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Root lodging is known to reduce the yield and quality of maize, which will be more serious driven by the changes in agriculture such as the higher planting density and the more extreme precipitation events. Here we describe a new cultivation method to reduce the root lodging of maize. We designed two planting layouts: twin plants (TP) and single plant (SP) in a hole with the same density. The vertical root-pulling resistance, angle and rate of natural root lodging, root and shoot morphology related to root lodging and maize yield were compared between two planting layouts. TP planting significantly increased the vertical root-pulling resistance and angle of natural root lodging. This can be partly attributed to the gripping force between the staggered crown roots of the two adjacent plants. Moreover, the TP planting could increase root-lodging resistance by increasing the root angle (acute angle between the stem direction and root) and stem diameter. Additionally, TP planting did not reduce the maize yield and biomass. Consequently, our study demonstrated that the twin plants in a hole are effective to decrease the root lodging of maize in southwest of China. This technique is simple, inexpensive, safe, stable, and has broader potential for increasing maize yield and quality. Twin plants layout in wide-narrow rows significantly increased the vertical root-pulling resistance of maize, which mainly attributed to the gripping force between the staggered crown roots of the two adjacent plants.

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, runoff and 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.

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It has been suggested that the increased yields of intercropping are strongly correlated to its effect on controlling water loss. However, studies of the effect of intercropping on controlling water loss on sloping land are few. In this study, with maize ( Zea mays L.) and potato ( Solanum tuberosum L.) as experimental crops, a comparison was made of surface runoff, soil evaporation, soil moisture content, crop transpiration and crop yield between the intercropping and the sole crop on sloping land during 2012–2013. Data showed that: (1) the accumulative runoff in maize and potato intercropping (IC) was not significantly different from that in sole potato (SP), but significantly decreased by 56.75–74.53% ( P P P = 0.034 in 2012 and P = 0.064 in 2013) as compared with that in SP; (3) the soil moisture content in IC at each observation period was higher than that in SM and SP ( P = 0.101 in late July and P P P

Better water comes from better trees, better paddies develop with better water, and better offspring prosper with better paddies (Ancient song of the Hani minority people).

In communities, plants often simultaneously interact with intra- and inter-specific neighbours and heterogeneous nutrients. How plants respond under these conditions and then affect the structure and function of communities remain important questions. Maize (Zea mays L.) was intercropped with potatoes (Solanum tuberosum L.). In the field experiment, we applied fertilizer both homogeneously and heterogeneously under monocropping and intercropping conditions. The heterogeneous nutrient treatment in intercropping was designed with different fertilizer placements, at intraspecific and interspecific rows, respectively. In the pot experiment, crops were grown under both homogeneous and heterogeneous nitrogen conditions with single plant, intraspecific and interspecific competition. Shoot and root biomass and yield were measured to analyse crop performance. In the field experiment, the heterogeneous nitrogen, compared with the homogenous one, enhanced the performance of the intercropped crop. Importantly, this effect of heterogeneous nitrogen was greater when fertilizer was applied at interspecific rows, rather than at intraspecific rows. Moreover, in pot experiments, the root foraging precision of the two crops was increased by interspecific neighbours, but only that of potatoes was increased by intraspecific neighbours. The integrated responses of plants to heterogeneous neighbours and nutrients depend on the position of nutrient-rich patches, which deepen our understanding of the function of plant diversity, and show that fertilizer placement within multi-cropping systems merits more attention. Moreover, the enhanced utilization of heterogeneous nitrogen could drive overyielding in multi-cropping systems.

The association of maize (Zea mays L.) and potatoes (Solanum tuberosum L.) is an overyielding multi-cropping system. However, knowledge on specific interactions in field conditions, especially below-ground interactions, is deficient. To evaluate the nature and strength of interspecific interactions between maize and potatoes, field and pot experiments were conducted using the ‘target’ technique, with three interaction models: no interaction (NI), below-ground interaction (BI) and full (both above- and below-ground) interaction (FI). Plants were sampled at flowering and harvest periods to measure biomass and calculate the log response ratio (lnRR), root:shoot ratio and land equivalent ratio (LER). In the field experiment, the lnRR value of both BI and FI treatments for potatoes was > 0, whereas for maize it was In the pot experiment, however, the lnRR values of both BI and FI treatments were In summary, our study suggests that the root facilitation produced by maize for potatoes is a mechanism for overyielding in the maize–potato intercropping system. The potential of this system merits further research.

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.

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 efiects of modifled 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) efiects on income, ii) efiects on production resources, iii) efiects 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 efiorts 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 agro-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.

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.

China experiences severe soil erosion problems, as a result of population pressure and a lack of land suitable for cultivation. In the south-west province of Yunnan, heavy monsoonal rains, combined with the fact that 95% of the province is mountainous, create erosion problems. This is exacerbated by the common practice of cultivating steep slopes due to lack of flat land. The best way to minimise soil erosion in these circumstances is to devise cultivation practices that conserve soil loss without reducing crop productivity. Work was carried out to consider the effectiveness of contour cultivation (CC) and contour cultivation plus straw mulch (CC+SM), in relation to their effects on soil erosion and maize productivity. Results were compared to the traditional practice of downslope cultivation (D) on 3 slope classes 3, 10 and 27°. In a wet year CC significantly reduced soil loss on the 3° and 10° slopes and adding straw mulch gave no extra protection. On the 27° slope, CC was not effective, but CC+SM reduced soil loss by almost 100%. In 1999, a drier year, no significant treatment effects were found on the 3° slope, but CC significantly reduced soil loss on the 10 and 27° slopes. The addition of straw mulch gave no extra reduction on either of the steeper slope in 1999. There was a tendency for yields to be higher under CC+SM and in 1999 this difference was significant on the 10° slope.