Cultivar Variation in Kentucky Bluegrass: P and K Nutritional Factors1
- B. J. Mehall,
- R. J. Hull and
- C. R. Skogley2
While many Kentucky bluegrass (Poa pratensis L.) cultivars have been evaluated for their capacity to produce quality turf, little is known about the contribution of nutritional factors to the variability observed between cultivars. Recognizing these nutritional characters could speed the development of turfgrasses adapted to low fertility soils. In 1978 and 1979, 15 Kentucky bluegrass cultivars of differing quality, growth pattern, and place of origin were compared for clipping production rate, leaf blade P and K content, and the resulting P and K efficiency ratio (mg dry wt./mg nutrient). Correlation coefficients between these factors and turf quality scores were determined in 1978. Field plots on an Enfield silt loam (coarse-silty over sandy skeletal, mixed, mesic, Typic Dystrochrept) were fertilized with 4.8 g N/m2/year and mowed twice weekly at 3.8 cm. On four dates each year, clippings were weighed and analyzed for P and K. Significant differences between cultivars were obtained for all factors tested. Despite substantial variability within and between seasons some cultivars exhibited reasonable consistency in their ranking for growth and nutrient content of clippings. Turf quality scores were correlated with leaf blade P content but not with clipping growth rate. The P and K efficiency ratios, based on the nutrient content of clippings, offered some promise as an indicator of cultivar nutrient use efficiency. The value of this factor for identifying cultivars adapted to low fertility soils remains to be demonstrated.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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