In order to clarify the input threshold of nitrogen fertilizer in the wheat season in Chaohu Lake Basin

the effects of different nitrogenous fertilizer levels (treatments of N0

N1

N2

N3

N4 and N5

applicated 0

157.5

210.0

262.5

310.0

420.0 kg/hm2) on yield

nitrogen accumulation in plant

nitrogen utilization

residual inorganic nitrogen amount in 0—20 cm soil and nitrogen loss in runoff were studied. At the same time

regression model was used to fit the correlation between them. The results showed that: (1) Compared with no nitrogen fertilizer

nitrogen fertilizer increased wheat yield

and the yield increased by 64.8% in the treatment of N3

which was the maximum. While

wheat yield declined when applying nitrogen fertilizer over 290.9 kg/hm2 through the analysis used quadratic function. (2) Nitrogen accumulation in plant and nitrogen use efficiency both showed a trend of increasing first and then decreasing with the increasing of nitrogen application

and when the actual nitrogen application amount was 296.6 kg/hm2

the nitrogen accumulation amount in the aboveground of wheat was the highest

and nitrogen utilization efficiency was the highest when the nitrogen application was 158.5 kg/hm2. (3) With the increasing of nitrogen application amount

the residual inorganic nitrogen in 0—20 cm soil and the nitrogen loss in runoff both increased gradually

but there was no significant change before nitrogen application amount was 310.0 kg/hm2. However

when the application amount reached 420.0 kg/hm2

the residual amount of inorganic nitrogen and nitrogen in runoff changed obviously

with an average accumulation amount of 67.0 kg/hm2 and an average loss rate of 8.3 kg/hm2. Therefore

when the nitrogen application amount was too high

it would increase the risks of soil inorganic nitrogen residues and nitrogen loss in runoff

and cause pollution to the environment. Combined with soil fertility conditions in Chaohu Lake

considering the effects of integrated fertility test and application amount on wheat yield

nitrogen accumulation in plant

nitrogen use efficiency

residual inorganic nitrogen in soil and runoff loss in this study

we thought the input threshold of nitrogen fertilizer was 157.5 to 262.5 kg/hm2.in Chaohu Lake Basin.