The Soil Air Permeability And Soil Structure Of Typical Black Soil

In order to study the law of typical black soil permeability and soil structure change,the soil permeability,soil broad structure index(GSSI),bulk density and so on were studied in different reclamation years,different restoration forest land and different restoration years.And to analyze the effects of soil reclamation and land restoration on soil ventilation and soil structure in order to provide theoretical support for further study of soil gas transport and soil structure change in typical black soil areasIn order to investigate the effect of tillage on soil air permeability of typical black soils,farmlands with different tillage periods of 17 years,30 years,40 years and no-tillage(natural secondary forest land)were selected for soil sampling.The air permeability of 0-20 cm soil layer in both vertical and horizontal directions were measured by using PL-300 soil permeability tester,then the anisotropy of air permeability was calculated.The results showed that soil air permeability in both directions decreased significantly with tillage periods increasing;comparing with natural secondary forest(0a),the air permeability decreased by 22.44%-95.44% and 40.45%-92.50% in vertical and horizontal direction,respectively.The soil air permeability from different reclamation years showed the same trend in both directions,and the air permeability became lower with deepening the soil layers.The anisotropy of soil air permeability of different reclamation years increased gradually with the increase of tillage time and showed a significant change when tillage periods longer than 30 a.The soil air permeability presented a significant negative correlation with bulk density,and a significant positive correlation with porosity,non-capillary porosity and organic matter.It can be concluded that the gas transport capacity of black soil gradually decreases with tillage period;and the bulk density,porosity,non-capillary porosity and organic matter could significantly affect air permeability of black soil.with the increase of the reclamation period respectively(P <0.05),the bulk density of the two soils increased by 20% ~ 22% and 8% ~ 23%.The thickness of the lower soil is larger than that of the surface soil,and the lagging effect of the reclamation on the soil bulk density is increased.The vertical bulk density increases by 3% ~ 17% and the horizontal bulk density increases by 0.5% ~ 13%,which shows that the effect of reclamation on the vertical direction Horizontal direction;bulk anisotropy greater than 1,horizontal bulk density greater than the vertical bulk density.with the increase of the reclamation period(P <0.05)and the average change range of the NCP / CP was 0.06 ~ 0.2,and the NCP / CP increased.The average change range of NCP / CP increased from 0.17 to 0.26,the anisotropy of NCP/CP is less than 1,with the reclamation period increased gradually decreased.With the increase of cultivated years,the GSSI value decreased year by year,and the average range of vertical average was 90.16 ~ 95.The average horizontal range was 83.97 ~ 94.79,and the ratio of soil to solid was lower than that of year.It can be considered that the effect of soil reclamation on soil structure increases the liquid phase and reduces the gas phase so that the GSSI value is far from the ideal state.The horizontal GSSI value is less than the vertical direction.The soil air perneability of five forestry is higer than arable land in both directions(P<0.05),in the virtical direction,the Salix matsudana Koidz is the best,in horizontial direction Populus X.is the best.The anisotropy of soil air permeability different forests have different value,Ulmus pumila L.and Salix matsudana Koidz is taller than 1,Larix gmelinii(Rupr.)Kuzen,Acer saccharum Marsh.,Populus X.are less tean 1.The improvement of NCP / CP in the soil showed vertical and horizontal NCP / CP increased,the vertical direction increased by 12.5% ~ 87.5% in the horizontal direction by 14.29% ~ 157.14%,and the improvement of the level of NCP / CP was higher than that of the vertical.the GSSI value was significantly increased(P <0.05).There was no significant change in the three-phase ratio of soils in different recovery modes.It can be concluded that the different restoration patterns of forest type mainly increase GSSI by increasing soil gas ratio,and the improvement of soil GSSI in the vertical direction is the best for larch,and the horizontal reverse is the best.The improvement in GSSI is more pronounced in the horizontal direction than in the vertical direction.Soil three-phase ratio and GSSI anisotropy value fluctuates near 1 but not 1.Soil heterogeneity,GSSI in the vertical and horizontal direction there is a small difference,but also reflects the soil heterogeneity.The soil permeability of Larix gmelinii(Rupr.)Kuzen was significantly higher than that of cultivated land in different restoration years,and showed a phenomenon of increasing year by year with the increase of recovery period.The vertical direction of the air ductility increased 6.06 ~ 10.69 times,the level of growth of 2.76 ~ 6.21 times.Indicating that vegetation recovery on the recovery of air permeability in the vertical direction than the horizontal direction(P <0.05).The larvae of Larix gmelinii were significantly larger than those of cultivated land(P <0.05).The horizontal air permeability is greater than the vertical air permeability.The ratio of soil solidification decreased with the increase of recovery period,and the gas ratio increased gradually(P <0.05).The GSSI value of Larix gmelinii forest was significantly higher than that of cultivated land,but it did not reach the significant level.STPSD shows the opposite of GSSI.For the restoration of the soil structure,the vertical direction 50 a is still slightly increased,and the horizontal direction is steady at 36 a,indicating that there is a hysteresis in the vertical direction.