Abstract:
The disposal of expired dairy products that are rich in organic carbon and nitrogen is one of the
major challenges faced by the dairy industry and causes significant economic, environmental and
health issues. Recycling of expired dairy products including yoghurt is an ideal solution to protect
the environment and to utilize them in a sustainable manner. Therefore, the present study was
carried out to find out the performance of organic soil amendment prepared from expired yoghurt
powder (EYP) on growth, yield and chlorophyll content of Radish (Raphanus sativus L.). A pot
experiment was set up according to Completely Randomized Design with four treatments {soil
without fertilizer (T1), soil with 1% EYP+157 mg K2O/pot (T2), soil with 2% EYP+157 mg
K2O/pot (T3), soil with inorganic fertilizer (T4)} with five replicates. In T4 treatment, a mixture of
inorganic fertilizers as a basal dressing (before seed sowing) and top dressing (after 3 weeks) was
applied at a rate of 177 mg N, 346 mg P2O5 and 157 mg K2O/pot and 177 mg N, 157 mg K2O/pot,
respectively according to the Department of Agriculture (DOA) recommendation. The root
diameter (cm), root volume (cm3
), root length (cm), total leaf area (cm2
), number of leaves, shoot
fresh weight (g), root fresh weight (g) and chlorophyll content (relative green index) were
measured. Data were analyzed using Minitab (version 17) and SAS (version 9.1.3) software
packages. One way ANOVA was conducted to examine the differences between treatments
followed by mean separation using Duncan‘s multiple range test. Root diameter, root length, root
volume, root fresh weight (48.6±0.88 g and 32.30±1.83 g in T4 and T2, respectively) were
significantly higher (p<0.05) in inorganic fertilizer (T4) and 1% EYP (T2) treatments than other
treatments. The leaf area and chlorophyll content were significantly higher (p<0.05) in all the
treatments compared to soil without fertilizer treatment (T1). The highest fresh shoot weight
(77.4±9.37 g) was obtained in inorganic fertilizer (T4) treatment showing significant difference
(p<0.05) than 2% EYP (T3) and soil without fertilizer (T1) treatments. According to the results, 1%
EYP (T2) treatment showed similar growth and yield performance with inorganic fertilizer (T4) and
is recommended as a soil amendment for radish. However, the fungal attacks and pest attraction to
EYP limit its application as a soil amendment and further studies are suggested to overcome the
limitations.
