EMBU SOM Trial
- 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.
- Data Access Statement
- Don't know
- 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
- Don't know
- Data policy
- Don't know
- Organizations
- IITAresearch organisationETH Zurichresearch organisationSNSFfunding agency
- People
- Bernard Vanlauweprincipal investigatorConsultative Group on International Agricultural Research, Nayrobi, kenyaMagdalena Necpalovadata managerETH ZurichDepartment of Environmental Systems SciencesWaswa Wycliffeexperiment managerInternational Centre for Tropical Agriculture(CIAT), Kisumu, KenyaMonicah Mucheru-Munaexperiment managerKenyatta University, Nairobi, KenyaJoahn Sixprincipal investigatorETH Zurich, Switzerland
Site: Embu
- Type
- research station field
- Location
- EmbuEmbu DistrictKenya
- Geographic location
- -0.5148611, 37.4557557
- Elevation
- 1350 Metres
- Visits permitted?
- Yes
- Visiting arrangements
- By arrangement with Monicah Mucheru-Muna
- Management
- Integrated soil fertility 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
- nitisol
- Soil description
- Well drained, extremely deep, dark red to reddish brown, friable clay, well structured; an ABC sequence of horizons with gradual to diffused and smooth boundaries. Strongly humic, umbric A horizon and an argillic B horizon with reddish colours and nitic properties. Clay cutans are present in the B horizon. Parental material: Mt Kenya phonolites (Kenyete); Geology: Phonolites; Physiography: Volcanic footridges; Effective soil depth: Very deep >150cm.
- Soil properties
Variable Depth Value (range) Units Ref year Estimated? Baseline? total soil nitrogen 0 – 15 Centimetres 0.3 Percent 2002 soil total carbon 0 – 15 Centimetres 2.9 Percent 2002 plant available phosphorous 0 – 15 Centimetres 2.54 parts per million 2006 soil pH 0 – 15 Centimetres 5.43 2002 cation exchange capacity 0 – 15 Centimetres 16.03 kilogram per mole 202 sand content 0 – 15 Centimetres 3 Percent 2002 silt content 0 – 15 Centimetres 22 Percent 2002 clay content 0 – 15 Centimetres 75 Percent 2002 soil density 0 – 15 Centimetres 1.26 gram per cubic centimetre 2004 - Climatic type
- Tropical
- Climate properties
Variable Time period Value (range) Units air temperature 2002 – 2007 19.57 (14.41 – 19.57) degree Celsius precipitation 2002 – 2007 1346.1 (683.5 – 2151.9) millimeter solar radiation 2002 – 2007 19.29 (17.83 – 23.79) megajoule per square meter
Design period: Main period (2002—)
- Design Type
- split split plot
- Description
- Plots measure 6 x 6 m
- Number of blocks
- 3
- Number of plots
- 11
- Number of subplots
- 2
- Number of replicates
- 3
- Number of harvests per year
- 2
- Crop
Crop Years grown maize 2002— - Factors
- Factor name
- Factor levels
- crop residue management process
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
No residues of any form applied- nitrogen fertilizer exposure Plot application: Whole plot
control exposure (0 kgN/ha)
nitrogen (120 kgN/ha)
- cropping system Plot application: Whole plot
cropped
bare fallow
- Measurements
Variable Material Units Frequency Scale Comment grain yield trait maize t/ha biannual all cropped plots core biomass maize t/ha biannual all cropped plots stover biomass maize t/ha biannual all cropped plots plant biomass maize t/ha biannual all cropped plots soil organic carbon Soil % irregular sample per site total soil nitrogen Soil % irregular sample per site total soil phosphorous Soil % irregular sample per site soil pH Soil cropped plots concentration of nitrate in soil Soil mg/kg cropped plots Collected 3 times during 2018 rainy season concentration of ammonium in soil Not specified mg/kg