Effects Of No-tillage And Ridge Tillage On Stability Of Microbial Community In Black Soil

Long-term traditional tillage has led to serious degradation of black soil in farmland in Northeast China,so other tillage methods have been introduced into production practice.At present,research on soil microorganisms under different tillage methods mainly focuses on the quantity,activity and community composition of microorganisms,but the understanding of soil microbial community stability after environmental disturbance is very limited.The stability of microbial community directly affects the self-balance and recovery ability of soil to environment disturbance,which is very important for the sustainable use of soil.This thesis takes dry-wet alternation of different frequencies and intensities as disturbance,systematically studies the response of soil microbial community structure and function to dry-wet alternation under different tillage modes in black soils,quantitatively evaluates the resistance and resilience of microbial community to interference under different tillage modes,and deeply analyses the main factors affecting the stability of microbial community.The internal relationship between the structure and functional stability of soil microbial community under different tillage modes was discussed,and finally the differences of soil microbial community stability under different tillage modes were clarified.This study not only helps to understand the microbial mechanism of soil ecosystem stability under different tillage modes,but also has important guiding significance for choosing reasonable tillage modes and sustainable management of soil ecosystem in the black soil region of Northeast China.The experimental results are as follows:1.Tillage can significantly change the diversity of soil microbial communities.The diversity of soil microbial communities under ridge cultivation is significantly higher than that under no-tillage cultivation.Moreover,ridge cultivation improves the uniformity of soil microbial communities and increases microbial groups such as Acidobacteria and Verrucomicrobia.Under the background of alternating wetting and drying,the diversity of soil microbial community in ridge farming was significantly higher than that in no-tillage soil,and the composition of soil microbial community in no-tillage was more stable than that in ridge farming soil.In production practice,reasonable ridge tillage can improve soil microbial community habitat,improve soil quality and increase crop yield under the condition of ensuring soil moisture content.The relative abundance of Proteus and Phytophthora in ridge soils and in no-tillage soils was significantly increased,but the Saccharibacteria and Phytophthora were significantly reduced,while the influence of dry-wet alternation on Phytophthora and other phyla was less.At the generic level,the relative abundance of beneficial bacteria was reduced,such as nitrobacteria and soil,which participated in nitrification.Rhizopus related to phosphorus transformation in soil.Experiments also showed that there were significant differences in soil microbial community structure between one drought-watering cycle and three drought-watering cycles under either tillage mode.However,under the same frequency of dry-wet alternation,the different degree of drought did not significantly affect soil microbial community structure,so the frequency of dry-wet alternation had a significantly higher impact on soil microbial community than that of dry-wet alternation.Strength.2.In the recovery stage,the CO2 emission rate of no-tillage soils was lower than that of ridge soils,indicating that the respiration function of no-tillage soils was weaker than that of ridge soils,and that the NO emission rate of no-tillage soils was higher than that of ridge soils,indicating that the nitrification function of no-tillage soils was stronger than that of ridge soils.The alternation of wetting and drying can stimulate the release of CO2 and increase the rate of CO2 emission.But in the recovery stage,the alternation of wetting and drying is relieved and the stimulation effect is terminated.The rate of CO2 emission in the control group increases gradually,and is significantly higher than that in the experimental group.It shows that the alternation of wetting and drying can stimulate the soil respiration,and it takes a long time to restore the functional strength of the control group.The N2 O release rate was stimulated,but after a long period of recovery,the N2 O release rate of no-tillage extreme drought treatment(VDW1 and VDW3)was significantly higher than that of other experimental groups and control groups.The N2 O release rate of ridge-tillage VDW1 and MDW1 treatment was significantly higher than that of other experimental groups and control groups,and ridge-tillage MDW3 and VDW3 decreased linearly at the later stage of cultivation,which indirectly indicated that the N2 O of no-tillage soil decreased linearly.Nitrification was more stable than ridge culture.3.The activity of two enzymes in no-tillage soil was stronger than that in ridge soil.During the period of restoration culture,the activities of beta-glucosidase and beta-N-acetyl glucosaminidase in all treatments of no-tillage soil decreased for a period of time and then stabilized,while those in ridge soil decreased continuously,indicating that the recovery of no-tillage soil was stronger than that of ridge cultivation.Dry-wet alternation can significantly increase the activity of beta-glucosidase,while dry-wet alternation can only promote the activity of beta-N-acetyl glucosaminidase at high frequency and low intensity,and inhibit the activity at low frequency and high intensity.Dry-wet alternation cannot restore the activity of beta-glucosidase,but can restore the activity of beta-N-acetyl glucosidase after removing the interference.Horizontal.4.The frequency and intensity of dry-wet alternation have a significant impact on the microbial diversity of no-tillage soils.The higher the frequency and drought intensity,the lower the microbial diversity of no-tillage soils,but the response of ridge soil microbial diversity to dry-wet alternation is not significant.The relative abundance of soil microbial communities could be affected by alternating wetting and drying treatments,but the effects varied with tillage methods and genera.