Reuse of plastic film by spring wheat after no-tillage maize can reduce water and nitrogen input

Objectives In the irrigated area of Hexi Oasis regions, maize and wheat rotation is common, and plastic film mulching is a standard practice for maize production. After harvest of maize, as high as 70% of the mulched film is still in good condition. This paper studied the effect of remained film on the following wheat production, and the suitable irrigation and nitrogen fertilizer rate, in order to make full use of the production materials and to increase the yield and nitrogen efficiencies of wheat.

Methods A field experiment was conducted in Hexi Oasis irrigation region. In the rotation system, no-tillage and conventional tillage were used in maize cultivation. In the no-tillage maize field, the remained films were kept used in following wheat production (NT), and in the conventional tillage field, the films were cleared away, and meshed and ploughed into soil (CT). For wheat, two irrigation amounts of reducing 20% of irrigation (I1) and conventional 2400 m³/hm² (I2), and three nitrogen rates of reducing 40% nitrogen (135 kg/hm², N1), reducing 20% nitrogen (180 kg/hm², N2) and conventional nitrogen (225 kg/hm², N3) were setup. Since the 20th day after germination, wheat plant samples were collected every 15 days, and the nitrogen contents were determined. The accumulation and distribution of nitrogen in different organs of spring wheat plants were calculated.

Results The nitrogen accumulation in aboveground of spring wheat in the treatments under NT were 10.9%–14.2% higher than those in treatments under CT. The I1N2 treatments under NT achieved the highest nitrogen accumulation in aboveground of spring wheat, which were 4.3%–6.1% higher than that in the I2N3 under CT. Across the two studies years, the amount and rate of nitrogen translocation and the contribution rate from leaf and stem to grain after anthesis were significantly higher in treatments under NT than under CT. Under NT, the treatment of I1N2 achieved the highest increase in the above three indexes. Compared with I1N3 under CT, the nitrogen translocation amount in leaves and stems were increased by 31.9%–45.7% and 54.5%–61.5%, the nitrogen translocation rate increase by 15.5%–16.3% and 20.8%–23.1%, and the nitrogen contribution rate to grain yield by 13.3%–29.0% and 26.4%–36.7%. Therefore, I1N2 treatment under NT obtained greater grain yield and harvest index by 15.2%–22.0% and 7.6%–10.0% than those of I2N3 treatment under CT.

Conclusions In the maize/wheat rotation system, keeping use of the remained films in maize production still performs well in the following wheat production. Furthermore, reducing 20% from the conventional irrigation amount and nitrogen fertilizer input will achieve higher yield and nitrogen use efficiency. Therefore, the technology system should be promoted in Hexi Oasis regions, that means in film mulching field of maize production, the film should be reused for the following wheat production, and combined with 1920 m³/hm² of total irrigation and 180 kg/hm² of total nitrogen input.