1.   Controversy has also surrounded the long-term effects of artificial fertilizer on the soil structure.

2.   Good soil structure might have been the key factor here, says Andrew Cottrell of Novartis.

3.   In addition they help conserve the existing soil structure by protecting the surface from the destructive force of winter rain.

4.   Mineralogical analysis and microscopic examination of soil structures is well advanced.

5.   Plants with a fibrous root system, creating plenty of organic matter, do most to improve the soil structure.

6.   They will grow good cereal crops so long as soil structure is maintained by the return of sufficient organic matter.

7.   Run-off is increased, especially on slopes, and there may be marked compaction or other deterioration of the soil structure.

8.   Conventional physical and chemical methods can leave the soil structure unsuitable for cultivation.

9.   And there, the gradual penetration of alien worms is having a profound effect on the soil structure.