Improvement of straw decomposition and rice growth through co-application of straw-decomposing inoculants and ammonium nitrogen fertilizer

Abstract

Background The growth of rice is reduced by the slow decomposition of accumulated straw, which competes with rice for soil nitrogen nutrient. In recent year, straw-decomposing inoculants (SDIs) that can accelerate straw decomposition and ammonium nitrogen (N) fertilizer that can quickly generate available N is increasingly adopted in China. However, it is still unknown whether the N demand of straw decomposition and crop growth can be simultaneously met through the co-application of SDIs and ammonium N fertilizer. Results In this study, we investigated the effect of the co-application of SDIs and ammonium bicarbonate on decomposition rate of wheat straw, rice growth and rice yield over two consecutive years in rice-wheat rotation system. Compound fertilizer (A0) was used as control. The ratios of ammonium bicarbonate addition were 20% (A2), 30% (A3) and 40% (A4), respectively, without SDIs or with SDIs (IA2, IA3, IA4). Our results revealed that without SDIs, compared with A0, straw decomposition rate, rice growth and yield were improved under A2; However, under A3, rice yield was decreased due to the slow decomposition rate of straw and limited growth of rice during late growth stage. Combining SDIs and N fertilizer increased straw decomposition rate, rice growth rate and yield more than that of N fertilizer alone, especially under IA3. Compared with A0, straw decomposition rate, tiller number, aboveground biomass, leaf area index, root length, and nitrogen use efficiency were significantly increased by 16%, 8%, 27%, 12%, 17%, and 15% under IA3. Consequently, the average rice yield of IA3 was increased to 10,856 kg/ha, which was 13% and 9% higher, respectively, than of A0 and A2. Conclusion Our results indicated that ammonium bicarbonate application alone carried a risk of nutrient deficiency during late growth stage and yield decline. Therefore, the co-application of SDIs and 30% ammonium N fertilizer substitution can be a favorable practice to simultaneously accelerate straw decomposition and increase rice crop growth.

Effects of Fertilization Practices on the Metabolic Functions of Soil Microbial Communities under Subsurface Irrigation with Stalk Composite Pipe

“…The SCP fertigation might have led to increased nitrogen exposure to the straw. This aligns with Liu et al's study [49], which found that higher nitrogen levels supported a faster rate of straw decomposition. There was no notable difference between the crude fiber content of the three groups of straws when SCP fertigation was applied.…”

A Moderate Wetting and Drying Regime Combined with Appropriate Nitrogen Application Increases Grain Yield and Nitrogen Use Efficiency in Rice

“…There are reports indicating that ammonium-N tends to be more readily retained when the paddy field is supplemented with CF [47,48]. Such an irrigation regime greatly facilitates the efficient and rapid uptake of nitrogen by the rice roots, which, traditionally, is highly advantageous for rice growth and development, such as more tiller numbers and higher total LAI [49,50]. In contrast, these parameters were all decreased in the AWMD regime (Figures 3 and 4).…”