학술논문
Crop responses to 15.sup.N-labelled organic and inorganic nitrogen sources
Document Type
Report
Author abstract
Author abstract
Source
Nutrient Cycling in Agroecosystems. Jan, 2008, Vol. 80 Issue 1, p49, 12 p.
Subject
Language
English
ISSN
1385-1314
Abstract
A major challenge for low-external-input farming systems is to secure the N supply. Lack of synchrony between mineralization of organic N sources and plant N requirements is causing many growers to use different techniques to overcome this problem. One of these techniques is the application of soluble water extracts of different farm residues and plants. A field study was conducted to study the crop uptake of applied 15.sup.N-labeled alfalfa and clover extracts as compared to the N uptake [from.sup.15]N-glycine and three levels of 15.sup.N-(NH.sub.[4).sub.2]SO.sub.4. The results show that total N accumulation in the field crops, squash and lettuce was primarily affected by the amount of added N (P a$? 0.05) and not by the form in which the N was applied (P a$? 0.05). The utilization efficiencies of N (pNdff) from plant extracts and glycine increased (P a$? 0.05) gradually from 10, 20, to 30 days after application in contrast to (NH.sub.[4).sub.2]SO.sub.4 which peaked in utilization efficiencies of 56% around 20 days after application. The pNdff reached 60%, 40% and 36% of the applied glycine, alfalfa and clover extracts, respectively in lettuce. Squash showed the same pattern during at 10, 20 and 30 days however, the proportion of N derived from most of the treatments was higher in squash than in lettuce (P a$? 0.05). These results indicate that plant extracts of clover and alfalfa can be used as efficient N fertilisers in low-external-input agroecosystems.