Effects of green manure combined with chemical nitrogen fertilizer on dry matter accumulation and yield formation of wheat in arid irrigation areas of northwestern China

To address the lack of suitable green manure application techniques for efficient wheat production and the underutilized yield potential in the arid irrigated regions of Northwest China, this study examined the effects of green manure combined with chemical nitrogen fertilizer on wheat dry matter accumulation, translocation, distribution, and yield formation. The objective was to identify optimal green manure management strategies for high-yield wheat cultivation. From 2022 to 2024, a two-factor randomized block design was implemented with wheat as the experimental crop. Treatments included two nitrogen levels: no chemical nitrogen fertilizer (N0) and 180 kg hm-2 of chemical nitrogen fertilizer (N1), and four green manure treatments: fallow after wheat harvest (G0) and incorporation of green manure at 15,000 kg hm-2 (G1), 30,000 kg hm-2 (G2), and 45,000 kg hm-2 (G3). Results showed that both green manure and chemical nitrogen fertilizer significantly improved wheat yield and harvest index, with green manure enhancing the yield-increasing effect of nitrogen fertilizer. Compared to N0, N1 increased grain yield, biological yield, and harvest index by 23.0%, 11.8%, and 10.4%, respectively. Compared to G0, G1, G2, and G3 increased grain yield by 22.2%, 32.5%, and 35.5%; biological yield by 14.4%, 18.5%, and 20.0%; and harvest index by 7.2%, 12.1%, and 13.4%, respectively. Furthermore, N1G1, N1G2, and N1G3 increased grain yield by 15.4%, 27.0%, and 24.0%; biological yield by 8.8%, 11.6%, and 11.2%; and harvest index by 6.1%, 13.8%, and 11.4%, respectively, compared with N1G0, with the highest yield observed in N1G2. Both green manure and nitrogen fertilizer enhanced the rate of dry matter accumulation, pre-anthesis translocation, and post-anthesis accumulation, as well as dry matter distribution to grains at maturity. Green manure reinforced the effects of nitrogen fertilizer on dry matter dynamics, with the most notable improvements observed at the 30,000 kg hm-2 incorporation rate. Compared to N1G0, N1G2 increased dry matter accumulation rates during the seedling to jointing, jointing to flowering, and flowering to maturity stages by 7.9%, 11.1%, and 8.0%, respectively. The maximum and average dry matter growth rates throughout the growing season increased by 10.4% and 11.5%, respectively. Post-anthesis accumulation and its contribution to total dry matter increased by 40.0% and 10.2%, while grain dry matter at maturity and its proportion increased by 27.0% and 14.0%, respectively. The application of green manure at 30,000 kg hm-2 combined with 180 kg hm-2 of chemical nitrogen fertilizer effectively promoted dry matter accumulation and translocation, making it a promising practice for achieving high wheat yields in the irrigated areas of Northwest China.