Some factors affecting the prevalence of white clover in grassland

The causes of the wide fluctuations in the prevalence of white clover (T. repens) in grassland are still largely undetermined. The results at many experiment stations have shown the importance of having large percentages of white clover in permanent grasslands. These findings are supported by results at the Storrs, Conn., Agricultural Experiment Station. Over a 3-year period, strains of clover, indigenous in old pastures of England, New Zealand, and the United States, have maintained the best stands in grass-clover seedings. Polish, Danish, and commercial white Dutch were the shortest lived of 18 strains. In respect to longevity, there appeared to be little choice between seed from northern, southern, or far western parts of the United States. Climatic conditions have been of less importance than fertilization or species of grasses in the maintenance of white clover in mixed stands. Clover has been much less prevalent with the turf-forming grasses, such as the bluegrasses and bents, than with species having more open stands. The retarding effects of nitrogenous fertilizers on clover in grassland were due chiefly to the increased grass competition caused by the nitrogen. In grazed permanent pastures, very little clover has been present without adding phosphorus. Pastures with complete minerals (PLK) had the most clover, but omission of K had little effect. In the case of an adjacent permanent meadow mowed in June for hay and grazed in late summer and fall, adding either potash or manure with superphosphate and limestone was very influential in promoting large amounts of clover. On Charlton fine sandy loam soil, minor elements have had no appreciable effects on clover. Lawnmowing to 1/2 inch for one season greatly decreased both Ladino and Kent clovers in Kentucky bluegrass-clover seedings, but Kent clover increased slightly under this management in a mixture with less bluegrass. Cutting to 1 inch was the standard of a comparison. The amounts of volunteer white clover increased with height when vegetation was mowed during 4 years under four different methods of fertilizing Kentucky bluegrass and Rhode Island bent grasses, cut when 2, 3, 4, and 5 inches in height. In grassland research, the writer feels that the use of a standardized or single method may defeat the purpose of many experiments.