Vegetation recovery with organic matter additions in semiarid Patagonia: is it a matter of water, or of nutrients?.

KOWALJOW, E.; MAZZARINO, M.J.

Bariloche

Congreso; VI Southern Connection Congress; 2010

Southern Connection

Wildfires in semiarid lands can modify soil nutrients cycling affecting vegetation reestablishment, generally limited by water. Increasing of soil organic matter is associated with an increased in water retention and increased in nutrients release. This study involved a three-year assessment of the impact of a single application of two amendments with high contents or organic matter on a disturbed (burned) ecosystem in semiarid Patagonia. Four treatments were evaluated: biosolids compost and municipal solid wastes compost (40 Mg ha-1), inorganic fertilizer (100 kg N and 35 kg P ha-1), and no application. Soil moisture was monthly measured and contents of soil organic carbon, inorganic N and available P were determinate after one and two years after application. Aboveground phytomass of the dominant species was evaluated after two and three years after application. Composts increased soil organic matter but, contrary to expectations, they did not increase soil water retention. Vegetation, especially perennial grasses, showed a higher increase with inorganic fertilizer than with composts. Since biosolids composts increased extractable P to even higher values than inorganic fertilizer, but had less effect on soluble inorganic N, the results imply that plant growth in this disturbed semiarid region was limited by N availability.