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.

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%.

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.

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.

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.

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.

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。

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.

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。

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。

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).

改善土壤理化性质和作物出苗率的最佳生物质炭施用量

确定改善土壤理化性质和作物出苗率的最佳生物质炭施用量,可为田间管理提供依据。以新疆盐碱土为研究对象,在生物质炭施用量分别为0、10、50及100t·hm^(-2)条件下,开展了膜下滴灌田间小区试验,对比了生物质炭施用量对土壤容重、温度、有机碳等理化性质和作物出苗率的影响,并进一步分析了作物出苗率与土壤理化性质的关系。结果表明,生物质炭施用量增加显著降低了0~30 cm土层的容重,棉花和甜菜的土壤容重分别降低0~0.32和0.04~0.25 g·cm^(-3)。与不施用处理比较,100 t·hm^(-2)的生物质炭施用量显著增加了棉花和甜菜不同生育期的5 cm深度地温,但10和50 t·hm^(-2)的施用量只显著增加了棉花蕾期和铃期的5 cm深度地温。施用生物质炭增加了棉花和甜菜的土壤有机碳含量,不区分年份和生育期增幅相应为0.98~13.2和0.66~12.1g·kg^(-1);苗期和收获期(不区分年份和作物)增幅分别为1.20~7.43和0.66~13.2 g·kg^(-1),苗期各施用量下有机碳均显著增加,收获期部分施用量下有机碳显著增加。出苗率大致随容重增加而增加,随土壤温度增加先增加后减小,最适宜作物出苗的温度为22~26℃;出苗率随土壤有机碳增加先增加后减小,但高生物质炭施用量导致的土壤有机碳增加过高抑制了作物出苗。当生物质炭施用量为10t·hm^(-2)时,棉花和甜菜的出苗率大于0.7,高于其他3种生物质炭处理,因此推荐10 t·hm^(-2)作为最优生物质炭施用量。

基于HYDRUS-2D模型的膜下滴灌暗管排水棉田土壤盐分变化

为研究膜下滴灌暗管排水条件下棉田土壤盐分变化规律,该研究基于新疆122团盐碱地暗管排水试验,通过膜下滴灌淋洗,监测0~200 cm土层土壤盐分变化,并应用HYDRUS-2D数值模型,模拟分析了暗管排水条件下,盐渍化棉田在2013和2014年生育周期内和秋季返盐阶段土壤盐分变化情况。结果表明:模拟值与实测值之间吻合度较高,模型可用于预测盐碱地土壤层剖面盐分含量变化。模拟结果显示,棉花生育期内滴灌条件下,盐分持续下降;棉花收获后土壤表层开始返盐;2013和2014年棉花吐絮期土壤含盐量与初始含盐量相比,在膜下,0~80 cm土层平均脱盐率分别达到了41.11%和55.56%;膜下及膜间,0~80 cm土层平均脱盐率分别达到了14.05%和17.88%;棉花收获后,土壤表层返盐明显,但与初始含盐量相比仍较低,0~80 cm土体盐分分别平均下降了5.55%和10.15%,0~200 cm土体盐分分别平均下降了2.58%和4.96%,说明暗管控制条件下,使用滴灌淋洗和暗管排盐的模式,土体内的盐分总量呈现降低趋势。研究可为西北内陆干旱区暗管排盐技术和膜下滴灌的推广和应用提供理论支撑和科学指导。

灌溉水温与施氮量对滴灌棉田土壤水热及棉花生长和产量的影响

【目的】探究膜下滴灌棉田土壤水热环境和棉花生长对灌溉水温与施氮量的响应机理,旨在确定北疆滴灌棉花合理的灌溉水温和施氮量。【方法】以新陆早42号棉花为试验材料,设置4个灌溉水温:15℃(T0)、20℃(T1)、25℃(T2)和30℃(T3);3个施氮水平:250 kg·hm^(-2)(F1)、300 kg·hm^(-2)(F2)和350 kg·hm^(-2)(F3),采用双因素完全随机试验设计。分析不同灌溉水温条件下施氮量对棉田土壤水热环境、棉花生长、产量和水氮利用效率的影响。【结果】常规灌溉水温与低氮处理降低土壤温度,抑制棉花生长,单株铃数降低并导致籽棉产量下降。适宜的灌溉水温和施氮量可以改善土壤水热环境,促进棉花生长发育,提高籽棉产量和水氮利用效率。与15℃常规灌溉水温相比,增温灌溉显著提高了土壤温度0.58—3.30℃,土壤储水量降低1.2%—7.2%,土壤呼吸速率显著提高5.7%—28.0%;随灌溉水温升高,棉花株高、叶面积指数及地上部干物质积累量先增高后降低,在灌溉水温为25℃时达最大。随施氮量增加,土壤储水量降低3.3%—6.7%,土壤呼吸速率显著提高3.6%—9.5%,棉花株高增加3.2%—4.9%,叶面积指数显著增加5.8%—11.0%,地上部干物质积累量显著增加1.2%—2.2%,均在施氮量为350 kg·hm^(-2)时达最大。水分利用效率、氮肥偏生产力及籽棉产量随灌溉水温升高均先增加后减少,随施氮量增加分别表现为增加、减少、增加的趋势。通径分析表明,土壤温度对籽棉产量直接作用最大,而施氮量通过促进棉花生长对籽棉产量间接作用最大。籽棉产量与水分利用效率均在T2F2处理达到最大值,分别为6652.3 kg·hm^(-2)、1.17 kg·m^(-3),且T2F2处理的氮肥偏生产力(22.17 kg·kg^(-1))显著大于T2F3处理(18.80 kg·kg^(-1))。【结论】综合考虑灌溉水温与施氮量对土壤温度,土壤呼吸速率,棉花生长、产量及水氮利用效率的影响,推荐北疆棉区适宜灌溉水温为25℃,施氮量为300 kg·hm^(-2)。

微咸地下水浅埋区膜下滴灌定额对棉花产量及水分利用效率的影响

【目的】探明新疆微咸地下水浅埋区膜下滴灌棉花的灌溉定额对棉花产量及水分利用效率的影响。【方法】2022、2023年4—10月开展膜下滴灌棉花灌溉试验,设置300(W1)、375(W2)、450(W3)、525 mm(W4)共4个灌溉定额,研究灌溉定额对田间土壤水盐动态分布、地下水埋深和矿化度及棉花生长、产量、水分利用效率等的影响。【结果】①各处理土壤脱盐率均随滴灌灌溉定额的增大而增大,且W4处理60 cm土层内土壤总脱盐率为29.78%~58.19%;②随着灌溉定额增大,灌水加强了对地下水的补给作用,抬高地下水位,使地下水矿化度由6 g/L降低为4~5 g/L,有利于棉花对地下水的吸收利用。③随着灌溉定额的增大,棉花株高、叶面积指数、干物质累积量及产量均呈先增大后减小的趋势,其中W3处理下棉花生长指标最优,其籽棉理论产量达到7127.66 kg/hm^(2);但是水分利用效率随灌溉定额的增大而减小。【结论】450 mm是较为适宜的灌溉定额,虽然水分利用效率不高,但包括了改善田间生态环境、满足生态耗水量,保证作物正常生长。

基于SHAW模型的北疆地区不同滴灌年限棉田冻融期土壤水热盐动态模拟研究

为探究SHAW(Simultaneous heat and water)模型在北疆地区长期膜下滴灌棉田冻融期土壤水热盐动态模拟的适用性,本研究选用滴灌起始年限为1998年(21 a)的棉田土壤水热盐实测数据对SHAW模型进行率定,以滴灌起始年限为2006年(13 a)、2008年(11 a)、2012年(7 a)和荒地(0 a)的水热盐实测数据进行验证。模型率定结果表明,随土壤深度增加土壤温度的模拟效果越好;土壤水盐的模拟效果先增强后减弱。模拟土壤温度Nash系数(NSE)、均方根误差(RMSE)和R2分别为0.713~0.993、0.209~2.498℃和0.911~0.994;模拟土壤水分NSE和RMSE分别为0.824~0.967和0.009%~0.032%;模拟土壤盐分NSE和RMSE分别为0.609~0.844和0.001~0.012 g/kg。模型验证结果表明,随滴灌年限增加模拟效果越好,模拟除荒地20~60 cm土层土壤温度NSE小于0.600,滴灌7、11和13 a地块各层土壤温度NSE均大于0.600,RMSE介于0.143~3.213℃;滴灌0、7、11和13 a地块模拟的各层土壤水分NSE均大于0.670,RMSE为0.009%~0.057%;滴灌0、7、11和13 a地块模拟的除120~140 cm土层土壤盐分NSE小于0.600,其他各层土壤盐分NSE均大于0.616,RMSE为0.000~0.016 g/kg。总体而言,SHAW模型适用于北疆地区冻融期长期膜下滴灌棉田的一维土壤水热盐模拟。

膜下滴灌棉花水-土壤改良剂耦合效应研究

采用二因素五水平正交组合设计方案,建立回归模型并进行效应解析后表明：灌水对棉花产量的影响大于改良剂;灌水对棉花生育期土壤脱盐率的影响大于改良剂;水-改良剂耦合效应对棉花产量和生育期土壤脱盐率均为协同效应;按照所建立的水-土壤改良剂对棉花产量的耦合模型和水-土壤改良剂对棉花生育期土壤脱盐率的耦合模型,通过计算机模拟,提出了高产抑盐的灌水-施用土壤改良剂方案：灌水指标为3 285~4 590 m3/hm2,施用改良剂指标为112.5~120 kg/hm2。

不同土质下灌水盐度对滴灌棉花生理及产量品质的影响

在干旱、半干旱地区利用微咸水进行灌溉可以缓解淡水资源供需矛盾,但其灌溉效果与土壤质地是否相关有待研究。该研究旨在探讨灌水矿化度对不同土壤质地滴灌棉花生长发育和籽棉产量、纤维品质的影响。2022年进行桶栽试验,设置2种玛纳斯河流域常见的棉田土壤质地(砂壤土T1、砂土T2)和4个灌水矿化度(0.85(S0)、2.00(S1)、5.00(S2)、8.00g/L(S3)),共8个试验处理,研究不同处理下棉花光合指标、株高、茎粗、产量及品质。结果表明:随灌水矿化度增大,在砂土中棉花苗期后株高、茎粗、净光合速率、蒸腾速率、单铃质量、单株铃数、产量、灌溉水利用效率和断裂比强度均呈现减小趋势,S3处理的蒸腾速率在蕾期较S0降低10.61%;而在砂壤土条件下,各指标呈先增后减趋势,S1处理净光合速率较S0增加8.40%。随灌水矿化度升高,2种土壤质地下棉花的最大荧光呈现减小趋势,非光化学淬灭呈现增加趋势。通过回归分析可知,砂土棉田棉花产量与灌水矿化度呈负相关关系,而在砂壤土棉田中,用小于3.69 g/L的灌溉水不会降低棉花产量。利用通径分析可知,在砂壤土条件下,棉花茎粗、蒸腾速率是影响产量的主要因素,株高是影响马克隆值的主要因素。在砂土条件下,非光化学淬灭系数、蒸腾速率是影响产量的主要因素,株高、蒸腾速率是影响马克隆值的主要因素。该研究可为玛纳斯河流域不同土质棉田合理利用微咸水资源提供理论依据与技术支撑。