Soil Recolonization by Saprophytic Fungi after Solarization and Soil Amendments

Abstract

The effects of solarisation using clear, UV stabilized , 25 µm low density polyethylene mulching combined with soil amendment of  chicken manures 12 th^-1 , mixed fungicides of Metalaxyl 2 g- Benlate  1.5 g L^-1 , Biocontrol agent of Trichoderma harzianum (T.h.) and NPK fertilizer 180 Kg h^-1,  were ascertained during summer 2008 for counting the total population density of thermotolerant soil fungi Aspergillus niger, A. terreus, Rhizopus sp., Penicillium spp., and Ttrichoderma harzianum ( T.h )  colonized in solarized soil amendments after mulching removal and repeated at 60 days intervals until may 2009. Population of these saprophytes was initially depressed to 8.19 and 4.29×10³ cfu/gm soil after 45 and 60 of mulching removal compared to 13.64 ×10³ in non-solarized soil, with the most greatly reduction after application mixed of Metalaxyl & Benlate., the highest population density of the above fungi 20.07 cfu×10³ was observed in non-mulching chicken manure ( CM ) plots. After 6 – 8 months a total counts of these fungi were significantly reinforced in the solarized amended soil even in plots treated with mixture of both   fungicides. Detection of  pine damping off disease in non-solarized control plots was 83.33% with severity of 60%.  Solar heating alone reduced the disease occurrence to 45 - 53.33% and severity to 10.42 - 11.67%. However, (CM), (Met.& Ben.) fungicide, and biocontrol agent of T.h. after along solarization (60 days) controlled soilborne disease to a lesser extent than other treatments. The effectiveness of these applications combined with solarization after 60 days on the disease infection were 29.17, 20, 15, and 28.33% ,respectively. Finally, in growth chamber, application of CM and T.h. increased the quantitative composition of cfu soil fungi to 7.34 and 5×10³ in spite of inoculating with pathogenic propagules of Fusarium proliferatum , Macrophominaphaseolina, and Rhizoctonia solani and the share of these pathogens in the both soil amendments were 13.89 and 30.9% respectively.