Section 3

Section 5 


Tradeoff Analysis: On-line course Kenya

Section 4 - Data requirements and structure


In this section we present the datasets that are required for the Tradeoff Analysis Model. We include a general discussion on each of the datasets that will be followed by an exercise where you have to look at the databases in the Tradeoff Analysis System. Before doing exercises 4-8 you will need to download the appropriate files.


Environmental data

The environmental data describe the spatial variation in growing conditions. The types of crops and the regional conditions determine how data collection is implemented. The variation in growing conditions is typically linked to the soil and weather conditions. In the case of the Machakos study area, data from different sources were available:

·         Weather data were available from two stations in Machakos and Kiboko. Two climatic zones were identified. One zone includes the areas below 1200 m.a.s.l. and the Kiboko station is considered to be representative for that area. The second zone includes all the areas above 1200 m.a.s.l. for which the Machakos station is representative.

·         Soil data are derived from the exploratory soil map of Kenya. Within the context of the Fertilizer Use Recommendation Program representative profiles have been analyzed for the most important soil units.



Exercise 3: Environmental data

  1. The Machakos project is named TO31_MK. All the data can be found in the directory c:\TO31_MK.
  2. Go to settings - data files in the main menu. Here you will be able to find the names of the soil and climatic map and the details on the different database files describing weather and soil conditions. Note that soil data and the references to the weather data are stored in the c:\TO31_MK\GIS directory .
  3. Check the dBase files that describe the soil and weather conditions in the dBase viewer in the Tradeoff Analysis System (tools - dBase in the main menu). Note: if you click on the column header you will receive a brief description of the variable name. Try to understand the structure of the soil data.. 
  4. What are the total carbon quantities for the chromic Luvisol and the orthic Acrisol.


Economic data

The dataset comprises farm survey from two projects, namely LEINUTS and NUTSAL, and includes 121 farms. LEINUTS was carried out from 1997 to 1999 including 4 growing seasons. The farm survey was done in Machakos District, in the area neighboring KARI-Katumani Field Station. NUTSAL was accomplished from 1999 to 2001, including 2 or 3 growing seasons. The farms are distributed in the areas of Kionyweni, Kasikeu, Kiomo, Kibwezi and Matuu. They were chosen as representative clusters of the farming systems of the region.The data were collected and stored using the NUTMON toolbox. The data were extracted from the database and restructured into the format for the econometric simulation model. Data files were created for each cropping activity.


Exercise 4: Economic data

  1. Go to settings - data files in the main menu. Here you will be able to find the names of the economic data files.
  2. Check the dBase files describing farm management and the correlated data.
  3. Find the average field size and quantity of fertilizer in maize and vegetable systems (go to a specific column and press the button).


Supplementary data

We described the basic economic and environmental data to run the Tradeoff Analysis System. This assumes that all the models are running for the study site. In reality, additional data are required to validate and, if necessary, calibrate the different bio-physical models. In addition, specific scenarios may require additional data to translate them into changes in model parameters.


Exercise 5: Supplementary data

  1. List a number of specific datasets that are required to calibrate the crop growth simulation models.
  2. What data would be needed to analyze the effect of improved crop varieties on the tradeoff between net return and soil nutrient depletion?


Section 3

Section 5