Time‐lapse monitoring of soil water content using electromagnetic conductivity imaging          下载免费PDF全文

J. Huang  E. Scudiero  W. Clary  D. L. Corwin  J. Triantafilis 《Soil Use and Management》2017,33(2):191-204

The volumetric soil water content (θ) is fundamental to agriculture because its spatiotemporal variation in soil affects the growth of plants. Unfortunately, the universally accepted thermogravimetric method for estimating volumetric soil water content is very labour intensive and time‐consuming for use in field‐scale monitoring. Electromagnetic (EM) induction instruments have proven to be useful in mapping the spatiotemporal variation of θ. However, depth‐specific variation in θ, which is important for irrigation management, has been little explored. The objective of this study was to develop a relationship between θ and estimates of true electrical conductivity (σ) and to use this relationship to develop time‐lapse images of soil θ beneath a centre‐pivot irrigated alfalfa (Medicago sativa L.) crop in San Jacinto, California, USA. We first measured the bulk apparent electrical conductivity (EC_a – mS/m) using a DUALEM‐421 over a period of 12 days after an irrigation event (i.e. days 1, 2, 3, 4, 6, 8 and 12). We used EM4Soil to generate EM conductivity images (EMCIs). We used a physical model to estimate θ from σ, accounting for soil tortuosity and pore water salinity, with a cross‐validation RMSE of 0.04 cm³/cm³. Testing the scenario where no soil information is available, we used a three‐parameter exponential model to relate θ to σ and then to map θ along the transect on different days. The results allowed us to monitor the spatiotemporal variations of θ across the surveyed area, over the 12‐day period. In this regard, we were able to map the soil close to field capacity (0.27 cm³/cm³) and approaching permanent wilting point (0.03 cm³/cm³). The time‐lapse θ monitoring approach, developed using EMCI, has implications for soil and water use and management and will potentially allow farmers and consultants to identify inefficiencies in water application rates and use. It can also be used as a research tool to potentially assist precision irrigation practices and to test the efficacy of different methods of irrigation in terms of water delivery and efficiency in water use in near real time.  相似文献   

Biochar has little effect on soil dissolved organic carbon pool 5 years after biochar application under field condition     

Xinliang Dong  Bhupinder Pal Singh  Guitong Li  Qimei Lin  Xiaorong Zhao 《Soil Use and Management》2019,35(3):466-477

Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha^?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg^?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition.  相似文献   

Maize harvest index and water use efficiency can be improved by inhibition of gibberellin biosynthesis          下载免费PDF全文

B. W. Hütsch  S. Schubert 《Journal of Agronomy and Crop Science》2018,204(2):209-218

Possibilities to improve maize harvest index and nutrient utilization efficiency by application of plant growth regulators were investigated. In container experiments, the effects of different growth regulators on the development of the maize (Zea mays L.) cultivars Pioneer 3906 and Fabregas were tested. Paclobutrazol (PAC) and chlorocholine chloride (CCC), two inhibitors of gibberellin biosynthesis, as well as gibberellic acid (GA₃) were applied at growth stage V5. Three weeks after application of PAC, shoot growth of both maize cultivars was strongly affected with a significant decrease in plant height in the PAC treatment by 44% and 36% for Pioneer 3906 and Fabregas, respectively. The growth‐retarded plants had higher leaf areas and reduced transpiration rates. The higher shoot growth after GA₃ application was accompanied by a reduction in leaf area and an increase in transpiration rate during 1 week before anthesis. CCC treatment showed no significant effects on plant height, leaf area and transpiration rate. The PAC‐treated cultivar Pioneer 3906 produced several cobs per plant, which were mainly barren at maturity. However, PAC application to Fabregas resulted in just one cob per plant with good kernel development and a grain yield, which was not significantly reduced in comparison with the control. With this similar grain yield in combination with a straw yield decrease of 32%, the harvest index was significantly improved by 12%. In addition, with PAC‐treated Fabregas plants, a 19% increased water use efficiency of the grain (WUE_grain) during the critical period of kernel setting was achieved. In this maize cultivar, CCC application also improved harvest index by 5%, but no effect on WUE_grain occurred. GA₃ treatment decreased harvest index of both maize cultivars, and it either reduced WUE_grain (Pioneer 3906) or showed no effect (Fabregas). Utilization efficiencies of N, P and K were not increased with growth regulator application, even in the PAC‐treated Fabregas plants with a significantly improved allocation of assimilates to the grain, mirrored by the higher harvest index. The results indicate that fertilizer applications must be adjusted to the reduced demand of growth‐retarded plants, most likely leading to higher nutrient utilization efficiencies.  相似文献   

Phosphorus bioavailability in ash from straw and sewage sludge processed by low‐temperature biomass gasification     

《Soil Use and Management》2018,34(1):9-17

Reuse of phosphorus (P) from waste streams used for bioenergy conversion is desirable to reduce dependence on nonrenewable P resources. Two different ash materials from low‐temperature biomass gasification of wheat straw and sewage sludge, respectively, were investigated with regard to their P bioavailability. A set of pot experiments with spring barley was carried out to compare the ash P fertiliser value with mineral P fertiliser and the sewage sludge feedstock. An indirect radioactive labelling approach with ³³P was used to determine the amount of P taken up from the fertiliser materials. Depending on the application rate, straw gasification ash produced a fertiliser response comparable to mineral P. However, P uptake from the ash was generally less than uptake from equivalent amounts of mineral P, and the calculated relative effectiveness was 44% after 6 weeks of plant growth. In contrast, the P fertiliser value of Fe‐rich sewage sludge after low‐temperature gasification was practically zero. These results suggest that ash from low‐temperature gasification could be developed into alternative P fertilisers; however, as the P bioavailability depends greatly on the feedstock used, a greater emphasis on feedstock composition is required.  相似文献   

不同施肥措施对灰枣园土壤速效养分含量的影响   总被引：2，自引：0，他引：2  

王宪奎  李建贵  刘隋赟昊  秦韵婷  郭艺鹏  李欢  韩超 《经济林研究》2016,(2):35-40

为了探讨灰枣生长期内不同施肥处理措施对枣园土壤速效养分含量的影响情况,于2014年3月采用不施肥、常规施肥和施用不同种类生物肥共3大类9种处理进行田间试验,并于同年7~10月在灰枣不同生长期测定了各处理区域土壤中的碱解氮、速效磷、速效钾、有机质这4种养分的含量,研究了不同施肥处理下灰枣不同成熟期土壤各养分的动态变化情况。结果表明,不同处理、不同成熟期土壤各养分含量间均有差异,施用生物肥可以显著提高土壤中各养分的含量。  相似文献   

3,5-二硝基水杨酸法与酶法测定甜玉米还原糖和蔗糖含量的比较     

杨泉女  周权驹  吴松健  王蕴波  张敏  洪宇  农华展  黄超宏 《中国农业科技导报》2017,19(11):125-131

针对目前测定甜玉米还原糖和蔗糖含量的3,5-二硝基水杨酸法和酶法进行比较研究,分析两者在育种中的应用。结果显示:酶法的测量准确度比3,5-二硝基水杨酸法高,且其稳定性和重现性都优于3,5-二硝基水杨酸法。通过两种方法对10个甜玉米杂交种种子的还原糖和蔗糖含量的测定,证实了两种方法在甜玉米还原糖和蔗糖含量的检测上是一致的。从育种实践考虑,酶法适于样品数较小的检测,3,5-二硝基水杨酸法更适合于大批量样品的检测。  相似文献   

高含固率木质纤维素厌氧发酵物总DNA的4种提取方法比较     

马旭光  刘素君  江滔  常佳丽  唐琼 《中国沼气》2020,(2):28-35

不同的样本特性和提取方法对获得微生物总DNA的质量有重要影响。文章基于高含固率木质纤维素厌氧发酵物腐殖酸、酚类物质含量高、质地均一性差、微生物浓度低的特点,研究了4种方法提取不同高含固率粪秸厌氧发酵物中微生物总DNA的效果。结果表明,常规的十二烷基磺酸钠法(sodium dodecyl sulfate,SDS)、十二烷基磺酸钠和溴化十六烷基三甲铵结合法(sodium dodecyl sulfate and cetyltrimethyl ammonium bromide,SDS-CTAB)和商业的粪便试剂盒法提取的DNA质量均较差,SDS法和试剂盒法未能获得聚合酶链式反应(polymerase chain reaction,PCR)扩增目的条带,SDS-CTAB法得到的条带较模糊;改进SDS-CTAB法获得的DNA杂质少、纯度高,具有较好的稳定性,A260/A280和A260/A230值分别为1.74~1.86和1.65~1.86,每克样品的DNA浓度在50 ng·μL^-1以上,电泳条带单一齐整、清晰明亮,PCR扩增的目的条带清晰度高,适宜后续分子生物学技术的分析。林格氏液洗脱、聚乙烯吡咯烷酮-40(Polyvinyl Pyrrolidone-40,PVP-40)洗涤液除杂以及裂解液和多种酶联合破壁是改进SDS-CTAB法获得该类专一性样本高质量微生物总DNA的关键步骤。  相似文献   

固态发酵醋糟饲料对育肥猪生长性能、养分表观消化率、血清指标及粪便中挥发性脂肪酸含量的影响     

杨立杰  薛新升  宋青龙  魏立杰  黄金秀  曾祥芳  谯仕彦 《动物营养学报》2020,(4):1576-1585

本试验旨在研究固态发酵醋糟饲料(SFVD)对育肥猪生长性能、养分表观消化率、血清指标及粪便中挥发性脂肪酸(VFA)含量的影响。选择体况相近[(59.04±0.33)kg]的健康“杜×长×大”三元杂交生长育肥猪60头,随机分为2个组,每组3个重复,每个重复10头猪。对照组饲喂基础饲粮+150 mg/kg土霉素钙,试验组饲喂基础饲粮+5%的SFVD。预试期6 d,正试期35 d。结果表明:与对照组相比,基础饲粮中添加5%的SFVD对育肥猪平均日采食量(ADFI)具有一定的促进趋势(P=0.056);显著降低了育肥猪饲粮中干物质(DM)、粗蛋白质(CP)、有机物(OM)和总能(GE)的表观消化率(P<0.05),对粗脂肪(EE)表观消化率有一定的促进趋势(P=0.052);显著提高了育肥猪血清谷草转氨酶(AST)和谷胱甘肽过氧化物酶(GSH-Px)活性(P<0.05),血清高密度脂蛋白(HDL)和免疫球蛋白A(IgA)含量也呈现出一定的升高趋势(P=0.055和P=0.077);显著提高了育肥猪粪便中丙酸含量(P<0.05),粪便中甲酸和总挥发性脂肪酸(TVFA)含量也呈现出一定的升高趋势(P=0.071和P=0.054)。由此可见,基础饲粮中添加5%的SFVD对育肥猪生长性能、肠道健康及免疫性能的提高具有潜在的促进作用。  相似文献   

‘马来西亚1号’菠萝蜜叶片氮磷钾动态的研究     

张峰  苏兰茜  白亭玉  吴刚  谭乐和  李雯  郭芮  赵正杰 《热带作物学报》2021,42(12):3508-3513

通过对海南省文昌市南阳镇、琼海市大路镇、乐东县黄流镇3个地区‘马来西亚1号’菠萝蜜叶片氮、磷、钾3种营养元素的周年变化规律跟踪调查分析,结果表明：3个地区菠萝蜜叶片营养元素变化规律相似。元素年平均含量表现为氮>钾>磷。根据实际生产中的生育期调研分析,将菠萝蜜的生长周期大致划分为2个批次3个时期：第一批次养树期（11—12月）、花芽分化期（1—2月）、结果期（3—4月）;第二批次养树期（5—6月）、花芽分化期（7—8月）、结果期（9—10月）。生长周期内,氮元素含量年变化呈现“N”字型变化趋势;磷含量在1—4月呈先上升后下降的趋势,随后呈缓慢上升趋势;钾含量变化趋势与氮含量变化相似,但钾元素含量变化没有氮元素变化明显。菠萝蜜叶片中大量元素含量的适宜范围为：全氮21.03~22.15 g/kg,全磷2.86~3.40 g/kg,全钾13.49~14.47 g/kg。在生长发育过程中,菠萝蜜需氮、钾元素较多,特别是在花芽分化期和结果期,应注意增施氮肥与钾肥,磷肥应于养树期施足。  相似文献   

单宁酸对生长猪胃-小肠仿生消化中消化酶活性及饲粮粗蛋白消化率的影响     

王亚  赵峰  张虎  赵威  徐二华  李浙烽 《畜牧兽医学报》2020,51(6):1332-1341

本试验旨在探讨单宁酸对生长猪胃、小肠仿生消化中消化酶活性及玉米-豆粕型饲粮干物质和粗蛋白消化率的影响，为评价单宁酸的生物学效应提供参考。试验一采用单因素完全随机设计，考察在无饲粮下2种单宁酸对猪模拟胃液、模拟小肠液消化酶活性的影响。设5个处理，单宁酸添加量分别为0 mg （胃液体积为20 mL，小肠液体积为22 mL）；单宁酸1，10 mg；单宁酸1，20 mg；单宁酸2，10 mg；单宁酸2，20 mg。测定各处理的胃蛋白酶、淀粉酶、胰蛋白酶和糜蛋白酶的活性。试验二考察玉米-豆粕型饲粮添加单宁酸对猪仿生消化中胃、小肠阶段消化酶活性及养分消化率的影响。采用单因素完全随机设计，设5个处理，单宁酸在饲粮中的含量分别为0 mg·（2 g）^-1；单宁酸1，10 mg·（2 g）^-1；单宁酸1，20 mg·（2 g）^-1；单宁酸2，10 mg·（2 g）^-1；单宁酸2，20 mg·（2 g）^-1。测定仿生消化中胃阶段0.5和4 h时胃蛋白酶活性，小肠阶段0.5、4和8 h时淀粉酶、胰蛋白酶和糜蛋白酶活性及生长猪胃-小肠仿生消化测定饲粮的干物质和粗蛋白消化率。结果表明：1）无饲粮的情况下，和空白对照组相比，2种单宁酸对模拟胃液中胃蛋白酶活性无显著影响（P>0.05），单宁酸1比单宁酸2更高地降低了模拟小肠液中淀粉酶、胰蛋白酶和糜蛋白酶的活性（P<0.05）。2）在饲粮进行仿生消化的胃消化0.5～4 h内，除4 h时10 mg·（2 g）^-1添加量外，添加单宁酸1时胃蛋白酶的活性均显著高于添加单宁酸2时的相应值（P<0.05），除单宁酸2在消化0.5 h外，2种单宁酸在添加10 mg·（2 g）^-1时胃蛋白酶活性均显著高于20 mg·（2 g）^-1添加量的相应值（P<0.05）。在小肠仿生消化0.5 h时，饲粮中添加单宁酸1、2的2个水平对消化液中淀粉酶活性无显著影响（P>0.05），但均显著降低了糜蛋白酶的活性（P<0.05）；单宁酸1的消化液中胰蛋白酶活性高于单宁酸2的相应值（P<0.05）。在小肠仿生消化4 h时，除添加水平为20 mg·（2 g）^-1时的糜蛋白酶活性外，饲粮中添加单宁酸1消化液中淀粉酶、糜蛋白酶活性高于添加单宁酸2的相应值，而胰蛋白酶活性低于添加单宁酸2的相应值（P<0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶和糜蛋白酶的活性（P<0.05）。在小肠仿生消化8 h时，饲粮中单宁酸的添加量影响了淀粉酶的活性，但单宁酸1和单宁酸2各两个添加量在淀粉酶的平均活性上无显著差异（P>0.05）。单宁酸1、2的两个添加量均降低了胰蛋白酶、糜蛋白酶的活性（P<0.05）。3）与对照组相比，两种单宁酸在两种添加水平下均显著降低了饲料粗蛋白消化率（P<0.05），且单宁酸2比单宁酸1更多地降低了饲粮粗蛋白的消化率（P<0.05）。综上所述，在有、无饲粮条件下，单宁酸对消化酶活性呈现不一致影响。单宁酸影响饲粮粗蛋白的消化率可能主要与消化液中糜蛋白酶活性降低以及单宁酸与饲粮中的化学成分形成螯合物降低了小肠消化酶的水解效率有关。  相似文献