Introduction Agroforestry systems that integrate trees with crops can enhance land productivity while promoting ecological sustainability. This study investigated the effects of row spacing and planting density on the growth, yield, and economic returns of relay-intercropped silage maize within walnut orchards in the arid region of southern Xinjiang, China.Methods A two-year field experiment was conducted, testing three planting densities (75,000, 90,000, and 105,000 plants per hectare) under four planting patterns, including wide-narrow rows and conventional equal row spacing.Results The results demonstrated that higher planting densities increased silage yield but reduced individual plant growth. The wide-narrow row pattern proved superior, enhancing early growth traits such as stem diameter and nitrogen content, as well as harvest characteristics like reduced plant height and larger leaf area. At the high planting density of 105,000 plants per hectare, the wide-narrow row configuration yielded the highest silage output (71.23 tha-1), increased economic profit by an average of 3,160 CNYha-1, and provided greater resilience against market price volatility.Discussion Principal component analysis confirmed that the combination of wide-narrow rows and high density optimizes agronomic performance, economic returns, and resource-use efficiency. These findings advocate for the adoption of this planting strategy as a sustainable approach to enhance productivity and economic stability in arid agroforestry systems.