Effects of film mulching on maize growth and soil water, fertilizer and heat under fertigation of drip irrigation

Irrigation water shortage and climate variability constrain agricultural production, especially in arid and semiarid regions. The fertigation technology of drip irrigation under film mulching has been applied in the West Liaohe River basin, China. However, few studies have focused on quantitative effects of filming for drip fertigation in this area. To systematically reveal the regulation effect of filming from the changes in maize growth and soil water, fertilizer and heat, field experiments were carried out by applying film drip irrigation and film-free drip irrigation at two basic soil fertility levels in 2014 and 2015 in Tongliao, Inner Mongolia. In this study, soil temperature sensor, TDR moisture monitor, plant photosynthetic instrument and sample chemical test were used to obtain the data, then count and compare the differences of these data for film mulching and bare land. The results showed that film drip irrigation increased the leaf area index and shortened the time of population canopy development in the early and rapid growth periods of maize compared with film-free drip irrigation. Under the fertigation technology of drip irrigation, filming could increase the emergence rate, the effective plant percentage and the NPK accumulation in grains, stems and leaves by 4.9%-5.2%, 5.7%-6.3% and 3.9%-19.8% respectively. Filming could increase the yield and the water use efficiency by 10.8%-14.2% and 17%-18.4% respectively. Moreover, it could improve the photosynthetic capacity and partial factor productivity (PFP) at the panicle leaf. The filming effect could be increased based on good soil fundamental fertility. Within 75 days after sowing, filming increased the soil water storage at the 1 m soil layer by 3.9%-15.7%. After the canopy was fully developed, soil water storage was close to or less than that of bare land. Under the fertigation technology of drip irrigation, filming could reduce the difference of the topsoil's water consumption at equal intervals, reduce the proportion of total water consumption of topsoil in 0-60 cm depth, and weaken the vertical difference of moisture consumption in moist soil. After irrigation between 1 to 7 days, filming reduced the soil water consumption at the drip irrigation tape and the film side by 7.59 mm and 9.44 mm respectively. Filming could increase the available nitrogen at the 0-20 cm soil layer by 2.13-12.0 mg/kg in the growth process, increase the nitrogen accumulation in grains, stems and leaves. Filming could increase the nitrogen uptake of maize at the 20-60 cm soil layer. The residual available nitrogen and available phosphorus at the 20-100 cm soil layer after harvest were not significantly affected or reduced by film mulching. The soil temperature decreased sharply after irrigation and effective rainfall, and recovered subsequently. The soil heat showed alternating cycle fluctuation with water supply and consumption changes. Filming significantly increased the soil temperature in the early and rapid growth periods. Because of film mulching, the 5 cm soil layer obtained more than 44.92℃ daily average soil accumulated temperature within 75 days after sowing, which was significantly reflected in water accumulation and heat loss (after well irrigation and rainfall) of the soil to the soil temperature recovery period. Filming could stabilize the soil temperature amplitude and obtain more soil accumulated temperature when the soil was cold. The research results can provide scientific basis and decision-making reference for the fertigation technology of drip irrigation under plastic film mulching in the West Liaohe Plain. © 2019, Editorial Department of the Transactions of the Chinese Society of Agricultural Engineering. All right reserved.