Soil Hydrothermal Characteristics At Different Film Mulching Degrees And Research On Spring Maize Responses To Supplementary Irrigation On The Loess Tableland

By overlaying precipitation over a planting area with that over covering area, film mulching cultivation mode is able to achieve the space deployment of precipitation resources and solve the contradiction between soil drought and precipitation resources waste, which is of important significance for the development of agriculture in water-deficient areas. In order to optimize film mulching cultivation pattern and understand the mechanisms of increasing crop production, the soil hydrothermal statuses responsive to different degrees of film mulching coverage(30%, 50%, 70%, 85%, 100% and CK(no film mulching)) were compared under the condition of no-crop dry farmland furrows on the Loess Tableland. Meanwhile, the effects of different irrigation quantities on maize yield and water use efficiency under the condition of ridge film mulching were studied. The main conclusions are as follows:1. In consideration of soil hydrothermal status under film mulching cultivation and economic benefits in farmland, the 85% film coverage was found to be the best.(1) The water conservation effects(Y, the increment of soil water storage from April to September) correlated with film coverage(X). The fitted equation was Y = 1.65 X + 42.60, with a correlation coefficient of R= 0.98**. The depth of rainfall infiltration under the film mulching condition was 3 m below the soil surface.(2) Soil temperature increased with the increment of film coverage, which helps crop emergence in low temperature season. Soil temperature for the 85% mulching was almost the same as the whole-film mulching. As film mulching degree increased from 30% to 85%, the soil surface temperature peaked earlier, with a higher peak value.2. Under the condition of furrow with the 85% film covering, the yield of spring maize showed an increasing trend with the increasing amount of irrigation. There were significant differences between irrigation treatments and CK(p < 0.05). The maximum yield occurred under a total of 120 mm irrigation during the test, having significant difference in comparison with other irrigation treatments. The water use efficiency was increased by 17.0% as compared to CK.(1) After the first irrigation, the quality of dry matter gradually increased with the increasing irrigation, and the results for the irrigation treatments of 40, 50 and 60 mm were significantly higher than CK(p < 0.05). Even if the irrigation water increased up to 60 mm, it still can promote dry matter accumulation. After the second irrigation(grain filling stage of maize), the biomass generally showed an increasing trend with increasing irrigation. The 60 mm irrigation had the biggest effect on biomass accumulation, which was significantly higher than CK, T1 and T2(p < 0.05). There were little responses of plant height and LAI of spring maize to increasing irrigation.(2) In the jointing stage of maize, the irrigation treatments of 50 and 60 mm could satisfy the water demand of maize and however, the water demand was greater in the grain filling stage. From the jointing to harvest stage, the water storage within 3 m soil layer at CK and 20 mm irrigation treatment had been reducing. The water storage in 50 cm soil layer under irrigation treatments had significant differences.