Effect of Defoliation and Soil Moisture on Grassland Re‐growth

The results of field experiments with leys dominated by Festuca pratensis and Dactylis species appear to concur with the theories proposed by Kramer and Jäntti. Complete defoliation, while the soil moisture was at or near permanent wilting percentage down to about 40 cm. depth, arrested growth almost completely but the growth rate of plants with assimilating parts left was 70 to 90 per cent of the corresponding rate on moist soil. The interaction of defoliation and soil moisture, however, seemed to be confined to cases where defoliation was practically complete. When a 4 cm. stubble was left the effect of drought was relatively no more strong than in swards cut to only 12 cm. Defoliation alone causes heavy crop reductions even in moist soil, and these reductions are evidently more important quantitatively than those resulting from the interaction with soil moisture.