1. Integrated Soil Fertility Management Inputs
Farming practices and soil health: Arbsucular Mcorrhizal Fungi (AMF) in maize and bean intercrop
Joyce Jefwa, J. Nyaga, P. Wachira, N. Karanja, J. Kahindi, S. Njuguini and S. Okoth
Maize yield and stover were significantly affected (p = 0.003 and0.00
Arbuscular mycorrhizal fungi (AMF) are widespread and associate with up to 80% respectively) by management practices . Inoculation with AMF enhanced yield
of plant species. Most roots in nature colonized by this fungi. This association is a only when applied in combination with farmer practice, mavuno and manure. The
norm rather than an exception. Arbuscular mycorrhizal association maintains all quality of colonization was not compromised by the practices with total
ecosystems (agriculture, forests, grasslands, drylands mountain etc) and plays key colonization and individual AMF features (arburscules, vesicles and internal
roles in restoration of degraded ecosystems both natural and agricultural. Crops such hyphae) all maintained under all management practices applied to soils of low
as bananas, cassava and other tuber crops, beans, Acacias and other legumes depend fertility and low phosphorus. In this soil fertilizer application did not compromise
AMF quality.
on this association.
They are associated with low soil fertility and low phosphorus. Tropical soil are Management
All fertilizer minus micronutrients % Yield in Stover in
All fertilizer minus K
highly depleted in nutrients and are predominantly low in phosphorus. Crop practices Colonization tons/ha tons/ha
production is therefore enhanced by use of fertilizer. This may however jeopardize Control 61.61a 1.06 1.34
the functions of soil organisms such as AMF and subsequent soil health and
All fertilizer minus P
AMF 71.70a 0.46 1.77
All fertilizer minus P
sustainable production. With Africas dire need to combat poverty, application of
All fertilizer minus P
FP 72.62a 2.142 2.56
Manure 65.47a 0.99 1.70
fertilizer is mandatory and a win win situation where production is enhanced and Mavuno 64.37a 1.62 2.63
sustained has to be targeted. All fertilizer minus P Minjingu 63.83a 5.10 5.60
The Arbuscular Mycorrhizal symbiosis has ability to enhance the ability of roots to FP + All fertilizer minus P
AMF 62.87a 1.07
All fertilizer minus P
2.03
access nutrient under low soil fertility conditions which are most prevalent in the Manure + AMF 70.08a 0.76 1.54
tropics and combat pests and diseases. A high percentage of fertilizer used is not Mavuno + AMF 72.64a 0.66 2.40
available to crops due to fixation in highly acidic soils and leaching. Application SED 4.89 0.54 0.46
rates can be reduced and loss minimized.
Management practices should therefore not only enhance yield but also sustain
Mavuno
production by maintaining soil health. neither fertilizer or AMF.
Control
Fertilizer type Recommended types
Manure 40‐60tons /ha
Mavuno fertilizer (40/ha)
Farmer practice : TSP + Farmer practice (TSP 200kg
CAN /ha and 150‐200 kg /ha CAN)
Mijingu phosphate rock 177kg/ha
(4kg/plot and CAN 0.4
kg/plot )
AMF (Seed coating)
AMF Inoculun 20g/ml
paste
AMF Colonization is an indicator of AMF functioning. Arbuscules (Fig A) are characteristics of At one of the trial sites, organic (MAN = Manure), Inorganic (MAV = Mavuno, FP = Farmer
active stage of nutrient exchange, vesicles (Fig B) depict a stage in preparation for rest of the practice CAN + TSP) and AMF inoculation applied singly and in combination with organic and
fungi while hyphae indicates links between soil environment and plant. inorganic ferilizer enhanced bean yield.
Effects of AMF Inoculation in bean yield in Taita (Season 2)
0.6
0.5
Yield in Kg/ha
0.4
0.3
0.2
ac ac ab ab c ab c
0.1 b
A B 0
AMF AMF + F AMF + AMF + None FP MAN MAV
P MAN MAV
Stained roots showing colonization by Arbuscular Mycorrhizal Fungi (AMF)
characterized by veicles (globose structures) and arbuscules appearing as deep blue AMF treatment
in thecortical cells of plant roots
AMF spores like colonization is also a good indicator of soil health. Spores are mostly produced in
% AMF colonizaion characteristics response to stress or the end of growth period. All management practices had no significant effect
Management Internal hyphae Arbuscules Vesicles on mean spore abundance (Spores were extracted from 150g dry weight soil)
practices
Maize Beans Maize Beans Maize Beans 1B
Control 60.95 55.44 0.99 0.99 7.11 6.87
AMF 66.95 * 2.26 0.90 5.22 3.17
FP 66.87 68.63 2.94 3.59 5.40 5.15
Manure 63.99 62.69 2.07 4.39 5.78 5.38
Mavuno 59.99 60.41 2.34 0.73 5.44 4.69
Minjingu 56.58 66.79 4.37 7.10 8.68
FP + AMF 72.52 47.77 2.26 1.60 9.96 10.80
Manure + AMF 64.10 54.00 0.34 3.67 9.18 9.00
Mavuno + AMF 60.21 59.57 1.46 0.55 6.81 6.57
SED NS NS NS NS NS NS
NS = Not Significant
2A
Photo of mau forest fungi by Dr. Musila 2B
Total AMF Colonization of roots as affected by managment practices. AMF inoculated plants 3.5
had the highest colonization and combination of AMF and mavuno and non-ammended and 3
non-inoculated control had the least colonization.
2.5
2
apr/08
1.5 okt/08
105
1 feb/09
0.5
100
0
% Colonization
Farmer practice
AMF
Control
F.P+AMF
Manure
Manure +AMF
Mavuno
Mavuno + AMF
95
(F.P)
90
85
80
F.P+ AMF
Mavuno+AMF
AMF
Control
Mavuno
Farmer Practice
Mijingu+CAN
Manure +AMF
Manure
(FP)
Management practices It is therefore possible to apply fertilizer without compromising their health. This
may however depend on the inherent fertility of the soil. Monitoring was done for
only three seasons. The long term effect of management practices is therefore
necessary.
Acknowledgements to all farmers who allowed this study to be undertaken, the assistants,
district agricultural officers and government representatives for their help and cooperation.