Abstract:The poor soil fertility, lower nitrogen fertilizer retention and total fertilizer application before sowing, are the key factors which result in the nitrogen imbalance between soil supplying and crop requirement, causing the wheat presenility and the limited soil water productivity potential on the semiarid rain-fed loess plateau. A field experiment was conducted in 2016 and 2017 on the rain-fed central Gansu province, to understand the effects of different treatments on the wheat dry matter accumulation, soil available nitrogen changing dynamics and yield formation. The three treatments were:(1) Whole field mulched by soil-plastic (PMS), (2) PMS with organic fertilizer application, and (3) without soil-plastic mulching and organic fertilizer application (CK), the chemical nitrogen (N), potassium (P) and phosphate (K) were applied before sowing totally in all treatments and with same amount. The results showed that the dry matter of PMO averagely increased by 11.93% in the whole growth period, further increased the dry matter accumulation rate in jointing-heading and filling-harvesting stages, as compared with PMS. Correspondingly, the max growth rate and average growth rate of dry matter increased by 11.53% and 11.42%, but the rapid growth stage did not significantly differ between PMO and PMS. The soil organic matter (SOM) content in 0—30 cm profile of PMO increased by 42.79% and 43.73% compared with PMS and CK, respectively. The soil available nitrogen (SAN) content in 0—50 cm profile correspondingly increased by 110.67% and 42.80%. The decrease extent of soil nitrogen accumulation in 0—50 cm profile from sowing to harvesting stage of PMO decreased by 111.15% but increased the SAN down-transporting, as compared with PMS. Compared with PMS, PMO optimized the grain yield component factors, significantly increased grain yield and biomass. However, it decreased the nitrogen fertilizer partial productivity and increased the SAN accumulation at harvesting stage. Consequently, the chemical fertilizer with organic fertilizer increased wheat biomass, dry matter accumulation rate and relieved nitrogen limitation in post-flowering stage, resulting in the higher grain yield. However, the SAN accumulation risk also occurred, which should be regulated by decreasing fertilizer application amount.