Experiments on the effect of inter-row cultivation of sugar beet, carried out in the three years 1939–41 on a sandy loam, led to the following results:
1. If the soil nutrients are in short supply hoeing or hand-weeding increases the yield of the beet, provided these operations are carried out before or shortly after singling.
2. Hoeing is more effective than hand-weeding, but it cannot yet be said with certainty whether this is due entirely to more efficient weed destruction, or whether there is some additional effect, such as mulching.
3. If adequate quantities of soil nutrients are present, inter-row cultivation has little effect on yield, and the crop can tolerate a considerable weed infestation without any effect on yield.
The results for sugar beet on the heavy clay-with-flints soil at Rothamsted show:
1. Additional hoeings after singling, above a modest minimum, have either no effect on yield or else depress it.
2. On the one occasion when pre-singling cultivations were given, the yield was increased.
3. In contrast with the Woburn results the effect of cultivation does not vary with, the level of manuring.