Characteristics and economic benefits of water consumption in intercropping fields with one plastic film mulching for 2 years and different irrigation levels

In order to optimize farming practice, plastic film recycling and water use efficiency of intercropping farming systems, a field experiment was conducted on maize-pea intercropping field at Hexi Corridor in Gansu Province. The experiment investigated the effect of three mulching patterns (NT: single plastic mulching for 2 years; CT: no tillage in fall with mulching and tillage in the next spring; CT: traditional mulching and tillage) on crop total water consumption and soil evaporation under high (7 200 m³.hm^-2), intermediate (6 450 m³.hm^-2) and low (5 700 m³.hm^-2) irrigation levels. The results showed that the level of water supply had a significant effect on the soil evaporation. The soil evaporation increased with increasing irrigation level, but there was no significant difference among different mulching patterns under the same irrigation level. There was a significant difference in soil evaporation between maize strip and pea strip during harvest period of pea in all the treatments. Soil evaporation in pea strip was 68.51% and 69.30% higher than in maize strip before and after pea harvest, respectively. In addition, pea strip was an important factor driving water consumption in the intercropping farming system. The maize strip, which occupied some 60% of the farmland, only accounted for 44.47% of soil evaporation. Then the pea strip, which occupied some 40% of the farmland accounted for 55.53% of the total soil evaporation. Moreover, the evaporation in maize-pea intercropping field was mainly occurred after pea harvest, as only 26.98% of the soil evaporation occurred before pea harvest. NT treatment significantly increased the benefits of cubic meter water. The mean of water benefit per cubic meter under different irrigation levels were 7.39% and 31.33% higher for NT than for RT and CT, respectively. In addition, the highest water benefit per cubic meter reached 2.51 Yuan.m^-3, which was observed under NT plus medium irrigation. In conclusion, NT reduced soil evaporation and non-productive water loss common under traditional mulching. Soil evaporation and total water consumption were positive correlated with irrigation level, with the highest water benefit per cubic meter under NT at moderate irrigation.