The impacts of simple fertilizer treatments on many of
the chemical and microbial properties of the soil were
not significantly different from those of the control.
They also were not as beneficial as the balanced treatFig.
3 Long-term changes in
contents of selected elements in
soil under long-term crop rotation
as influenced by direct N
and K and residual P fertilizers.
Data for 1984 from Steynberg
(1986). For abbreviations, see
Fig. 1
Fig. 4 Mean (1991–1999) grain yield of maize as influenced by
direct N and K and residual P fertilizers under long-term crop rotation.
Means±SE with the same letter do not differ significantly
according to Duncan’s multiple range test (P=0.05)
ments in terms of grain yield returns. Overall responses
were positive in balanced fertilizer treatments, suggesting
that judicious use of inorganic fertilizers may, in the
long-term, maintain soil quality and productive capacity.
It might, however, be necessary to consider supplemental
liming to counteract the resulting acidifying effect and
decline in Ca2+ and Mg2+ levels
The impacts of simple fertilizer treatments on many ofthe chemical and microbial properties of the soil werenot significantly different from those of the control.They also were not as beneficial as the balanced treatFig.3 Long-term changes incontents of selected elements insoil under long-term crop rotationas influenced by direct Nand K and residual P fertilizers.Data for 1984 from Steynberg(1986). For abbreviations, seeFig. 1Fig. 4 Mean (1991–1999) grain yield of maize as influenced bydirect N and K and residual P fertilizers under long-term crop rotation.Means±SE with the same letter do not differ significantlyaccording to Duncan’s multiple range test (P=0.05)ments in terms of grain yield returns. Overall responseswere positive in balanced fertilizer treatments, suggestingthat judicious use of inorganic fertilizers may, in thelong-term, maintain soil quality and productive capacity.It might, however, be necessary to consider supplementalliming to counteract the resulting acidifying effect anddecline in Ca2+ and Mg2+ levels
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