| The 179 samples of available calcium and magnesium in 0 to 20 cm and 20 to 40 cm from the main rice producing areas in Heilongjiang Province were determined.The abundance of calcium and magnesium in the main rice producing areas in Heilongjiang Province and the influencing factors of available Mg were studied.Three fertilization treatments,conventional fertilization?FFP?,fertilization amount:N 110 kg·hm-2,P2O5 46 kg·hm-2,K2O 75 kg·hm-2;optimal fertilization?INM?,fertilization amount:N 95 kg·hm-2,P2O5 46 kg·hm-2,K2O 75 kg·hm-2;optimized addition of magnesium?INM+Mg?,fertilizer application rate:N 95 kg·hm-2,P2O5 46 kg·hm-2 K2O 75 kg·hm-2,MgO 15 kg·hm-2.The magnesium content,dry matter weight and yield of rice plants were measured.The effect of magnesium fertilizer on rice growth and development was studied,provided guidance for farmers to use magnesium fertilizer rationally.The main results as follows:1.The content of available magnesium in paddy fields of Heilongjiang Province is generally rich.The available magnesium content of the 0-20 cm soil layer was between 45-1130 mg·kg-1,the average content is 282 kg·hm-2.The content of available magnesium in most samples is concentrated in the middle level or above,accounting for 97%of the total samples;The available magnesium content in the20-40 cm soil layer was between 21-831 mg·kg-1,the average content of 243 mg·kg-1.The content of available magnesium in most soil samples was concentrated at the middle level or above,accounting for94%of the soil samples.From the distribution of soil available magnesium in the main rice growing areas,the available magnesium content in the soil of Heilongjiang paddy field is high in the west and low in the central and eastern China in the 0-20 cm soil layer;in the 20-40 cm soil layer,the available magnesium content in the paddy soil of the west Heilongjiang is high,and the east The middle is lower.2.The soil available calcium content in paddy fields of Heilongjiang Province is extremely rich.The available calcium content in 0-20 cm soil layer was between 328-8680 mg·kg-1,the average content was3045 mg·kg-1.Most of the samples had higher soil available calcium content,accounting for 93%of soil samples;20-40 cm soil The available calcium content in the layer was between 200-9227 mg·kg-1,the average content was 2688 mg·kg-1.The content of available calcium in most samples was higher than the level,accounting for 85%of the total samples.The calcium content in 20-40 cm soil layer is lower than that in the upper layer.From the perspective of available calcium distribution in the main rice production areas,in the 0-20 cm soil layer,the available calcium content in the paddy fields of the central and western Heilongjiang is higher,the northeast Heilongjiang is lower.In the 20-40 cm soil layer,the available calcium content in the paddy fields of the west Heilongjiang is high,the south is lower.3.The relationship between soil pH,CEC,soil available potassium,soil exchangeable potassium and soil available magnesium content was analyzed by a subgroup method and correlation regression analysis.Soil magnesium content was positively correlated with soil pH,exchangeable potassium,available calcium,and cation exchange.4.Field contrast test results showed that when rice was applied with panicle fertilizer,increasing the application of 15 kg·hm-22 MgO had no significant effect on magnesium content,dry matter weight and yield in rice stems and leaves.Compared with conventional fertilization,the dry matter weight of optimized fertilization increased by 27.6%?p<0.05?,the yield increased by 41.3%?p<0.05?,and dry matter weight of the optimized magnesium treatments increased by 29.6%?p<0.05?.The yield increased by 42.2%?p<0.05?;however,there was no significant difference between optimized fertilization and optimized magnesium addition.It showed that adding magnesium fertilizer can not increase the dry matter weight and yield of rice,while the content of magnesium in soil was rich. |
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