# Shared Flashcard Set

## Details

Lab 2: Determining Economic N Rates
Lab 2: Determining Economic N Rates
17
Agriculture
08/29/2016

Term
 why it is necessary to apply fertilizer at economic rates
Definition
 because in most Southeastern soils, the amount of N released from crop residues and soil organic matter is insufficient to obtain adequate crop yields
Term
 what an economic N rate is
Definition
 a rate that increases net income
Term
 some steps involved in determining economic N rates
Definition
 -establishing field plots w/ different N rates-analyzing the data taking into account the prices of the fertilizer applied and the crop produced
Term
 the objective of the Determining Economic N Rates exercise
Definition
 to acquaint you w/ a procedure commonly used to determine the optimum economic rate of N fertilizer to be applied to a given crop
Term
 curvilinear
Definition
 line that increases at a decreasing rate
Term
 equation for flat response curve
Definition
 Yield = a; where “a” is a constant
Term
 equation for a straight line response
Definition
 Yield = a + b(N rate); where “a” and “b” are regression coefficients
Term
 equation for a curvilinear response
Definition
 Yield = a + b(N Rate) - c(N Rate)2, where “a”, “b”, and “c” are regression coefficients.
Term
 the effect of adding N fertilizer when there's a flat response curve
Definition
 no effect
Term
 the effect of adding N fertilizer when there's a straight line response curve
Definition
 the increase in yield obtained by adding N should have a value that is greater than the cost of the fertilizer.
Term
 the effect of adding N fertilizer when there's a curvilinear response curve
Definition
 the increase in yield obtained by each additional unit of N decreases as the rate of N increases.recall the law of diminishing returns
Term
 when the addition of N fertilizer should be stopped
Definition
 when the value of the crop obtained by an additional N increase is equal to the cost of the fertilizer N added to obtain that yield increase.
Term
 relationship between yield value and cost of fertilizer when there's a straight line response
Definition
 dY x Py > dN x Pn ordY/dN > Pn/Pythus, Pn/Py < bwhere dY = increase in yield with application of a given rate of fertilizer N (dN)Py = value of each unit of crop yield (for example lb, or bushel)dN = N rate applied (lb N/A)Pn = cost of 1 lb N/Ab= dY/dN, which is the slope of the straight line Y = a + b(N rate)
Term
 the ideal ratio to apply N fertilizer
Definition
 The ratio of fertilizer price to crop price has to be lower than the slope of the line for it to be economical to apply fertilizer N.
Term
 the relationship between N fertilizer input and crop output when there's a curvilinear response to fertilizer input
Definition
 at first: dY x Py > dN x Pnthen: dY x Py = dN x Pn ordY/dN = Pn/Py
Term
 when increasing the N fertilizer input on a curvilinear response curve should be stopped
Definition
 when the slope of the line is equal to the ratio of unit price of fertilizer N to unit price of the crop
Term
 why increasing the N fertilizer input on a curvilinear response curve should be stopped when the slope of the line is equal to the ratio of unit price of fertilizer N to unit price of the crop
Definition
 because dY/dN is the slope of the curvilinear equation
Supporting users have an ad free experience!