1.   Properly looked after they can produce several crops a year and remain fertile for centuries without needing a fallow period.

2.   The farmers who have undoubtedly profited from producing heavier crops of higher-yielding varieties that rely on nitrates also share the blame.

3.   The land is so poor that much of the seed will not produce a crop.

4.   This earth is not fertile enough to produce crops.

5.   ...the correct way to produce a crop of tomato plants.

6.   The potential for producing multi-purpose crops is clearly very great.

7.   Scientists at the seed company Nickerson International have produced a crop of potatoes which have been genetically modified to resist pests such as the Colorado beetle and tuber moth.

8.   It will produce increased crops and cope with shaking.

9.   Scattered around him were complete skeletons reminding him of when his country was able to produce crops and feed animals.