Effect of organic amendments on the health of rice and peanut crops in coastal sandy soils of Thua Thien Hue province, Central Vietnam.

The purpose of this research was to assess the impact of vermicompost on the growth of rice and peanut crops and on the occurrence of pathogens in sandy soils of the Thua Thien Hue province. The field experiments showed that locally produced vermicompost can improve rice and peanut production on sandy soils with low fertility. THe rice yield significantly increased with an organic amendment of 15 tons/ha. The height and the number of flowers on peanut plants greatly improved with 12 tons/ha. The application of 8 tons/ha improved the number of stems per plant, but reduced their respective heights. THe incidence of major diseases caused by Cercospora arachidicola, Sclerotium rolfsii and Aspergillus niger on peanut and by Pyricularia oryzae, Helminthosporium oryzae and Rhizoctonia solani on rice was assessed as a function of organic fertilization rate. Some relationship between the rate of fertilizer and the incidence of some diseases was observed, but no significant difference was obtained. The cold weather at the beginning of 2008 delayed plant growth and probably also reduced disease incidence, which seemed to be low that year. Other pathogens such as Leptosphaerulina crassica, Cercosporidium personatum and Fusarium ssp. on peanut and Rhynchosporium oryzae , Curvularia luntana and Cercospora oryzae on rice were also identified in the experimental fields. A long-term analysis conducted over several years would enable an assessment to be made of the real impact of organic amendments on root and foliar fungal diseases.