Pusat Aplikasi Isotop dan Radiasi, Badan Tenaga Nuklir Nasional
Abstract
USING THE N-15 METHOD TO DETERMINE N-SOIL, N-GREEN
MANURE, AND N-UREA AVAILABILITY AFTER SIX SEASONS IN AN
ALLEY CROPPING SYSTEM. Nitrogen (N) is the most important nutrient for crop
growth and production. This study was conducted to determine whether in each of
six seasons and after these seasons the N-soil, N-green manure, N-green manure +
urea, and N-urea is still available for crops. Upland rice and corn were planted
successively for six seasons. In each season upland rice and corn were planted and
applied with N-fertilizers at rate of: control (0N), N1 (100% green manure), N2 (50%
green manure + 50% urea), N3 (100% urea). N-15 labelled urea was added at each
season to determine the A-value of the crops.
In each seasons it was shown that crops used N-soil as well as N-fertilizer. With the
increase of the availability of N-fertilizers the use of N-soil decrease and so could
preserve N-soil. With preservation of N-soil it could be assumed that soil quality has
increased. The N-15 method could be used to determine the availability at each
fertilizer rate?s in each season and at the end of the sixth season