Long-term Effects of Crops Residues Management on Soil Chemical Properties and Yields in Cotton - Maize - Sorghum Rotation System in Burkina Faso

In cotton and cereals production systems, one of the most important causes of soil fertility depletion is the inappropriate crop residues management.

Aims: To improve the productivity and soil fertility, crop residues management (CRM) and fertilization effects on soil chemical properties and crops yields were assessed in a cotton-cereals rotation.

Study Design: The experimental design was simple non-randomized blocks design having 3 treatments.

Place and Duration of Study: This long-term experiment was carried out on station from 1982 to 2012.

Methodology: The treatments were three crops residues management practices, combined with rock phosphate (25% P2 O5 and 35% CaO) application and the use of inorganic fertilizers. Extensive CRM consisting in exportation of crop residues was compared to semi-intensive CRM (recycling the residues into compost) and intensive CRM (recycling crop residues into farmyard manure). Soil samples were collected at 0-20 cm depth and chemical characteristics analysed. Cotton, maize and sorghum yields were also evaluated.

Results: Continuous cropping during 30 years affected significantly (P =.05), the main chemical characteristics of soils under the different crop residues management practices. From 25th to 30th year, the decrease of soil carbon, Nitrogen, total P contents was very high as well as that of exchangeable bases, particularly Ca2+ and Mg2+ contents. The cation exchange capacity (CEC) decrease was 63%, 31% and 26%, respectively in extensive, semi-intensive and intensive CRM. Recycling crop residues into compost or farmyard manure did not prevent soil chemical degradation and crops yields decrease but reduced them significantly.

Conclusion: Moreover, integrated management of crop residues, reduction of soil tillage frequency and preventing soil erosion are suggested for a sustainable maintenance of soil chemical properties.