Aiming at reducing agricultural pollution caused by plastic film, the study compared with new plastic film mulching and bare field, to investigating the effects of re-used plastic film mulching on soil temperatures, seed emergence and all seedlings period were studied in Hetao area, China. The results showed that, (1) compared with bare field, the soil temperature of re-used film mulching increased 1.3~4.0 °C and 0.7~1.8 °C separately in the highest and lowest temperature stage. The soil average temperature of upper soil layer (0~20 cm) increased 1.7~2.1°C, and 1.3~2.0 °C lower than new film mulching. (2) Compared with bare field, Daily maximum and minimum temperatures of re-used film mulching were postponed about 1 hour, similar as new film mulching. (3) During emergence stage (7 days after sowing), accumulated temperature of re-used film mulching was 21.6°Cand 23.8 °C higher than that of bare field in depth of 5 cm and 10 cm. Compared with new film mulching, it was 12.4 °Cand 10.0 °C lower in depth of 5 cm and 10 cm. (4) Mulching with re-used film could effectively shorten seed germination for 1-2 days and shorten all seedlings period for 2-3 days compared with bare field, and no difference with new film mulching.

In this paper the effects of two types of tillage (conventional tillage-CT and zero tillage-ZT) with three different soil fertilization patterns(chemical fertilizer, chemical-organic fertilizer and organic fertilizer) on soil rapidly available nitrogen, rapidly available phosphorus, rapidly available kalium and soil respiration flux in ridge cultivation maize fields were studied. The results indicate that in 2005 and 2006, soil rapidly available nitrogen of two tillage type in different fertilization treatments were organic fertilizer (OF) > chemical-organic fertilizer (OCF) > no fertilizer (CK) > chemical fertilizer(CF); Except For OF, the decreasing of soil available nitrogen contents of each fertilization treatments for ZT were more than those of CT. Rapidly available phosphorus for ZT were OCF >OF > CF >CK, and for CT were OCF > CK >OF> CF; rapidly available kalium for ZT were OCF >OF > CK > CF. soil respiration for different of fertilization patterns for ZT were OCF >OF > CK > CF. In ZT, soil available N and P had close relation with soil respiration flux, especially in OCF treatment. While in CT, soil available N had close relation with soil respiration flux.

Aiming at reducing agricultural pollution caused by plastic film and increasing soil moisture and water use efficiency (WUE), the field experiments were conducted to investigate the effects of re-used plastic film mulching on soil moisture, sunflower’s yield and water use efficiency by compared with new plastic film mulching and bare field in Hetao area, China. The results showed that, soil water of re-used film mulching increased at different degree. Compared with bare field and new film mulching, soi1 moisture of re-used film were higher significantly 1.5 percentage points in 0-100 cm, and especially 1.9 or 2.6 percentage points in 0-10 cm during sunflower’s growth stage. Soil water of re-used film was more than that of bare field 24.8 mm (in 2010) and 33.0 mm (in 2011) before seeding, and 21.6mm (in 2010) and 24.5mm (in 2011) at harvest when soil water was replenished to same level for each treatment before sowing. Meanwhile, the grain yield of re-used film was higher significantly than that of bare field 11.4% (in 2010) and 16.8% (in 2011), and WUE of re-used film was higher significantly 15.7% (in 2010) and 22.7% (in 2011) respectively, no significant with new film. So it was worth to apply re-used film to agriculture production for improving the soil moisture, enhancing water use efficiency and increasing the yield of sunflower. We suggest that the application of re-used film mulching is a suitable soil management practice for increase water and WUE in Hetao area or other areas with similar conditions.

Aiming at reducing agricultural pollution caused by plastic film, the effects of re-used plastic film mulching on soil moisture, temperatures and soil erosion during fallow period of cropland were studied, the study also investigated plastic film residue and sunflower’s yield, which compared with new plastic film mulching and bare field in Hetao region. The results showed that, compared with bare field, (1) the average soil moisture in 0~100 cm of re-used film mulching increased 2.1%, the water storage capacity in 0~100 cm and 0~20 cm increased 24.8~33.0mm and 14.9~15.5mm separately. (2) The soil average temperature significantly increased 3.1~2.8°C, especially soil temperature in 5 cm and 10 cm increased 1.7~4.6°C and 2.8~4.1°C separately (p < 0.05). (3) The amount of soil erosion significantly reduced by 68.77%. (4) Compared with new plastic film mulching, the residual plastic film of re-used film mulching cropland significantly reduced 50%, and the film use efficiency increased 1 time. (5) In addition, compared with bare field, sunflower yield of re-used film mulching was significantly increased 11.4% in 2010 and 16.8% in 2011 (p < 0.01), and compared to the new film treatment, the yield decreased 3.3% in 2010 and 2.6% in 2011 (p < 0.05). So re-used plastic film mulching can improve the ecological environment of cropland in fallow period, reduce the film pollution and increase grain yield.