Effect of Supplemental Irrigation and Organic Fertilization Rates on Soil Fertility and Contamination
KIMA Aimé Sévérin
*
Environment and Agricultural Research Institute, Burkina Faso.
YANOGO Wendzoodo Amélie Pélagie
Joseph Ki Zerbo University, Burkina Faso and cApplied Sciences and Technology Research Institute, Burkina Faso.
OUOBA Samuel
Joseph Ki Zerbo University, Burkina Faso and Ouagadougou Polytechnic School, Burkina Faso.
SANDWIDI Béné-Wendé Bernice
Yembila Abdoulaye Toguyeni University, Burkina Faso.
KIMA Etienne
Department of Agriculture, Livestock and Fish Ministry, Burkina Faso.
*Author to whom correspondence should be addressed.
Abstract
Objective: To determine the combined effect of compost and different irrigation regimes on soil chemical and biological properties as well as pesticide sequestration, in a rain-fed tomato farming context.
Experimental Set-up: The experimental set-up adopted was a split plotarrangement in a Randomised Completely Block Design (RCBD) with four replications and nine treatments.
Location and Duration: The experiment took place at the IPD-AOS site in Wayalgin, Ouagadougou (Sudano-Sahelian zone), during two consecutive wet seasons.
Methodology: The primary factor corresponded to three irrigation levels (100%, 75% and 50% of tomato water requirements), equivalent respectively to 36, 24 and 12 liters of water per furrow (3, 2 and 1 watering cans). The secondary factor involved three doses of compost: 0, 5 and 10 t/ha, i.e. 0, 2 and 4 kg per sub-plot. Each block comprised three main plots (for irrigation doses), subdivided into three sub-plots according to compost doses, making a total of 36 sub-plots.
Results: Results showed that composting at 10 t/ha significantly increased carbon and organic matter contents at all irrigation levels (D50%, D75%, D100%), with respective increases of 43%, 79% and 23%. Similarly, doses of 5 and 10 t/ha increased nitrogen content by 50%, 125% and 62%, depending on the irrigation level. Potassium content also increased, albeit unevenly. On the other hand, the sum of exchangeable bases increased by around 40% and cation exchange capacity by 32%, regardless of treatment. Finally, although the effect of compost amendments on soil biological activity was mixed, pesticide residues were detected only in the amended soils, suggesting a possible scavenging effect of the compost
Conclusion: These treatments durably improved soil fertility while reducing the risk of groundwater contamination.
Keywords: Supplementary irrigation, compost, chemical pesticide, soil fertilization, pollution, tomato