| The agricultural production in Yunnan Province produces about 1600×10~4t of crop straw per year,and burnning straw is polluting the environment and wasting resources.Tobacco is a dry crop.when the straw directly returned to the field,the maturity cycle is long.It is difficult to improve soil properties and improve soil fertility in a short period of time.Long-term straw returning has a certain impact on soil acidity and soil organic carbon(SOC)content.Many studies have shown that straw returning can effectively regulate the acidity of acidified soil and contribute to the accumulation of soil organic carbon.This test sets the temperature and humidity two factors,the temperature is set to three levels of 15°C,25°C and 35°C,the humidity is set to three levels of 30%,65%and100%.The samples were taken at 0 day,12 day,24 day,48 day,72 day and 96 day to simulate the effects of several crop straws returning on soil acidity and SOC content under different temperature and humidity conditions,in order to provide a reference for the straw returning under actual farming conditons.The results showed that:For soil pH:(1)It can be seen from the dynamic change of soil pH under different temperature and humidity conditions with adding 4 different straw treatments and blank soil that straw returning can significantly improve acid soil and increase soil pH.(2)In each treatment,the best effect is 2%decomposed rice straw+25°C+100%humidity,the pH of different sampling time is higher than the lowest pH group in the blank soil treatment by6.52%?41.36%,the average is higher than 28.74%;2%corn stalk+25°C+100%humidity,the pH of different sampling time is higher than the lowest pH group in the blank soil treatment by 6.63%?31.93%,the average is 23.67%higher;2%decomposed corn stalk+35°C+100%humidity,the pH of different sampling time were higher than the lowest pH group of 4.89%?37.69%in the blank soil treatment,and the average was 27.74%higher.Followed by 2%corn stalk+35°C+100%humidity,the pH of different sampling time is higher than the lowest pH group of 6.63%?33.19%,the average is 23.44%higher;2%corn stalk+15°C+100%Humidity,pH at different sampling times were higher than the lowest pH group in the blank soil treatment by 6.63%?33.69%,the average was 23.21%higher;2%rice straw+15°C+100%humidity,the pH was higher than the blank soil treatment at different sampling time The lowest pH group was 5.91%?32.01%,the average was 22.83%higher;2%decomposed corn stalk+25°C+100%humidity,the pH of different sampling time was higher than the lowest pH group of 4.89%?31.77%in the blank soil treatment,the average It is 23.08%higher.(3)The results showed that among the factors affecting the change of soil pH under different straw returning,the humidity had a greater influence on the soil acidity than the temperature.The soil acidity was significantly higher when the soil humidity is 100%than the soil humidity is 30%and 65%.For soil organic carbon content:(1)It can be seen from the dynamic change of soil organic carbon content under different temperature and humidity conditions with adding 4different straw treatments and blank soil that straw returning can significantly improve the soil organic carbon content and soil fertility.(2)In each treatment,the best effect is 2%rice straw+15°C+65%humidity.The SOC content in different sampling time is higher than the lowest SOC content in blank soil treatment by 3.78%?5.95%,the average is higher.5.41%;2%rice straw+25°C+65%humidity,the SOC content in different sampling time is higher than the lowest SOC content in the blank soil treatment by 1.84%?6.71%,the average is 5.27%higher;2%decomposed rice straw+35°C+65%humidity,the SOC content of different sampling time is higher than the lowest SOC content in blank soil treatment by 4.14%?8.96%,the average is 5.4%higher;2%corn stalk+25°C+65%humidity,different sampling time SOC The content was higher than the lowest SOC content in the blank soil treatment by 3.29%?6.67%,the average was 5.47%higher;2%corn stalk+35°C+65%humidity,the SOC content in different sampling time was higher than the SOC content in the blank soil treatment.The lowest is 3.18%?8.02%,with an average of5.35%higher.Followed by 2%rice straw+35°C+65%humidity,the SOC content in different sampling time is higher than the lowest SOC content in the blank soil treatment by1.9%?7.53%,the average is 4.79%higher;2%decomposed rice straw+25°C+65%humidity,the SOC content of different sampling time is higher than the lowest SOC content in blank soil treatment by 4.13%?5.87%,the average is 4.79%higher;2%corn stalk+15°C+65%humidity,SOC content at different sampling time The lowest SOC content in the blank soil treatment was 2.9%?5.95%,the average was 5.03%higher;2%decomposed corn stalk+25°C+65%humidity,the SOC content in different sampling time was higher than the SOC content in the blank soil treatment by 3.61%?8.86%,with an average of4.97%higher.(3)The results showed that among the factors affecting the change of soil organic carbon content under different straw mulching,the effect of humidity on soil organic carbon content was greater,and the soil organic carbon content was significantly higher when soil humidity was 65%than when the soil humidity is 30%and 100%.The returning of several crop straws to soil pH,the higher the soil water content,the more improvement the soil pH has.The lower temperature of the straw directly returning to the field is more conducive to increasing the pH of the soil.When the straw is decomposed,the higher temperature is more beneficial to increase the pH of the soil.For the soil organic carbon content,it is not conducive to the accumulation of organic carbon content in the soil when the water content is too high or too low.The effect of temperature on the soil organic carbon content after straw returning to the field is not significant. |
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