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

Abstract

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.