Abstract: We investigated the effects of applying crayfish by-products on soil physicochemical properties based on a field experiment with treatments including no fertilization (N0), chemical fertilizer application (N12), and different application rates of crayfish powder (X200, X250 and X300). We analyzed the changes in soil bulk density, pH, organic matter and nutrient contents under different treatments. The results showed that there was no significant difference in soil bulk density of the 0-20 cm soil plough layer between the N0 and N12 treatments in two years of the trial, while the soil bulk density in X200, X250 and X300 were 7%, 8.4% and 8.5% lower than that in the N12 treatment respectively. Soil pH in the N0 treatment was the highest in two years, while there were minor differences among the N12, X200, X250, and X300 treatments. In two years of the trial, the contents of soil organic matter, total nitrogen, total phosphorus, total potassium, alkali-hydrolyzable nitrogen and available phosphorus in the X200, X250 and X300 treatments did not show significant differences compared with the N12 treatment, while the soil available potassium content showed a significant decreasing trend in the later growth stage of rice. Compared with the N0 treatment, the contents of soil organic matter, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen and available phosphorus in the N12, X200, X250 and X300 treatments significantly increased in two years, among which the increase ranges of soil organic matter were 4.9%-17.3%, 5.5%-14.6%, 4.6%-16% and 6.8%-14.5% respectively; soil total potassium content did not show significant differences. Except for the N12 treatment, soil available potassium content in the X200, X250 and X300 treatments significantly decreased in the later growth stage of rice. In conclusion, applying crayfish powder can reduce soil bulk density, increase soil organic matter content and soil nutrient contents (except available potassium), thus contributing to improving soil structure and fertility.

Key words: crawfish by-product, soil bulk density, soil organic matter, soil total nutrient, soil available nutrient