The decline in soil fertility and the rainfall deficit strongly limit the cultivation of organic cotton in Burkina Faso. Zaï, a water and soil fertility management technique, can be explored to improve soil and organic cotton productivity. The objective is to determine the effects of zaï on the evolution of the chemical properties of the soil and on the productivity of organic cotton. A trial was implemented in the North Sudanese zone of Burkina Faso in an experimental design in completely randomized Fisher blocks with three (3) treatments including L1 (plowing + 1 t/ha of compost), L5 (plowing + 5 t/ha of compost), ha of compost), Z1 (zaï+1 t/ha of compost). The parameters measured focused on carbon, nitrogen, phosphorus, potassium, exchangeable bases, cation exchange capacity and soil pH and seed cotton yields. The study shows that plowing combined with 5 t/ha compost and zaï combined with 1 t/ha compost significantly improve the chemical properties of the soil. Plowing combined with 5 t/ha of compost (L5) presented the highest average yield (1114±65 kg/ha). Zaï and plowing combined with 1 t/ha of compost recorded identical average yields (782±81 kg/ha and 752±23 kg/ha). Zaï combined with 1 t/ha of compost can be vulgarized in the North Sudanese zone of Burkina Faso and can be a means of adapting to increasingly difficult rainfall conditions marked by pockets of drought.

Low crop yields are often explained by unfavourable rainfall conditions, the natural poverty of the soil in terms of nutrients and the low use of fertilisers. In order to find appropriate solutions for the sustainable management of soil fertility, a study was carried out on the Fertility Maintenance Trial (FTM), an experimental system established in 1960 in central western Burkina Faso, where organic and/or mineral fertilisation regimes combined with crop rotations have been tested. The approach of this study consisted of a synthesis of existing agronomic data from 2011-2019 on the three (03) crop rotations. Soil samples were taken from a depth of 0-20 cm for physico-chemical analysis. We also measured yields on the cotton and sorghum plots during the 2018 and 2019 seasons. The results show that yield variability can be attributed not only to fertilisation, but also to crop rotations and the annual rainfall recorded over the period. The sorghum-cotton and sorghum-cowpea rotations produced the highest average sorghum yields, at 547 kg.ha-1 and 642 kg.ha-1 respectively. Sorghum monoculture recorded the lowest sorghum production. Chemical analyses revealed higher phosphorus use in the sorghum-cowpea rotation compared with the other rotations. The study of cropping system efficiency also revealed the role of legumes in crop rotations in maintaining and preserving soil fertility. In addition, we recommend integrated soil fertility management (organic and mineral fertilisation, crop rotations, etc.) for sustainable management of productive capital on cotton farms in Burkina Faso.