Effects of Irrigation Water Quality and Drip Tape Arrangement on Soil Salinity,Soil Moisture Distribution,and Cotton Yield (Gossypium hirsutum L.) Under Mulched Drip Irrigation in Xinjiang,China

More and more attention is being focused on saline water utilization in irrigation due to the shortage of fresh water to agriculture in many regions. For purpose of reducing the risks of using of saline water for irrigation, the mechanism of soil moisture and salinity distribution and transport should be well understood for developing optimum management strategies. In this paper, field experiments were carried out at Junggar Basin, China, to study the effects of drip irrigation water quality and drip tape arrangement on distribution of soil salinity and soil moisture. Six treatments were designed, including two drip tape arrangement modes and three irrigation water concentration levels （0.24, 4.68, and 7.42 dS m^-l）. Results showed that, soil moisture content （SMC） directly beneath the drip tape in all treatments kept a relatively high value about 18% before boll opening stage; the SMC in the narrow strip in single tape arrangement （Ms） plot was obviously lower than that in the double tapes arrangement （Md） plot, indicating that less sufficient water was supplied under the same condition of irrigation depth, but there was no significant reduction in yield. Mulching had not significant influence on salt accumulation but the drip tape arrangement, under the same condition of irrigation water depth and quality, compared with Md, Ms reduced salt accumulation in root zone and brought about relatively high cotton yield.

Effects of Soil Water Content on Cotton Root Growth and Distribution Under Mulched Drip Irrigation

The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. Based on the field experiments, three treatments of soil water content were conducted with 90%, 75%θf, and 60%θf （θfis field water capacity）. Cotton roots and root-shoot ratio were studied with digging method, and the soil moisture was observed with TDR （time domain reflector）, and cotton yield was measured. The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments, the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition, while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition, and the root weight was in between under 60%θf For the three water treatments, the cotton root weight decreased with soil depth, and decreased more significantly in deeper soil layer with the soil moisture increasing. And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf. The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film, and little in the soil outside plastic film. The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf. Root-shoot ratio decreased with the soil moisture increasing. The soil water content affected cotton yields, and cotton yield was the highest under 75%θf. The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.

Analysis on Major Agronomic Traits and Yield of Huayu Series of Peanut Cultivars under Mulched Drip Irrigation

[Objective] This study aimed to investigate the appearance of major agronomic traits and yield potential of Huayu series of peanut cultivars under the condition of mulched drip irrigation, so as to provide core parent materials for new peanut cultivar breeding in Xinjiang during Thirteenth Five-Year Plan. [Method] A total of 16 peanut cultivars of Huayu series were studied systematically by field experiment and laboratory analysis. In addition, the main stem height, lateral branch length, pod number per plant, 100-pod weight, 100-kernel weight, pod length, pod width and yield of different peanut cultivar were compared. [Result]Under the condition of mulched drip irrigation, the appearance of major agronomic traits of peanut cultivars in Xinjiang was better than that in Shandong areas. In Xinjiang, the yields of the peanut cultivars were increased in varying degrees. However,there were some differences in appearance of major agronomic traits, as well as yield, among different peanut cultivars. Among all the peanut cultivars, the single-plant productivities of Huayu 22, Huayu 28 and Huayu 50 were higher than those of the other cultivars, and the yields of Huayu 33 and Huayu 50 were higher than those of the other cultivars. Meanwhile, the late two cultivars' comprehensive traits were excellent. [Conclusion] In the high-yielding breeding of peanut in Xinjiang, Huayu 33 and Huayu50 can be used as core parent materials. Under the condition of mulched drip irrigation, their yield potential can be further explored.

Localized salt accumulation: the main reason for cotton root length decrease during advanced growth stages under drip irrigation with mulch film in a saline soil

High salinity in soil can prevent root growth of most plants. To investigate soil salinity dynamics under drip irrigation with mulch film （DI） and its effects on cotton root length, we conducted field experiments in saline soil based on a monolith method using flooding irrigation with mulch film （FI） as a control at the Korla Experimental Station of the Xinjiang Academy of Agricultural Sciences, China in 2009 and 2010. The results showed that the total root length decreased 120 days after sowing （DAS） under DI, and was mainly centered in the 0-30 cm soil layer and at distances of 30-70 cm from the drip-lines. There was almost complete overlap in the area of root length decline and salt accumulation. In the soil depth of 0-30 cm and at distances of 30-70 cm from the drip-lines at 110 to 160 DAS in 2009 and 171 DAS in 2010, the electrical conductivity （EC） in all soil samples was at least 3 mS/cm and in some cases exceeded 5 mS/cm under DI treatment. However, EC barely exceeded 3 mS/cm and no reduction in root length was observed under FI treatment. Correlation analysis of soil EC and root length density indicated that the root length declined when the soil EC exceeded 2.8 mS/cm. The main reason for the decrease of root length in cotton under DI was localized accumulation of salinity.

Effects of soil moisture on cotton root length density and yield under drip irrigation with plastic mulch in Aksu Oasis farmland

Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.

Cotton's Water Demand and Water-Saving Benefits under Drip Irrigation with Plastic Film Mulch

The primary purpose of this research was to give suitable irrigation program according to the growth period and water requirement.A cotton field experiment with mulched drip irrigation was conducted at the National Field Observation and Research Station for Oasis Farmland Ecosystem in Aksu of Xinjiang in 2008.Water balance method was adopted to study the water requirement and water consumption law of cotton under mulched drip irrigation in Tarim Irrigated Area.Statistical analysis of experimental data of irrigation indicates that the relationship between yield of cotton and irrigation presents a quadratic parabola.We fit the model of cotton water production on the basis of field experimental data of cotton.And the analysis on water saving benefit of cotton under mulched drip irrigation was done.Results indicate that water requirements for the irrigated cotton are 543 mm in Tarim Irrigated Area.The water requirements of seedling stage is 252 mm,budding stage is 186 mm,bolling stage is 316 mm and wadding stage is 139 mm.the irrigation amount determines the spatial distribution of soil moisture and water consumption during cotton life cycle.However,water consumption at different growth stages was inconsistent with irrigation.Quantitatively,the water consumed by cotton decreases upon the increase of irrigation amount.From the perspective of water saving,the maximal water use efficiency can reach 3 091 m3/ha.But the highest cotton yield needs 3464 m3/ha irrigation water.In summary,compared to the conventional drip irrigation,a number of benefits in water saving and yield increase were observed when using plastic mulch.At the same amount of irrigation,the cotton yield with plastic mulch was 30.2% higher than conventional approaches,and the efficiency of water utilization increased by30.2%.While at the same yield level,29.3% water was saved by using plastic mulch,and the efficiency increased by 41.5%.

Green High-yield and High-efficiency Cultivation Techniques of Integrated Management of Water and Fertilizer for Maize under Mulch Drip Irrigation

The green high-yield and high-efficiency cultivation techniques of integrated management of water and fertilizer for maize under mulch drip irrigation are described from the aspects of high yield target of maize and its component factor indexes,pre-sowing preparation,sowing,post-sowing management,field management at the seedling stage,integrated management of water and fertilizer for target yield of maize,rational application of micro-fertilizer,comprehensive prevention and control of diseases and pests,timely harvest,etc.,in order to provide a reference for agricultural technicians,maize farmers and maize industry development in northern Xinjiang.

Effect of Different Norms of Under-Mulch-Drip Irrigation on Diurnal Changes of Photosynthesis and Chlorophyll Fluorescence Parameter in High Yield Cotton of Xinjiang

Under-mulch-drip irrigation is an advanced irrigation technique, which combines plastic-film-covered cultivation with drip irrigation. The influence of different norms of under-mulch-drip irrigation on diurnal changes of photosynthetic rates and chlorophyll fluorescence parameters of cotton was studied, in order to understand the physiological mechanisms of water-saving and high-yielding farming in Xinjiang. Results indicated that limited drip irrigation, which supplies 2/3 of 375 m3 ha-1, the widely-used irrigation norm in cotton cultivation in Xinjiang, caused a water deficit in cotton field. Compared with the proper drip irrigation, the leaf photosynthetic rate under limited drip irrigation decreased during 9:00 to 11:00 a. m. , and was significantly suppressed at midday, and then recovered afterwards. Using the chlorophyll fluorescence method, the absorption, transfer and transformation features of solar radiation by cotton leaf were investigated. Under limited drip irrigation, the variable fluorescence (Fv) and primary light transfer efficiency of PSII (Fv/Fm) in cotton leaves were reduced because of the high light intensities and high temperatures at noon, and the decrease in XinluzaoS was greater than that in Xinluzao6. Therefore, it could be concluded that Xinluzao6 has a higher drought-tolerance, and the Fv/Fm ratio could be used as a drought-resistance index for cotton.

Soil particle size distribution and its relationship with soil water and salt under mulched drip irrigation in Xinjiang of China

Soil particle size distribution(PSD),one of the most important soil physical attributes,is of great importance to soil water movement,soil erosion and soil solute migration.In this study,the soil PSD of 563 soil samples from the mulched drip irrigated cotton fields in Xinjiang of China were measured by laser diffraction particle size analyzer.The soil PSD characteristics and its relations with soil water and salt were studied by using the combined methods of textural triangle,fractal and multifractal analysis.The results showed very low clay content(about 1.52%) while really high sand content of the studied soil,and a complex shape of bimodal or unimodal of soil PSD.The results also showed that the two indices,i.e.,standard deviation and the peak value of soil particle relative volumes,were good indicators of soil PSD and thus had good relations with fractal and multifractal characteristics.The correlative analysis further indicated that the mulched drip irrigation had a significant impact on the distribution of the soil salt,while this impact withered for the deeper soil layer.The soil texture feature was found to dominate soil water and salt distribution,especially the surface soil salt content and the deep soil water content.

Response of spatial structure of cotton root to soil-wetting patterns under mulched drip irrigation

The matching relationship between the spatial structure of cotton cluster root systems and soil-wetting patterns under mulched drip irrigation forms the theoretical basis for the technical design of mulched drip irrigation.A 2-year field experiment was conducted,in which different soil-wetting patterns were produced by setting different emitter discharge rates.The envelopes of cotton cluster root length densities were derived using the topological methodology and used to examine the effects of different soil-wetting patterns on the spatial structure of root systems and water uptake capacity within row spaces.The results showed that the root systems in rows of cotton grown under narrower and deeper soil-wetting patterns exhibited a single-peak distribution,while those under wider and shallower soil-wetting patterns exhibited a two-peak distribution.Furthermore,cotton rows grown near mulch edges experienced lower moisture stress,and wider and shallower soil-wetting patterns contributed to greater root growth rates in the vertical direction and resulted in more even potential water uptake capacities.The findings of this study revealed that wider and shallower soil-wetting patterns were more desirable for mulched drip irrigation of cotton and should be considered in the technical design of drip irrigation systems.

Effects of timing and duration under brackish water mulch drip irrigation on cotton yield in northern Xinjiang,China

The brackish water is an important potential water source and has frequently been utilized to drip-irrigate cotton due to the water shortage in the arid region of Xinjiang,northwestern of China.The brackish water is usually saline water with salinity ranging from 1 g/L to 5 g/L,which is widely distributed in this area,so the reasonable use of that brackish water may not only play a vital role in the local agricultural production,but also save plenty of freshwater.However,irrigation with brackish water usually causes the reduction of crop yield and soil salinization which can negatively impact plants through three major components:osmotic,nutritious and toxic stresses.Therefore,a field experiment,with eight different time-series irrigation modes using brackish water(3.5±0.2)g/L and freshwater(<1 g/L),beneath a combined film and drip-irrigation system was carried out to study the changes of soil salt content and cotton yield aiming to search for a balanced method during the 2 cotton growing seasons in 2012 and 2013.The results indicated that the time-series irrigation modes determined the soil salinity and moisture distribution based on observed spatio-temporal distribution of water content and electric conductivity,and soil salinity generally gathered at the depth of 0-10 cm and 60 cm of soil with the increase of irrigation quota.Moreover,the results demonstrated that the yields of cotton which was grown using brackish water and freshwater were better than those only using freshwater and the soil salinity with reasonable irrigation timing was not accumulated obviously.

减氮施炭对温室膜下滴灌黄瓜土壤呼吸和氮素气态损失的影响

为降低温室蔬菜过量施氮的不利影响,明确减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,以不覆膜不施炭(CK)为对照,设置覆膜(M)、覆膜施炭(MB)、覆膜施炭减氮(MBN_(80%))共4个处理,对覆膜条件下减氮施炭处理对黄瓜产量、耗水量、土壤养分动态、土壤呼吸、N_(2)O排放和氨挥发的影响进行探讨。结果表明:与CK相比,M可降低温室膜下滴灌黄瓜全生育期耗水量20.95%,提高水分利用效率41.03%,降低0~20 cm表层土铵态氮48.12%,降低全生育期氨挥发32.35%、N_(2)O排放量14.34%和CO_(2)排放量12.68%(<0.05)。施炭后,与CK相比,MB可降低耗水量28.37%,提高水分利用效率55.60%,降低表层土铵态氮30.0%,提升硝态氮12.37%,有机质56.28%,降低氨挥发36.68%、N_(2)O排放18.64%,但却显著增大了CO_(2)排放4.66%(p<0.05)。同M对比,MB可在M基础上,进一步提升表层土有机质和铵态氮含量,降低氨挥发,但促进了CO_(2)排放。覆膜施炭减氮20%后,与CK相比,MBN_(80%)可增产25.47%,降低耗水量32.43%,提升水分生产率72.67%,降低表层土铵态氮56.33%,增加有机质51.72%,降低氨挥发40.48%、N_(2)O排放20.79%(p<0.05)。CK全生育期全球增温潜势(global warming potential,GWP)和活性氮排放分别为13.57 t·CO_(2)-eq·hm^(-2)和6.54 kg·hm^(-2),M可显著降低GWP(14.15%)和活性氮排放(27.37%);在M基础上施炭,将进一步降低活性氮排放,但导致GWP显著增大;而在MB基础上减氮20%,可同时显著降低GWP和活性氮排放(p<0.05)。与CK相比,MBN80%在通过施炭20 t·hm^(-2),减氮20%条件下,实现增产25.47%,降低耗水量32.43%,增加有机质51.72%,增加收入17.52%,降低活性氮排放35.32%和GWP 2.28%,也可在MB的基础上,进一步实现增产,降低氨挥发,并破解M和MB处理CO_(2)排放增大的问题(p<0.05)。研究揭示了减氮施炭条件下温室膜下滴灌黄瓜土壤呼吸和氮素气态排放特征,为实现温室蔬菜节水增产固碳减排提供理论依据和技术支撑。

滴灌条件下不同覆盖材料对玉米产量效益及土壤水分的影响

为探明不同覆盖材料对滴灌水肥一体化条件下玉米产量和土壤水分分布的影响,以普通PE地膜和裸地为对照,分析全生物降解膜、加厚PE地膜、玉米秸秆等3种材料覆盖下对玉米产量和水分的影响。结果表明,玉米秸秆、加厚PE地膜和生物降解膜覆盖后玉米产量为13114.5~13708.5 kg/hm^(2),较普通PE地膜增产1.4%~6.0%;水分利用效率为24.17~25.11 kg/(mm·hm^(2)),较普通PE地膜提高2.3%~3.8%。产值与效益均高于普通PE地膜,均以玉米秸秆处理最高,分别为38383.8、24283.8元/hm^(2);生物降解膜次之,分别为37674.0、21624.0元/hm^(2);加厚PE地膜排第3,分别为36720.6、21570.6元/hm^(2)。收获后覆盖处理土壤水分均呈典型的“双峰”曲线,上层含水量高于下层,对深层土壤水分影响较大。在降水量低、蒸发量高的沿黄灌区,覆膜的主要作用是减蒸保水,用可生物降解的环保型降解地膜、易回收型的加厚PE地膜或固炭培肥型的秸秆替代普通PE膜可行。

两种覆盖方式下灌水定额对土壤温度变化、棉花产量及水分利用效率的影响

【目的】探究不同覆盖方式和灌水定额对棉花生产的影响。【方法】于2017―2019年在新疆阿拉尔市开展大田试验,其中,2017―2018年膜下滴灌试验以新陆中46号为供试材料,设置24 mm(M1)、30 mm(M2)和36 mm(M3)3个灌水定额;2018―2019年无膜滴灌试验以中棉619为供试材料,设置36 mm(W1)、45 mm(W2)和54 mm(W3)3个灌水定额;分析不同处理对10 cm、20 cm、40 cm土层土壤温度和土壤含水量、籽棉产量以及灌溉水利用效率的影响。【结果】2种模式下棉田10 cm、20 cm和40 cm土层土壤含水量和籽棉产量均随灌水定额的增大呈增加趋势。M2、M3处理的籽棉产量分别较M1处理显著增加8.82%~11.47%和14.24%~18.96%;W2、W3处理的籽棉产量分别较W1处理显著增加15.18%~22.61%和32.53%~46.29%。土壤温度和灌溉水利用效率均随灌水定额的增大呈降低趋势。M2、M3处理的灌溉水利用效率分别较M1处理显著降低10.82%~12.94%和20.70%~23.84%;W2、W3处理的灌溉水利用效率分别较W1处理降低1.91%~7.85%和2.47%~11.65%。2018年灌水定额相同时,M3处理的土壤含水量、0~40 cm土层土壤温度、籽棉产量和灌溉水利用效率均高于W1处理。基于逼近理想解排序法(technique for order preference by similarity to ideal solution, TOPSIS)的综合评价表明,膜下滴灌处理配套30 mm灌水定额,无膜滴灌处理配套54 mm灌水定额可取得较好的效果。【结论】提高灌水定额可以在一定程度上弥补无膜种植模式引起的籽棉产量降低,但会降低灌溉水利用效率。研究结果可为无膜滴灌植棉技术在当地的推广提供参考。

新疆灌区农业节水发展现状与对策建议

水是新疆可持续发展的生命线,也是新疆农业发展的瓶颈。农业是新疆用水大户,占经济社会总用水量的90%以上,南疆农业用水占比更高。新疆节水潜力重点在农业,农业节水是新疆经济社会可持续发展的根本出路。为提高新疆农业水资源利用效率,促进农业高质量发展,本文梳理回顾了新疆灌区农业节水发展历程,分析了农业节水发展现状及存在问题,结合新时期国家对新疆农业发展的新定位、新要求,提出了大力发展适水型现代农业、加大高效节水工程建设、持续推进降盐节水、加强数字化灌区建设、加强农业节水宣传培训、健全农业节水服务体系等对策建议,以期为新疆现代农业可持续发展和保障国家粮棉油安全提供有力支撑。

膜下滴灌微咸水棉花临界氮稀释曲线模型与氮肥用量推荐

为了优化膜下滴灌微咸水条件下棉花生产氮素管理,该研究于2017—2019年在新疆库尔勒市开展3 a定位施氮试验。以新陆中棉花为试验材料,设置施氮水平0(NF0)、150(NF1)、250(NF2)、300(NF3)、350(NF4)、450(NF5)kg/hm^(2),各试验处理灌水量均为487.5 mm,分析施氮量对棉花地上部干物质量、氮素累积吸收量、产量和氮肥利用效率的影响,构建了膜下滴灌微咸水棉花临界氮浓度稀释曲线模型。结果表明:棉花氮素累积吸收量随生育期进程的推进而增大,棉花临界氮浓度与最大地上部干物质量符合幂函数关系。氮肥农学利用率和表观利用率均与施氮量呈二次多项式关系,氮肥生理利用率和偏生产力均与施氮量呈线性关系。NF1、NF2和NF3处理的氮素营养指数均小于1,表明氮素营养供应不足,棉花生长受到氮素限制。NF4和NF5处理的氮素营养指数接近于1,说明棉花氮素营养状况较好,但NF5产量和氮素利用效率较低,NF4获得最高产量和较高的氮素利用效率。因此,南疆膜下滴灌微咸水棉花生育期推荐施氮量为350 kg/hm^(2)。该研究构建的临界氮浓度稀释曲线模型对田间施氮管理具有重要意义。

基于作物水分亏缺指数和盐分淋洗系数的新疆棉田节水控盐优化方法

通过灌溉对作物根区土壤水盐环境进行适时适度的调控是促进新疆绿洲农业可持续健康发展的重要举措,其中最为关键的一环当属灌溉制度尤其是灌水定额的优化。为了提高灌水控盐效率,该研究以新疆沙湾市膜下滴灌盐碱棉田为研究对象,以当地传统灌溉制度为对照,在基于作物水分亏缺指数(plant water deficit index,PWDI)评估并实施智能灌溉的基础上开展了2 a(2021与2022)田间灌水控盐试验,通过设置不同的盐分淋洗系数(2021年:1.0与2.0;2022年:1.0、1.4、1.8、2.2与2.6)探讨灌水定额对土壤水盐运移与棉花生长以及水分吸收利用的影响。结果表明,在固定PWDI阈值(评估值超过阈值时开启灌水)的情况下,在一定范围内随着盐分淋洗系数的增大,灌水定额增加,灌水周期延长,灌水总量增大,更多盐分被被淋洗到根区下部甚至根区以下,从而改善根域水盐环境,减轻水盐胁迫,促进棉花生长并增产,但灌溉水利用效率呈缓慢下降趋势。然而,当盐分淋洗系数(灌水定额)增大到一定程度时,长期优越的根域水盐环境导致棉花徒长,即营养生长旺盛而生殖生长迟滞,灌水周期缩短,灌水总量急剧上升,产量不再增加反而有下降趋势,灌溉水利用效率显著降低。综合考虑盐分淋洗、棉花生长与产量以及水分利用效率,当试验区PWDI阈值取为0.5时建议对应的盐分淋洗系数取为2.2。该研究可为新疆盐碱棉田高效生产以及绿洲农业可持续健康发展提供理论依据与技术支撑。

灌水梯度及覆膜组合模式对滴灌棉田蒸散规律的影响

为研究地膜覆盖与灌水对棉田蒸散量及水热状况的影响,开展测坑和桶栽试验,设置三个灌水水平:3360(W1)、4200(W2)、5040 m^(3)·hm^(-2)(W3);两种地膜覆盖方式:覆膜(P1)和裸土(P2)。结果表明:(1)覆膜能有效降低棉花全生育期总蒸散量,W1、W2、W3灌溉水平下,覆膜处理棉花蒸散量分别降低25.31%、25.39%、25.75%。灌水量与蒸散量呈正相关关系,P1方式下,W3处理比W1、W2处理棉花蒸散量分别提高8.71%、7.50%;P2方式下,W3处理比W1、W2处理棉花蒸散量分别提高8.82%、8.02%。(2)覆膜能改变棉田土壤水热状况,可有效提高土壤温度和土壤含水率,覆膜对土壤水热状况的影响随土壤深度的增加而减弱;土壤温度与灌水量呈负相关关系,土壤含水率与灌水量呈正相关关系。(3)土壤含水率对裸土处理棉花蒸散量的相关系数影响最大,并随着土层深度的增加而降低;土壤温度对棉花蒸散量的相关系数随土层深度增加而升高,P1处理在20 cm土层相关系数最高,P2处理则在25 cm土层最高。探索覆膜滴灌对干旱区农田蒸散过程的影响对理解绿洲水文循环过程具有重要的理论意义,同时也可为干旱区有限水资源合理利用提供科学参考。

不同矿化度水源膜下滴灌对棉花土壤盐分分布及生长的影响

利用微咸水膜下灌溉是缓解干旱区农业灌溉资源短缺的有效途径之一,分析不同矿化度水源膜下滴灌对土壤盐分分布及作物生长的影响对于确定灌溉水源矿化度阈值具有重要意义。开展4 a不同梯度矿化度水源膜下滴灌棉花测坑试验,设置6个处理矿化度分别为1 g/L(CK)、2 g/L(A)、3 g/L(B)、4 g/L(C)、5 g/L(D)和6 g/L(E),分析不同梯度矿化度水源膜下滴灌土壤盐分累积及棉花生长特征,确定微咸水膜下滴灌棉花灌溉矿化度阈值。结果表明:2019-2022年,0~100 cm平均土壤电导率以每年0.920 dS/m、0.995 dS/m、1.196 dS/m和1.188 dS/m的速率呈线性增长的趋势。随着灌溉年限增加,不同梯度微咸水膜下滴灌下土壤电导率呈现增加趋势。5 g/L和6 g/L处理土壤盐分累积最大,分别为38.70%和39.19%;灌水12 h后,宽行表层20~40 cm土壤盐分累积最为明显,土壤电导率为0.30~2.1 dS/m;窄行土壤盐分在40~60 cm土层处出现累积,土壤电导率为1.26~1.93 dS/m。矿化度为3 g/L水源膜下滴灌棉花土壤盐分累积量较小,对棉花叶片光合作用指数影响最小,生长指标和产量达到最大,微咸水膜下滴灌棉花适宜的灌溉水源阈值为3 g/L。

再生水与黄河水轮灌对向日葵生长及土壤环境的影响

为探究河套灌区适宜的再生水灌溉向日葵模式,针对向日葵关键生育阶段(出苗—现蕾期、现蕾—灌浆期、灌浆—蜡熟期)设置T1(HHH)、T2(HZZ)、T3(ZHZ)、T4(ZZH)、T5(ZZZ)共计5组黄河水(H)与再生水(Z)灌溉方式,结合膜下滴灌技术开展连续两年野外大田试验,结果表明,各试验处理黄河水灌溉量服从T5<T2<T4<T3<T1,反之,再生水灌溉量服从T1<T3<T4<T2<T5;再生水与黄河水轮灌对膜内和膜外0~40 cm土壤pH无显著性影响;再生水灌溉水量越高,膜内土壤含盐量变化幅度、土壤及籽粒中典型重金属元素含量越大;T2处理对应轮灌方式相对其他灌溉方式更有利于促进向日葵生长、增加籽粒产量、提高籽粒粗蛋白和粗脂肪含量;然而T3处理对应土壤及籽粒中砷、铅、镉、铬含量相对其他试验处理更低,且相对T1处理节约黄河水量100~120 mm,籽粒产量、生物量、籽粒粗蛋白和粗脂肪含量则分别提高了4.34%~7.19%、6.20%~6.68%、9.25%~20.50%、7.39%~13.37%;短期再生水灌溉不会导致向日葵籽粒和收后0~100 cm土体中的典型重金属元素含量超标。以节水控盐、增产提质为目标,推荐T3处理对应轮灌方式为河套灌区向日葵生育期内适宜的再生水灌溉方式,该研究结果可为内蒙古河套灌区再生水安全高效灌溉向日葵提供理论指导。