The study investigates the impact of urea and adult palm fertilizer on the survival and body tissues of the earthworm Pheretima hawayana, highlighting significant declines in earthworm abundance in agricultural settings compared to home gardens. Experimental results indicate that higher concentrations of both fertilizers reduce the survival rates of the earthworms and negatively affect their body wall tissues. The findings suggest detrimental effects of these fertilizers on soil health due to reduced earthworm populations.

1. EFFECTS OF UREA AND ADULT PALM FERTILIZER MIXTURE ON THE SURVIVAL AND BODY WALL TISSUES OF THE EARTHWORM, Pheretima hawayana O. K. C. DE SILVA Department of Zoology University of Kelaniya

2. Introduction Inorganic fertilizers are used to enhance crop production. In Sri Lanka, urea and Adult Palm fertilizer Mixture are widely used. They may negatively affect soil organisms including earthworms.

3. Introduction cont’d… Earthworms are ecologically important soil organisms. The Inorganic fertilizers such as urea and APM fertilizers affect the abundance, species richness, species heterogeneity, and body wall tissues of earthworms.

4. A field survey in different agricultural sites to see whether the abundance of earthworms decreased with the addition of urea and APM fertilizer. Laboratory experimentation to find out how the survival is reduced and Find out the impacts earthworm’s body wall tissues by the fertilizers.

5. Field survey; Study area

6. Study sites Site A – Home garden Site B – Banana plantation

7. Study sites cont’d… Site C– Coconut plantation Site D – Pineapple plantation

8. Field survey cont’d… Earthworms in four randomly selected 1m 2 areas in each site were collected. Body colour recorded and earthworms preserved in 5% formalin. Earthworms found could be classified to the genus Notoscolex and their abundance was recorded.

9. Results of the Field Survey Variation of the abundance of Notoscolex spp between the four study sites Abundance of Notoscolex spp ± SE

10. Field survey cont’d… Soil pH, moisture content, organic matter content and temperature were measured in all sites. Soil organic matter content and pH– significantly different between sites. Soil moisture content and the temperature - remained unchanged between sites.

11. Results of the Field Survey cont’d… Variation of soil pH between the four field study sites

12. Laboratory Experiment Earthworm Pheretima hawayana were collected from the wild and used for the experiment. Pheretima hawayana

13. Laboratory Experiment cont’d… Batches of 15 earthworms were introduced to each container and acclimatized under laboratory conditions. Recommended urea amount for brinjal (300 kg ha -1 year -1 ) was selected as the reference fertilizer amount.

14. Group of replicate Urea treatment C1 (n=4) 1.5g of urea per container(30 g m -2 ) C2 (n=4 ) 0.1g of urea per container(1.96 g m -2 ) C3 (n=4 ) 3.0g of urea per container(58.8 g m -2 ) C4 (n=4 ) C0 (n=4 ) 16.2g of urea per container(317.6 g m -2 ) Control treatment

15. Laboratory Experiment cont’d… Live earthworms present in each replicate container were counted weekly. Soil pH, % of moisture content, % of organic matter content and soil temperature were also measured weekly.

16. Results of The Laboratory Experiment first week ( ), second week ( ) and third week ( ) % Survival of P. hawayana ± SE

17. Laboratory Experiment cont’d… The experimentation repeated with the APM fertilizer mixture. APM fertilizer amount recommended for coconut (3 kg plant -1 year -1 ) was selected as the reference fertilizer amount.

18. Group of replicate APM fertilizer treatment C1 (n=4) 2.2 g of fertilizer per container (43.2 g m -2 ) C2 (n=4 ) 1.0 g of fertilizer per container (19.6 g m -2 ) C3 (n=4 ) 5.0 g of fertilizer per container (98.0 g m -2 ) C4 (n=4 ) C0 (n=4 ) 21.6 g of fertilizer per container (424.3 g m -2 ) Control treatment

19. first week ( ), second week ( ), third week ( ) and fourth week ( ) % Survival of P. hawayana ± SE Applied APM fertilizer amount (g m -2 ) Variation of the % survival of P. hawayana in different APM fertilizer treatments

20. Results of The Laboratory Experiment cont’d… Soil pH in urea or APM added treatments was high after the first week of exposure and it gradually decreased But the soil moisture content, soil organic matter content and temperature remained unchanged.

21. Histological experiment Healthy earthworms were exposed into 1. A container with no fertilizer (i.e. control) 2. A container with 58.8 g m -2 of urea 3. A container with 424.3 g m -2 of APM fertilizer Kept for a week.

22. Histological experiment cont’d… Control Urea added APM fertilizer added CU EL EL CM CM EL CM CM - circular muscle layer CU - cuticle EL - epithelial layer

23. Conclusions Abundance of earthworm Notoscolex spp was significantly lower in the crop fields than in the home garden probably due to urea and APM fertilizers. The % survival of P. hawayana decreased with the increasing urea and APM concentrations and with the exposure period.

24. The % survival of earthworms including P.hawayana could be extremely low around crop plants in the field, but not in the areas between them. Both urea and APM fertilizers reduce the survival of earthworms by damaging the body wall tissues.

25. Thank You