Effects Of Different Mulching Methods On Microenvironment Of Apple Root System

The old course of the Yellow River is one of the four major apple producing areas in China.Northern Jiangsu,which belongs to the old course of the Yellow River,has a long history of apple cultivation.However,in recent years,there are a series of problems in orchards in this area,such as chaotic farming mode,high temperature and rain in summer,fruit cracking,sunburn,yield and quality decline and so on.In this study,the root soil of summer apple orchards in northern Jiangsu was taken as the research object,With clear tillage as control,20 soil indexes such as soil temperature and humidity,soil nutrient content,soil enzyme activity and number of soil microorganisms were measured and analyzed under ground mulching(T1),ridging and covering grass(T2)and natural grass(T3)treatments.In order to screen out the suitable cultivation measures of apple orchards in summer in this area,and provide some theoretical support for the rational application of orchard tillage measures in apple cultivation in the old course of the Yellow River.The main results of this study are as follows:1.Compared with clear tillage,the soil temperature of apple roots decreased significantly under the treatments of ground mulch(T1),ridging and covering grass(T2)and natural grass(T3),and the cooling effect decreased with the deepening of soil layer.Among them,the cooling effect of ridging and covering grass treatment is significant.In 0-10 cm soil layer,compared with clear tillage,the soil temperature decreased by 1.8℃,1.2℃,1.1℃ and 1.3℃ respectively in the four months of June-September growing season,and the soil temperature was stable at 23.2-25.1℃.In 10-20 cm soil layer,compared with clear tillage,the soil temperature decreased by 2.2℃,1.9℃,1.4℃ and 1.8℃ respectively in the four months of June-September growing season.In 20-40 cm soil layer,compared with clear tillage,the soil temperature decreased by 2.0℃,1.7℃,1.6℃ and 1.8℃ respectively in the four months of June-September growing season.In 40-60 cm soil layer,compared with clear tillage,the soil temperature decreased by 2.0℃,1.7℃,0.8℃ and 1.4℃ respectively in the four months of June-September growing season.The effect of natural grass treatment was the second,and the effect of ground cloth mulching was the worst.2.In the growing season from June to September,treatments such as ground mulching(T1),ridging and covering grass(T2)and natural grass(T3)increased the soil water content of apple root in varying degrees compared with the control,and the water content of 0-20 cm soil layer in apple root changed significantly.Compared with clear tillage,the water conservation effect of grass mulching(T2)was the best,and the soil surface water content increased by 40.8%,38.4%,55.3% and 53.1% respectively in the four months of the June-September growing season,soil water content is between 17.28% and 36.56%.The effect of natural grass treatment was the second,and the effect of ground cloth mulching was the worst.3.Compared with the clear tillage,the treatments of ground mulching(T1),ridging and covering grass(T2)and natural grass(T3)all increased the content of soil nutrients in varying degrees,among them,the increase of soil nutrients in 0-20 cm of apple root system is the largest,and the soil nutrient content decreased significantly with the deepening of soil layer.In the 0-20 cm soil layer,the effect of ridging and covering grass(T2)was the best,and the contents of soil organic matter,nitrogen,phosphorus,potassium,available potassium,nitrate nitrogen and ammonium nitrogen increased by 25.4%、37.1%、43.2%、34.1%、38.0%、34.5%、21.0%、28.7% and 25.7%,respectively.The effect of natural grass treatment was the second,and the effect of ground cloth mulching was the worst.4.Compared with the clear tillage,the treatments such as ground mulching(T1),ridging and covering grass(T2)and natural grass(T3)all increased the soil enzyme activity in varying degrees,and the increase of soil enzyme activity in the surface soil was the largest.Compared with clear tillage,the difference of natural grass(T3)treatment was the most significant,and the activities of soil urease,sucrase,FDA hydrolase,dehydrogenase and phosphatase increased by 7.1%,91.2%,142.6%,130.4% and 108.5%,respectively.The second was ridging and covering grass(T2)treatment,whose soil urease,sucrase,FDA hydrolase,dehydrogenase and phosphatase activities increased by 8.4%,61.6%,113.7%,96.5% and 65.0% respectively compared with clear tillage.The effect of ground cloth mulching treatment was inferior to that of grass mulching and natural grass mulching treatment.5.Compared with clear tillage,the number of microorganisms in apple roots soil increased in varying degrees under the treatments of ground mulching(T1),ridging and covering grass(T2)and natural grass(T3).The treatment of ridging grass(T2)was the best,under which the number of soil bacteria,fungi,actinomycetes and nitrogen-fixing bacteria increased by 13.5%,8.9%,10.2% and 11.2% respectively compared with clear tillage.The effect of natural grass treatment was the second,and the effect of ground cloth mulching was the worst.The effect of natural grass treatment was the second,and the effect of ground cloth mulching was the worst.The results of principal component analysis showed that the treatment of ridging and covering grass was the most suitable for summer orchard in the old course of the Yellow River.And g ridging and covering grass can improve the photosynthetic effect and fruit quality of fruit trees by reducing soil temperature,increasing soil fertility,soil enzyme activity and increasing the number of microorganisms,accelerating soil material circulation and promoting mineral element absorption of fruit trees.