Effects Of Mixed Organic And Inorganic N Fertilizer On Soil Fertility And Nitrogen Balance Of Summer Maize

The experiment was conducted at the Maize Technological Innovation Center of the north China plain(NCP)and the State Key Laboratory of Crop Biology of Shandong Agricultural University from 2014 to 2015 in Shandong Province.The maize genotype was ZD958.Cow manure was used as the organic fertilizer.Under the equal nitrogen application of 200 kg N hm-2,there were three different nitrogen treatment: single urea application(U),single manure application(M),and the mixed application of 50% urea and 50% manure(U+M),and one control treatment of no nitrogen application(CK).This experiment was to explore the effects of the mixed organic and inorganic fertilization under long-term fertilization on the distribution and stability of soil aggregates,nitrogen output in summer maize field,dry matter accumulation and yield of summer maize.The main results were as follows: 1 Effects of Mixed Organic-Inorganic Fertilization on Soil Organic Carbon and Organic Carbon Content in Soil AggregatesLong-term application of organic fertilizer and mixed organic-inorganic fertilizer significantly increased soil organic matter content compared with no fertilization and single urea application.Single urea application increased the soil organic matter content but had no significant difference compared with no fertilization treatment.In 0~10 cm soil layer,single organic fertilizer and mixed organic-inorganic fertilizer application significantly increased organic carbon content in macroaggregates that size bigger than 0.25 mm,while there was no significant difference in single urea application when compared with no fertilization.2 Effects of Mixed Organic-Inorganic Fertilization on Distribution and Stability of Soil AggregatesThe application of organic fertilizer increased the dry aggregates content of > 5 mm and 5~2 mm size in soil layer of 0~10 cm.The content of macroaggregates in dry aggregates was not significantly increased in soil layer of 0~10 cm.The content of 0.5~0.25 mm water-stable aggregates was significantly increased under the application of organic fertilizer in 0~10 cm.Sole organic fertilizer application and mixed organic-inorganic fertilizer application significantly increased the MWD and GMD,when compared with sole urea application and non-fertilization treatments.Long term of sole urea application decreased MWD and GMD compared with non-fertilization treatments.Sole organic application and mixed organic-inorganic fertilizer application increased the content of macroaggregates and improved the soil aggregates stability;long term of sole urea application decreased the macroaggregates to some extent and reduced the aggregates stability,resulting in degradation of soil structure.3 Effects of Mixed Organic-Inorganic Fertilization on Nitrogen Flow and Balance in Summer Maize FieldThat nitrogen applied in the soil was mainly absorbed by the plant,accounting for 105.86%~124.12% of the total nitrogen input.Mixed organic-inorganic fertilization increased the nitrogen content of the grain and nitrogen accumulation of the plant.Nitrogen loss was mainly caused by ammonia volatilization loss,mixed organic-inorganic fertilization had a total ammonia volatilization accumulation loss of 13.95%,sole urea application had a total ammonia volatilization accumulation loss of 17.32% and sole organic fertilizer application had a lowest total ammonia volatilization accumulation loss of 6.81%.The content of NO3--N in leaching at every growth stage of sole urea application significantly higer than other treatments,accounting for 11.0% of total nitrogen application.Nitrate leaching in mixed organic-inorganic application and sole organic application is low,respectively,taking 2.68% and 2.01% amount of total nitrogen application.Sole urea application had a highest nitrogen loss,taking 26.58% of total nitrogen application,and sole organic application and mixed organic-inorganic application significantly decreased the total nitrogen loss compared with sole urea application,respectively accounting for 8.15% and 15.35% of the total nitrogen application.Mixed organic-inorganic application and sole organic application significantly reduce nitrogen loss.Under fertilization treatments,it maintained a surplus nitrogen balance in summer maize field.Sole urea application had a significantly highest ammonia volatilization and leaching loss,thus its surplus nitrogen was lowest.Sole organic fertilizer application was conducive to reduce ammonia volatilization and leaching loss and increase the initial nitrogen content,while decrease the crop uptake,thus sole organic fertilizer maintain a highest surplus nitrogen.Through decreased the ammonia volatilization and leaching loss,mixed organic-inorganic application and sole organic application significantly improve the nitrogen surplus.4 Effects of Mixed Organic-Inorganic Fertilization on Dry Matter Accumulation and Yield of Summer MaizeMixed organic-inorganic fertilization promoted the accumulation of dry matter after anthesis,increased the proportion of dry matter accumulation after anthesis,increased the biomass at mature period and maintained a high ratio of dry matter distribution in grain,thus increased grain yield compared with sole urea application.Although sole organic fertilizer application increased the dry matter accumulation after anthesis,but it decreased the the ratio of dry matter distribution in grain,thus the yield had no significant difference compared to sole urea application.Mixed organic-inorganic fertilization had an 8.47% and 17.52% higher yield than that of single urea application and single organic fertilizer application in 2014.And mixed organic-inorganic fertilization had a 3.95% and 8.39% higher yield than that of single urea application and single organic fertilizer application in 2015.