新疆棉田地膜残留对棉花产量及土壤理化性质的影响

为了探讨地膜残留对棉花产量的影响,该文在全面调查新疆北疆短绒棉主栽区地膜残留状况的基础上,根据地膜残留趋势,人工设置地膜残留密度梯度（0、250、500、1 000、1 500、2 000 kg/hm2）,选择新陆早33号（发达根系）和新陆早13号（不发达根系）2个棉花主栽品种,研究了地膜残留对棉花产量性状和土壤理化性质的影响。结果表明,随着地膜残留密度的升高,2个品种产量和成苗率均呈下降趋势,新陆早13号减产趋势更加明显,早熟度明显提前。如果按照现有的地膜残留趋势,则覆膜68 a左右,即现在往后38 a,残膜密度将达到1 000 kg/hm2,新陆早33号和新陆早13号产量分别下降18.1%、13.5%,成苗率分别下降8.4%、16.5%,早熟度分别上升17.0%、26.7%。当残膜密度为2 000 kg/hm2（覆膜141 a左右）时,新陆早33号和新陆早13号产量分别下降38.3%、45.2%,成苗率分别下降13.0%、21.1%,早熟度分别上升32.2%、27.7%;生物量、根冠比和根系表面积等生长指标都与没有残膜下生长的棉株存在显著差异。地膜残留可导致土壤理化性质恶化,水分分布不均,土壤营养下降。其中在残膜密度为2 000 kg/hm2时,碱解氮、速效磷分别下降55.0%、60.3%。研究表明新疆地膜残留对棉花产量和土地产生明显影响,如不及时采取措施,将严重危害棉花可持续发展与土地的可持续利用,必须引起足够重视。同时发现,应用、培育发达根系的棉花品种可以一定程度上缓解地膜残留对产量的不利影响。

Effects of plastic film residue on cotton yield and soil physical and chemical properties in Xinjiang

Abstract: Background: Xinjiang is currently one of China's three largest cotton-planting regions. Cotton plantations account for more than half of the total agricultural area in Xinjiang. All cotton plantations in Xinjiang involve film mulching. However, this leaves behind plastic film residue, which has become a very serious problem. The average residual percentage is 24%, allowing plastic film residue to seriously harm soil quality and cotton yield. At present, because cotton yield has been improved, little attention has been paid to the hazards of plastic film residue. Purpose: The paper analyzed the effects of plastic film residue accumulation on soil quality and cotton yield by setting a density gradient. The paper studied the trends in and reasons for yield variation. Differences between cotton varieties with different root depths were compared. Method: On the basis of the complete survey of plastic film residue in the production area of short-staple cotton in northern Xinjiang, 6 density plastic film residue gradients were vetted based on the number of continuous years of film mulching: 0 (0 years), 250 kg/hm2 (13 years), 500 kg/hm2 (31 years), 1000 kg/hm2 (68 years), 1500 kg/hm2 (104 years), and 2000 kg/hm2 (141 years). The weight ratio of plastic film residues of 0-25, 25-100, and 100-200 cm2 was 1:1:1, and the films were mixed into the soil at a uniform depth of 0-40 cm. Cotton varieties included "Xinluzao 33" (deep root system) and "Xinluzao 13" (shallow root system). The area of each plot was 10 m2 and each gradient was evaluated three times. Yield-related traits and the physiochemical characteristics of the soil were studied. Conclusion: The density of plastic film residue can reach 1000 kg/hm2 after 68 years of continuous film mulching, and the cotton yield of "Xinluzao 33" and "Xinluzao 13" was found to decrease by 18.1% and 13.5%, respectively. The stand establishment rates decreased by 8.4% and 16.5%, respectively, and the degrees of precocity increased by 17.0% and 26.7%, respectively. The density of plastic film residue was found to reach 2000 kg/hm2 after 141 years of continuous film mulching, and the yields of the two varieties decreased by 38.3% and 45.2%. Stand establishment decreased by 13.0% and 21.1%, and degrees of precocity increased by 32.2% and 27.7%. The yield of "Xinluzao 33" decreased significantly when film density was 500 kg/hm2. The yield of "Xinluzao 13" decreased significantly when film density reached 1000 kg/hm2 and decreased again at 2000 kg/hm2. Biomass, root/shoot ratio, and root surface area were significantly different from the control group. High concentrations of plastic film residue caused soil quality to deteriorate and caused uneven distribution of soil moisture. When the density of soil plastic film residue exceeded 1000 kg/hm2, the infiltration of soil moisture was hindered. Soil moisture levels decreased significantly at depths of 30-40 cm. Plastic film residue was found to cause depletion of soil nutrients. When the density of soil plastic film residue reached 2000 kg/hm2, pH increased by 10.1%, and organic matter, alkaline hydrolysis of N, available P, and available K decreased by 16.7%, 55.0%, 60.3%, and 17.9%, respectively. Significance: It is the first time that we studied the effects of plastic film residue accumulation on soil quality and cotton yield by setting density plastic film residue gradients, and made clear the damage degree of film residue. Without timely measures, it will seriously endanger the sustainable development of cotton and the sustainable use of land. We found applying and cultivating deep root system cotton could mitigate the hazards of residual film. This study provided theoretical support for the reasonable preventive measures of government and cotton growers.