N2-Fixation in Field Settings: Estimations Based on Natural 15N Abundance

1986 ◽  
Vol 13 (6) ◽  
pp. 699 ◽  
Author(s):  
G Shearer ◽  
DH Kohl
Keyword(s):  
N2 Fixation ◽  
Small Difference ◽  
Sampling Strategy ◽  
Field Evaluation ◽  
Field Conditions ◽  
Site Specific ◽  
Natural 15N Abundance ◽  
Advantages And Disadvantages ◽  
Growing Body ◽  
15N Abundance

This paper reviews a growing body of literature on the use of variations in the natural abundance of 15N to estimate the fractional contribution of N2-fixation to N2-fixing systems. This method is based on the small difference in 15NN abundance which frequently occurs between N derived from N2-fixation and N derived from other sources. The requirement of the method is that this difference be significant. Whether this requirement is met is site specific and must be empirically established at each site of interest. Advantages and disadvantages of this method are compared with those of more conventional methods. Sources of error, including heterogeneity of 15NN abundance of non-atmospheric N sources are considered. Tests of the method, under both greenhouse and field conditions, are described. Estimates based on this method compare favourably with other methods for field evaluation of N2-fixation, provided that the site and the sampling strategy are appropriate for application of the method. Applications of the method in several ecosystems are described.

Pattern of natural 15N abundance in lakeside forest ecosystem affected by cormorant-derived nitrogen

2006 ◽  
pp. 69-86 ◽  
Author(s):  
Kayoko Kameda ◽  
Keisuke Koba ◽  
Satoru Hobara ◽  
Takashi Osono ◽  
Masakazu Terai
Keyword(s):  
Forest Ecosystem ◽  
Natural 15N Abundance ◽  
15N Abundance

scholarly journals Delineation of Management Zones for Site-Specific Information about Soil Fertility Characteristics through Proximal Sensing of Potato Fields

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1854
Author(s):  
Humna Khan ◽  
Aitazaz A. Farooque ◽  
Bishnu Acharya ◽  
Farhat Abbas ◽  
Travis J. Esau ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Prince Edward Island ◽  
Tuber Yield ◽  
Sampling Strategy ◽  
Time Domain Reflectometry ◽  
Specific Information ◽  
Proximal Sensing ◽  
Site Specific ◽  
Management Zones ◽  
Ground Conductivity

The delineation of management zones (MZs) has been suggested as a solution to mitigate adverse impacts of soil variability on potato tuber yield. This study quantified the spatial patterns of variability in soil and crop properties to delineate MZs for site-specific soil fertility characterization of potato fields through proximal sensing of fields. Grid sampling strategy was adopted to collect soil and crop data from two potato fields in Prince Edward Island (PEI). DUALEM-2 sensor, Time Domain Reflectometry (TDR-300), GreenSeeker were used to collect soil ground conductivity parameter horizontal coplanar geometry (HCP), soil moisture content (θ), and normalized difference vegetative index (NDVI), respectively. Soil organic matter (SOM), soil pH, phosphorous (P), potash (K), iron (Fe), lime index (LI), and cation exchange capacity (CEC) were determined from soil samples collected from each grid. Stepwise regression shortlisted the major properties of soil and crop that explained 71 to 86% of within-field variability. The cluster analysis grouped the soil and crop data into three zones, termed as excellent, medium, and poor at a 40% similarity level. The coefficient of variation and the interpolated maps characterized least to moderate variability of soil fertility parameters, except for HCP and K that were highly variable. The results of multiple means comparison indicated that the tuber yield and HCP were significantly different in all MZs. The significant relationship between HCP and yield suggested that the ground conductivity data could be used to develop MZs for site-specific fertilization in potato fields similar to those used in this study.

FIELD EVALUATION OF INSECTICIDES FOR THE CONTROL OF THE EUROPEAN SKIPPER, THYMELICUS LINEOLA (LEPIDOPTERA: HESPERIIDAE), IN QUEBEC

1979 ◽  
Vol 111 (12) ◽  
pp. 1313-1317 ◽  
Author(s):  
Michel Letendre ◽  
Jeremy N. McNeil
Keyword(s):  
Bacillus Thuringiensis ◽  
Larval Mortality ◽  
Field Evaluation ◽  
Field Conditions ◽  
Target Effects

AbstractThe efficacy of seven chemical insecticides, five commercial preparations of Bacillus thuringiensis, and two preparations containing diatom dust were tested against the European skipper, Thymelicus lineola (Ochs.), under field conditions. Satisfactory control was obtained with carbaryl, carbofuran, methomyl, permethrin, trichlorfon, Dipel 45B(=Dipel SC), Dipel WP, Thuricide 26B, Thuricide HPC, and Novabac 3 while dimethoate, chlorpyrifos, and the diatom dusts afforded little or no foliage protection. While larval mortality occurred less rapidly when B. thuringiensis preparations were applied, their use is strongly recommended as they afford the same degree of foliage protection as chemical insecticides and diminish possible undesirable off-target effects.

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