Open AccessNitrogen fertilization to optimize the greenhouse gas balance of hemp crops grown for biomass
Author(s) -
Finnan John,
Burke Brendan
Publication year - 2013
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12045
Subject(s) - sowing , nitrogen , agronomy , biomass (ecology) , growing season , environmental science , nitrogen deficiency , yield (engineering) , human fertilization , nitrogen balance , chlorophyll , greenhouse gas , greenhouse , chemistry , biology , horticulture , ecology , organic chemistry , materials science , metallurgy
Nitrogen trials were carried out on hemp crops grown in I reland over a 3 year period to identify nitrogen fertilization strategies which optimize the greenhouse gas (GHG) and energy balances of hemp crops grown for biomass. Nitrogen rates up to 150 kg N ha −1 were used in the study. Yield increased with nitrogen rate up to 120 kg N ha −1 for early (Ferimon), mid (Felina 32) and late maturing (Futura 75) varieties. Variety had a significant effect on yield with yields increasing with maturation date. In 2 years of the study, certain application rates of nitrogen were applied either at sowing, at emergence, after emergence or split between these dates to determine if nitrogen rates could be reduced by delaying or splitting the applications. The application of nitrogen at times later than sowing or in splits during the early part of the growing season had no significant effect on biomass yield compared with the practice of applying nitrogen at the time of sowing. Late applications of nitrogen reduced leaf chlorophyll content and height early in the growing season. Later in the growing season, there was no difference in height between treatments although the highest concentrations of chlorophyll were found in the leaves of the late application treatment. Nitrogen rate and the timing of nitrogen application had no effect on plant density. Biomass yield, net energy and net GHG mitigation increased up to an application rate of 120 kg N ha −1 , this result was independent of soil type or soil nitrogen level. Net GHG and energy balance of hemp crops grown for biomass are optimized if late maturing varieties are used for biomass production and a nitrogen rate of 120 kg ha −1 is applied at sowing.