Comparative study on the application of straw, biochar, dimethylpyrazole phosphate, and polyaspartic acid on nitrogen cycle, soil properties, and yield of potted rice

Aims

Straw, biochar, dimethylpyrazole phosphate (DMPP), and polyaspartic acid (PASP) are promising materials to improve soil productivity and alleviate agricultural pollution. However, the comparison of these four materials in rice cultivation, in terms of fertilizer use efficiency and crop yield enhancement, remains limited. A pot experiment was therefore conducted to elucidate the comparative impacts of these materials on gaseous nitrogen loss, rice growth, nutrient uptake, soil properties, and soil nitrifying bacteria during different growth stages with the aim of identifying the optimal material facilitating rice production.

Methods

Six treatments were designed as follows: no nitrogen fertilizer (PK), conventional fertilization (NPK), partial substitution of nitrogen in NPK with straw (NPKS), partial substitution of nitrogen in NPK with biochar (NPKC), NPK plus DMPP application (NPKD), and NPK plus PASP application (NPKP).

Results

For the whole growth period, the inhibition of NH₃ volatilization only occurred in NPKP (17.22%) in comparison with NPK, while DMPP and PASP effectively reduced N₂O emissions by 40.54% and 25.29%, respectively. Moreover, all materials contributed to nitrogen fixation in soil while significantly decreasing the population of AOB bacteria, with PASP and straw demonstrating a significant inhibitory effect on AOA bacteria. Furthermore, straw was more favorable to nutrient uptake and utilization by rice, inducing additional accumulation of nitrogen (71.96%), phosphorus (21.03%), and potassium (14.97%). Lastly, straw, DMPP, and PASP increased the rice yield (> 6%), whereas the impact of biochar was less pronounced.

Conclusion

When considering factors such as environment, soil properties and crop yield, the application of biodegradable PASP demonstrates comprehensive advantages in rice cultivation.