| In order to scientifically evaluate the He Bei Plain farmland nitrogen(N) intensive degree of double cropping wheat- maize, using the production data of 391 farmers and field test data, and using the APSIM simulation under different nitrogen crop productivity, the farmland nitrogen balance status quo as well as the straw returned to the influence of nitrogen balance were systematically analyzed. The main results were as follows:(1)Hebei Plain wheat- maize farmland nitrogen have a favorable balance, the average annual amount of surplus was 136.1 kg/ha, which accounted for 70.2% of total nitrogen input fertilizers. The growth period of wheat, maize, nitrogen surplus amount on average was 91.7 kg/hm2 and 44.4 kg/hm2.(2)In 2014, an average yield of the wheat- maize was 15010.3 kg/hm2 and the average nitrogen mass was 512.8 kg/hm2. Under the simulation on the production function, the farmers average yield of N application rate was 211.3 kg/hm2. However, the high yield production demonstration in Hebei Plain wheat- maize was 20810 kg/hm2, the theoretical value of the corresponding N application rate was 410 kg/hm2. There were 5800 kg/hm2 of gap between Average yields of the farmers and high-yield demonstration production, in the process of production of future development, at the same time of high yield production demonstration, nitrogen can be reduced on the basis of the current, according to the average yield of 2014, it can reduce the nitrogen input 102.8 kg/hm2.(3) Amount of the farmers that the wheat- maize yield in Hebei Plain was lower than the obtained production can be respectively accounted for 97.1% of the total survey farmers, including low input low output and high input low output ratio were 32.7% and 64.4%. Amount of the farmers can obtain output is only 2.9%, including low input high output and high input high output ratio were 0.7% and 2.3%. Therefore, increasing crop yield and nitrogen using efficiency, it should focus on improving production conditions and improving the field management technology(including nitrogen management measures).(4) The maize straw returned was an important source of nitrogen input. Maize straw nitrogen content was 0.94% on average, and increases with the rising of the part of the straw –the nitrogen content of top 1/3, middle 1/3 and bottom 1/3 were 1.2%, 1.06% and 0.7%, top 1/3 top 1/2 and top 2/3 of straw biomass per unit area were 15.7%, 31.75% and 58.9% of whole straw. Different parts and proportion of maize straw returned effected the farmland nitrogen balance- when maize straw returned bottom 1/3, 1/2 and 2/3, the amounts of surplus nitrogen wheat- mazie to the whole straw returned surplus nitrogen were decreased by 47.8 kg/hm2, 25.8 kg/hm2 and 12.7 kg/hm2. Key words:Hebei Plain; Wheat; Maize; double cropping system; Nitrogen balance;... |
PDF Full Text Request