Nitrogenous fertilizer (NH4 No3, 33.5% N) in onion had signilicant
effect in increasing the population density of soil Acari. The recommended rate
(296 kg/fed.) highly increased the mite population density espcciallv in Gua 6.
while higher nitrogen level (358kg/fed.), the Acari groups tended lo decrease in
number.
Urea plus potassium sulphate adopted in fodder beet held flourished
higher densities of soil Acari groups in comparatively with those treated with
urea only. The population density of Astigmata reached its maximum at the
recommended rate of nitrogen (100 kg.! fed.) plus the lower rate of potassium
(40 kg/fed.). In onion field nitrogenous fertilizer (269 kg/fed. Urca) caused a
positive effect on population growth of Astigmata in comparison, while al a high
nitrogen level, the astigmalid mite species tended to decrease in density. Iii
fodder beet field, population density of acarid mites, highly increased at the
recoinniended rate of urea (100 kg/fed) plus the lower rate of potassitini sulphate
(40 kg/fed.).
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