Effect of cyanobacterial inoculation and fertilizers on rice seedlings and postharvest soil structure

The effect of soil inoculation with urea, Nostoc muscorum, and Tolypothrix tenuis on rice seedlings, nutrient contents, and structure of postharvest soil was studied. Tolypothrix tenuis and T. tenuis + urea produced the highest increase in oxidizable C (54.60% both) which resulted 7.63% higher than urea. Tolypothrix tenuis also produced the highest increase in soluble C (241.14%). Regarding nitrogen (N) soil content all treatments produced a positive difference. No treatment exerted any effect on soil available phosphorus (P). The percentage of aggregates >50 (m increased with all treatments from 6 to 12%, except N. muscorum. Tolypothrix tenuis produce the highest effect, with 50% more of these aggregates than urea. Seedling dry weight and shoot length were higher than control for all treatments. Shoots were longest with N. muscorum + urea being this treatment more effective than each Cyanobacteria alone. There was no effect on the number of leaves. Except for N. muscorum, all treatments increased the seedling N content. Postharvest soil showed a better quality when inoculated with T. tenuis or T. tenuis + urea compared to urea. Cyanobacterial fertilizers are a promising alternative to avoid soil pollution caused by agrochemicals and recover the nutrient content and structure lost after harvest as they bring to soil combined N (some of them are N fixers), exopolysaccharide that improve soil structure and bioactive substances that enhance seedlings growth.