In:
Agronomy Journal, Wiley, Vol. 88, No. 4 ( 1996-07), p. 614-621
Abstract:
An understanding of N cycling in agricultural systems is necessary to optimize N‐use efficiency and reduce N losses to the environment. The objectives of this research were to evaluate N cycling in a highly fertilized grassland in a humid temperate climate and to observe the effects of N surplus and deficit on NH 3 absorption‐desorption by the grass. Soil, plant, and weather measurements were taken concurrently and soil‐plant‐atmosphere N transport were determined. After N application, soil inorganic N decreased rapidly to background levels, due to possible microbial immobilization and plant N demand. Much of the immobilized N was remobilized during the growth period, but at insufficient rates to avoid N stress by the crop, as shown by absorption of NH 3 . During spring, 45% of the plant N was derived from applied fertilizer, with the balance obtained from mineralized organic N (49%) and absorption of NH 3 (6%). During summer, fertilizer N accounted for 60% of accumulated grass N and NH 3 absorption accounted for 11% of N not derived from fertilizer (4% of the total N), with the balance coming from mineralized organic N. Soil water content and wind speed were the dominant factors influencing the crop NH 3 compensation point (CP). The daily NH 3 CP was variable, but the average seasonal NH 3 CP was about 14 μg m −3 .
Type of Medium:
Online Resource
ISSN:
0002-1962
,
1435-0645
DOI:
10.2134/agronj1996.00021962008800040020x
Language:
English
Publisher:
Wiley
Publication Date:
1996
detail.hit.zdb_id:
1471598-3
