Effects of Phosphorus and Rhizobium Inoculation on Growth and Nitrogen Fixation of Hamate (Stylosanthes hamata cv. Verano) Grown on Kamphaeng Saen Soil Series.

Abstract

Pot experiment was established to determine the influences of Rhizobium inoculation (non-inoculation and inoculation) at three phosphorus rates (0, 10 and 40 Kg P/ha) on oven-dry matter, N yield and nitrogen fixation activity at different ages of harvesting (2, 2½, 3, 3½, and 4 months) of Hamata legume (Stulosanthes hamata cv. Verano) grown on Kamphaeng Saen Soil Series which was one of the most common soils used for growing forage crops for dairy production in the central and western parts of Thailand. The experiment was conducted at Kasetsart University (BangKhen Campus) for a period of six months. Oven-dry matter and N yield of Hamaia legume were significantly increased with phosphorus fertilization and Rhizobium inoculation at all ages of harvestion and oven-dry matter as well as N yield of this legume were the highest at age of 3½ and 4 months. The activity of nitrogen fixation measured by acetylene reduction method was significantly increased with phosphorus fertilization and Rhizobium inoculation. Maximum nitrogen fixation activity of this legume was observed at the age of 3½ month at the rate of 2.07 u moles C2H4/plant. hr. for non-inoculation and at the rate of 3.77 u moles C2H4/plant. hr. for inoculation.