地膜覆盖时间对新疆棉田水热及棉花耗水和产量的影响

该文主要研究不同的地膜覆盖时间对棉田水热及棉花产量的影响。设置了6个地膜覆盖时间:40 d(J1)、55 d(J2)、70 d(J3)、85 d(J4)、100 d(J5)和140 d(全生育期覆盖,CK),2016和2017年在阿克苏绿洲典型滴灌棉田进行田间试验,分析不同地膜覆盖时间对土壤温度、土壤水分、耗水量(crop evapotranspiration,ET_c)、产量、水分利用效率(water use efficiency,WUE)的影响。结果表明,不同地膜覆盖时间可影响土壤水热状况。随着地膜覆盖时间延长,0～80 cm土层含水率逐渐增加,ET_c持续降低,WUE呈增加趋势,但超过100 d后对ET_c及WUE无显著影响。J1、J2、J3和J4处理在揭除膜后,土壤含水率迅速降低,土壤深层水快速消耗,进入铃期后处理间差异才逐步开始缩小。地膜覆盖时间小于100 d会显著减少单株成铃数,降低单铃质量,最终造成减产。J1～J5覆盖时间中,J5处理产量(2 a平均为6 800 kg/hm~2)和WUE(2 a平均为11.5 kg/(hm~2·mm))最高(P0.05),且J5与CK差异不显著(P0.05),可见,地膜覆盖100 d较适宜。该研究结果可为绿洲棉区合理地使用地膜提供科学依据,也为残膜回收及降解地膜的安全应用提供理论支持。     

降解地膜对南疆棉田土壤水热及棉花产量的影响

为探讨降解地膜对南疆棉田土壤水热及棉花产量的影响,选取3种氧化-生物双降解地膜[天壮1号(T-1)、天壮2号(T-2)、天壮3号(T-3)]及一种新型生物降解地膜(HS),以PE普通地膜为对照,通过测定棉田降解地膜的降解情况及土壤水热,计算其棉田耗水及土壤生长度日,筛选适宜南疆棉田生产的降解地膜。结果表明:在棉花进入吐絮期时,T-3和HS的降解率达88.6%和58.7%,而T-1和T-2仅为15.9%和13.4%。不同降解地膜对棉田的水热状况也存在一定影响,对于生育期总耗水量而言,T-3和PE的耗水量较大,为688.6 mm和690.7 mm,但T-3的耗水模数明显高于PE处理。在土壤生长度日上,4种降解地膜在棉花全生育期土壤生长度日均低于PE地膜,其中T-3和HS的土壤生长度日比PE地膜低了294.3℃·d和222.8℃·d。在棉花产量和水分利用效率上,T-1比PE高6.2%和7.2%,HS明显低于PE地膜,但T-3和PE地膜差异不大。综上,T-1和T-2增温保墒效果好,产量较高,但降解效果差。T-3降解速度较好,增温保墒的性能低于PE地膜,但能够满足作物对温度和水分的需求,使棉花产量和水分利用效率接近PE地膜。因此,在南疆棉田降解地膜T-3替代PE地膜应用于棉花生产具有一定的可行性。     

地膜残留对连作棉田土壤氮素、根系形态及产量形成的影响

【目的】为探讨土壤中的残膜含量对棉花根区环境及生长发育的影响。【方法】在大田条件下,以新陆中47号为供试材料,设置了0(CK)、225、450、675和900 kg·hm~(-2)共5个残膜量处理,于2013-2014开展2年小区模拟试验,研究了棉田土壤氮素、根系形态、产量性状随土壤中残膜含量的变化规律。【结果】随着残膜量的增大产量均呈下降趋势,450、675、900 kg·hm~(-2)残膜量处理的产量均显著(P0.05)低于0 kg·hm~(-2)(CK),其中900 kg·hm~(-2)处理的产量降低了22.2%。残膜阻碍根系生长,根长、根直径、根表面积、根体积、根尖数均随残膜量的增加而下降,其中,900 kg·hm~(-2)处理较0 kg·hm~(-2)(CK)分别下降了33.7%,24.3%,19.72%,66.4%和35.3%;0 kg·hm~(-2)与225、450、675、900 kg·hm~(-2)残膜量处理在花期和铃期均具有显著性差异(P0.05)。随着残膜量的增加土壤中的铵态氮和硝态氮呈增加趋势,与0 kg·hm~(-2)(CK)相比,900 kg·hm~(-2)处理在铃期铵态氮增加了36.6%、硝态氮增加了40.1%。【结论】残膜降低氮素利用率,阻碍了根系生长,不利于棉花产量的提高。     

Temporal and Spatial Dynamics of Soil Salinity after Different Durations of Plastic Film-based Mulching in a Drip-irrigated Cotton (Gossypium hirsutum L.) Field in Southern Xinjiang,China

[Objective] Plastic film-based mulching is widely used to improve water harvesting and crop productivity in semiarid areas. It is also extensively used for cotton (Gossypium hirsutum L.) production in inland northwestern China, especially in temperature-and rainfall-limited areas. However, it is unclear whether the technology can sustainably maintain the soil water level and salt balance. The primary objectives of this study were as follows: (i) to determine whether different durations of plastic film-based mulching influenced temporal and spatial variations in soil salinity in drip-irrigated cotton fields; and (ii) to determine the optimum duration for plastic film-based mulching. [Method] We imposed six treatments, plastic film-based mulching continuously for 40, 55, 70, 85, and 100 d, as well as a control (CK) for the whole growth period, in drip-irrigated cotton fields in the oasis of southern Xinjiang. [Result] The mean soil water content in the 0–80-cm layers increased as the plastic film-based mulching duration increased. Compared with CK, the soil water content decreased from 14.5% to 7.5% from 40 d to 85 d, and the soil water content of the 100-d film mulching treatment was 4.4% greater than that of the CK. The average soil salt content increased as the plastic film-based mulching duration decreased, and there was a greater influence on the 0–40-cm soil layer than on the 60–80-cm soil layer. The longer the film mulching duration, the greater the salt suppression effect. However, after a plastic film-based mulching duration of more than 100 d, the moisture preservation and salt suppression began to decline. [Conclusion] The 85-d to 100-d period in which salt suppression was associated with plastic film-based mulching approximately covers the whole cotton growth period. These results provide a theoretical basis for the control of soil salinization and for maintaining high yields in the cotton fields of Xinjiang.     

Effect of Drip Irrigation under Film on Soil Water and Salt Movement in a Residual Film Cotton Field

[Objective] This study explores the effect of mulching film residue on the spatial and temporal distribution of soil water and salt in a cotton field under drip irrigation. [Method] Three treatments of 0 kg·hm^-2, 225 kg·hm^-2 and 450 kg·hm^-2 residual mulching film were applied. Soil salt content was measured and the difference between the mulching treatments was analyzed using a soil drilling method to delaminate 0–40 cm soil before cotton sowing, after harvesting and on days 1, 3 and 5 after watering during the blooming period. [Result] The results showed that residual mulching film reduced soil moisture uniformity in the drip irrigated cotton field. An uneven distribution of salt in different soil layers was also observed after irrigation. The soil salinity of the 0 kg·hm^-2 residual film treatment decreased in each soil layer over time, while the soil salinity of the 225 kg·hm^-2 and 450 kg·hm^-2 treatments decreased 1 and 3 days after irrigation, but then increased 5 days after irrigation (non-significant difference). With respect to distribution of soil salinity following irrigation, uniformity in the 0 kg·hm^-2 residual film treatment was best, followed by the 450 kg·^hm-2 treatment and the 225 kg·hm^-2 treatment. The effect of residual mulching film on soil salinity balance before and after sowing of cotton was as follows: 250 kg·hm^-2 > 450 kg·hm^-2 > 0 kg·hm^-2. As the depth of the residual film increased, the enrichment of soil salts in the topsoil was more likely to occur. [Conclusion] It can be concluded that residual mulching film hinders the downward migration of soil salinity. Under conditions of elevated residual mulching film, the soil salinity migration is disrupted to the degree that soil salt enrichment occurs at the soil surface.