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.

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.

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%.

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.

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.

Characteristics of Mulching Plastic Film Residue in Cotton Fields in the Yellow River Delta

In order to get a clear picture of distribution characteristics of mulching plastic film residue in cotton fields in the Yellow River Delta and make scientific pollution prevention and control strategies, an investigation was conducted in Dongying City. Five typical cotton fields were chosen, and then the number, distri- bution density and area of residual film were measured. The results showed that the residual film was 18. 84-53. 53 kg/hm^2 in cotton fields for more than 20 years, and the differences between fields were larger. The residual density was 225-340 thousand per hectare. There were great differences among residual pieces. The proportion of residual pieces over 25 cm^2 was 94. 1%, that between 100 cm^2 and 500 cm^2 was more than 50. 0%, and that bigger than 500 cm^2 was about 21. 0%. In the Yellow River Delta cotton region, large, thin and difficult to recovery were the main characteristics of mulching plastic film residue, and it had the possibility of mi- grating to deep soil. Thus, the ecological risk of mulching plastic film residue was higher. Key words The Yellow River Delta; Cotton field; Residue of mulching plastic film; Distribution characteristic

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.

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。

冬灌制度对膜下滴灌棉田土壤理化性质、酶活性和微生物群落的影响

为明确不同冬灌制度的应用效果,以南疆膜下滴灌棉田为研究对象,选取每年冬灌处理(CK)、不冬灌处理(H1)及隔年冬灌处理(H2)3种冬灌制度,结合高通量测序技术对冬灌后土壤的理化性质、生物学性质以及微生物群落组成进行测定与分析。结果表明:(1)各处理间0~20 cm土层土壤总盐含量无显著差异,与CK相比,H1和H2处理显著降低了脲酶(0.96%~1.35%)和转化酶活性(1.17%)以及微生物量氮含量(4.21%~7.03%),但H2处理显著提高了土壤有机质(14.30%)、全氮(14.29%)、全磷(4.55%)和全钾(7.40%)含量;H1处理显著降低了土壤有机质(6.03%)、全磷(12.5%)和水分(23.08%)含量,提高了微生物量碳氮比(7.37%)。(2)不同处理下细菌群落的丰度和多样性以及真菌群落的丰度无显著差异,但与CK相比,H1和H2处理显著提高了真菌的辛普森指数(4.12%~4.55%)。此外,H1较CK处理提高了细菌放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)和真菌担子菌门(Basidiomycota)的相对丰度,H2较CK处理提高了细菌变形菌门(Proteobacteria)、芽单胞菌门(Gemmatimonadetes)和真菌被孢霉门(Mortierellomycota)的相对丰度。(3)相关性分析结果表明细菌的群落结构主要受微生物量碳含量的影响,真菌的群落结构和多样性分别受转化酶和脲酶活性的影响。在无法保证每年冬灌用水的情况下,隔年冬灌更有利于保障膜下滴灌棉田的土壤耕地质量。

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。

南疆膜下滴灌棉花咸淡水轮灌模式研究

[目的]探究不同咸淡水轮灌方式对南疆膜下滴灌棉田水盐、棉花生长及产量的影响,寻求安全、高效、高产的咸淡水轮灌制度。[方法]以棉花为研究对象,在新疆阿拉尔现代农业综合试验站开展大田试验,试验共设置9个咸淡水轮灌处理,探究不同的咸淡水轮灌处理对土壤水盐、棉花生长及产量的影响。[结果]棉花生育期内,随着灌溉微咸水比例的增大,土壤水盐量呈增加趋势,相同微咸水占比条件下,棉花生育前期连续灌溉淡水有利于降低根区土壤盐分水平。微咸水灌溉占比越大对棉花的生长抑制作用越大,花铃期适量的微咸水灌溉有利于促进棉花的生殖生长,但微咸水灌溉频率过高会显著降低棉花的单铃质量。适宜的咸淡水轮灌方式既要保证棉花生育前期的营养生长也要在花铃期适时适量灌溉微咸水以促进棉花生殖生长。[结论]南疆棉花种植中,灌溉微咸水占比不宜过高,建议在苗期、蕾期及花铃前期减少微咸水灌溉频率,在花铃期适当提高微咸水灌溉频率。本研究中最优的咸淡水轮灌处理为“淡淡咸”处理。

“以肥调水”缓解干旱对无膜滴灌棉花生理特性和产量的影响

【目的】研究“以肥调水”缓解干旱对南疆无膜滴灌棉花生理生长的调控作用,提高水资源限制条件下棉花产量。【方法】以中棉619为供试材料,设置亏缺灌溉(W1:45 mm)和充分灌溉(W2:54 mm)2种灌水定额,低氮(F1:150 kg·hm^(-2))、中氮(F2:225 kg·hm^(-2))和高氮(F3:300 kg·hm^(-2))3个施氮量,分析不同灌水定额和施氮量对棉花生理生长指标和籽棉产量的影响。【结果】灌水定额的增加促进了棉花生长,提高了棉花2年平均叶面积指数(leaf area index,LAI)、叶绿素相对含量(soil and plant analyzer development,SPAD值)和净光合速率(net photosynthetic rate,Pn),降低了棉花超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)、过氧化物酶(peroxidase,POD)活性和丙二醛(malondialdehyde,MDA)含量。随着施氮量的增加,棉花2年平均LAI、SPAD值、抗氧化酶活性和Pn随之增加,MDA含量减少,棉花受水分亏缺的影响减轻。W1处理下施氮量的增加提高了棉花产量,W2处理下随着施氮量的增加棉花产量呈先增后减趋势,在水氮交互作用下,W2F2处理下2年平均产量最高(6821.86 kg·hm^(-2)),其次是W1F3处理(6717.72 kg·hm^(-2))。在优劣解距离法(technique for order preference by similarity to ideal solution,TOPSIS)分析中,W1F3和W2F2处理的综合评分较为接近,分别为0.57和0.56,并且W1F3和W2F2处理下籽棉产量差异不显著。【结论】亏缺灌溉下增加施氮量可有效缓解干旱对棉花生理性状和籽棉产量的不利影响。推荐南疆无膜滴灌棉田45 mm灌水定额(生育期灌水10次)搭配300 kg·hm^(-2)施氮量作为灌溉和施肥策略,以保障在水资源限制条件下的棉花产量。

基于元分析的新疆膜下滴灌棉田精量施氮研究

【目的】明确施氮对棉花产量及其构成因子的影响,并为氮肥的精量施用及棉花高产提供理论借鉴。【方法】以新疆膜下滴灌棉田为研究对象,采用元分析(meta-analysis,meta分析)和通径分析,研究不同施氮量、施氮方案、气候条件等对棉花产量的综合效应及影响机制。【结果】与不施氮相比,施氮能显著提高棉花产量,增产效应为43.38%。施氮量为360~480 kg·hm^(-2)时,对棉花的增产效应最大;施氮量超过此范围,棉花产量不再显著增加,本研究推荐的经济施氮量为360~420 kg·hm^(-2)。基肥20%,追肥80%且按照6%、8%、22%、25%、12%、7%的比例随水滴施6次的施氮方案对棉花的增产效应最大。对于年蒸发量>2000 mm、年降水量<60 mm、年日照时间<2864 h、年有效积温>4000℃、无霜期>200 d的地区,且土壤为砂质土、土壤初始有机碳含量<5.8g·kg^(-1)、初始速效氮含量≤60 mg·kg^(-1)的棉田,施氮的增产效应最明显。通径分析结果表明,施氮通过提高土壤硝态氮含量,从而增加棉花叶面积指数,对棉花产量的提升贡献最显著。【结论】建议新疆植棉区施氮量为360~420 kg·hm^(-2),采用上述优化方案合理施氮,可以实现膜下滴灌棉田的高产并降低环境风险。

不同水氮配施对北疆膜下滴灌棉花生长发育的影响

研究灌水频率、灌溉定额和施氮量对膜下滴灌棉花生长、产量和水分利用效率的影响,探明灌水频率、灌溉定额和施氮量的最优组合模式,为膜下滴灌棉花的水氮管理提供科学合理的灌溉技术依据.试验设置3个灌水频率:7 d(D1),10 d(D2),13 d(D3),2个灌溉定额:4400 m^(3)/hm^(2)(W1),3300 m^(3)/hm^(2)(W2)和2个施氮水平:300 kg/hm^(2)(F1),225 kg/hm^(2)(F2),共12个处理,每个处理3次重复.结果表明:D1的株高较D2,D3分别降低2.90%和7.96%;叶面积指数与灌水频率呈正相关,D1的叶面积指数较D2,D3分别提高1.96%和7.28%;蕾铃生物量和地上部生物量之比随灌水频率的增加而增加;D1的产量较D2和D3分别增加3.84%和11.76%;W1的产量较W2增加5.56%;F1的产量较F2增加13.49%;D1的水分利用效率WUE较D2和D3分别增加2.75%和9.80%;W2的WUE较W1增加22.71%;F1的WUE较F2增加11.37%.说明D1水平避免棉花过度生长,提高棉花群体发展,增强群体光合作用和物质生产能力,确保地上部生物量的生殖生长,并且随着灌溉定额和施氮量的增加,棉花株高、叶面积指数和地上部生物量也显著增加,从而提高棉花产量.此外,高频减水能够保持根层水分的适宜程度,满足棉花水分需求,高氮能够满足棉花生长的需氮量,减少水分蒸发损失,提高水分利用效率.所以,综合考虑棉花产量和水分利用效率,得出灌水频率7 d,灌溉定额3300 m^(3)/hm^(2),施氮量300 kg/hm^(2)为较优管理模式.

长期膜下滴灌棉田土壤盐分演变规律

为探索棉田长期采用覆膜滴灌技术是否存在土壤积盐的问题,2009—2013年对新疆玛纳斯河灌区5块不同膜下滴灌年限盐碱地棉田土壤可溶性总盐和离子进行了连续定点监测.分析并呈现了现行灌溉制度下应用膜下滴灌技术1—16 a盐碱地棉田可溶性总盐和离子时空演变规律及盐分组成变化.结果表明:滴灌4 a内棉田属于盐土,可溶性总盐由最初的20.44 g/kg快速下降至7.98 g/kg,棉花产量及成活率快速增加.滴灌12 a以后,棉田可溶性总盐小于2.57 g/kg,棉田属于非盐化土,棉花成活率基本稳定在84.53%以上,单产超过5100 kg/hm^(2).随着滴灌年限的延长,棉田土壤中的钠吸附比(SAR)和w(Cl-/SO^(2-)_(4))(Cl-与SO^(2-)_(4)质量比的比值)逐年降低,说明现行灌溉制度下土壤碱化度逐年降低,阴、阳离子的组成也逐年发生变化,Cl-的淋洗效果优于SO^(2-)_(4).

滴灌水盐氮调控对棉田水肥盐运移及棉花产量的影响

为明析覆膜滴灌条件下水盐氮调控对土壤水盐养分运移变化、棉花生长指标及产量的影响,通过两年三因素全组合大田试验,设置灌水量三水平(W1:2700 m^(3)·hm^(-2)、W2:3600 m^(3)·hm^(-2)和W3:4500 m^(3)·hm^(-2))、含盐量三水平(S1:3 dS·m^(-1)、S2:6 dS·m^(-1)和S3:9 dS·m^(-1))、施氮量三水平(F1:105 kg·hm^(-2)、F2:210 kg·hm^(-2)和F3:315 kg·hm^(-2)),研究了不同水盐氮组合对土壤水分、盐分、氮素分布及植株生长、产量的影响。结果表明:土壤水分主要聚集在30~40 cm土层,不同土层深度的含水率基本呈先增大后减小的变化趋势;蕾期和花铃期的S3F3W1和S2F3W1比S1F3W1的0~40 cm土层平均含水率增大1.3%~21.8%;同一灌溉量下S1F3组合的平均含水率比S1F2和S1F1增大1.39%~13.83%。土壤盐分生育期内呈现先减少后增加的变化趋势;S1土壤盐分随施氮量的增大而先增大后减小,S2、S3土壤盐分随施氮量的增加而减少。W2、W3处理中,氮素在40~60 cm土层中缓慢积聚;S1处理的氮素含量明显高于S2、S3。土壤水分、盐分、氮素含量交互影响,在适宜的土壤水分、氮素条件下,较低的土壤含盐量,能使植株更好地利用养分,利于植株的生长进而促进产量的形成。为获得较高的经济效益,低、中盐土壤推荐灌溉量为3600 m^(3)·hm^(-2),施氮量为210 kg·hm^(-2);高盐土壤推荐灌溉量为4500 m^(3)·hm^(-2),施氮量为315 kg·hm^(-2)。研究为探索干旱区多年膜下滴灌棉花农田生态系统水盐养分运移机制及水肥高效利用提供科学的理论依据。