclopedia, Sixth Edition. 2001
...Large-scale mechanized farming and continued planting of wheat without regard to crop rotation have exhausted the soil of large areas. High-yield wheat, one of the...
14) nitrogen cycle. The Columbia Encyclopedia, Sixth Edition. 2001
...compounds to the soil for uptake by the next generation of plants. For this reason crop rotation in which a leguminous crop is rotated with a nonleguminous one is...
15) 2. Muslim Spain. 2001. The Encyclopedia of World History
...the 11th century, cotton; these crops, together with new methods of field irrigation and crop rotation, led to "a green revolution" in Spain. 8 Cordoba, with a population...
16) root crop. The Columbia Encyclopedia, Sixth Edition. 2001
...is lowest. Because they require thorough cultivating they are often desirable in a rotation of crops-beets and turnips being most frequently so used. Root crops,...
17) soil. The Columbia Encyclopedia, Sixth Edition. 2001
...management issues. Various methods of cultivation conserve soil fertility (see cover crop; rotation of crops). Minimum-tillage systems, often entailing herbicide...
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