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Legumes` residues as
alternatives to synthetic nitrogen fertilizers for sustained
vegetable production, particularly in the tropics and
subtropics, are increasing dramatically. However,
quantitative information concerning plant growth parameters
succeeding their incorporation remains destitute. Sun hemp
residue N release, potato N recovery and productivity as
well as how N release coincides with potato N uptake were
investigated. Litter decay was estimated using litter bags
and first order exponential function. Potato N acquisition,
yield and NUE was quantified under different rates of
residue-N (100, 200 and 400 kg ha-1),
in relation to mineral nitrogen (MN) and zero N treatment.
Residue decay presented an accelerated rate, 0.0215 g N g-1
day-1,
with significant mineralized proportion of the initial
nitrogen content after 6 weeks of incorporation. Potato
foliage N accumulation exhibited quadratic patterns and
peaked between 52.5 and 56.5 DAP. However, linear patterns
were best fitted within potato tubers as well as whole
plant, with superior estimates under sun hemp treatments.
Additionally, yield was increased by increasing residue
nitrogen rate. However, N productivity presented an inverse
trend to nitrogen dose. The high negative correlation
indicated that litter N mineralization matched potato N
recovery leading to affordable N supply and economic yield.
Keywords: Solanum tuberosum L, Crotalaria junceae L.,
N accumulation, synchrony
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