Efficient fertilization pattern for rice production within the rice-wheat systems

Abstract

Context

Rice is a staple food for nearly half of the global population. Traditional nitrogen (N) fertilization practices, characterized by high inputs and frequent applications, face increasing challenges related to low N use efficiency (NUE) and rising labor costs.

Research question

Previous studies have highlighted the benefits of controlled-release blended fertilizers (CRBF) for enhancing rice production. While limited research has been conducted on the effects of CRBF with different fertilization techniques and their applicability within rice-wheat systems.

Methods

A three-year field experiment was conducted at two sites with contrasting soil fertility levels. Six treatments were evaluated: broadcast conventional fertilization of urea (BCF), broadcast conventional fertilization of urea with a 25 % reduction in N (BRF), broadcast fertilization of CRBF with a 25 % reduction in N (BBF), whole-layer fertilization of CRBF with a 25 % reduction in N (WBF), side-deep fertilization of CRBF with a 25 % reduction in N (SBF), and a control without N fertilization.

Results

Compared to BCF, SBF increased rice yield by 3.2–8.8 % primarily due to a 5.1–6.7 % increase in panicle numbers, and all CRBF treatments enhanced NUE by 27.6–60.8 % with SBF exhibiting the highest. Notably, SBF improved rice yield and NUE by 6.0–7.0 % and 19.4–25.2 % compared to other CRBF treatments in low-fertility site, respectively, while no significant differences were observed among CRBF treatments in high-fertility site. This pattern reflects the differing responses of rice growth and soil N availability to fertilization patterns under varying soil fertility conditions. Our structural equation model results indicate that fertilization patterns primarily influence rice yield by affecting soil NH₄⁺-N levels and subsequently altering root growth. Economic analysis revealed that SBF resulted in a 37.2–40.1 % increase in net income compared to BCF, primarily due to reduced labor costs and improved yields, with smaller differences among CRBF treatments in high-fertility site.

Conclusions

CRBF emerges as a viable alternative to conventional N fertilization, effectively delivering high rice yields and enhanced economic returns across sites with varying soil fertility. SBF optimizes N supply and boosts rice production, yielding significant increases in both yield and NUE, particularly in low-fertility environments.

Implications

The findings of this study offer a novel perspective on achieving high yields and efficient fertilization strategies in rice cultivation within rice-wheat systems, potentially guiding future agricultural practices toward improved sustainability and productivity.