Comparison of the effect of Cow manure, Vermicompost and Azolla on safflower growth in a saline-sodic soil

Soil salinization and sodicity are two most important factors in land degradation, especially in arid and semi-arid regions of the world. Considering that saline-sodic soils have poor physical, chemical and biological properties that reduce the absorption of nutrients by plants and eventually decline their growth and yield. Application of the soil amendments, such as organic matter, can be a suitable method for improving the fertility of saline-sodic soils.

In this study, a saline-sodic soil was chosen from Alborz, and then it was mixed with three levels of 1%, 3% and 5% (weight) of Cow manure, Vermicompost and Azolla, and incubated for 5 months at the moisture of field capacity and temperature of 20 ° C. Then, safflower seeds were planted and treatments were placed in a greenhouse for two months. During this period, soil moisture was maintained at the field capacity, through weekly weighing and irrigation with distilled water. After this period, plant indices including: height of shoots, fresh and dry weight of shoots and roots, chlorophyll content of leaves and safflower leaves area were accurately measured.

After the incubation period and then the cultivation period, the addition of modifiers was observed to change the growth of safflower plant compared to the control. The lowest stem height was related to 5% cow manure treatment and the highest safflower height was related to 5% vermicompost fertilizer, which had the significant differences with control treatment. The 3 and 5% vermicompost and 1% Azolla fertilizer had the highest fresh weight of root and shoot compared to others, indicating the highest amount of water in these treatments for use of safflower plant. Different treatments did not have a significant effect on dry weight increasing of safflower plants. The chlorophyll content of safflower leaves was not significantly different in treatments than control, except for 5% cow manure application, which significantly decreased and 3% Azolla fertilizer treatment showed a significant increase compared to control. The leaf area was significantly increased in 5% vermicompost and 1% Azolla treatments and 5% cow manure had the lowest leaf area.

Safflower plant growth changes were mainly negative in cow manure treatment, while Azolla fertilizer treatment was almost unchanged and Vermicompost fertilizer treatment showed significant positive changes in most plant analyzes. More precisely, vermicompost fertilizer at 5% level and then Azolla fertilizer at 3% level could provide the most suitable substrate for safflower growth in saline-sodic soil. Therefore, according to the results obtained in this experiment, under similar conditions, the use of cow manure in saline-sodic soils is not recommended.