玉米间作马铃薯及起垄的水土保持效应

【目的】探讨间作体系下地表特性(如地表糙度)对土壤侵蚀的影响。【方法】结合野外和人工模拟降雨试验,观测了种植方式(单作玉米,单作马铃薯和玉米马铃薯间作)和耕作(起垄和无垄)方式下的径流和侵蚀量特征。【结果】大田条件下起垄和种植方式具有显著的交互效应(P <0. 01)。间作起垄的径流量显著低于间作无垄(P <0. 05)、玉米起垄(P <0. 01)和玉米无垄(P <0. 001)。侵蚀量的结果与径流量相一致,间作起垄的侵蚀量分别比间作无垄、玉米起垄和玉米无垄减少了82. 29%、52. 16%和30. 02%。模拟条件下间作高垄的径流量最低,40和80 mm/h降雨强度下间作高垄的径流量低于间作低垄、玉米高垄和玉米低垄。侵蚀量的变化与径流量相类似,7月初40 mm/h降雨强度下间作高垄、间作低垄、玉米高垄的侵蚀量分别比玉米低垄减少了39. 39%、45. 90%和67. 21%。【结论】间作条件下起垄控制土壤侵蚀效果最好,这对于区域土壤侵蚀的防治具有重要的指导意义。

施肥位置与杂草管理对间作玉米、马铃薯生长和产量的影响

【目的】施肥和除草是农业生产中两大重要的管理措施。近年来,施肥位置作为一种精准施肥措施越来越引起关注,本研究调查了施肥位置与杂草防控在玉米、马铃薯间作中对作物生长和产量的影响。【方法】采用2∶2间作行比,进行了玉米、马铃薯间作大田试验。杂草管理设除草和不除草,施肥位置处理包括:均匀施肥(HF)、种间行施肥(TERF)和种内行施肥(TRAF),共6个处理,每个处理3次重复。调查了间作玉米、马铃薯的株高、生物量、根系总生物量和产量,以及杂草生物量。【结果】施肥位置和杂草管理对玉米产量、生物量和株高均有显著影响,且存在显著的交互效应(产量P <0.001、生物量P=0.002、株高P=0.007)。相比于均匀施肥,在不除草情况下,种间行和种内行施肥均显著提高了玉米的产量、生物量和株高。而在除草情况下,种内行施肥显著提高了玉米的产量和生物量,种间行施肥仅显著增加了玉米的株高。除草对马铃薯株高无显著影响(P=0.494),但显著提高了马铃薯产量和生物量(P <0.001)。施肥位置对马铃薯产量(P=0.114)、生物量(P=0.580)和株高(P=0.772)均无显著影响。在均匀施肥和种内行施肥下,除草显著提高根系总生物量(P <0.001),但在种间行施肥下则无显著影响。不论除草与否,与均匀施肥相比,种内行施肥显著提高了玉米、马铃薯的根系总生物量(P <0.001)。施肥位置(P=0.001)和生长位置(P <0.001)均对杂草生物量有显著影响。与均匀施肥相比,种内行施肥显著降低种间行和马铃薯种内行的杂草生物量,而种间行施肥对种间行杂草生物量无显著影响,但显著降低两种作物的种内行杂草生物量。【结论】在玉米、马铃薯间作体系中,种内行施肥结合除草,可显著促进玉米和马铃薯根系发育,抑制杂草生物量,进而提高产量及肥料施用效果。

深松耕和绿肥还田对云南坡耕地耕层土壤物理性状的影响

利用间作、深松耕和绿肥还田对土壤耕层结构不同的改善作用,将三者集成于同一系统中以发挥各自优势并催生彼此间的协同效应,从而建立适宜持续改善坡耕地耕层结构的耕作措施。于2016~2019年以滇东北规模化种植模式玉米间作马铃薯为研究对象,在此基础上集成利用深松耕与绿肥还田措施。本试验设置6个处理,分别为:T1.玉米单作(对照);T2.玉米/苕子;T3.玉米‖马铃薯;T4.玉米‖马铃薯/苕子;T5.深松耕+玉米/苕子;T6.深松耕+玉米‖马铃薯/苕子,研究不同措施对土壤紧实度、容重和剪切力的影响。结果表明,不同种植模式中,单作处理土壤容重、紧实度和剪切力均高于间作处理;6个处理中,深松耕+玉米‖马铃薯/苕子处理土壤容重、紧实度和剪切力均低于其他处理,在玉米收获期差异显著(P<0.05),与对照相比,土壤容重4年分别降低4.60%、7.00%、3.86%和3.17%;紧实度4年分别降低16.98%、15.06%、30.82%和16.75%;剪切力4年分别降低19.59%、47.72%、23.4%和28.31%。研究表明,玉米间作马铃薯与深松耕、绿肥还田集成应用技术通过利用协同效应,发挥各自优势,达到持续改善土壤耕层结构,为云南山区坡耕地耕层合理构建提供依据。

Use of Farmers’ Indicators to Evaluate the Sustainability of Cropping Systems on Sloping Land in Yunnan Province, China

Diversity in the biophysical and socio-economic attributes of agricultural systems makes them uniquely niche based. Farmers are expert in local biophysical and socio-economic situations and can contribute in developing pragmatic indicators of agro-environmental development. During evaluation of an agricultural research project in Yunnan, China, local farmers were capable of evaluating the effects of modified technologies on existing cropping systems and discussed their attitudes to the interventions using their own indicators. Farmers＇ response can be grouped into seven major aspects： i） effects on income, ii） effects on production resources, iii） effects on crop management, iv） existing local knowledge about the technology, v） availability of inputs, vi） access to information, and vii） socio-economic conditions of farming households. Farmers concluded that environmental conditions in the experimental catchment in comparison to an adjacent untreated catchment were better in terms of soil and water losses, vegetation cover and natural resources, infrastructures and catchment management, use of environmentally-friendly technologies, and crop productivity. Success in soil and water conservation programmes depends on the efforts of the farmers and other local users and their greater involvement helps to identify more pragmatic indicators. Furthermore, it increases ownership of the programme, enhances interactions with the project scientists, increases farmers＇ awareness of ago-environmental problems and their possible consequences. These development will enable scientists to develop better targeted interventions and increase the likelihood of adoption of tested technologies by local communities. The use of paired adjacent catchments improved evaluation activities and is proposed as good practice for future catchment improvement programmes.

Synergistic effects of vegetation layers of maize and potato intercropping on soil erosion on sloping land in Yunnan Province, China

Intercropping, as an overyielding system, can decrease soil erosion on sloping land through the presence of dense canopy covers. However, the structure mechanism in canopy is still unclear. We conducted a two-year field experiment on runoff plots, exploring whether the interaction between vegetation layers reduce soil erosion in maize and potato intercropping systems. The maize, potato, and weed layers in the intercropping system were removed by a single layer, two layers and three layers, respectively(total of 8 treatments including all layers removed as the control). Then, throughfall, runoff and sediment were measured at the plot and row scale on a weekly basis. Based on the difference between each treatment and the control, we calculated and found a relative reduction of runoff and sediment by any combination of the two vegetation layers greater than the sum of each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 15.65% and 46.73%, respectively. Sediment loss decreased by 33.96% and 42.77%, respectively. Moreover, runoffand sediment reduced by the combination of all vegetation layers(no layers removed) was also larger than the sum of that by each single layer. In 2016 and 2017, the highest relative reduction of runoff reached 7.32% and 3.48%, respectively. So, there were synergistic effects among multi-level(two or three layers) vegetation layers in terms of decreasing soil erosion on sloping land. Maize redistributes more throughfall at the maize intra-specific row and the maize and potato inter-specific, which is favorable for the synergistic effect of reducing soil erosion. This finding shows an important mechanism of maize and potato intercropping for soil and water conservation, and may promote the application of diverse cropping systems for sustainable agriculture in mountainous areas.

An Awareness-Adoption Matrix for Strategic Decision Making in Agricultural Development Projects: A Case Study in Yunnan Province, China

Significant achievements have been made in generating sustainable agricultural technologies in developing countries. Usually, these new technologies have been more effective in increasing production and productivity than existing technologies. However, many new technologies considered ＇effective＇ have not been successful in alleviating the associated sustainability problems, due to poor adoption by targeted users. Success of any novel technical intervention should be judged on the basis of how widespread adoption is in the target area by targeted users. In this context, a case study identified the factors affecting farmers＇ adoption of improved technologies extended by an agricultural development project in a rural Village in Yunnan Province, China. Initial adoption/adaptation of project technologies was influenced by farmers＇ awareness of the technology. Farmers were more aware of polythene mulch, contour cultivation, intercropping and tree planting technologies than others. This led to a comparatively high initial uptake of polythene mulch, contour cultivation, sweet chestnut, and intercropping technologies. Farmers had inadequate knowledge about some Project technologies, the adoption of which was particularly low. This reveals the need for increasing farmers＇ awareness about the rationale for Project technologies to achieve greater adoption/adaptation of project technologies by farmers over wider areas. Farmers＇ testing of the technology leads to better adoption/adaptation compared to mere awareness. However, considerable time and resources are required for testing/trying technologies. This justifies the usefulness of comparatively quick and less resource demanding options for awareness creation. Development of effective cropping technologies is important for sustainable agricultural development. The success of any agricultural development project, especially in terms of improving sustainability, depends on how widely those improved technologies are adopted/adapted by farmers in the targeted region. Therefore, farmers＇ adoption of technologies should be a key criterion for judging the success of any project. The awareness-adoption matrix is a useful tool to guide research and development projects to achieve expected adoption/adaptation of technologies. Use of the matrix helps identification of weak and strong aspects of research and development projects and thus assists strategic decision-making.

An Evaluation of the Introduction of Modified Cropping Practices in Yunnan Province,China,Using Surveys of Farmers’ Households

Problems associated with land degradation are serious in China. Sloping land in South China has experienced a decline in crop productivity by 30-60% due to soil erosion and it has been predicted that most topsoil will be lost within the next 100 years if current erosion rates continue. Considering these situations, an agro-environmental research and development project （Sustainable Highland Agriculture in South-East Asia- SHASEA） was conducted in a catchment in Yunnan Province, China, to address the objectives of increasing crop productivity in sustainable and environmentally-friendly ways. A range of cropping practices was developed and implemented in a rural upland catchment （Wang Jia）. At the end of the project, farmers were surveyed to evaluate project effectiveness. All farmers from Wang Jia Catchment, who were involved in project implementation, were surveyed. A sample of farmers working in an adjacent catchment （not associated with the project） was surveyed for comparative purposes. Farmers had different perceptions of the cropping practices employed. Contour cultivation was preferred and likely to be adopted. Others practices such as straw mulching and intercropping were seen as less appropriate and unlikely to be adopted. Polythene mulch was recognized as effective, but likely to be adopted only if financial returns were favourable. The availability of relevant information had an important impact on the extent of technology testing by farmers and their willingness to adopt the practices in the future.