Effects Of Different Water And Fertilizer Management And Tillage Practices On Soil Nutrients And Rice Yield In Post-flooded Rice Fields

In China,the Poyang Lake Plain is an important commercial grain production base.The polder area of Poyang Lake is prone to flooding due to the uneven distribution of rainfall and runoff between years.Flooding occurs during the rice growing season,and flooding has become a significant constraint to the Poyang Lake plain area’s consistent and high supply of rice.To understand the features of the physical and chemical properties of soil in the flooded area of Poyang Lake,we researched the physical and chemical properties of rice soil in the typical flooded area of Poyang Lake in this study.Rice soils in the typical submerged area of Poyang Lake were used for the study,and rice pot experiments were carried out to investigate the effects of various water and fertilizer management methods(conventional submerged irrigation W0,intermittent irrigation W1;single application of chemical fertilizer F0,an additional application of soil conditioner F1 and charcoal-based fertilizer F2)and tillage measures(tillage depth 18 cm T0 and 22 cm T1)on soil physicochemical indicators,rice growth,soil microbial and enzyme activities.The results were as follows:(1)According to an investigation of the current situation of typical paddy soil in waterlogged areas,the average p H of paddy soil in waterlogged areas of Poyang Lake is5.19,with strong acidity,and the health grade is primarily "medium" and "sub-health".More than half of the volume weight of soil unsuitable for crop growth is accounted for.The survey area has high total nitrogen,organic matter,and alkaline nitrogen content,with79.31%,72.41%,and 72.42% of nutrient levels reaching "rich".Potassium and phosphorus deficiencies were severe in the survey area,with soil effective phosphorus and fast-acting potassium nutrient levels primarily "medium" and "deficient".In terms of the soil health grade single index,the health grade of soil organic matter content is primarily "healthy",and the health grade of soil available phosphorus is primarily "medium" and "sub-health",respectively,and the overall distribution of soil available potassium is uneven,with the "sub-health" state accounting for slightly more than the "healthy" state.(2)Based on the rice yield of each treatment,intermittent irrigation(W1)and tillage depth of 22 cm(T1)increased rice yield.The rice yield of F1W1,F2W1,and F2W0 treatments had no significant difference under the plowing depth of 18 cm(T0),but was significantly higher than that of F0W0 treatments,with increases of 67.71%,63.02%,and59.53%,respectively.With a plowing depth of 22 cm(T1),the rice yield of the F1W1 treatment was significantly higher than that of the F0W1 treatment,with a 21.56% increase.Furthermore,the F2W0 treatment increased rice yield by 25.59% and 17.66% compared to the F1W0 and F0W0 treatments,respectively.The addition of carbon-based fertilizer(F2)significantly improved the dry matter accumulation of rice as compared to when soil conditioner(F1)or fertilizer(F0).(3)Comparatively to chemical fertilizer(F0)alone,adding soil conditioner(F1)can raise the p H and CEC levels of the soil,however adding carbon-based fertilizer(F1)does not appear to raise the p H levels but raises the CEC levels.Comparing T1+F2W1 to T1+F0W1,there was a significant increase in the amounts of soil’s readily available potassium and phosphorus,which increased by 34.72% and 69.64%,respectively.However,there was no measurable change in the amounts of total nitrogen,organic matter,or alkali solution nitrogen.Throughout the rice growth period,the tillers at the jointing stage were the most numerous,with a trend of increasing at first and then decreasing.Adding carbon-based fertilizer(F2)improved plant height at the jointing and heading stages.The plant height of rice treated with T1+F2W0 was the greatest at the jointing,heading,and mature stages.(4)The addition of carbon-based fertilizer(F2)and soil conditioner(F1)can increase the content of soil bacteria and actinomycetes as well as the total number of microorganisms,with the addition of carbon-based fertilizer(F2)having a greater improvement effect.The application of soil conditioner(F1)can increase the content of soil fungi.A plow layer depth of 22cm(T1)can increase the content of bacteria and fungi in the soil.Intermittent irrigation(W1)can increase the total number of soil microorganisms.The T0+F0W1 treatment had the highest catalase and acid phosphatase activities,while the T0+F1W1 treatment had the highest urease activity.In summary,following a flood disaster,the soil quality and rice yield could be improved by reusing rice straw in combination with chemical fertilizer,carbon-based fertilizer,intermittent irrigation,and a plowing depth of 22 cm.