In Burkina Faso, vegetable production is a very important asset for the socio-economic development. However, many constraints negatively affect its potential. The use of biological fertilization has been proved to be a satisfactory alternative to these issues. Therefore, this experiment uses some composts based on local substrates (Bokashi compost and compost enriched with Trichoderma harzianum) to study their agro-economic benefit on onion and their effects on soil chemical properties. The study was carried out in the Central-West region of Burkina Faso, using a completely randomized Fisher block design with six treatments in three replications. The applied treatments were: T0 (control); T1 (Trichoderma harzianum enriched compost + 175 kg ha-1 of NPK (14-23-14) + 50 kg ha-1 of urea (46%)); T2 (compost enriched with Trichoderma harzianum); T3 (350 kg ha-1 of NPK (14-23-14) + 100 kg ha-1 of urea (46%)); T4 (Bokashi compost + 175 kg ha-1 NPK (14-23-14) + 50 kg ha-1 urea (46%)); T5 (Bokashi compost). The results showed that the use of biological fertilizers enhanced onion yield compared to that of the control plot. In addition, the combination of compost enriched with Trichoderma harzianum and mineral fertilizer led to better yield increase of more than 200% compared to the control plot. Moreover, these biological fertilizers were able to stabilize soil pH neutrality and significantly increased soil organic matter content and its mineral properties (N, P, K, Mg, Ca). Then, for a sustainable and efficient agriculture, it would be necessary to disseminate these two composts in particular that enriched with Trichoderma harzianum having better agro-economic benefit and increasing soil fertility.

To rise to the challenge of access to safe drinking water, hygiene and sanitation, Catholic Relief Services through his project named Koom yilma provided fifty-seven (57) elementary schools with boreholes in the centre-north region in Burkina Faso. This study aims to assess the organoleptic, physicochemical and heavy metal contents of water consumed in these schools. Thus, twenty-three (23) parameters were analyzed according to international standards. The results showed that the turbidity of 25% of water samples from boreholes were between 5.4-66.33 NTU, so non-compliant with WHO standard. The pH of 17.30% of water samples was between 8.52-8.9. 0.325-2.62 mg/L of iron were observed in 28.85% of water samples. The content of potassium was above WHO standard in 13.46% of water. Concerning nitrate and arsenic, 3.8% of samples were non-compliant with WHO standards. Water from Saada borehole was contaminated with 101.725 mg/L and those from Yaoghin with 125 µg/L of arsenic. Globally, waters from boreholes located in schools were of good quality except those of Saada and Yaoghin. Despite these good results, it is necessary to monitor the physicochemical and toxicological quality of these groundwater because of the geological context of site (gold region). That will prevent the consumption of water contaminated with heavy metal and therefore chronic diseases among children.