Effects of film overlying soil technology on soil heat balance for mechanized vegetable planting: Experimental study and numerical modelling

The applicability of the film-mulching technologies for mechanized vegetable development is limited in hot-arid regions. Rising film temperatures and heat waves in the gap air have markedly raised the dehydration risk of transplanted seedings. Identifying the suitable planting patterns and ridge shapes is essential for crop growth. Therefore, a novel concept of film overlying soil (FOS) technology was proposed. Detailed investigations confirmed the superior performance of the black film scheme with simultaneously soil cover at planting rows. The three-dimensional transient model was developed based on the theoretical analysis and numerical simulation. The periodic dynamic variation of the ridge intercepted radiation was analyzed. The model prediction accuracy was verified by field trials, and the index of agreement ranges from 93.55 % to 98.28 %. The twelve different mulching configurations were constructed to evaluate the impacts of the overlying soil layer on the ridge thermal regime. The results indicate that the FOS technology affects the temperature distribution at different soil depths by balancing the heat transfer between the upper and lower soil layers of the film. It is favorable to restrict the planting row spacing to 300 ∼ 500 mm for the ridge top width of 600 mm. Moreover, the results demonstrate that the soil cover ratio of 0.58 is a reasonable compromise for assumed cases. It is appropriate to covering 2 ∼ 2.5 cm thick soil layer on the planting rows for the general ridging cultivation. The FOS technology provides an effective alternative to improve the soil thermal environment and guarantees the survival rate of transplanting seedling.