Effects of topdressing with nitrogen fertilizer on wheat yield, and nitrogen uptake and utilization efficiency on the Loess Plateau

Abstract

Studies from various countries show that topdressing with nitrogen fertilizer can effectively increase winter wheat grain yields. However, information on its effects on wheat yields on the Loess Plateau in China is scarce. Thus, we investigated yields, N concentration and uptake, nitrogen use efficiency (NUE), and partial factor productivity of nitrogen (PFPN) of winter wheat at a site on the Plateau in three consecutive years following four treatments: no N application; 150 kg N ha−1 and 46 kg P ha−1 applied as base dressing; 198 kg N ha−1 and 46 kg P ha−1 applied as base dressing; and 150 kg N ha−1 and 46 kg P ha−1 applied as base dressing + 48 kg N ha−1 applied as topdressing in the spring. Topdressing with N fertilizer resulted in significant increases in wheat yield, wheat biomass production, and N concentrations and uptake in wheat grain, straw, and chaff. PFPN was 6.9%, 15.2%, and 5.5% higher, and NUE 28.1%, 31.6%, and 12.5% higher, in the three years with top dressing than with base dressing alone. Topdressing N fertilizer for winter wheat is recommended on the Loess Plateau.