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To reveal the evolution law of the mechanical failure of the root-soil composite and identify the main control factors and their coupling and mutual feeding relationship, this paper takes the most common naturally growing plants in Yan 'an area as the research object and studies the evolution process of the mechanical deformation and failure of the root-soil composite by applying the methods of in-situ pull-out test, indoor direct shear test of the root-soil composite, numerical simulation, and theoretical analysis. The mechanical characteristics of root-soil interaction were analyzed, and the mechanism of root-soil fixation was explained. The results show that: (1) the root-soil composite's mechanical deformation and failure characteristics have obvious regularity and stages and are affected by plant growth state, root morphology, soil physical and mechanical properties, and other factors. (2) There are obvious evolutionary stages in the deformation and failure process of the root-soil composite, that is, the coordinated deformation stage of the root-soil, the stress redistribution stage, the secondary root break stage, the main root break stage and the complete failure stage, which correspond to the linear deformation section, the acceleration section, the shock rise section, the steep fall and the residual deformation of the F-S curve (Force-displacement curve)obtained by the in-situ pull out test. (3) In the in-situ pull-out test, the final failure body of the root-soil composite was inverted cone shape. The root fracture interface was basically near the boundary of the final inverted cone failure body, in which the stress state of the root system was directly affected by the stress-strain state of the microelement and the characteristics of the root material. (4) The plant roots showed obvious oblique deformation and axial tensile stress with the soil shear dislocation on the fracture surface, which verified the rationality of the oblique root hypothesis based on the transformation of shear stress to tensile stress.

期刊论文 2025-03-07 DOI: 10.1038/s41598-025-92179-2 ISSN: 2045-2322

Malawi's export earnings are dominated by tobacco, accounting for over 60% of export earnings. The demand for an alternative export commodity, pigeon pea, has been rising over the past decade, especially from India. In addition to their export potential, pigeon pea is an effective cover crop to protect soil heath and productivity in the dry season. They are mostly grown in southern region on very small farms, however, there are opportunities for expansion into central region given the existence of larger farms and agroecological suitability for the crop. Currently, social norms in the central region constrain this expansion. Livestock, and goats in particular, are left to roam free in the dry season by over two-thirds of farmers, relative to only one-third in the south. This leads to significant damage to pigeon pea crops and discourages farmers from growing them and taking advantage of the increased export demand. Much land is left bare and the few farmers that do grow crops during the dry season are forced to put up fences. This study assesses ex-ante implications, especially on agroecological transformation and economic growth, of shifting local governance arrangements among farmers around keeping livestock towards controlled systems. These externalities have been understudied in the development programming, yet their impacts are substantial, especially in lower-income countries. The policy solution under study is for the local government and non-state actors to support local governance arrangements through indirect payments to agroecosystem services. These can include information campaigns on benefits of controlled livestock systems, training and subsidizing modern goat house construction and feed preservation, and contract farming and product certification for adhering to acceptable community norms. Medium-term policy interventions include varietal development of adaptable short duration pigeon pea, initiating a review of the appropriate laws, and instituting more studies to understand these community norms.

期刊论文 2024-06-01 DOI: 10.1177/00307270241247326 ISSN: 0030-7270

The village de Encantadas (VEIM) has been suffering from a situation of beach erosion. The problem is a result of the confluence of physical and anthropic phenomena; it is a present condition inherited from the increase in the incidence and intensity of physical and human variables in recent periods. Cumulatively, the sedimentary stock deficit has resulted in soil loss towards the interior of the village, causing damage such as the loss of circulation, mobility, and transit space, as well as the deterioration of residential and, mainly, commercial buildings. The impacts suffered have mobilized organized social groups from the local community, and based on their request, a technical visit was carried out followed by conversations and guidance. A report of this experience is presented, aiming to subsidize further technical referrals regarding the identified problems.

期刊论文 2024-01-01 DOI: 10.53766/RGV ISSN: 1012-1617
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