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Effect of Sugarbeet Density and Harvest Date on Most Profitable Nitrogen Rate
Author(s) -
DeBruyn Amanda H.,
O'Halloran Ivan P.,
Lauzon John D.,
Van Eerd Laura L.
Publication year - 2017
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2017.03.0141
Subject(s) - fertilizer , sucrose , agronomy , yield (engineering) , field experiment , tonne , cane , mathematics , biology , chemistry , sugar , biochemistry , materials science , organic chemistry , metallurgy
Core Ideas First evaluation of profitable N rates in sugarbeet using variable revenue and costs. Most profitable N rate was 136 kg N ha −1 , regardless of plant density or harvest date. More fertilizer N needed to maximize root yield than profits or sucrose yield (recoverable white sucrose per tonne). Opportunity to modify payment structure to reward sucrose over root yield. Risk of potential N losses was lower with higher plant density and later harvest.The response of sugarbeet ( Beta vulgaris L.) root and sucrose yield to N fertility is well known, but the influence of recent changes of higher plant densities and/or earlier harvest dates may influence optimal fertilizer N rates. An experiment, in a split‐plot design, was established in 2013 to 2015 at two locations each year. There were 10 whole plot treatments consisting of combinations of five N rates and two plant densities and subplot of harvest date (mid‐September, late October). A lack of interactions among N rate, harvest date, and plant density for root or sucrose yield and profit margins, suggested no need to adjust fertilizer N based on these production practices. Nitrogen use efficiency (NUE) indices and N remaining in the field at harvest suggest a higher potential for N loss with an early than late harvest and at low vs. high plant densities; therefore, from an environmental perspective and based on equivalent profit margins, late harvest and high plant densities were recommended. Based on regression analysis, the N fertilizer rate to maximize root yield, recoverable white sucrose per tonne (RWST) and profit margins was 157, 12, and 136 kg N ha −1 , respectively. Less fertilizer N (113 vs. 152 kg N ha −1 ) was required with legume compared to grass species as the previous crop. This was the first study in a humid, temperate climate to establish recommended fertilizer N rates based on profit margins and identify an opportunity to restructure grower payments to encourage higher RWST.