| Soil compaction is a serious problem.Due to unreasonable tillage in successive years in the main sugarcane producing area,the soil is severely hardened,restricting the development of crop roots and damaging the formation of stalk yield,seriously affecting the sustainable and healthy development of the sugarcane industry.Subsoiling tillage can improve the physical and chemical properties of the soil in the plow layer,and is more conducive to the development of crop roots,and deep planting is conducive to roots to absorb soil moisture and nutrients.The field experiment was conducted from March 2019 to January 2021,at the agricultural new town(107°31? to 108°06? E and 22°17? to22°57? N)of Guangxi University.In this experiment,four sugarcane varieties(Guitang 42,Funong 41,Zhongzhe 9 and Liucheng 05136)were used to conduct on field test.There are three tillage treatments: deep tillage and deep planting30cm(STP30),conventional tillage and planting 20cm(CTP20),shallow tillage and shallow planting10cm(RTP10).We discussed the effects of three tillage methods on the physical and chemical properties of sugarcane soil,root system architecture,rhizosphere microbes and industrial and agronomic traits of sugarcane,in order to provide support for guiding sugarcane seed breeding and tillage methods,the main results of the experiment as follows:1.Soil physical and chemical properties: Deep tillage and deep planting(STP30)significantly reduced the soil bulk density in the 20-30 cm soil layers of the newly planted sugarcane land,and the bulk density in the 0-10 cm soil layer was smaller,while the change was more significant in the stubble cane land(P <0.05).Under the conditions of shallow tillage and shallow planting(RTP10),conventional tillage and planting(CTP20),and deep tillage and deep planting(STP30),soil porosity and soil bulk density were opposite and decreased with the increase of soil layers.The variation trend of soil water content under the three tillage methods was basically consistent with soil porosity.2.Root development and nutrient utilization: The change of planting depth can affect the root development of sugarcane,and the root development characteristics of sugarcane among different varieties are different.Deep tillage and deep planting(STP30)significantly increased the number of root tips,total root length and average root diameter of newly planting sugarcane and stubble cane,and the differences among treatments were STP30 > CTP20 > RTP10,and the effects of STP30 on root development were significantly higher than those of the other two treatments(P < 0.05).Deep tillage and deep planting(STP30)significantly increased the soil organic matter,total nitrogen and available phosphorus in the rhizosphere of newly planting sugarcane and stubble cane,and the differences between treatments were STP30 > CTP20 > RTP10,which was significant(P < 0.05).3.Rhizosphere microbes and enzyme activities: The change of planting depth could affect the microbial community richness of sugarcane rhizosphere soil,and the greater the planting depth was,the greater the influence was on the microbial community richness and the higher the community diversity was,with a significant effect(P < 0.05).Tillage methods mainly changed the abundance of Acidobacteria,Proteobacteriaes,Chloroflexi and Nitrospirae.Deep tillage and deep planting(STP30)significantly increased the activities of catalase,sucrase,urease and acid phosphatase in the rhizosphere soil of newly planting sugarcane and stubble cane,and the difference between treatments was STP30 >CTP20 > RTP10,the difference was significant(P < 0.05).4.Industrial and agronomic traits: Deep tillage and deep planting(STP30)promotes the increase of plant height,stem diameter,root to shoot ratio,yield,and reduces lodging rate.In conclusion,deep tillage and deep planting can improve soil physical and chemical structure,reduce soil bulk density,increase porosity and moisture content,activate soil carbon,nitrogen and phosphorus,strengthen the activities of rhizosphere microbes and soil enzyme activities,promote the growth and development of sugarcane root system,and thus improve sugarcane industrial and agronomic traits. |
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