Chlorophyll 2009 and 2010 PLOS

Data collected in the field in 2009 and 2010. Column headings include the following: 1) Year – year that study was conducted. 2) Stage: Refers to the stage of dry bean development when data was collected including; 2-4 or 8-16 TL (trifoliolate leaf stage). 3) Rep: refers to replication or block number. 4) Bean: Refers to the bean market class used in the intercropping treatment plots including B - for black beans, N for Navy beans, NONE for when beans were not presents in a plot. 5) Grass: refers to grass species used in the intercropping treatment plot including R (Annual Ryegrass), O (Oats), C (Corn), W (Wheat), and NONE (when grass species was not present in the plot). 6) Chloro – Chlorophyll intensity in SPAD units

Soil Test Results for 2010 PLOS

Data collected in the field in 2010. Column headings include the following: 1) Year – Year that study was conducted. 2) Stage: Refers to the stage of dry bean development when data was collected including; Plant (Planting Stage); 2-4, 4-8, or 8-16 TL (trifoliolate leaf stage); Flower (flowering stage). 3) Bean: Refers to the bean market class used in the intercropping treatment plots including B - for black beans, N for Navy beans, NONE for when beans were not presents in a plot. 4) Grass: refers to grass species used in the intercropping treatment plot including R (Annual Ryegrass), O (Oats), C (Corn), W (Wheat), and NONE (when grass species was not present in the plot). 5) Rep: refers to replication or block number. 5) Salt - Refers to the soluble salt content in ppm. 6) OM - soil organic matter content in LOI percentage 7) Zn - soil zinc concentration in ppm 8) Fe - soil iron concentration in ppm 8) Mn - soil manganese concentration in ppm 9) Cu - soil copper concentration in ppm 10) NO - soil nitrate nitrogen concentration in ppm

The relationship between plant surface half-life risk factor (P) and EIQ value for 116 herbicides (Senseman data set).

<p>Filled circles with error bars represent means and standard errors, grey open circles represent individual herbicides (N = 116). For box-plots, dark bars represent median EIQ value, boxes enclose the first and third quartiles; preemergence (PRE) and postemergence (POST) boxplots represent the data for P = 1 and P = 3, respectively.</p

Quantitative Evaluation of the Environmental Impact Quotient (EIQ) for Comparing Herbicides

<div><p>Various indicators of pesticide environmental risk have been proposed, and one of the most widely known and used is the environmental impact quotient (EIQ). The EIQ has been criticized by others in the past, but it continues to be used regularly in the weed science literature. The EIQ is typically considered an improvement over simply comparing the amount of herbicides applied by weight. Herbicides are treated differently compared to other pesticide groups when calculating the EIQ, and therefore, it is important to understand how different risk factors affect the EIQ for herbicides. The purpose of this work was to evaluate the suitability of the EIQ as an environmental indicator for herbicides. Simulation analysis was conducted to quantify relative sensitivity of the EIQ to changes in risk factors, and actual herbicide EIQ values were used to quantify the impact of herbicide application rate on the EIQ Field Use Rating. Herbicide use rate was highly correlated with the EIQ Field Use Rating (Spearman’s <i>rho</i> >0.96, P-value <0.001) for two herbicide datasets. Two important risk factors for herbicides, leaching and surface runoff potential, are included in the EIQ calculation but explain less than 1% of total variation in the EIQ. Plant surface half-life was the risk factor with the greatest relative influence on herbicide EIQ, explaining 26 to 28% of the total variation in EIQ for actual and simulated EIQ values, respectively. For herbicides, the plant surface half-life risk factor is assigned values without any supporting quantitative data, and can result in EIQ estimates that are contrary to quantitative risk estimates for some herbicides. In its current form, the EIQ is a poor measure of herbicide environmental impact.</p></div

Picture taken in 2009 showing that beans planted in monoculture appeared more chlorotic than those in grass intercropped plots.

<p>Picture taken in 2009 showing that beans planted in monoculture appeared more chlorotic than those in grass intercropped plots.</p

The influence of risk factors on the calculated environmental impact quotient (EIQ) as determined by simulation analysis (N = 100,000) for herbicides applied before crop emergence (PRE) and herbicides applied after crop emergence (POST).

<p>The influence of risk factors on the calculated environmental impact quotient (EIQ) as determined by simulation analysis (N = 100,000) for herbicides applied before crop emergence (PRE) and herbicides applied after crop emergence (POST).</p

Experimental plot plan for one of the four replicates of the study showing rows of grass species (sub-plots) planted perpendicular to rows of dry beans (main plots).

<p>Experimental plot plan for one of the four replicates of the study showing rows of grass species (sub-plots) planted perpendicular to rows of dry beans (main plots).</p

Effect of grass species intercrops on bean leaf chlorophyll intensity (SPAD units), bean tissue and soil nutrients (mg kg⁻¹) and dry bean grain yield (tons ha⁻¹) in 2009 and 2010 near Lingle, WY.

†<p>Means within a column and year followed by the same letter are not statistically different (alpha  = 0.05).</p>‡<p>Means without letters were not significantly different from other treatments within a year.</p><p>Effect of grass species intercrops on bean leaf chlorophyll intensity (SPAD units), bean tissue and soil nutrients (mg kg⁻¹) and dry bean grain yield (tons ha⁻¹) in 2009 and 2010 near Lingle, WY.</p

Histogram of Monte Carlo simulation of 100,000 EIQ values calculated by random draws of values for risk factors included in the EIQ formula (Eq 1).

<p>For box-plots, dark bars represent median EIQ value, boxes enclose the first and third quartiles, and whiskers extend to minimum and maximum observed EIQ values.</p

Relationship between Field EIQ and herbicide use rate (A,B) and the EIQ (C,D) for two herbicide data sets.

<p>(A) Relationship between maximum herbicide use rate and Field EIQ for Senseman data set; (B) relationship between herbicide field use rate and Field EIQ for Beckie data set; (C) relationship between herbicide EIQ and Field EIQ for the Senseman data set; (D) relationship between herbicide EIQ and Field EIQ for the Beckie data set. Spearman’s rank correlation <i>rho</i> and P-value are provided in each panel.</p