Capability of crop canopy sensing to predict crop parameters of cut grass swards aiming at early season variable rate nitrogen top dressings

2017 ◽  
Vol 8 (2) ◽  
pp. 792-795 ◽  
Author(s):  
G. Portz ◽  
M. L. Gnyp ◽  
J. Jasper
Keyword(s):  
Cross Validation ◽  
N Uptake ◽  
Calibration Data ◽  
Variable Rate ◽  
Nitrogen Application ◽  
Crop Canopy ◽  
Validation Data ◽  
Intensively Managed ◽  
Independent Calibration ◽  
Crop Parameters

This study aims to evaluate actual biomass and N-uptake estimates with the Yara N-Sensor in intensively managed grass swards across several trial sites in Europe. The dataset was split by location into an independent calibration data (UK and Finland) and a validation data (Germany) for the first two cuts. Yara N-Sensor readings were better correlated with N-uptake (R2=0.71) than actual biomass (R2=0.53) for the 1st cut. At the 2nd cut, the R2 values for both parameters were higher (0.80 and 0.56). A cross-validation with a German grass trial indicated the potential for predicting N-uptake (R2>0.8). It can be concluded that the technology has the potential to guide management decisions and variable rate nitrogen application on European grass swards.

Algorithm for Variable-Rate Nitrogen Application in Sugarcane Based on Active Crop Canopy Sensor

2015 ◽  
Vol 107 (4) ◽  
pp. 1513-1523 ◽  
Author(s):  
Lucas R. Amaral ◽  
José P. Molin ◽  
James S. Schepers
Keyword(s):  
Variable Rate ◽  
Nitrogen Application ◽  
Crop Canopy

Calibration and data reduction for X-hotwires using cross validation

2021 ◽  
pp. 095441002110403
Author(s):  
Mohan Vijaya Anoop ◽  
Budda Thiagarajan Kannan
Keyword(s):  
Cross Validation ◽  
Low Flow ◽  
Calibration Data ◽  
Inversion Algorithm ◽  
Present Scheme ◽  
Wire Probe ◽  
Data Inversion ◽  
Turbulent Jet Flow ◽  
High Reynolds ◽  
Yaw Angle

A strategy for calibration of X-wire probes and data inversion is described in this article. The approach used has elements of full velocity vs yaw-angle calibration with robust curve fitting. The responses of an X-wire probe placed in a calibration jet are recorded for a set of velocity and yaw inputs followed by fitting cross-validated splines. These spline functions trained from calibration data are evaluated for the probe responses during measurement. X-wire probes are calibrated for low to moderate velocities (0.65 m/s to 32 m/s) and yaw angles in the range −40° to 40° and comparisons with conventional interpolation schemes are made. The proposed algorithm can be extended to calibration of other multiple wire probes and for higher velocities. Some measurements in a single round turbulent jet flow at high Reynolds number using the proposed inversion algorithm are also presented. The present scheme is found to perform better particularly at low flow magnitudes and/or extreme flow angles than the schemes used previously.

Rasch Validation and Cross-Validation of the Health of Nation Outcome Scales for Monitoring of Psychiatric Disability in Traumatized Refugees in Western Psychiatric Care

Assessment ◽  
2016 ◽  
Vol 23 (6) ◽  
pp. 734-743 ◽  
Author(s):  
Sabina Palic ◽  
Michelle Lind Kappel ◽  
Guido Makransky
Keyword(s):  
Rasch Analysis ◽  
Cross Validation ◽  
Psychiatric Care ◽  
Psychiatric Disability ◽  
Psychiatric Clinic ◽  
Treatment Needs ◽  
Validation Data ◽  
Group A ◽  
Data Culture ◽  
The Rasch Model

There are no validated measures of psychiatric disability for traumatized refugees in Western psychiatric care. This is a serious shortcoming as it precludes monitoring of global treatment outcomes in this group, as well as appropriate matching of treatment needs to the disability levels. Using Rasch analysis, we evaluated the psychometrics of the Health of Nation Outcome Scales (HoNOS) in pretreatment data of consecutive refugee patients ( N = 448) from a Danish psychiatric clinic. Then, we carried out a cross-validation of the pretreatment HoNOS model on posttreatment data from the same group. A revised 10-item HoNOS fit the Rasch model at pretreatment and also showed excellent fit within the cross-validation data. Culture, gender, and need for translation did not exert serious bias on the measure’s performance. The results establish good monitoring properties of the 10-item HoNOS as the first validated measure of psychiatric disability for traumatized refugees in Western psychiatric care.

scholarly journals Optimizing Nitrogen Application for Growth and Productivity of Pomegranates

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 366
Author(s):  
Silit Lazare ◽  
Yang Lyu ◽  
Uri Yermiyahu ◽  
Yehuda Heler ◽  
Alon Ben-Gal ◽  
...  
Keyword(s):  
N Uptake ◽  
N Fertilization ◽  
Field Conditions ◽  
Nitrogen Application ◽  
N Application ◽  
Environmentally Responsible ◽  
Irrigation Solution ◽  
Vegetative Indices ◽  
Leaf N ◽  
Usage Efficiency

Quantification of actual plant consumption of nitrogen (N) is necessary to optimize fertilization efficiency and minimize contamination of earth resources. We examined the performance of fruit-bearing pomegranate trees grown in soilless media and exposed to eight N-fertigation treatments, from 5 to 200 mg N L−1. Reproductive and vegetative indices were found to be optimal when 20 to 70 mg N L−1 was supplied. Nitrogen application levels over 70 mg L−1 reduced pomegranate development and reproduction. N uptake in low-level treatments was almost 100% and decreased gradually, down to 13% in 200 mg N L−1 treatment. N usage efficiency was maximized under 20 mg N L−1, in which case 80% to 90% of added N was taken up by the trees. At high N application, its efficiency was reduced with less than 50% utilized by the trees. Leaf N increased to a plateau as a function of increasing irrigation solution N, maximizing at ~15 to 20 mg N g−1. Therefore, analysis of diagnostic leaves is not a valid method to identify excessive detrimental N. The results should be valuable in the development of efficient, sustainable, environmentally responsible protocols for N fertilization in commercial pomegranate orchards, following adaptation and validation to real soil field conditions.

scholarly journals Supplemental Material: Contrasting northern and southern European winter climate trends during the Last Interglacial

2021 ◽  
Author(s):  
Sakari Salonen ◽  
et al.
Keyword(s):  
Cross Validation ◽  
Calibration Data ◽  
Climate Trends ◽  
Last Interglacial ◽  
Winter Climate ◽  
Paleoclimate Reconstructions

Paleoclimate reconstructions, pollen–climate calibration data, and cross-validation results.

scholarly journals Optical sensors for variable rate nitrogen application in dairy pastures

2017 ◽  
Vol 79 ◽  
pp. 223-227
Author(s):  
K. Wigley ◽  
J.L. Owens ◽  
J.A.K. Trethewey ◽  
D.C. Ekanayake ◽  
R.L. Roten ◽  
...  
Keyword(s):  
Optical Sensors ◽  
Vegetation Index ◽  
N Uptake ◽  
Variable Rate ◽  
Water Index ◽  
Foliar N ◽  
Normalised Difference Vegetation Index ◽  
Fertiliser Application ◽  
Vegetative Indices ◽  
Simple Ratio

Reducing the amount of nitrogen (N) fertiliser applied to dairy pastures down to agronomically optimised levels would have positive economic and environmental results. The ability of commercially available optical sensors to estimate biomass yield and foliar-N uptake in pastures was investigated. Vegetative indices (Simple Ratio, SR; Water Index, WI; and Normalised Difference Vegetation Index, NDVI) from two active optical reflectance sensors (N-Sensor, Yara; and Greenseeker, Trimble) were compared with manually measured biomass and N-uptake in above-ground foliage. There were three measurements over time, from pastures that had received different N fertiliser applications rates (0, 10, 20, 40 and 80 kg N/ha). It was found that the sensors were able to detect differences in biomass and foliar N-uptake following defoliation of grazed pastures. The tested optical sensors have the potential to inform a real-time variable rate fertiliser application system. Keywords: pasture, nitrogen, optical sensors

Effects of Variable Rate Nitrogen Application on cv. Barbera Performance: Vegetative Growth and Leaf Nutritional Status

2018 ◽  
Vol 69 (3) ◽  
pp. 196-209 ◽  
Author(s):  
Matteo Gatti ◽  
Cecilia Squeri ◽  
Alessandra Garavani ◽  
Alberto Vercesi ◽  
Paolo Dosso ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Vegetative Growth ◽  
Variable Rate ◽  
Nitrogen Application ◽  
Cv Barbera

scholarly journals Statistical Stability and Spatial Instability in Mapping Forest Tree Species by Comparing 9 Years of Satellite Image Time Series

2019 ◽  
Vol 11 (21) ◽  
pp. 2512 ◽  
Author(s):  
Nicolas Karasiak ◽  
Jean-François Dejoux ◽  
Mathieu Fauvel ◽  
Jérôme Willm ◽  
Claude Monteil ◽  
...  
Keyword(s):  
Time Series ◽  
Tree Species ◽  
Cross Validation ◽  
Satellite Image ◽  
Support Vector ◽  
Validation Data ◽  
Spatial Instability ◽  
Classification Errors ◽  
Leave One Out ◽  
The Impact

Mapping forest composition using multiseasonal optical time series remains a challenge. Highly contrasted results are reported from one study to another suggesting that drivers of classification errors are still under-explored. We evaluated the performances of single-year Formosat-2 time series to discriminate tree species in temperate forests in France and investigated how predictions vary statistically and spatially across multiple years. Our objective was to better estimate the impact of spatial autocorrelation in the validation data on measurement accuracy and to understand which drivers in the time series are responsible for classification errors. The experiments were based on 10 Formosat-2 image time series irregularly acquired during the seasonal vegetation cycle from 2006 to 2014. Due to lot of clouds in the year 2006, an alternative 2006 time series using only cloud-free images has been added. Thirteen tree species were classified in each single-year dataset based on the Support Vector Machine (SVM) algorithm. The performances were assessed using a spatial leave-one-out cross validation (SLOO-CV) strategy, thereby guaranteeing full independence of the validation samples, and compared with standard non-spatial leave-one-out cross-validation (LOO-CV). The results show relatively close statistical performances from one year to the next despite the differences between the annual time series. Good agreements between years were observed in monospecific tree plantations of broadleaf species versus high disparity in other forests composed of different species. A strong positive bias in the accuracy assessment (up to 0.4 of Overall Accuracy (OA)) was also found when spatial dependence in the validation data was not removed. Using the SLOO-CV approach, the average OA values per year ranged from 0.48 for 2006 to 0.60 for 2013, which satisfactorily represents the spatial instability of species prediction between years.

Soil nitrogen dynamics as affected by landscape position and nitrogen fertilizer

2005 ◽  
Vol 85 (5) ◽  
pp. 579-587 ◽  
Author(s):  
Y. K. Soon ◽  
S. S. Malhi
Keyword(s):  
N Mineralization ◽  
N Uptake ◽  
Grain Filling ◽  
Landscape Position ◽  
Slope Position ◽  
Organic N ◽  
Net N Mineralization ◽  
Nitrogen Application ◽  
N Application ◽  
Upper Slope

The influence o f landscape position on the dynamics of N in the soil-plant system has not been adequately studied. Our aim with this study on a predominantly Black Chernozem soil was to evaluate the effect of slope position (upper vs. lower) and N fertilizer application (none vs. 60 kg N ha-1) on soil and wheat (Triticum aestivum L.) N through the growing season. Landscape position had a dominant effect on soil NO3− and soluble organic N (SON) concentrations, especially in the surface 15 cm. These pools of soil N and net N mineralization were greater at the lower than at the upper slope position. The landscape effect is attributed to higher organic matter content (as measured by organic C) and water availability in lower compared with upper slope positions. Nitrogen application had no measurable effect on soil NO3− and SON concentrations. Exchangeable and non-exchangeable NH4+ were little affected by slope position or N fertilization. Nitrogen application increased wheat N uptake; however, its influence was less than that of slope position, especially on N accumulation in wheat heads during grain-filling. Although N application increased wheat yields, landscape position exerted the greater influence: grain yield was less on upper than lower slope positions due to earlier onset of crop maturity. During grain filling, net N mineralization was suppressed at the upper slope position and by N application. The increase in crop yield and N uptake due to N application was not significantly different between slope positions. This study demonstrated that landscape position had a greater influence on N dynamics and availability than the application of typical amounts of fertilizer N and that the two effects were mostly independent of each other. Key words: Available N, landscape position, N uptake, net N mineralization, soluble organic N

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