Effect Of Soil Moisture Content And Bulk Density On Rhizosphere Soil Biological Characteristics Under Different Sowing Date

The effects of different bulk density, moisture content and sowing date on growth of maize, changes in rhizosphere soil enzyme activitys, microbial biomass carbon and nitrogen content, microbial quantity on maize seedling stage by pot experiment. The effects of bulk density, moisture content, sowing date and three interactions to rhizosphere soil biological characteristics were further discussed in order to provide the theory basis for the healthy development of soil ecosystems and sustainable use of maize soil in Jilin province. The results of the study summarized as follows:1. Rhizosphere soil microbial quantity was clearly influenced by bulk density, moisture content, sowing date and there interactions. High moisture content and the temperature rose would significantly improve soil microbial quantity. Bacteria, fungi and actinomycetes were increased with the bulk density increasing, with the highest values were reached at 1.2g/cm³ or 1.3g/cm³, then the quantity decreased with the increase of bulk density.2. Rhizosphere soil microbial biomass carbon and nitrogen content were clearly influenced by bulk density, moisture content, sowing date and there interactions. The treatments of high moisture content × high temperature sowing would significantly improve soil microbial biomass carbon and nitrogen content, microbial biomass carbon increase rate was 20.11%-46.82%, microbial biomass nitrogen was increased by 5.67%-30.05%. The each treatment group increase, and then decrease trend with the bulk density increasing, that the difference between treatments was significant.3. Rhizosphere soil enzyme activitys were clearly influenced by bulk density, moisture content, sowing date and there interactions. The rhizosphere soil enzyme activitys of high moisture content were significantly higher than that of low moisture content. Compared with the normal sowing, the temperature was increased, and the soil enzyme activity increased significantly during the late sowing soil enzyme activities were restricted by water. The highest value of enzyme activity were reached at 1.2g/cm³ or 1.3g/cm³.4. Rhizosphere soil organic carbon and total nitrogen content were significantly influenced by moisture content. However, due to the culture experiment time was short, the temperature and bulk density had no significant effect on organic carbon and total nitrogen content.5. The treatments of different bulk density, moisture content, sowing date made a great difference on maize emergence. Due to the high temperature during late sowing, seeding emergence rates were significantly faster than the normal sowing treatments, but emergence rates were lower than the normal sowing treatments. In the treatment group with difference moisture content under the same sowing date, the emergence of the high moisture content treatments were obviously early, and the emergence rates were better than low moisture content. Bulk density of 1.2g/cm³ and 1.3g/cm³ were easier to maize emergence,and that the biomass of maize decreased with the delay of sowing date.All the analysis showed that effect of bulk density, moisture content, sowing date on rhizosphere soil biological characteristics of maize seedling stage was significant. Under suitable conditions of moisture and temperature, bulk density at 1.2g/cm³-1.3g/cm³ range that more suitable for microbial growth, and the optimal treatment group was B1.3M70%T₂.