Lysimeter and field studies on nitrogen 15 in a tropical soil i. applied nitrogen 15 labelled ammonium carbonate and the movement of nitrogen 15 labelled nitrate in a loam soil the effect of initial soil moisture content on infiltration rate

Nkrumah, M.; Griffith, S.M.; Ahmad, N.; Gumbs, F.A.

Plant and Soil 114(1): 3-12

1989


ISSN/ISBN: 0032-079X
DOI: 10.1007/bf02203075
Accession: 007527587

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Abstract
Twenty four plots, each 2.0 m2 in area, were established at St. Augustine loam soil series as field plots and microplots (containing lysimeters) in a completely randomised block design of four treatments (mulched fertilized, unmulched fertilized microplots; mulched fertilized and unmulched fertilized field plots), replicated three times. Labelled (15N) and unlabelled (NH2)2CO fertilizer were applied at rates of 400 kg N ha-1 and CaH2PO4 and KC1 were applied at rates of 100 and 150 g ha-1 respectively to the field plots and microplots. Mulch (bagasse) was maintained to a depth of two cm and the plots were kept bare with regular applications of gramoxone. The maximum depth of leaching as measured by diffusion of NO3--15N in both the dry and wet seasons was 30 cm. The potential for downward movement of water and NO3--15N was low in the wet season because high intensity rainfall followed high soil moisture contents. Effects of mulching on the mobility of applied N fertilizers were inconclusive. Infiltration rates were significantly (P = 0.25) inversely correlated with soil moisture content, supporting the hypothesis that high intensity rainfall on a saturated soil surface is more likely to result in NO3--15N dispersion than NO3--15N leaching.

Lysimeter and field studies on nitrogen 15 in a tropical soil i. applied nitrogen 15 labelled ammonium carbonate and the movement of nitrogen 15 labelled nitrate in a loam soil the effect of initial soil moisture content on infiltration rate