We have found a decrease in the number of Rhizobium in Castilla-La Mancha soils, produced by the use of different t!llage_syst~ms. Number of rhizobia per soil gram was cero for R. etli and very low for R. ciceri and Bradyrhizobium sr. (Lupinus) in the following treatments: soils submitted to conventional tillage (mouldboard) and minimum tillage with Chisel, soils treated with pig slurry and those where plants had been treated with herbicides. However the number of fast growth rhizobia likes Sinorhizobium meliloti and R. leguminosarum bvs. viciae and trifolii, was higher. With fue purpose to recuperate rhizobia biodiversity, different legumes were inoculated with rhizobia and sown in these soils. Nitrogenase activity and yield were also analyzed. The best nodulation results were obtained in the treatment No tillage + Inoculation. With respect to yield, no significant differences were found in this treatment. Inoculation of legumes produced an increase of rhizobia number in the most of the treatments. The best result was the increase of R. etli number from cero to 25.2 x 103. In soils where pig slurry was added the rhizobia number was lower (21.8 x 102). Regarding the Test of Rhizobium species, an increase of two fold in the number of rhizobia/g soil was observed in the most of the treatments.

Trabajo presentado en las 2as Jornadas de la Asociación Española de Leguminosas, celebradas en Cuenca (España), del 25 al 27 de abril de 2006

Este trabajo ha sido financiado por la Junta de Comunidades de Comunidad de Castilla - La Mancha, proyecto 168/CH-4