Management of Algarrobo (Prosopis alba, P. chilensis, P. flexuosa, and P. nigra) in the semiarid regions of Argentina

Prosopis alba, P. chilensis, P. flexuosa, and P. nigra are collectively known as 'algarrobo' and are deep-rooted, nitrogen-fixing trees that produce sweet pods that are still eaten by humans and rapidly eaten by livestock in the semiarid regions of Argentina. These trees are the essential component of the agroforestry land use system in these parts of Argentina. However, existing algarrobo stands need to be thinned to 30 to 50 adult trees per hectare and undesirable trees eliminated to provide a more favorable water supply for the algarrobo. New plantings need to be established in Argentina and this paper reports planting techniques which can be used by farmers with little equipment. To overcome dormancy the seeds are soaked in room temperature water for 72-96 h, which yields 75% germination. Field establishment of containerized transplants in polyethylene bags gave 50% survival six months after transplant, bare root transplants of P. chilensis and P. caldenia gave 65% and 75% survival respectively two months after transplant, and manual direct seeding gave 50% survival three months after seeding. Seedlings were also established by feeding intact pods to cattle. When 0.5 kg of pods are fed per day, at least one germinated seedling per feces occurs in periods when soil moisture is favorable.