| Agroforestry is a common ecological restoration model in the process of karst rocky desertification.The soil moisture conservation and agronomic interception techniques of agroforestry is an effective way to alleviate drought and water shortage in karst rocky desertification areas.In order to clarify the changes of soil physical properties and soil moisture of agroforestry in different karst areas,the response of runoff and sediment yield intercepted to rainfall and the effect of various measures on reducing the flow and sediment are explored.On the Guizhou Plateau,which represents the overall structure of the karst ecological environment in southern China,the most typical and representative Bijie Salaxi,Guanling-Zhenfeng Huajiang,and Shibing Karst were selected as the research areas.During the period 2017-2020,by the literature analysis and investigation in the Karst demonstration areas,we selected 6 agroforestry types for soil moisture conservation and agronomic interception experiments: walnut（Juglans regia L.）+corn（Zea mays Linn.）and walnut（Juglans regia L.）+soybean（Glycine max（Linn.）Merr.）in Bijie Salaxi,Zanthoxylum bungeanum（Zanthoxylum bungeanum Maxim.）+Vietnamese Sophora Root（Euchresta japonica Hook.f.ex Regel）and Zanthoxylum bungeanum（Zanthoxylum bungeanum Maxim.）+peanut（Arachis hypogaea Linn.）in Guanling-Zhenfeng Huajiang,pear（Pyrus pyrifolia ‘Whangkeumbae’）+soybean（Glycine max（Linn.）Merr.）and pear（Pyrus pyrifolia ‘Whangkeumbae’）+Radix Pseudostellariae（Pseudostellaria heterophyllaa（Miq.）Pax ex Pax et Hoffm）in Shibing,total 6 kinds of agroforestry as the research objects,using the three measures of hole like soil preparation+super absorbent polymer,hole like soil preparation+ super absorbent polymer+litter,hole like soil preparation+super absorbent polymer+straw respectively.The research object includes a total of 14 runoff plots and 6 experimental plots.A total of 84 soil moisture monitors（5TE）were buried in the 14 runoff plots.A total of 360 test runs were conducted on the 6 test plots using a portable 5TE.12 typical runoff and sedimentary rainfalls,a total of 252 sediment samples were collected,a total of 360 ring blade soil samples were collected from 20 plots for laboratory physical attribute analysis,combined with weather station data,using single factor analysis of variance,runoff plots monitoring,coefficient of variation,linear fitting and analytic hierarchy process reveal the physical properties and moisture change laws of soil moisture conservation in agroforestry in different karst areas,clarify the agronomic interception mechanism,put forward soil moisture conservation and agronomic interception technologies for agroforestry,and integrate soil moisture conservation and agronomy in agroforestry interception technology system and demonstration application,at the same time build agroforestry soil moisture and agronomic interception monitoring and evaluation index system,establish a monitoring and evaluation model and conduct comprehensive evaluation and verification of effectiveness,for agroforestry soil moisture conservation and agronomic interception and monitoring evaluation provide scientific and technological reference.The conclusions are as follows:（1）The physical properties of the agroforestry soils in the three study areas before and after the soil moisture conservation were significantly different（except for the control group）.Compared with before the soil moisture conservation,the soil bulk density of each agroforestry in each study area after the soil moisture conservation increased to varying degrees,the increase range was as follows: Bijie Salaxi study area(0.05 g.cm-3)> Guanling-Zhenfeng Huajiang study area(0.04 g.cm-3)> Shibing Karst study area(0.03 g.cm-3),the field water holding capacity and capillary water holding capacity are increased,the total porosity and capillary porosity are both decreased;compared with the control group,each moisture conservation treatment reduced the bulk density of each layer of soil,soil bulk density showed: hole like soil preparation + super absorbent polymer + straw <hole like soil preparation + super absorbent polymer + litter < hole like soil preparation + super absorbent polymer,but the difference is not significant（P>0.05）,increasing the field water holding capacity,capillary water holding capacity,total porosity and capillary porosity,the difference is significant（P<0.05）,including hole like soil preparation + super absorbent polymer + straw treatment increase maximum.In general,hole like soil preparation + super absorbent polymer + straw has a better effect on soil structure of mixed agroforestry,followed by hole like soil preparation + super absorbent polymer + litter,and finally hole like soil preparation + super absorbent polymer.The research results can provide a theoretical reference for soil improvement in rocky desertification areas.（2）After agroforestry by different moisture conservation measures in different research areas,the soil moisture content of 0-15 cm and 15-30 cm soil layers have increased to varying degrees and are higher than that of the control group.The soil moisture content increases with soil depth;The coefficient of variation and standard deviation of soil water content are smaller than those of the control group,and decrease with the increase of soil depth.In general,the soil moisture content of the 0-30 cm soil layer is: hole like soil preparation + super absorbent polymer + straw> hole like soil preparation + super absorbent polymer + litter> hole like soil preparation + super absorbent polymer,coefficient of variation and standard deviation to the opposite.In general,different moisture conservation measures can increase the soil moisture content of agroforestry and the stability of profile soil moisture.Among them,the hole like soil preparation + super absorbent polymer + straw treatment has the highest layered soil moisture content and the best effect.By comparing the three research areas,it is found that the soil moisture in the 0-30 cm soil layer is the highest（32.98 %）,the soil moisture coefficient of variation is the smallest（2.3 %）,and the stability is the highest after pear + soybean is applied with straw in the Shibing Karst research area.（3）The agronomic interception measures in different research areas all have a certain effect of reducing flow and sediment,and the runoff and sand production are positively correlated with rainfall,and the runoff and sand production under the same rainfall show the control group> hole like soil preparation + super absorbent polymer> hole like soil preparation + super absorbent polymer + litter litter> hole like soil preparation + super absorbent polymer + straw,and the effect of reducing flow and sand is opposite,and the hole like soil preparation + super absorbent polymer + straw is reduced sand works best.By comparing the agronomic interception effects of different agroforestry in the two research areas,it is concluded that the same measures have more runoff and sediment yield in the Guanling-Zhenfeng Huajiang research area than in the Shibing Karst research area,but the Guanling-Zhenfeng Huajiang research area.The effect of reducing current and sediment is better than that of Shibing Karst research area.（4）Use analytic hierarchy process to construct a monitoring and evaluation system suitable for soil moisture conservation and agronomic interception benefit of agroforestry in karst rocky desertification area.The indicator system includes a three-tier system structure of target layer,criterion layer and indicator layer.There are a total of 11 sub-indicators of three types of evaluation indicators.The comprehensive evaluation of the benefits in the three demonstration areas shows that the regional ecological benefits,economic benefits and social benefits all have a positive role in promoting.The ecological benefits,economic benefits and social benefits in 2019 are significantly higher than in 2018,and the increase ranges are 1.09～4.92 %,2.85～17.78 % and 0.76～3.78 % respectively.The economic benefits of the three demonstration areas have grown faster,with Shi Bing having the largest increase in economic benefits（17.78 %）.Compared with 2018,the comprehensive evaluation of benefits in 2019 has increased to varying degrees,manifested as: Shibing Karst demonstration area（0.471 2）> Guanling-Zhenfeng Huajiang demonstration area（0.405 2）> Bijie Salaxi demonstration area（0.336 9）.This study can provide a feasible technical reference basis for the development of soil moisture conservation and agronomic interception technologies in agroforestry in rocky desertification areas,and the realization of the overall development of ecology,economy and society.（5）Propose key technologies suitable for soil moisture conservation and agronomic interception of agroforestry in karst rocky desertification areas,and verify the application of the obtained results.Based on the existing technologies and mature technologies of soil moisture conservation and agronomic interception in agroforestry in the three demonstration areas,the ternary soil moisture conservation technology and key innovative technologies common to data collection and experimental devices applicable to agroforestry in karst rocky desertification areas are proposed.Through technology demonstration,a total of 61.98 hm2 of demonstration area for soil moisture conservation and agronomic interception in mountain agroforestry was built,which played a positive role in promoting ecology,farmers’ recognition and recognition.Compared with the control group,the soil bulk density of the demonstration site was lower than that of the control group,and the decrease range was 0.2～0.8 g.cm-3.The field water capacity,capillary water capacity,total soil porosity and capillary porosity all increased,and the rising ranges are: 4.08～13.48 %,3.03～8.47 %,0.98～9.37 %,1.39～7.89 %,the physical structure of the soil is improved,and the construction of the Salaxi demonstration site is the best.Moreover,different agronomic interception measures also have a significant blocking effect on runoff and sediment,and soil erosion is effectively controlled. |
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