Influence of the density of Piliostigma reticulatum (DC) Hochst on the soil macrofauna in the northern Sudanian zone of Burkina Faso

SustainSahel scientists at the UNB - Nazi BONI University found the populations of soil macrofauna communities increase with the density of Piliostigma reticulatum.

Queen termites surrounded by worker termites. Termites, although in too high abundance can be regarded as pests, are important indicators for environmental sustainability. Photo: Gnissien Moussa, UNB

Earthworms embedded in a block of soil. Earthworms are frequently used as soil health indicators in production systems studies.

Figure 1. Distribution of termite and ant communities at different densities of P. reticulatum

Figure 2. Distribution of millipede and earthworm communities at different densities of P. reticulatum

Agroforestry is one of the most widespread strategies for combating land degradation in the Sahelian zones of West Africa. Woody plants, whether trees or shrubs, improve soil fertility by improving fertility under and around the tree/shrub crowns thanks to their root systems, their growth habit and their litter. Within these areas, the biological activity of macrofauna communities develops, ensuring better soil structuring and functioning. However, woody plants are maintained at different densities in the fields, which raises the need to propose optimal densities of those woody plants that most enhance the population of soil macrofauna communities.

This paper presents the results of the effects of different densities of P. reticulatum (DC) Hoscht on the abundance of soil macrofaunal communities under two types of tillage. The experimental design included two factors: 1. tillage, and 2. shrub density. The tillage consisted of zaï and no-till. The zaï treatments included densities of 0, 500, 1000 and 2000 plants/ha of P. reticulatum (DC) Hochst. and the direct seeding 500 and 2000 plants/ha. Pruning/copiccing and mulching were respectively practiced as management methods for the shrubs and their biomass.

Effects of P. reticulatum (DC) Hochst density on soil macrofauna

In Zaï, termites (Picture 1) were most abundant at 1,000 plants/ha, ants at 2,000 plants/ha, and millepedes at 500 plants/ha (Figure 1).

In no-till, termites were more abundant at plant density 2,000 plants/ha cropping system, while ants, earthworms (Picture 2) and millipedes were more abundant under fallow than at the 2,000 plants/ha density (Figure 1 and 2).

Take-home message: Densities of 1,000 to 2,000 P. reticulatum (DC) Hochst plants/ha showed the highest numbers of soil macrofauna communities and can be recommended for improving soil biological activity.

Written by: Moussa Gnissien, Moussa Barro, Kalifa Coulibaly, Jean-Marie Douzet, Hassan B. Nacro, Nazi BONI University, CIRAD.

Influence of the density of Piliostigma reticulatum (DC) Hochst on the soil macrofauna in the northern Sudanian zone of Burkina Faso

Effects of P. reticulatum (DC) Hochst density on soil macrofauna

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