| In order to explore the effect of different fertilization treatments on soil structure and root growth of maize,the differences of soil physical properties,agglomerate and maize root distribution under different fertilization treatments were studied.The aim of this study was to explain cause of the differences among fertilization treatments including soil quantity,root distribution,nutrition simulation and grain yield.The particle size grading,soil bulk density,porosity,aggregate stability,aggregate carbon and nitrogen contents of aggregates were determined by bulk density ring,agglomerate analyzer and elemental analyzer.The results showed that the soil bulk density of 0-20 cm soil layer was less than 20-40 cm soil layer,soil bulk density of organic fertilizer reduced to a certain extent,porosity and the water holding capacity in the field increased.These provide a good environment for the root growth.In the 0-20 cm soil layer,aggregates mainly exist in the form of sticky granules,accounting for more than 40%of the number of aggregates,followed by large aggregates,micro-aggregates content of the least.Compared with CK,the content of>1 mm agglomerates of organic manure increased significantly,and the stability of aggregates was greatly improved.The content of organic carbon and total nitrogen decreased with the decrease of agglomerate grain size.The content of carbon and nitrogen was the highest in large aggregates.The contents of carbon and nitrogen in M1 and MiNP were the highest.The content of organic carbon and total nitrogen in the 20-40 cm soil layer increased significantly in>1 mm agglomerate,the content of organic carbon and total nitrogen of M1 and MiNP treatments were high.The organic carbon and total nitrogen proportion of>1 mm aggregate increased significantly.The images of six major growth stages(seedling stage,jointing stage,tasselling period,silking period,milk maturation stage and maturation stage)and four different soil depths(0-10 cm,10-30 cm,30-50 cm and 50-70 cm)of maize root system were obtained through CI-600 root system monitoring system,micro-root canal technique,and they are processed by WinRhizo Tron 2013c software.The results are as follows:1.With the increase of soil depths,the total root length of maize increased first and then decreased,and the total root length above 50 cm soil layer was more than 70%.The total root length of 0-10 cm soil layer did not change significantly with the growth period,but at same growth period,total root length significantly increased of NP treatment,followed by them of M1NP and M1NPK.Compared with CK,total root length of M1NPK was the highest in 10-30cm soil layer.The total root length of M1NP was at jointing stage30-50 cm,and the total root length of M1NPK was the highest in the same period.The total root length of M1NP treatment in 30-50 cm soil layer was significantly higher than that of other treatments at jointing stage,tassel stage and silking period.The total root length in 50-70 cm increased with the growth period,but there was no obvious difference among treatments.2.With the increase of soil depth and the growth period,the mean diameter of root system decreased slowly,and finally became stable.And there was no significant difference between treatments of the same soil layer during the same period.3.With the increase of soil depth,the total volume of root increased first and then decreased,and the total volume of root was mainly concentrated in soil layer above 50cm,accounting for 80%of the total volume measured.The total volume trend of growth stages is same to the total volume trend of soil depth.In the 0-10 cm soil layer,the total volume of NP and M1NPK treatments was significantly higher than that of other treatments before the silking period.In 10-30 cm soil layer,the total volume of NP treatment was significantly higher than other treatments,M1NPK followed.In 30-50 cm soil layer the total volume of M1NP and M1NPK treatment was significantly higher than other treatments.The total volume of fertilization treatments did not change significantly in 50-70 cm soil layer.The nutrient simulation and yield of aboveground between different fertilizations showed that the long-term fertilization significantly increased the nutrient simulation and increased the yield.The nutrient simulation and yield of M1NPK treatment is the highest in different fertilization treatments.In conclusion,the use of NP fertilization improved the total length and total volume of root but not contribute to the improvement of soil quality.However,the application of M1NPK fertilizer improved the soil structure and quantity by reducing the bulk density,increasing porosity,improving soil water holding capacity,increasing the content of macromolecules,the stability of aggregates and the carbon and nitrogen contents of aggregates.Meanwhile it increased the total root length,total volume of maize roots,the nutrient accumulation and the yield of maize.Therefore,the use of organic and inorganic fertilization was an effective fertilization measure to improve soil quality and obtain continuous and high yield. |
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