Effects of different nutrient management systems on wheat yield and nitrogen use efficiency

The effects of different nutrient management systems，including historical low-input，modern intensive high-input and optimum-input，on wheat growth and nitrogen use efficiency were evaluated in a longterm field experiment. The results indicated that: nitrogen partial productivity was obviously high in low-input system related to low nutrient rate，but wheat tillering，aboveground biomass accumulation，nitrogen uptake and yield were negatively affected by nutrient deficiency. Mean wheat yield inlow-input system of the two study years was only 3.79 t/hm2. Based on root-zone nutrient management，20% of 46% of chemical fertilizer and total cattle manure were saved in optimum-input system，compared with high-input system，with no yield penalty，and significantly improved nitrogen partial productivity. According to the two study years，mean of wheat yields in optimum-input and highinput systems were 9.27 and 9.28 t/hm2，and nitrogen partial productivities were 68 and 27 kg/kg，respectively. Massive nutrient in high-input system increased un-productive tillering and led to nitrogen luxurious uptake during the vegetative growth stage，these were unprofitable to further yield improvement. In conclusion，optimization of fertilizer rate and fertilization time were essential to maintain wheat yield and improve nitrogen use efficiency.