The Effects Of Nitrogen Application Methods And Mulching Types On Soil Temperature And Crop Water And Nitrogen Use Efficiency

The Hetao Irrigation District in Inner Mongolia is an important food production and security base in China.Broadcast fertilizer and white plastic film cover planting are the main agricultural production methods in the region.However,the white plastic mulching film is liable to produce agricultural film residue and local temperature is too high,and conventional broadcast fertilizer is easy to volatilize,resulting in less efficient use of nitrogen fertilizer.This study mainly focuses on the selection of plastic film types and the applicability of nitrogen fertilizer application methods in order to increase the efficient use of water and fertilizer in farmland and reduce the “white pollution” of farmland,thus providing a theoretical basis for high-yield crop production and prevention and control of agricultural non-point source pollution.For this purpose,through two years of field trials,white and black degradable membranes,plastic mulches were set up,as well as fertilization methods such as broadcast fertilizer,hole fertilizer and furrow fertilizer application.To study the effects of different mulching types and nitrogen application methods on soil temperature at different depths,and to explore the effects of different mulching types and nitrogen application methods on crop water and nitrogen use efficiency and yield,and based on RAGA-PPC,an evaluation model of mulching type and nitrogen application method was constructed.The key indicators of farmland development were evaluated,and the types of coating and fertilization suitable for the region were selected.It provides technical support for the efficient,high-yield and sustainable development of agriculture in the region.The main results are as follows:(1)Black degradable films have a greater rate and degree of degradation than white degradable films.The biomechanical properties of degradable membrane were best between different degradation rates of plastic film,and the mechanical properties of white plastic film between different color plastic film were better than those of black plastic film.The black mulch has low light transmittance,and the weed control efficiency and fresh weight control efficiency are all over 80%.(2)The surface temperature of the black film was greater than that of the white film.The soil filming temperature was greater than that of the black film.The black film could effectively reduce the soil temperature in the 0-15 cm soil layer,which was 1.1°C lower than the white plastic film.The average ground temperature of the white and black degradable membranes was 0.4°C and 1.6°C higher than that of the damaged zone.In the 0-15 cm soil layer,the average temperature difference reached 1.05°C with a white fast and slow degradable film covering,and the black degradative film covered 0.59°C.The ground temperature under different nitrogen application methods is mainly different after top dressing.The deep-growing plantation on both sides was vigorous and the canopy density in the field was high,which effectively reduced the solar radiation.The temperature in the 0-15 cm soil layer was lower than that on the unilateral deep planting and broadcast fertilizer.(3)The coating treatment mainly affects the change of moisture content in 0-40 cm soil layer,and the water-retaining effect of degradable membranes during the slow growth period is similar to that of ordinary membranes.The amount of nitrate nitrogen covered by the biodegradable membrane is lower than the ordinary membrane,and there was no significant difference in the average content of nitrate nitrogen in the 0-40 cm soil layer between ordinary membrane treatment and the degradable membrane.The average content of nitrate in white mulch is greater than that in black mulch.There was no significant difference in moisture content of each fertilization treatment in 0-20 cm soil layers before top dressing;After top-dressing,the deeper treatment with better growth will reduce the moisture content in the 0-20 cm soil layer because the crop evapotranspiration becomes larger;The nitrate nitrogen applied in the spreading process is mainly concentrated in the 0-20 cm soil layer,and the nitrate nitrogen mainly distributed in the 0-40 cm soil layer under the hole fertilizer and furrow application.The release of nitrogen was most rapid under the hole fertilizer,and the application of bilateral hole fertilizer was the best.(4)The results showed that the yield and water and nitrogen use efficiency under different degradation rate degradation membranes were as follows: slow> medium speed > rapid.Black mulch cover yield and water and nitrogen use efficiency higher than white mulching.The yield and water and nitrogen use efficiency under the different nitrogen application modes were as follows: double deep application> deep application> single application.Bilateral deep application of nitrogen fertilizer partial productivity and nitrogen fertilizer agronomic efficiency is greater than unilateral deep.(5)Based on the RAGA-PPC model,an evaluation system based on film characteristics,crop growth,yield,and water and nitrogen use efficiency was established to evaluate the plastic film.The results showed that the coverage of black mulch film was better than that of white mulch film.The coverage of the biodegradable film with different degradation rates was in the order of slow speed> medium speed> fast,and the black degradable film had similar slow covering effect to the black common mulch film.The evaluation system of different nitrogen application methods is mainly based on crop growth,yield,and water and nitrogen use efficiency.The results showed that the yield and water and nitrogen use efficiency were higher in both bilateral and bilateral ditch applications,and the best in bilateral points.