Soil management, such as organic amendments application, may play an important role in the effects of pesticide residues on soil microbial activity. In order to evaluate these effects, a field experiment was set up. Deltamethrin and profenofos were used for treatment and applied at the recommended dose. Manure, urban waste compost and green waste compost were provided at a rate of 20 t / ha. Respiratory activity was measured every hour. After 7 days of incubation, glucose, nitrogen and phosphorus were added. The interaction between organic amendments and pesticides have showed that only treatment with deltamethrin-manure have significantly decreased the basal respiration (RB) with 0.038 mg C-CO2 g-1 soil compared to the pesticide control (0.058 mg C-CO2 g-1 soil). Profenofos- cattle manure and profenofos-compost treatments have significantly inhibited SIR (Substrate Induction Respiration) compared to profenofos-control (0.097). Both deltamethrin and profenofos have significantly increased the lag time and maximal respiration compared to the control (P˂0.05). The organic amendments and pesticides interaction have significantly reduced the lag time (11h), compared to the pesticide control (26h). Cattle manure has reduced microbial catabolism in the presence of deltamethrin, but urban waste compost and green waste compost have stimulated microbial catabolism (BR) and anabolism (SIR).

Sorghum is the staple crops in the Saharan areas of West Africa. Like other crops, its production is highly dependent on the improved crop seed varieties and on water use efficiency (WUE) and nitrogen use efficiency (NUE). The objective of this study was to assess the effect of sorghum root growth and water and nitrogen use efficiency on grain yield and harvest index under rainfed and drip irrigation conditions. The study was conducted in the Central region of Burkina Faso in 2014. The improved seed variety Sariaso 14 was sown. 60 kg ha-1 of nitrogen was applied. A randomized split-split-plot design with four replications was used. The results showed that the two watering systems had significant effects on sorghum WUE, NUE, root growth, grain yield and harvest index. Root growth was found to be twice higher in the rainfed condition than in the irrigation one. On the other hand, WUE and NUE were higher by 92 and 26% respectively in the irrigated plot. Irrigation was found to improve grain yield and harvest index by 44% and 56% respectively. Irrigation is considered more beneficial for farmers given the erratic distribution of rainfall.