It’s nice to see a randomized trial of three different techniques for planting tree seedlings.  The locally developed Zaï technique did not fare well.  A similar study is available here.  Time for farmers to change?

In the Sahel of Africa, where 90 % of the population depends on natural resources for their livelihood, a large part of the soils are structurally unstable, prone to crusting and hard setting, and have low water holding capacity, which hamper vegetation establishment. The effect of soil restoration techniques on survival and growth of seedlings of Acacia nilotica, Acacia tortilis and Jatropha curcas was tested in completely barren, degraded land in a Sahelian ecosystem in Burkina Faso. A total of 522 seedlings (174 plants of each plant species) were planted in a randomized complete block design with three replicates combining three soil preparation techniques: half-moon, zaï and standard plantation. Survival and growth rates evaluated over 20 months were significantly higher using the half-moon technique compared with the other two techniques. Survival rates of plant species planted using half-moon technique were 62.5, 28.57 and 10.71 % for A. nilotica, A. tortilis and J. curcas respectively, but in zaï and standard planting, seedling survival was zero. The low survival rate of J. curcas using the half-moon technique may indicate that J. curcas is unsuitable for barren and degraded land, whereas A. nilotica and A. tortilis appear to be promising tree species for rehabilitation of degraded land.

Source: Success of three soil restoration techniques on seedling survival and growth of three plant species in the Sahel of Burkina Faso (West Africa) – Springer