Nitrogen (N) plays a vital role in plant growth; however, the yield response to N fertilizer is regularly declining in the major cropping systems due to overuse and the upper limit of yields. Heavy losses of N are also documented due to its excessive use in the rice-wheat rotation system, resulting in low nitrogen-use efficiencies (NUE) and environmental problems. Therefore, a three-year field experiment was performed with different N managements to investigate the impact of reduced N input rates in this exhaustive cropping system. Reducing the N application rates did not affect the wheat and rice yields significantly, only during the second wheat season was the yield slightly reduced as compared to higher N input treatments. Decreasing the N input rates in the prior crop and present crop, and the interactions of both rice and wheat seasons (R × W) did not influence the yields of either crop. A reduction in N fertilizer had a considerable impact on dry matter production during the wheat seasons but demonstrated no effect during the rice season. The accumulation of N was significantly reduced during both crop seasons by lowering the rate of N application. In addition, the NUE indices were significantly influenced by N fertilizer application rates. In conclusion, N fertilizer input rates for both rice and wheat crops can be lowered as compared to present fertilization rates without any risk of yield decline. Lowering the N input increases the NUE and effectively reduces N losses, and soil N status can also be maintained.

Ammonia (NH₃) volatilization from paddy fields is a major issue which leads to poor fertilizer use efficiency and is considered a severe threat to the atmosphere. The previous research studies gave importance to the use of nitrogen fertilizers to mitigate NH₃ volatilization, while very little emphasis was given to the role of other fertilizers, such as phosphorus (P), for the alleviation of NH₃ volatilization in rice fields. Considering P importance herein, we conducted two consecutive field experiments using an innovative, controlled-release, phosphorus-blended fertilizer (CRPBF, with levels CRP0, CRP1, and CRP2). We compared CP0 (in which no fertilizer was applied), CP1 (112.5 kg P ha⁻¹ P of locally recommended fertilizers), and CP2: (P and K blended fertilizers) to determine the best possible way to reduce NH₃ volatilization without affecting the yield and quality of rice. The results of the study suggested that the yield of rice increased significantly with the application of CRP1 (11.11 t ha⁻¹) and CRP2 (11.99 t ha⁻¹). The addition of CRP1 and CRP2 to the rice field also enhanced yield-related components, i.e., panicle weight, total spikelets per unit area, spikelets per panicle, and above-ground biomass. CRP0 showed a lower yield and related components when compared to CP2. The addition of CRP1 and CRP2 demonstrated lower protein contents when compared to other treatments. The CRPBF application improved starch content and taste scores, and reduced the chalkiness of the rice grain during both years. The results showed a decreasing trend in NH₃ volatilization from CRPBF amendments by improving the nitrogen use efficiency traits when compared to other treatments: CRP2, CRP1, and CRP0 reduced NH₃ volatilization by 45%, 35%, and 15%, respectively. The results of this study indicate that, due to the episodic nature of NH₃ volatilization, CRPBFs with 50% P and 100% P can markedly reduce NH₃ volatilization from paddy fields without compromising the yield and quality of the crop, and could be a promising alternative to the ordinary commercial fertilizers used in rice fields.

The rice transplantation method is still the predominant cultivation practice. However, with increasing water scarcity, high-cost production, and adverse effects on soil health and the surrounding environment, alternative crop production methods should be practiced for sustainable rice production. In the current study, we evaluated the transplantation and direct seeding rice cultivation methods under different nitrogen (N) and zinc (Zn) fertilization rates. We used four different input rates for both N (i.e., N0 = 0 kg ha-1, N1 = 90 kg ha-1, N2 = 120 kg ha-1, and N3 = 150 kg ha-1) and Zn (Zn0 = 0 kgha-1, Zn1 = 5 kg ha-1, Zn2 = 10 kg ha-1, a nd Zn3 = 15 kg ha-1). The results showed that the transplantation rice method coupling with N3 and Zn2 substantially improved yield and yield-related components compared to the direct seeded method and other fertilizer treatments. Considering weed density and non-productive tillers, the transplantation rice method coupled with N3 and Zn2 recorded lower weed density and non-productive tillers as compared to the direct seeded rice method coupled with nitrogen and zinc fertilization treatments. The transplantation method with N3 and Zn2 significantly improved leaf area index, leaf area duration, net assimilation rate, and photosynthetically active radiation in comparison to other treatments applied. Furthermore, the transplantation rice method recorded higher economic returns compared to the direct seeded rice method. It was concluded from the findings of this study that the transplantation rice method, along with a suitable amount of N and Zn fertilizers, could enhance yield-related components, leading to higher production and substantially higher net income. While the transplantation method showed promising results, future research should explore ways to address the challenges of the direct seeding method, such as managing weed density and non-productive tillers, to make it a viable alternative for sustainable rice production.