Analysis And Construction Of Ideal Physical Properties Of High Yield Paddy Soils In Different Regions Of China

As one of the main food crops in China,rice has a wide distribution area.As early as 6000 years ago,our ancestors began to plant rice.According to the records in the Xia Dynasty,Yu Lingyi gave the common people rice,which could be planted in the low humidity area.China has a long history of rice cultivation.It is the first country in the world to cultivate rice,and also the origin center of rice in the world.With the continuous growth of population in China,the demand for rice yield is increasing,and good soil physical properties are an important guarantee for high yield of rice.The relationship between rice yield and basic soil fertility(rice yield without fertilization)and physical properties of different types of paddy fields in different regions,such as bulk density,composition change of soil micro aggregate,aeration porosity and saturated hydraulic conductivity,is explored.The physical indexes of different types of paddy fields in different regions are defined and defined to further standardize and improve water It is very important to provide data support for the construction technology of reasonable plough layer.In this paper,the paddy soil in the Northeast Plain of China(paddy field in the coastal saline area of Liaoning Province,paddy field in the inland saline area of Jilin Province),the southwest plateau mountainous hilly area(paddy field in the mountainous hilly area of Guizhou Province,paddy field in the mountainous hilly area of Sichuan Province),the southern river network plain area(paddy field in the double cropping rice area of Hunan Province and paddy field in the double cropping rice area of Jiangxi Province)is taken as the research object,and the yield and basic physical properties of each province are referred The main results and conclusions are as follows: 1(1)The subsoil of paddy field in the saline area of Northeast Plain has high soluble salt,so it should not be ploughed too deep,otherwise it will turn the subsoil salt to the upper layer,which will have a negative impact on the growth of rice.The comprehensive analysis shows that the ideal plough depth is suitable in the range of 16-20 cm.The reasonable depth of plough layer and the thickness of plough bottom are 16-20 cm and 9-11 cm respectively.(2)The subsoil of paddy field in the mountainous and hilly area of southwest plateau has high soluble salt content,so it is not suitable to plough too deep.Otherwise,turning the subsoil salt to the upper layer will have a negative impact on the growth of rice.Comprehensive analysis shows that the ideal plough depth is suitable within 18-20 cm.The reasonable depth of plough layer and the thickness of plough bottom are 18-20 cm and 7-10 CM respectively.(3)There is a positive correlation between rice yield and plough depth in the double cropping rice area of southern river network,when the yield is between 9000-15000 When kg /hm2 is used,the range of plough depth is larger than the actual one;the plough bottom thickness is also positively related to the rice yield.When the ideal lower limit value and the upper limit value reference value of plough bottom are used in the formula,the range of plough bottom is 2.48-7.88 cm,which is inconsistent with the actual situation.The ideal range values of plough depth and plough bottom should also be determined according to the actual situation: the reasonable plough depth and plough bottom thickness of paddy field in double cropping rice area of southern river network plain are 18-25 cm and 7-10 CM respectively.(4)The hardness index of the ideal plough layer is 200-1000 kpa,and that of the ideal plough bottom is 1000-2000 kpa under the condition of draining and drying,but for the paddy field with high water content,the change of soil hardness is obviously influenced by the water content The ideal tilth soil bulk density is 1.06-1.21 G / CM2,the ideal plough bottom soil bulk density is 1.36-1.64 G / CM2,and the soil microaggregate is mainly composed of 0.25 mm-0.05 mm particle size,the average value of characteristic soil aggregate ratio(& Lt;0.01 mm / & Gt;0.01 mm)in high yield paddy field was 0.26.The results showed that the soil saturated hydraulic conductivity of high yield paddy field varied from 1.80 cm / 24 h to 32.5 cm / 24 h,and the soil saturated hydraulic conductivity of low yield paddy field varied from 0.21 to 0.26,the mean value was 7.89 cm / d.