Impact of application of neem leaves and poultry manure on nutrient dynamics of a Haplic Acrisol

Abstract

A 12-week incubation study of a Haplic Acrisol amended with ground neem leaves (Azadirachta indica Adr. Juss.) (20, 40, 60, 80 and 100 t h71) plus 10 t h71 poultry manure in pots were carried out at the Technology Village of the University of Cape Coast, Ghana, to assess the changing patterns of NH4þ N, NO37 N and available P. The study lasted for 12 weeks starting from 17 April 2004. Thepeak of release of NH 4þ N occurred at the 2nd week after incubation of samples; the peak of release of the available P occurred also at the 2nd week and the NO37 N occurred at the 4th week. Theproduction of NH 4þ N and available P had proportional relationships with the quantity of neem leaves and poultry manure incorporated into the soil. The amount of NO37 N produced was not proportional to the quantity of the neem leaves and the poultry manure as above. The higher levels of the neem leaves (100 t, 80 t and 60 t) plus the poultry manure produced lower cumulative values of NO37 N than the lower levels (40 t and 20 t) of the neem leaves plus the poultry manure. This exception was assigned to the probable nitrification inhibitory role played by the active ingredient (azadirachtin) in the neem leaves which was expected to increase with the increasing levels of the neem leaves. The poultry manure was found to enhance the release of NH4þ N, NO37 N and available P in the neem leave-poultry manure soil amendment. The moisture content of treatments significantly increased in relation to the amount of neem leaves and poultry manure in the amendment