Agroforestry Mechanism And Soil Environmental Effects Based On The Karst Culture

Karst area has characteristics of a large number of soluble rock,abundant rainfall especially erosive rainfall,low environmental capacity and strong disturbance of human activities,which seriously damage the originally fragile ecological environment.Unique natural geography factors combined with unreasonable human activities make the karst area highly prone to soil erosion.There is a certain causal relationship between soil erosion and rocky desertification.Three major problems of soil erosion,rocky desertification and poverty are intertwined in karst area.There are great theoretical and practical significance for conducting control measures which contain ecological,economic and social benefits in karst area in order to improve the ecological environment of the karst area,increase the economic income of the peasants,and promote the sustainable development of the rural economy.Based on the theories of ecology,systems science,economics,soil and water conservation and sociology,this study selects the karst plateau mountain bijie Salaxi potential-light rocky desertification comprehensive control demonstration zone and karst plateau canyon Guanling-zhenfeng Huajiang middle-intensive rock desertification comprehensive control demonstration zone as study area.Through the questionnaire survey,the history of the transformation from the traditional planting mode to the modern agroforestry model,the influencing factors,the development status and problems of the agroforestry,farmers’ basic social consciousness characteristics about agroforestry and cultural changes caused by the transformation of planting patterns is clarified.Finally,based on this,the countermeasures for sustainable management of agroforestry based on karst culture are proposed.The typical agroforestry models in the demonstration area are selected to study its effects on soil nutrient and physical properties.Finally,based on the questionnaire survey and experimental observations,it provides corresponding countermeasures and suggestions for the sustainable development of agroforestry management in the demonstration area.The conclusions of the study are as follows:(1)Problems of soil erosion and rocky desertification caused by fragile natural environment in the karst area and the unreasonable human activities.The contradiction between the original farming culture and the natural environment prompted the research area to form the existing agroforestry models gradually.Government policy is the primary driving factor for the mode change.The differences in natural geography factors such as landform type,water resources characteristics,elevation and rocky desertification grade,and the differences in socio-economic-cultural factors such as environmental awareness,development concepts,government policies,and economic income of farmers in the demonstration area have led to different present situation about management and development of agroforestry in the two demonstration areas.The main agroforestry modes are apple + corn + potato,mulberry + ryegrass,rose + potato,rose + walnut + potato + vegetable,walnut + corn,rose + garlic,etc.in bijie Salaxi potential-light rocky desertification comprehensive control demonstration zone;the main agroforestry models are pepper + sweet potato,pepper + sweet potato,dragon fruit + sweet potato,dragon fruit + pepper + sweet potato,honeysuckle + Pepper and so on in Guanling-zhenfeng Huajiang middle-intensive rock desertification comprehensive control demonstration zone.(2)Questionnaire research showed that the development of agroforestry in the karst area mainly has the following problems: lack of capital and technical support,weak links with agricultural development institutions,low enthusiasm for farmers’ production and management,low awareness of local culture by farmers,low environmental awareness and uncomplete infrastructure.These problems have caused the economic benefits of agroforestry operations to fail to meet the needs of farmers,which hindered the sustainable development of agroforestry in the study area.(3)There are differences in soil nutrient indexes under different agricultural planting patterns in zhenfengguanling-Huajiang Demonstration Zone,and the soil nutrients have characteristic of surface accumulation.The analysis of the membership function shows that the soil comprehensive nutrient evaluation scores are Pitaya(0.838)>chili + sweet potato(0.744)> honeysuckle + pepper(0.722)> Pitaya + sweet potato(0.713)> Pitaya + pepper + sweet potato(0.71)> pepper + Pitaya(0.706)> pepper(0.679)> pepper + sweet potato(0.63).In general,there is no significant difference in the comprehensive evaluation results of soil nutrients under different agricultural planting patterns.Compared with the single pepper,the integrated nutrients of the honeysuckle + pepper pattern soil improved.The comprehensive nutrient of the soil under the pepper and sweet potato mode is reduced.Under the same fertilization and agricultural management measures,the agroforestry does not absolutely increase the comprehensive nutrient of the soil,and may also reduce it compared with single planting.Compared to Pitaya,interplanting of Pitaya and other crops reduces the overall nutrient content of the soil.Compared with monocropping,the basic physical properties of the soil under Pitaya and pepper intercropping mode have been improved.(4)There are differences in soil nutrient indicators of different agricultural planting pat terns in Bijie Salaxi Demonstration Zone.In general,soil nutrients have characteristic of s urface accumulation.The soil comprehensive evaluation nutrient scores under different agri cultural planting patterns are corn(y)(0.689)>Apple+Corn+Potato(p+y+t)(0.676)>Walnut+Co rn(h+y)(0.673)>Rose+Potato(m+t)(0.647)>Rose(m)(0.636)>Rose+Garlic(m+d)(0.596)>Rose+Wal nut+Potato+Vegetables(m+h+t+s)(0.595)>Mulberry + Ryegrass(s+h)(0.488).Overall,soil bu lk density,soil porosity and soil moisture conditions were improved in forest and herbage pattern or rose intercropping model compared to monoculture.(5)Eight typical planting patterns in Bijie Salaxi Demonstration Zone were selected to study the characteristics of soil aggregates,the results showed as following:under dry siev ing conditions,m+h+t+s,m+d had the highest content of soil aggregates >5mm,m+t with0.5-1mm agglomerate content,and other models with 2-5mm soil aggregates maximum;s oil granular fractal dimension was p+y+t>s+h>m+t>m>m+h+t+s>y>h+y>m+d.The MMD v alue was the largest in the m+d plot,and the MMD value of p+y+ t was the smallest;th e value of the GMD was m+d>y>m+h+t+s>s+h>m>m+t>p+y+t>h+y.Under the wet sieving treatment,soil granular fractal dimension was y>m+h+t+s>h+y>m+d>m+t>m>p+y+t>s+h;MMD was s+h>m+t>m>m+d>p+y+t>h+y>y>m+h+t+s;GMD was s+h>m+t>m+h+t+s>m+d>m>p+y+t>y;corn single plot had the largest soil granular fractal dimension,and mulberry+ ryegrass plot had the smallest soil granular fractal dimension.The results showed that t he D,MMD and GMD values under wet sieving treatment can better reflect the actual sit uation in the study area,In order to increase soil corrosion resistance,the corn planting a rea should be reduced in response to national policies,this provides a theoretical basis for the development of agroforestry in the study area.