Effects of different film residue and irrigation quota on nutrient and water use efficiency of cotton under drip irrigation

Objectives Plastic film residue has been concerned in water resources shortage area, as it restricts cotton growth and reduces water and fertilizer usage efficiencies. Investigation of the relationship between quantity of film residue and irrigation quota would provide theoretical support for the risk threshold assessment of plastic film residue and sustainable cotton production in the area.

Methods A typical cotton field using drip irrigation under plastic films was chosen for the field experiment in Xinjiang. Film residue of 0, 225 and 450 kg/hm² (denoted as T1, T2 and T3, respectively) and irrigation quotas of 3450 m³/hm², 4650 m³/hm² and 5850 m³/hm² (denoted as W1, W2 and W3) were setup in the experiment. The biomass, nutrient uptake and water efficiency of cotton were investigated.

Results 1) The evapotranspiration of cotton field was significantly affected by irrigation quota, film residue level and their interactions. Biomass, water use efficiency (WUE) and nutrient uptake of cotton were affected by single factor more obviously, either plastic film residue or irrigation condition. 2) Higher film residue led to decreased WUE and less biomass accumulation and nutrient uptake of cotton, and lower yield consequently. The nutrient uptake of individual organ and the whole plant was obviously reduced, and the utilization efficiency of N and P increased gradually. 3) Increasing irrigation quota in between W1 and W2 increased the evapotranspiration of cotton field significantly. The biomass, seed cotton yield and nutrient uptake of cotton were increased in the same time. But when the irrigation quota is increased from W2 to W3, all the above indicators are gradually reduced. 4) With the amount of residue film in the range of 0–450 kg/hm², cotton yield was reduced by 9.6%–13.1%. With the increase of irrigation quota, the yield was increased by 10.1%–13.4%. But water consumption was increased by 6.8%–29.2%. The results showed that the increase of irrigation quota in a cotton field with residue plastic film certainly could slow down the decrease effect to biomass, seed cotton yield and WUE of crops, but it would significantly increase the water consumption.

Conclusions Properly increasing the amount of irrigation can slow down the negative effect of the residue film pollution, but the response of the irrigation to the residue film is based on increasing the water consumption on cotton field. Therefore, the accumulation of residue film will increase the water consumption of cotton field. Take measures on removing the plastic film residue in cotton field can promote crop growth, increase yield and efficient use of water and fertilizer in arid area of Xinjiang.