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Soil data needs in agricultural extension services

March 26, 2021
With inputs from Fatunbi Oluwole, Rachel Creamer, Johan Leenaars, and  Mary Steverink-Mosugu

[Left] Susan Nguku, Ward Extension Officer Kyome/Thana Ward (Mwingi West sub-county, Kitui County). [Right] Daniel Munyoki, Soil Extension Officer in a soil pit, Kitui County

Soils4Africa aims to develop a continental-scale Soil Information System (SIS), built upon a baseline of primary soil data collected from 20,000 locations across Africa. The project is driven by the overarching goal of producing a baseline, which can be used for informing and monitoring of sustainable intensification in Africa.

The continent comprises around 33 million smallholder farms that contribute almost 70% of the food supply. Extension workers, in most cases, are employees of government departments.  They are the single most important source of agricultural information for smallholder farmers. Any significant push towards the uptake of sustainable intensification practices would have to engage the extension workers significantly.

From a soil data point of view, it is extension workers that collect and analyse samples from smallholder farms, manage the process of laboratory analysis, synthesize the results, and prescribe soil management measures on their basis. Thus, extension workers will be the ones who will carry benefits of any soil information system down to the farm level.  

Agriculture extension and soil data use in Kitui County, Kenya

Kitui is a mostly agrarian county, with a population of around 1.1 million over 30,000 square kilometers. It is further divided into 8 sub-counties and 40 wards. The elevation varies between 400 and 1830 meters above the sea level. Temperatures vary between a minimum of 14-22 degrees centigrade to a maximum of 26-35 degrees centigrade. Rainfall is distributed over two rainy seasons annually and varies between 500-1050 mm. It lies in the ‘Sub-humid [Tropics-Warm]’ agro-ecological zone. The dominant soil in the area is identified as ‘well drained, moderately deep to deep, dark reddish brown to dark yellowish brown, friable to firm, sandy clay to clay; in many places with a topsoil of loamy sand to sandy loam.’ The dominant crops in the area are maize, green grams, cowpeas, and beans. Farm management is rather intense, compared to the majority of farm management intensities in Africa, and includes the use of external inputs.

In Kenya, extension services are provided at county and sub-county levels by extension offices that come under the Ministry of Agriculture (Directorate of Extension, Research Liaison, and Technical Training). Susan Nguku is the Ward Extension Officer for the Kyome/Thana wards in Kitui county (Mwingi West sub-county) in southeast Kenya.  Her responsibilities include supervising all extension work happening in the county, organizing field days and field visits, organizing capacity building trainings for farmers, providing advisory on various aspects of agricultural production and livestock rearing, and facilitating farmer-to-farmer learning. Soil lies at the core of the advisory services provided to farmers. Soil samples are collected and tested at the beginning of the sowing season. This happens at least once every 2 years, and additionally as per demand by individual farmers. Based on the results, farmers are advised with regards to land preparation measures, crop choice, and fertilization needs.

Daniel Munyoki is the Soil Extension Officer for Kitui county. He oversees the soil sample collection process. He then takes the samples to the soil laboratory at University of Nairobi himself, where he puts the samples through various tests, analyses the results and prepares reports and advice that are eventually relayed to farmers in Kitui county through extension offices at sub-county and ward levels.

The main indicators that the Kitui county agriculture extension office tests for are:
  • soil structure, mostly to determine drainage needs of the land
  • chemical properties such as macronutrient contents (Nitrogen, Phosphorous, Potassium) and pH
  • soil micronutrient contents, especially Iron and Boron since Kitui county soils are deficient in these nutrients
Based on the results of tests for these soil properties, the office advises farmers as to what kind of crops farmers could grow, what kind of land preparation and soil fertility measures they need to take; whether additional fertilizers are needed, what kind (organic fertilizer, NPK, CAN), and in what dosage.  Further, soil acidity is an issue across much of the county, and knowing the pH of soil helps determine whether measures to control soil pH are necessary and of what kind (e. g. liming is commonly used).

The only source of secondary data Daniel uses is a handbook that catalogues various crop varieties and lists the conditions necessary for their cultivation and good performance. He formulates his advice regarding crop choice comparing the soil test results with the information in the handbook.

At the sub-county/ ward level where Susan operates, farmers as well as extension officers are more interested in the advice rather than specific soil indicators and test results.

Soil Information Gaps in Agriculture Extension

The soil information gap in Kitui county’s agriculture extension office is one of technical capacity among personnel. There is only one Soil Extension Officer for an entire county, catering to almost 1000 farmers annually on average. Each round of lab work takes 2 to 7 days. Training packages for newly recruited extension officers focus mostly on communication and community outreach. This does not lessen the concentration of responsibilities regarding soil information management upon the Soil Extension Officer.

Another gap is in terms of soil testing infrastructure. According to Susan, it is often not possible to test soil samples, for a variety of logistical reasons. The samples then have to be sent to other labs which can take an inordinate amount of time to run the tests and return the results. For example, results of some samples sent to a regional laboratory in December 2019 are still awaited as of December 2020.

A soil information system for Africa: pointers from Kitui

For its soil information needs, Kitui county’s agriculture extension office depends almost exclusively on primary data collection and analysis. Given that, what needs of theirs could a soil information system best serve?
  • From the point of view of an extension officer specializing in soil and having some grounding in soil sciences, an SIS would serve as a baseline to monitor changes in soil properties over a certain period of time. However, for it to have long-term utility, the data would have to be updated every 5 years or so (since various key soil properties change over that period). 
  • For a soil-specialized extension officer, who is closely involved in sample collection and laboratory analysis, standard sampling/laboratory protocols will be very useful as they can help them repeat these processes year after year and monitor change with greater accuracy.
    Conversely, from a soil information system’s point of view, it would be worth exploring whether/how extension workers can be engaged in soil sampling and analysis, and in continuing to grow the system after it is set up.  This would require particular attention to assuring the application of adequate, harmonized, laboratory procedures. 
  • From the point of view of an extension officer tasked with a wide range of responsibilities (not a soil specialist) a soil information system will be of utility if, apart from specific soil indicators, it also has a guide (handbook) that helps interpret their values.