TITLE:
N-Credits from Different Maturing Cowpea Varieties to Carrot in Rotation
AUTHORS:
Listowel Aditwin Akologo, Harrison Kwame Dapaah, Julius Yirzagla
KEYWORDS:
N-Credit, Sustainable, Cropping Systems, Incorporation, Nitrogen Fixation
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.14 No.4,
April
28,
2023
ABSTRACT: Legumes constitute a major component of sustainable cropping systems due
to their biological nitrogen fixing potential. A field study was conducted in
2020 and 2021 at Ashanti-Mampong in the forest transition zone of Ghana to
quantify nitrogen credits to carrot from early (70 - 75 days) and medium
maturing (80 - 85 days) cowpea varieties (Asetenapa and Soronko) respectively,
and Obatanpa maize variety as a reference crop. The experimental design was a
split plot with five Nitrogen levels (0, 30, 45, 60 and 90 N kg/ha) applied to
carrot as sub-plots following the legumes and the maize variety as main plots. NPK
(15:15:15) was applied at the rate of 250 kg/ha to provide the nitrogen. The
sub-plot treatments (0, 30, 45, 60 and 90 N kg/ha) were planted following the
two cowpea varieties and the maize variety as a reference crop. Soronko had the
highest number of nodules (176) while Asetenapa had the lowest nodules (55).
Nitrogen credit to carrot from the early-maturing cowpea (Asetenapa) was 32 N
kg/ha in the first year of incorporation and 18 N kg/ha in the second year
after incorporation. N-credit from the medium-maturing cowpea (Soronko) was 18
N kg/ha and 29 N kg/ha in the first and second year after incorporation
respectively. Obatanpa maize variety with 0 kg N/ha fertilizer level produced
the lowest carrot yield, indicating that the soil amendment increased yields.
The species and maturity of legumes are important determinants of their N
credit contribution to crops in rotation.