Effects of Potassium Fertilization and Pratylenchus penetrans on Yield and Potassium Content of Red Clover and Alfalfa


  • C. B. Willis


Red clover and alfalfa were inoculated with Pratylenchus penetrans and grown in an Alberry sandy loam soil to which potassium (K[sup+]) was added at seeding at 0, 41.5, 83, and 166 [mu]g/g. In one experiment with alfalfa, additional K[sup+] was added after each forage cut to replace that which was removed. Nematode populations were not consistently affected by K[sup+] fertilization. Nematode infection stunted red clover and alfalfa and resulted in lower yields at all K[sup+] levels, except for alfalfa at the lowest K[sup+] level. Nematode infection had no effect on taproot yields. However, it resulted in lower rootlet yields from red clover at all K[sup+] levels, lower rootlet yields from alfalfa only at the highest K[sup+] level in one experiment, and lower rootlet yields at all but the lowest K[sup+] level in a second experiment, potassium fertilization enhanced yield of red clover and alfalfa. Yield increases were smaller from increased K[sup+] fertilization in nematode-infested soil than in noninfested soil. Pralylenchus penetrans had little effect on the K[sup+] content of red clover or alfalfa. The stunting of plants from nematode infection resulted in less K[sup+] being removed from the soil. Key Words: potassium nutrition , Medicago saliva, root-lesion nematode, Pratylenehus penetrans, Trifolium pratense.