Machanga SOM trial Kenya

Objective
(i) To determine the relationship between organic resource quality/quantity and the quantity/quality of the SOM pool and distinct SOM fractions for a set of soils and climates relevant for the target benchmark areas (ii) To evaluate the impact of inherent soil properties (e.g. texture) and climate on the relationships between organic resource quality/quantity and the quantity/quality of the SOM pool and distinct SOM fractions (iii) To quantify the effect of fertilizer N and growing crops on the relationships between organic resource quality/quantity and the quantity/quality of the SOM pool and distinct SOM fractions;
Description
The experiment aims at unravelling relationships between the quality of organic resources and the quantity/quality of the SOM pool and distinct SOM fractions as affected by various modifiers of the decomposition process.
Farm operation data?
Sample archive?
Samples available?
 
Data Access Statement
Available to collaborators only
Data Access Notes
Anyone interested in using the data from SOM trials in Kenya needs to contact Bernard Vanlauwe and then it will be discussed if a collaboration is possible and access for free can be provided versus no collaboration with the cost to the data access will be agreed.
Data license
No data license
Data policy
No
Organizations
IITA
research organisation
ETH Zurich
research organisation
SNSF
funding agency
People
Bernard Vanlauwe
principal investigator
Consultative Group on International Agricultural Research, Nayrobi, kenya
Magdalena Necpalova
data manager
ETH Zurich
Department of Environmental Systems Sciences
Monicah Mucheru-Muna
experiment manager
Kenyatta University, Nairobi, Kenya
Waswa Wycliffe
experiment manager
International Centre for Tropical Agriculture(CIAT), Kisumu, Kenya
Joahn Six
principal investigator
ETH Zurich, Switzerland
Daniel Mugendi
principal investigator
Embu University College, Embu, Kenya

Site: Machanga

Type
research station field
Location
Machanga
Mbeere Dstrict
Kenya
Geographic location
-0.4574444, 37.6603946
© OpenStreetMap contributors
Elevation
1022 Metres
Slope
Visits permitted?
Yes
Visiting arrangements
By arrangement with Monicah Mucheru-Muna
Management
The organic residues are applied only at the start of the first season. Each plot receives 60 kg P/ha and 60 kg K/ha per growing season. Tillage by hand
Soil type
arenosol
Soil description
Ferric Arenosol. Well drained (in places imperfectly drained), deep, yellowish red to reddish brown, loose, sand to loamy sand. Parental material: Quartz rich Basement System Rocks; predominantly granitoid gneisses; Erosion: Nil, site well conserved; Effective soil depth: Deep to very deep (>150 cm).
Soil properties
VariableDepthValue (range)UnitsRef yearEstimated?Baseline?
soil pH0 – 15 Centimetres5.27 2002
soil total carbon0 – 15 Centimetres0.3 Percent2002
total soil nitrogen0 – 15 Centimetres0.02 Percent2002
plant available phosphorous0 – 15 Centimetres6.28 parts per million2006
cation exchange capacity0 – 15 Centimetres2.35 kilogram per mole2002
sand content0 – 15 Centimetres80 Percent2002
silt content0 – 15 Centimetres7 Percent2002
clay content0 – 15 Centimetres13 Percent2002
soil density0 – 15 Centimetres1.51 gram per cubic centimetre2004
Climatic type
tropical savanna climate
Climate properties
VariableTime periodValue (range)Units
precipitation 2002 – 2007 780 (563 – 1251) millimeter

Design period: (2002—)

Design Type
split split plot
Description
Plots measure 6 x 6 m
Number of blocks
3
Number of plots
33
Number of subplots
66
Number of replicates
3
Number of harvests per year
2
Crop
CropYears grown
maize
Factors
crop residue management exposure
Plot application: Whole plot
Tithonia diversifolia  (1.2 t/ha)
Tithonia diversifolia  (4 t/ha)
Calliandra calothyrsus  (1.2 t/ha)
Calliandra calothyrsus  (4 t/ha)
maize stover  (1.2 t/ha)
maize stover  (4 t/ha)
sawdust  (1.2 t/ha)
sawdust  (4 t/ha)
farmyard manure  (1.2 t/ha)
farmyard manure  (4 t/ha)
control exposure
nitrogen fertilizer exposure
Plot application: Whole plot
control exposure
nitrogen  (120 kgN/ha)
cropping system
cropped
bare fallow
Measurements
VariableMaterialUnitsFrequencyScaleComment
grain yield traitmaizet/habiannualall cropped plots
core biomassmaizet/habiannualall cropped plots
stover biomassmaizet/habiannualall cropped plots
plant biomassmaizet/habiannualall cropped plots
soil organic carbonSoil%irregularsample per site
total soil nitrogenSoil%irregularsample per site
total soil phosphorousSoil%irregularsample site
soil pHNot specifiedcropped plots
concentration of nitrate in soilSoilmg/kgCollected 3 times during 2018 rainy seasoncropped plots
concentration of ammonium in soilSoilmg/kgCollected 3 times during 2018 rainy seasoncropped plots