Absorption of Fall-Applied Nitrogen in Satsuma Mandarin Orchard with Rat Tail Fescue as Cover Crop

Abstract

A ¹⁵N-tracer method was used to study the absorption of nitrogen applied in the fall to satsuma mandarin trees and Rat tail fescue, Vulpia myuros, in a pot test in which a satsuma mandarin tree was grown with the grass (Rat tail fescue) as a cover crop. Nitrogen absorption by the trees in a plot covered with Rat tail fescue was about 41% of that in the plot without cover crop. The difference of the nitrogen distribution was particularly observed in new leaves and fine roots. The absolute amount of nitrogen absorbed by the grass in a sod culture plot was about twice that absorbed by the trees in the plot, and the absorbed nitrogen was distributed in the aboveground parts in Rat tail fescue. The trees utilized 19.5% of the fall-applied nitrogen in the plot with Rat tail fescue and 48.1% in the plot without cover crop. However, total utilization (trees+grass) in the sod culture plot reached 60.9%, which was about 1.3 times the rate in the plot without a cover crop.