灌溉方式对地表蒸发和梨果实发育的影响

为了解决地面灌溉中灌溉水利用效率低、果实品质差的问题,于2013年在河北工程大学永年校区以5年生田间梨树为试材,研究不同地面灌溉方式对土壤水分含量、地表蒸发量、梨产量与品质的影响。4种地面灌溉方式包括沟灌、畦灌、覆草畦灌和覆草非灌溉。测定不同处理的土壤含水量、地表蒸发量和果实品质。结果表明,不同灌溉方式的土壤含水量差异显著,覆草畦灌和沟灌显著高于畦灌和覆草非灌溉处理。覆草畦灌和沟灌较畦灌可显著减少地表的蒸发量,覆草非灌溉、覆草畦灌、沟灌和畦灌3—8月的累积地表蒸发量分别是77.92、114.64、163.1、203.73 mm。沟灌的灌溉水利用效率为1.99 kg/m3,显著大于覆草畦灌和畦灌,分别提高了1.45、1.06 kg/m3。沟灌显著提高了果实的单果重、可溶性固形物含量、总糖含量和维生素C含量。综上,沟灌既能减少地表蒸发又能提高果实产量和品质,是当前较好的地面灌溉方式。     

PAM对潮土水分蒸发量的影响

地表蒸发引起土壤水的散失是造成作物低产的重要原因之一。PAM 是众多保水剂中一种,其具有超强的吸水和保水能力,能够抑制土壤水分的蒸发,增加土壤含水量,增强土壤持水功能,对沙质土壤水分的调控具有重要作用。本文以分布于重庆三峡库区的潮土为研究对象,研究不同剂量、不同剂型的PAM对土壤蒸发量的影响,以期为农业灌溉上PAM的推广应用提供理论依据。研究结果显示：PAM能抑制土壤水分的蒸发。对不同剂量的PAM处理,潮土累计蒸发量较对照减少2.37%～12.459%;以200mg/kg抗蒸发效果最为明显。对同分子量不同电荷密度剂型的PAM处理,冷沙黄泥累计蒸发量较对照减小7.34%～17.81%,以30%抗蒸发效果最好,对同电荷密度不同分子量剂型的PAM处理,潮土累计蒸发量分别较对照减小12.25%～18.53%;以1000万的PAM抗蒸发效果最为明显。     

土壤耕作和水分管理对水稻土壤肥力性状的影响

为了探讨耕作方式和水分管理对水稻土壤肥力性状的影响,以金优253为材料进行大田试验,设置常耕、免耕二种土壤耕作方式,浅水层灌溉、交替灌溉、水气平衡灌溉三种水分管理方式,然后在水稻成熟期测定分析土壤肥力因子的变化。结果表明,土壤碱解氮含量以浅水层灌溉最高,水气平衡灌溉次之,交替灌溉的最低,土壤有效磷含量从高到低分别为水气平衡灌溉、交替灌溉、浅水层灌溉;土壤速效钾含量从高到低分别为交替灌溉、水气平衡灌溉、浅水层灌溉;土壤有机质含量从高到低分别为水气平衡灌溉、浅水层灌溉、交替灌溉;土壤pH值从高到低分别为水气平衡灌溉、交替灌溉、浅水层灌溉。三种灌溉方式下常耕稻田土壤碱解氮、有效磷和有机质含量含量高于免耕稻田,免耕稻田pH值、土壤速效钾含量却高于常耕稻田。水分管理对土壤肥力的影响比耕作方式的影响更大。     

微喷补灌对麦田土壤物理性状及冬小麦耗水和产量的影响

黄淮海麦区水资源短缺,探明畦灌和微喷补灌对麦田土壤物理性状及冬小麦耗水特性、产量和水分利用效率调节的差异,可为该地区冬小麦节水高产栽培提供理论和技术支持。2016—2018年冬小麦生长季,设置畦灌和微喷补灌两处理,研究其对麦田0～40 cm土层土壤容重、总孔隙度、毛管孔隙度、田间持水率,及冬小麦各生育阶段棵间蒸发量、蒸腾量、籽粒产量和水分利用效率的影响。结果表明微喷补灌处理与畦灌处理相比, 0～20 cm土层土壤容重降低,总孔隙度、毛管孔隙度和田间持水率增加;冬小麦返青后春季分蘖明显减少,返青至拔节期的棵间蒸发量和蒸腾量及全生育期总耗水量均显著减少;籽粒产量无明显变化,但水分利用效率显著提高,说明微喷补灌可以改善麦田土壤物理性状,优化冬小麦群体结构,通过减少棵间蒸发和植株无效蒸腾降低麦田耗水量,从而在维持高产水平的同时提高水分利用效率。     

Effect of Mulch and Irrigation Water Amounts on Soil Evaporation and Transpiration

Soil evaporation, transpiration, evapotranspiration, and yield of pepper as affected by mulch and five amounts of irrigation water were studied in greenhouse pot experiments during 1996 (March 26–July 13). Five different amounts of irrigation water were imposed on covered and open soil surface clay loam soil in five replicates. Water losses by evaporation and/or transpiration were measured daily by weighing. Irrigation water was applied once weekly. The amount of irrigation water added to each treatment was determined from the differences in weights.
Covering soil surface reduced the required amount of irrigation water. With deficit (under) irrigation, the reduction in applied irrigation water was about 14%. and increased to 29 % with excess (over) irrigation. Transpiration in covered soil surface treatments were higher than transpiration in open soil surface treatments with limited irrigation water applied, With limited (deficit) irrigation, increasing irrigation water applied decreased the percentage of soil evaporation and the contribution of soil evaporation to crop evapotranspiration. With excess irrigation, increasing water applied increased the percentage of soil evaporation and its contribution to the total evapotranspiration. Soil evaporation reduced pepper yield significantly, and this might be owing to the reduction in the available soil water associated with limited-to-complete irrigation.     

Crop water stress index for scheduling irrigation of Indian mustard (Brassica juncea) based on water use efficiency considerations

The study was conducted to determine the feasibility of canopy temperature based crop water stress index (CWSI) for scheduling irrigation of Indian mustard (Brassica juncea). Field crop experiments were conducted in Hamirpur, Himachal Pradesh (India) during three consecutive cropping seasons (2015, 2016 and 2017). The experimental field was divided into five plots with different levels of irrigation treatments based on depletion of total available soil water (TASW) in the crop root zone. The maximum soil moisture depletion (SMD) of TASW at 10%, 30% and 50%, full irrigated (non-stressed) and extremely dry (full stressed) conditions were maintained in respective plots. Relationships were developed between canopy-air temperature differential (T_C-T_A) and vapour pressure deficit (VPD) for non-stressed and fully stressed conditions to generate non-water-stressed baseline (NWSB) and maximum water-stressed baseline (MWSB) baselines for Indian mustard crop. The CWSI was computed for different SMD of TASW by using a proven empirical approach based on the baselines. The irrigation treatment corresponding to 30% SMD with a mean CWSI of 0.4 resulted in optimal yield and maximum water use efficiency. Results of the study suggest that established CWSI value can be used to detect stress and schedule irrigations for Indian mustard.     

Spatial distribution of soil water,soil temperature,and plant roots in a drip-irrigated intercropping field with plastic mulch

Intercropping and drip irrigation with plastic mulch are two agricultural practices used worldwide. Coupling of these two practices may further increase crop yields and land and water use efficiencies when an optimal spatial distribution of soil water contents (SWC), soil temperatures, and plant roots is achieved. However, this coupling causes the distribution of SWCs, soil temperatures, and plant roots to be more complex than when only one of these agricultural practices are used. The objective of this study thus was to investigate the effects of different irrigation treatments on spatial distributions of SWCs, soil temperatures, and root growth in a drip-irrigated intercropping field with plastic mulch. Three field experiments with different irrigation treatments (high T1, moderate T2, and low T3) were conducted to evaluate the spatial distribution of SWCs, soil temperatures, and plant roots with respect to dripper lines and plant locations. There were significant differences (p < 0.05) in SWCs in the 0–40 cm soil layer for different irrigation treatments and between different locations. The maximum SWC was measured under the plant/mulch for the T1 treatment, while the minimum SWC was measured under the bare soil surface for the T3 treatment. This was mainly due to the location of drippers and mulch. However, no differences in SWCs were measured in the 60 100 cm soil layer. Significant differences in soil temperatures were measured in the 0 5 cm soil layer between different irrigation treatments and different locations. The soil temperature in the subsoil (15 25 cm) under mulch was higher than under the bare surface. The overlaps of two plant root systems in an intercropping field gradually increased and then decreased during the growing season. The roots in the 0 30 cm soil layer accounted for about 60% 70% of all roots. Higher irrigation rates produced higher root length and weight densities in the 0 30 cm soil layer and lower densities in the 30 100 cm soil layers. Spatial distributions of SWCs, soil temperatures, and plant roots in the intercropping field under drip irrigation were significantly influenced by irrigation treatments and plastic mulch. Collected experimental data may contribute to designing an optimal irrigation program for a drip-irrigated intercropping field with plastic mulch.     

Interactive effects of elevated atmospheric CO2 concentrations and plant available soil water content on canopy evapotranspiration and conductance of spring wheat

The present study was conducted to investigate the possible interactive effects of rising atmospheric CO₂ concentration [CO₂] and drought stress on water use of wheat. Spring wheat (Triticum aestivum cv. “Minaret”) was grown either in 1 m diameter lysimeters with 0.4 m soil depth (1998) or in the field (1999) in open-top chambers under two CO₂-concentrations (ambient, ambient + 280 ppm) and two watering regimes (well-watered = WW with a plant available water content PAW > 40 mm and drought stressed = DS, 10 mm < PAW < 30 mm) beginning after first node stage. Canopy evapotranspiration (E_C) was measured continuously from first the node stage until the beginning of flag leaf senescence using four open-system canopy chambers (0.78 m³). Seasonal changes of the absorption of photosynthetically active radiation (APAR) of the canopy and root growth (1999) were also measured.

In both growing seasons leaf area index increased in response to elevated [CO₂] in both water treatments. The related effects of [CO₂] on canopy radiation absorption (APAR) were, however, smaller. E_C was linearily related to APAR in both growing seasons. While elevated [CO₂] reduced the slope of this relation under WW conditions by ca. 20% in both growing seasons, it was not reduced (1998) and even increased (1999) under drought. Canopy conductance (G_C) calculated as E_C divided by vapour pressure deficit of air, showed a non-linear relationship to APAR that was best explained by saturation curves. Under WW conditions, elevated [CO₂] reduced the initial slope of G_C versus APAR as well as G_C at saturating light conditions (ca. −30%), while under DS conditions no effect of elevated [CO₂] could be detected. Under high light conditions (PAR > 400 μmol m⁻² s⁻¹) a critical “threshold value” of PAW (T_PAW, ca. 40 mm) could be identified above which G_C did not respond to PAW. While in 1998 G_C did not respond to elevated [CO₂] at PAW < T_PAW, it was slightly increased at low PAW values in the field experiments of 1999. The reduction of T_PAW by elevated [CO₂] may be explained by enhanced root growth (1999) that would have given the plants better access to soil water resources. The present results suggest that below a critical soil water content elevated [CO₂] will not reduce canopy water loss of wheat or may even enhance it.     

Assessing evidence on the agronomic and environmental impacts of turfgrass irrigation management

In recent years, rising competition for water coupled with new environmental regulations has exerted pressure on water allocations for turfgrass irrigation. In this article, we reviewed published scientific and industry evidence on the agronomic and environmental impacts of turfgrass irrigation using a robust systematic review methodology. Our focus was on the links between (i) irrigation management (amount and frequency), (ii) agronomic responses to irrigation (turf quality, growth rates and rooting) and (iii) environmental impacts (nitrogen leaching). Based on an initial screening of 653 studies and data extracted from 83 papers, our results show that in most cases, under moderate levels of deficit irrigation (50%–60% of actual evapotranspiration), turf quality can be maintained at an acceptable level but with lower water consumption compared to irrigating back to field capacity. Irrigation beyond field capacity was found to increase the risk of nutrient leaching. However, evidence also showed that the concentration and total loss of in leachate were influenced more by nitrogen (N) rates, soil characteristics, turfgrass species and turfgrass growth rates than by irrigation practices. Our analyses suggest that turfgrass irrigation should be scheduled to apply water at moderate levels of deficit irrigation, sufficient to maintain turfgrass quality but limited to promote a deep and extensive rooting system. The findings provide new insights and valuable evidence for both scientists and practitioners involved in turfgrass research and management.     

Hyper-spectral estimation of wheat biomass after alleviating of soil effects on spectra by non-negative matrix factorization

Hyper-spectral technology has been proven to be an effective method for the fast and non-destructive monitoring of crop biomass. However, the biomass estimation accuracy of this method is limited due to the effects of background factors, such as soils and water. In this study, a spectral separation method, non-negative matrix factorization (NMF), was proposed to alleviate the effects of soil on spectra. With the application of the NMF method, pure vegetation spectra were extracted from the field-observed spectra of wheat canopy, which were collected in four growing seasons from the tillering to the booting stages of wheat. Then, prediction models of wheat biomass (WB) were established and validated using the extracted spectra with the partial least squares regression (PLSR) method. The results showed that the NMF method could effectively separate the vegetation spectra from the mixed canopy spectra. Based on the extracted vegetation spectra, the WB prediction accuracy could be greatly improved with an increase of 31.7% for the R²_p and an increase of 46.6% for the ratio of performance to deviation (RPD) as compared to the original spectra, indicating that the NMF method could significantly improve the performance of the WB prediction model. This method has potential application in the estimation of biomass using remote sensing technology.     

不同土壤改良剂对滴灌模式下次生盐碱化土壤改良效果研究

为筛选出适合当地滴管模式下次生盐碱化土壤的土壤改良剂,在常年滴灌、次生盐碱化严重的地块,选用5种不同土壤改良剂进行大田试验,研究其对次生盐碱化土壤的改良效果。结果表明：施用土壤改良剂能在一定程度上改善次生盐碱化土壤结构,降低土壤盐分,提高土壤养分,对糯玉米株高的影响表现出循序渐进的趋势,对糯玉米叶绿素含量的影响表现出“前强、中弱、后平”的趋势,而且能够提高糯玉米的产量、产值、净增产及产量构成,但对土壤含水量、全氮含量、糯玉米茎周的影响不明显。不同土壤改良剂适宜性综合判定结果为：滴施型土壤改良剂在改善土壤理化性质和提高糯玉米产量方面较基施型土壤改良剂效果显著,滴施型聚马来酸类的盐碱土改良剂最适宜当地次生盐碱化土壤,其次为黄腐植酸类的盐碱土壤改良剂。     

农业节水灌溉经济效益的分析和计算

干旱缺水是制约农业生产发展的主要因素之一,而农业节水灌溉就是用尽可能少的水投入,取得尽可能多农作物产品的一种农业高效用水模式;对农业节水灌溉经济效益的分析和计算从理论上进行了系统的阐述,供相关人员参考。新疆生产建设兵团各垦区是荒漠、半荒漠人工垦荒绿洲灌溉农业区,缺水问题尤显突出。要使垦区农业经济健康持续稳定的发展,必须发展节水农业,提高灌溉水的利用率,提高单方水的生产效率,节水扩灌,改善农业生产技术措施,提高粮、棉、果、牧的产量和品质;只有通过农业节水才能满足“生态维护用水”的需求,防止生态脆弱区生存环境的进一步恶化,降低各种自然灾害（大风、沙尘暴、浮尘等）发生的频率,减少农田沙化的进度。     

Moisture Stress Effects on the Yield and Water Use of Sorghum Hybrids and their Parents*

Little is known of the relationship between hybrids and parental material with respect to water use and drought resistance. Responses of sorghum (Sorghum bicolor [L.] Moench) F₁ hybrids to moisture deficits are partially determined by parental material. The yield and water use of six sorghum hybrids and their respective male and female parents were evaluated under stressed and well irrigated conditions during 1980 and 1981 at Tucson, Arizona. The soil was Comoro loamy sand (coarse-loamy, mixed, calcareous, thermic typic Torrifluvent) with an average available soil moisture of 16 % at field capacity. Changes in soil moisture were monitored semi-weekly by neutron modulation. Meteorological data were collected daily. The 1980 season had higher maximum temperatures and pan evaporation than the 1981 season. Differences in cumulative water use among entries were apparent within the same water treatments during 1981. Mean cumulative evapotranspiration (ET) for the stressed treatment was 248 and 281 mm for 1980 and 1981, respectively, and ET under well irrigated conditions was 419 and 528 mm for 1980 and 1981, respectively. Hybrids produced greater grain yield than their parents under both water treatments. This was due to greater seed number for hybrids. Seed numbers were more stable for hybrids over both treatments than for parents. Hybrids four and seven had the greatest grain yield in 1980 and 1981, respectively, under stressed conditions. Water use efficiency (WUE) was significantly different within water treatments but was not so between the irrigated and stressed treatments. Hybrids WUE was generally greater than that of parents except for hybrid five under irrigated conditions in 1981. Hybrids with WUE and stable yields were not necessarily reflective of parental material under stressed and non-stressed environments.     

Multi-scale optical flow estimation of the video based on gradient optimization

A new algorithm based on gradient optimization is proposed for optical flow estimation of video images with different motion ranges. The original video images are transformed by using Loggabor filtering on phases and measures,and then the spatio-temporal gradient is calculated by using the obtained feature images. The optical flow is calculated with the spatio-temporal gradient. The video images are layered and processed with coarse-to-fine image pyramid method. The theoretical analysis and experimental results show that the algorithm is suitable for the video optical flow motion estimation of the significant range. It can not only obtain the video images following the human visual resolution characteristics, but also optimize the spatio-temporal gradient, while the optical flow calculation is more accurate. Besides, the time complexity of this algorithm is equivalent to that of the traditional optical flow method, and the accuracy of the algorithm is superior to the methods suggested by Horn-Schunck, Duan,et al.     

人工国槐林春季大型土壤动物群落结构对人为管理方式的响应

为了解林业生态试验站人为管理方式对人工国槐林春季大型土壤动物的物种组成及多样性的影响,分别于2011、2012年5月中下旬,对山西农业大学林业生态试验站国槐林大型土壤动物进行调查。2011年捕获大型土壤动物58个类群675号,2012年共捕获大型土壤动物37个类群共计210号;类群数少了21个,群落个体数减少了465号;2011年特有类群共40个,其个体数占总捕获数的39.43%,2012年特有类群为19个,其个体数占总捕获数的39.73%,2年的特有类群个体数占总捕获数的百分比相近。春季国槐林大型土壤动物群落结构受不同人为管理方式的影响较大,秋、冬季耕土会极大改善国槐林第2年春季大型土壤动物的群落结构,类群数和个体数大幅度下降,植食性类群减少;秋、冬季耕土可以作为小面积人工林地下害虫防治的重要手段予以广泛应用。     

The effect on some physical properties of a vertic tropaquept soil of the number of cultivations after different quantities of water and after different soaking periods

A Vertic Tropaquept soil was cultivated four times at one month intervals after applying 100, 200 and 300 mm of water in amounts of 100 mm on various days. Results suggest that physical properties of the surface soil, including percolation, were not influenced markedly by cultivation after application of higher water quantities nor by the number of cultivations beyond a certain limit. One cultivation (7.5 kJ m⁻²) after an application of 200 mm water, and applied without any delay was found to be best. Thus, a saving of energy, water and time for wet cultivation of rice paddies could be achieved.     

华北冬小麦开花期补灌的增产效应及其影响因素

为阐明华北地区冬小麦开花期补灌增产效应及其影响因素,制定稳产节灌制度,于2007—2016连续10年进行了大田定位试验,研究在冬小麦拔节期灌水基础上,播前底墒、长期不同施氮及生育期降水等对开花期补灌增产效应及水分利用的影响。裂区设计,灌水量为主区,设春灌1次水(拔节期75mm,W1)和2次水(拔节期和开花期各75mm, W2) 2个处理;施氮量为副区,设6个水平,分别为0 (N0)、60 (N60)、120 (N120)、180 (N180)、240 (N240)、300 kg hm-2 (N300)。冬小麦开花期补灌增产效应受播前底墒影响显著,播前2 m土体贮水量越大开花期补灌增产率越小。施氮水平也显著影响开花期补灌增产效应,随着定位试验年限的增加,N0和N60处理土壤有机质和全氮含量逐年下降,从第6年开始开花期补灌的增产效应基本丧失。在足墒播种和正常供氮(施氮量不低于120kghm-2)条件下,开花期补灌的增产效应还受冬小麦生育期有效降水量的影响,尤其是拔节–开花期的有效降水量。开花期补灌增产率随生育期以及开花后的有效降水量的增加而降低。拔节–开花期有效降水量大于25.3 mm时,开花期补灌没有显著优化穗数、穗粒数、千粒重、生物量、收获指数等产量性状,最终增产不显著;此情景下,拔节期灌1次水(75 mm左右),即可在维持较高产量的前提下,降低耗水、提高水分利用效率,实现稳产与节水协同。本研究表明,华北平原冬小麦在足墒播种、施氮量不低于120 kg hm-2、拔节期灌水前提下,拔节–开花期有效降水量可作为开花期灌水与否的重要决策依据。     

冷水串灌茭白效应研究

用水库底层冷水串灌茭田后改变了茭白生长的小气候环境,为此,对气温、水温、茭白的经济性状、生育期、经济效益五个方面进行观测和分析。其差异明显,经济效益和社会效益显著提高。     

Use of soil and vegetation spectroradiometry to investigate crop water use efficiency of a drip irrigated tomato

An agronomic research was conducted in Tuscany (Central Italy) to evaluate the effects of an advanced irrigation system on the water use efficiency (WUE) of a tomato crop and to investigate the ability of soil and vegetation spectroradiometry to detect and map WUE. Irrigation was applied following an innovative approach based on CropSense system. Soil water content was monitored at four soil depths (10, 20, 30 and 50 cm) by a probe. Rainfall during the crop cycle reached 162 mm and irrigation water applied with a drip system amounted to 207 mm, distributed with 16 irrigation events. Tomato yield varied from 7.10 to 14.4 kg m⁻², with a WUE ranging from 19.1 to 38.9 kg m⁻³. The irrigation system allowed a high yield levels and a low depth of water applied, as compared to seasonal ET crop estimated with Hargraves’ formula and with the literature data on irrigated tomato. Measurements were carried out on geo-referenced points to gather information on crop (crop yield, eighteen Vegetation indices, leaf area index) and on soil (spectroradiometric and traditional analysis). Eight VIs, out of nineteen ones analyzed, showed a significant relationship with georeferenced yield data; PVI maps seemed able to return the best response, before harvesting, to improve the knowledge of the area of cultivation and irrigation system. CropSense irrigation system reduced seasonal irrigation volumes. Some vegetation indexes were significantly correlated to tomato yield and well identify, a posteriori, crop area with low WUE; spectroradiometry can be a valuable tool to improve irrigated tomato field management.     

An investigation of water quenched solution surface evaporation by the high-temperature slag of a power station

Slag water surface evaporation phenomenon exists in the system of water cooling slag removal. The authors study the relationship between slag water (which is from the JINJIE power plant in Shaanxi)surface evaporation rate and the relative humidity(40%~90%)and the water surface temperature(35-75 ℃),which at an atmospheric pressure and the wind speed is 0.5 m/s,and then obtains an empirical equation. The experiment measures three kinds of concentrations of the slag water surface evaporation rate,and compares the measuring results with those of the pure water surface evaporation rate at the same experimental conditions. According to the comparison results,the authors analyze underlying causes of slag water evaporation from the thermodynamic point of view,that is surface temperature and composition and content changed the surface free energy,thus affects the slag water surface evaporation rate. It is found that water surface evaporation rate is 1.1~1.2 times of the rate of slag water when the temperature is over 50 ℃,while the water surface evaporation rate is slightly higher than that of slag water when the temperature is lower than 50 ℃,and the slag water surface evaporation rate changes in 10% in a certain concentration range.