Optimization Of Soil Amendments For The Remediation Of Soils With Continuous Cropping Obstacles In Strawberry Cultivation

As nutrient rich fruit of high economic efficiency, strawberries have been grown rapidly in the past years. However, continuous cropping obstacles are getting worse in strawberry cultivation, shown as the spread of disease and pests, deterioration of soil phisochemical properties, enrichment of pathogenic microbes in the rhizhosphere, and production of toxic substances by the plants. With the development of agriculture, it is also urgent to seek for an efficient way of recycling the byproducts of agriculture, including straws and manures. These agricultural wastes can be digested by earthworms, which will produce vermicompost, being of good physiochemical and biological quality.In this study, vermicompost was used, together with slime and slow-release fertilizers,and carbon-rich material, composed soil amendment to reduce continuous cropping obstacles caused by strawberry growth. Pot and field experiments with strawberry growth were carried out to study the effects of soil amendments and to optimize the ingredients of the amendments. The results were as following:1. Reasons that cause continuous cropping obstacles in strawberry cultivation: The results showed that soil pH decrease significantly after cultivation, ranging from5.8to5.9. Total fungal abundance was7to8times higher than CK. Soil total salt content was between1100-1400mg/kg, especially Ca2+、NO3-、SO42-; instead some nutrient increased as a result of fertilizer use. The main cause of cropping obstacles in the investigated plot was probably the accumulation of fungi and acidification of soils. Increase of salt could also contribute to the deterioration of soils.2. Optimization of soil amendment:Vermicompost, slime, and slow-release fertilizer were mixed at different ratios and applied in the treatments. The best result was obtained with the formula.The growth of strawberry was clearly improved and soil pH was6.67, most favorable for strawberry growth. Soil nutrients as well as total salt concentration were within a suitable range. The amendment of this formula eliminated continuous cropping obstacles effectively.3. Recommended dosage of soil amendment in practical use:Experiments were set up using soil amendments at different concentrations, e.g.0,1.5,2,2.5,3and3.5kg/m2, to monitor growth conditions of strawberry as well as the change of soil properties. The optimal dosage was2kg/m2when the best growth and yield was obtained. Soil pH was6.02, while total salt was1033.41mg/kg. Soil nutrients were suitable for the growth of strawberries, with the exception of nitrate, which was a bit higher than need.4. To improver to reduce nitrate content, using organic carbon as the main raw material with different dosage of modifier to process soil salinization. Results show that the organic carbon as the main raw material of modifier can significantly reduce the soil nitrate, removal efficiency significantly, reaching98%. For continuous cropping obstacle of soil with high nitrate content, at the same time of using strawberry conditioner, can be combined with the right amount of organic carbon, and improve the effect of improvement.