Influence of soil fertility amendment practices on ex-situ utilisation of indigenous arbuscular mycorrhizal fungi and performance of maize and common bean in Kenyan highlands

Citation:
Okoth S. "Influence of soil fertility amendment practices on ex-situ utilisation of indigenous arbuscular mycorrhizal fungi and performance of maize and common bean in Kenyan highlands." Tropical and Subtropical Agroecosystems. 2014;17:129-141.

Abstract:

Arbuscular Mycorrhizal Fungi (AMF) are important
in agriculture and have received attention as they are
considered a part of an active and diverse soil
biological community essential for increasing the
sustainability of agricultural systems. However, most
of agricultural practices have a negative impact on
AMF association and agricultural soils are AMF
impoverished. Interventions to replenish AMF
include re-introduction through inoculation or
manipulation of existing AMF to increase density. A
major problem with inoculation is that there is
possible competition with native (indigenous) AMF
species. Indigenous AMF will be more adapted to the
soil environment than introduced strains but with
conflicting results on the effects of AMF inoculation
on crop yield, more field studies for different
ecological areas are required. The objective of the
study was to compare the effect of inoculating crops
with indigenous AMF applied applied singly or
combined with other Soil Fertility Amendment
Practices (SFAP) on root colonisation and subsequent
performance of maize (Zea mays L.) and common
bean (Phaseolus vulgaris L.). Analysis was also done
on the best soil amendment practice that encourages
crop colonisation by AMF. This was tested under
field experiment and compared with control treatment
(no soil amendment practice) and three other soil
fertility amendment practices used singly or in
combination with AMF; (1) MAVUNO (macro- and
micronutrients and secondary nutrients) fertilizer, and
(2) Calcium Ammonium Nitrate (CAN) and Triple
Super Phosphate (TSP) (3) cattle manure. Maize and
bean performances were determined and compared
between the treatments for a period of two
consecutive seasons with the experiment replicated in
two benchmark sites of Embu district (highlands of
central Kenya) and Taita-Taveta district (coastal
highlands). Soils at Embu have high soil pH than at
Taita which results in low phosphorus levels and
possible micronutrients deficiencies. Even though no
significant differences were observed from root
colonisation by AMF with application of SFAP,
significant differences were observed at the crop
yield. Bean crop was more responsive to AMF
inoculation than maize in terms of yield. Combination
of AMF inoculant with other organic and inorganic
fertilizers resulted in higher crop yield compared to
AMF applied singly. Thus, utilisation of indigenous
AMF species has potential to constitute an
environmentally friendly method of soil fertility
amendment over time to improve maize and bean
production potential of small-scale holders but
consideration should be done on the local soil
nutrients conditions, other soil fertility amendment
practices in use and the targeted crop.
Keywords: Arbuscular Mycorrhizae Fungi; Soil
fertility amendment practices; indigenous species;
inoculation; crop yield; colonisation intensity.

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