Soil Mineral N Dynamics in a Maize Crop Following Different Soil Fertility Amendments in Different Soil Fertility Status in Sub-humid and Semi-arid Regions in Central Kenya
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Date
2009-01
Authors
Mucheru-Muna, M.
Mugendi, D.N.
Mugwe, J. N.
Kung'u, J.B.
Merckx, R.
Vanlauwe, B.
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Agricultural Biological and Environmental Statistics
Abstract
Abstract: Nitrogen is the major limiting nutrient in crop production and it is also one of the nutrients that
is easily lost from the plant-soil system in various ways. Due to this, N supply, N management and N-use
efficiency will continue to be important factors in crop production and at the same time a reminder of
the concern as to the availability of fossil fuel reserves for future fertilizer N production. Determination
of the synchrony of the N applied and its uptake following application of tithonia, calliandra, lantana,
mucuna, manure and fertilizer amendments was carried out during the 2005 long and short rains season
in two existing experiments that had been established during the 2004 short rains. The experiments were
in two distinct agro-ecological areas (Mucwa – sub humid & Machang’a – semi arid) in the central
highlands of Kenya. The relatively high levels of mineral N (over 30 kg N ha-1) were recorded at the
beginning of the seasons in the three sites posing a challenge because the high amounts of mineral N are
not utilized by the crops as at this time when the rooting system is not adequately established. The bulk
of mineral-N found in the soil in all the treatments and sampling periods in both seasons in the three sites
was in the form of nitrate-N. This could be as a result of the rapid conversion of ammonia to nitrate
following mineralization of inputs in the soil. In Machang’a the amount of ammonium-N was relatively
high compared to Meru South due to the drier condition of the soils in that site. The amount of
ammonium-N and nitrate-N fluctuated across the seasons, for instance in Machang’a during the LR 05
season, the percentage of the ammonium-N was relatively high during the 0 WAP (47%), however it
declined at 4 WAP (14%), and then at 8 WAP (13%), then increased at 8 WAP (28%) and remained the
same until the end of the season. There was a very weak correlation between maize grain yields and
mineral N at all sampling times in the three sites. In seasons when rainfall was well distributed, the N
uptake was relatively high with most of the mineral N being taken up during 0-12 weeks after planting
(WAP).
Description
Keywords
N uptake,, Organic inputs,, Nitrate,, ammonium
Citation
(impact factor: 1.21). 01/2009; 5(6):978-993.