磷肥减施对集约化露天菜地周年磷损失削减效果评价     

王瑞  施卫明  李奕林 《土壤学报》2023,60(1):224-234

集约化菜地因高量施肥以及大水漫灌导致其在农田磷污染排放中的占比最高,目前已成为种植业磷损失的优先阻控对象。在定量评估菜地周年磷损失量的基础上,明确蔬菜合理的磷肥投入阈值范围,通过源头控制菜地磷的迁移、流失,对于有效降低中国农业面源污染造成的环境压力具有重要意义。以太湖流域露天菜地为研究对象,设置农民习惯施磷(对照)和减量施磷处理(减施20%、30%、50%和100%),通过为期一年的蔬菜轮作试验,明确土壤磷素环境阈值及磷素周年径流流失特征。结果表明,菜地磷环境阈值为78.9 mg·kg^-1,所有处理土壤表层有效磷(Olsen-P)含量均超过环境阈值。随施磷量的减少,菜地总磷(TP)径流损失浓度降低,并主要以可溶性磷(DP)流失形态为主,DP/TP比例为50.1%～63.1%。磷径流损失负荷呈现出明显的季节性特征,夏秋季磷素流失量为1.93～3.26 kg·hm^-2(以P计),占全年磷素流失通量的59.2%～63.2%。结构方程模型结果表明,当季施磷量直接且极显著影响TP流失浓度,并且TP流失浓度对TP流失负荷存在极显著的正向影响,影响系数为0...  相似文献   

不同氧化度六方水钠锰矿的结构研究   总被引：1，自引：0，他引：1  

殷辉  冯雄汉  赵巍  胡天斗  谭文峰  刘凡 《土壤学报》2013,50(1):96-105

通过反复试验法(trial-and-error)粉末X射线衍射(XRD)结构模拟和X射线吸收光谱(XAS)研究了不同锰平均氧化度(manganese average oxidation state,Mn AOS)六方水钠锰矿的结构变化特点.合成的系列六方水钠锰矿中(样品HB1到HB6),Mn AOS由3.92减小为3.67,晶胞参数b由2.838 (A)增加至2.848 (A).在a-b平面上的紧密堆叠尺寸(CSD)由12.0 nm减小至7.0 nm,沿c轴堆叠的锰氧八面体层数约为10.6～13.4层.随着Mn AOS逐渐降低,样品中八面体空位含量由18％减小至8％.Mn AOS与空位含量呈极显著正相关,它们与晶胞参数b呈负相关.X射线吸收近边结构光谱(XANES)线性拟合表明,样品中Mn主要以+4价存在,随着空位含量的减少,低价锰(Mn2+/3+)含量逐渐增多.扩展X射线吸收精细结构光谱(EXAFS)全多重散射模型拟合分析表明,不同氧化度六方水钠锰矿样品的晶体结构和Mn局域配位环境基本相同.由于空位含量和颗粒尺寸减小,从HB1到HB6的表观锰位点占有率(focc)由0.74减小至0.66.随着Mn AOS逐渐降低,Mn-Mn(O)配位壳平均键长增加.  相似文献   

不同恢复年限对土壤有机碳组分及团聚体稳定性的影响   总被引：9，自引：1，他引：8  

闫靖华  张凤华  谭斌  杨海昌 《土壤学报》2013,50(6):1180-1190

通过干旱区典型内陆河玛纳斯河流域绿洲田间定位实验,研究了盐渍化弃耕地不同复垦年限对土壤活性有机碳组分及对团聚体稳定性的影响。结果表明,恢复初期降低了土壤微生物量碳(MBC)和易氧化有机碳(LOC)的含量,降低幅度小。随着恢复年限的增加,土壤有机碳含量增加,显著提高了土壤MBC和LOC的含量以及土壤水溶性有机碳(WSOC)和土壤热水溶性有机碳(HWSOC)的含量和分配比例,其中恢复1年、5年和10年的土壤HWSOC分别比弃耕地高61.04%、143.46%和132.43%。连续人工种植后SOC和大团聚体(﹥0.25㎜)含量增加,土壤团聚体稳定性增强,其中恢复10年0-5cm、5-10cm土层﹥0.25mm团聚体占57.30%和56.50%,团粒指数下降到43.00%。相关分析表明,﹥0.25㎜水稳性团聚体的含量与土壤TOC和土壤HWSOC达到显著正相关,干旱区盐渍化绿洲农田土壤HWSOC对维持土壤团聚体稳定性的贡献明显。  相似文献   

Long-term phosphorus fertilisation increased the diversity of the total bacterial community and the phoD phosphorus mineraliser group in pasture soils   总被引：1，自引：0，他引：1  

Hao Tan  Matthieu Barret  Marlies J. Mooij  Olivia Rice  John P. Morrissey  Alan Dobson  Bryan Griffiths  Fergal O’Gara 《Biology and Fertility of Soils》2013,49(6):661-672

Fertilisers, especially nitrogen (N) and phosphorus (P) supplies, are frequently used in agricultural soil management to attain high crop yields. However, the intensive application of these chemical inputs can decrease the quality of agricultural soils and increase the probability of environmental pollution. In this study, the impact of P fertilisation on the diversity of the soil bacterial community was assessed. For this, a culture-independent approach targeting 16 rRNA and phoD genes was used on DNA extracted from pasture soils subjected to three different P fertilisation regimes for a long-term (42 years). As alkaline phosphomonoesterase (ALP) is necessary for mineralisation of organic P, an inverse relationship between the level of potential ALP activity and soil available P was expected. Indeed, a lower ALP activity was observed in soil subjected to higher chemical P fertiliser input. Analysis of the prevalence of three divergent families of ALP (PhoA, PhoD and PhoX) in metagenomic datasets revealed that PhoD is the most frequent ALP in soil samples and was selected as the most representative ALP possessed by the soil bacterial communities. Diversity of the phoD phosphorus mineraliser group, as well as the total bacterial community, was both increased in response to long-term P fertilisation. Specifically, phosphorus fertilisation decreased the relative abundance of certain taxa, including Acidobacteria and Pseudomonas fluorescens. In conclusion, this study shows that P fertilisation affects the microbial diversity of soil ecosystems, which might potentially modulate the soil biogeochemical cycle.  相似文献   

INTERACTION OF MOLYBDENUM AND PHOSPHORUS SUPPLY ON UPTAKE AND TRANSLOCATION OF PHOSPHORUS AND MOLYBDENUM BY BRASSICA NAPUS     

Hongen Liu  Chengxiao Hu  Xiaoming Hu  Zhaojun Nie  Xuecheng Sun  Qiling Tan 《Journal of plant nutrition》2013,36(12):1751-1760

A hydroponic trial was conducted to assess interaction of molybdenum (Mo) and phosphorus (P) on uptake and translocation of P and Mo by Brassica napus. Molybdenum was applied at four rates (0, 0.01, 0.1 and 1 mg L^?1) and P at three rates (1, 30, and 90 mg L^?1) in nutrient solution. The results indicated that P increased shoot growth and 0.01 mg L^?1 Mo improved the growth of shoots and roots. Molybdenum increased shoot P uptake and root P concentration and uptake when higher P was provided, and had a stimulating effect on P translocation from shoots to roots. P increased shoot Mo concentration and uptake, decreased those in roots, and enhanced Mo transport from roots to shoots. These results implied that both Mo and P had beneficial effects on Mo and P absorption and translocation and co-application of them were necessary to promote growth and utilization of Mo and P for Brassica napus.  相似文献   

Anthracnose disease of Amomum villosum caused by Colletotrichum fructicola in China     

Song  Lisha  Lin  Wei  Jiang  Ni  Zhang  Zhanjiang  Tan  Guiyu  Wei  Shugen 《Journal of General Plant Pathology》2021,87(4):259-263

In May 2019, leaf spots were found on Amomum villosum in Guangxi Province, China. Light yellow-green spots first appeared at the tips or edges of leaves. A fungus was isolated from the leaves and identified as Colletotrichum fructicola based on morphological characteristics and molecular identification using the DNA sequences from ITS, TUB2, ACT, and GAPDH sequences. Similar leaf spots developed after leaves were inoculated with the isolate. This is the first report that C. fructicola causes leaf spots on A. villosum.

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DArTseq physical mapping of QTLs linked to Karnal bunt (Tilletia indica) resistance in two historical wheat populations     

Livinus Emebiri  Sukhwinder Singh  Mui-Keng Tan 《Plant pathology》2021,70(8):1779-1789

Karnal bunt, a disease of wheat, durum, rye, and triticale, is subject to strict quarantine restrictions worldwide. The disease is considered a major threat to food security, due to its use as a non-tariff trade barrier by several wheat-importing countries. In this paper, we analysed seven years of phenotypic data to search for quantitative trait loci (QTLs) associated with resistance in common wheat, validated the QTLs using an independent population, and assessed the potential of genomic selection as a tool for pre-emptive breeding. The QTL study used phenotypic data collected from artificially inoculated field experiments involving two historical Karnal bunt resistance populations: WH542 × HD29 and WH542 × W485. QTL analyses detected four significant (p < 0.001) QTLs on chromosomes 1A, 3A, 4B, and 6B, which explained between 13.7% and 15.7% of the phenotypic variation. A panel of 130 cultivars was used to validate QTL effects. These were genotyped with the same DArTseq protocol, and two of the four QTLs were significantly (p < 0.001) associated with Karnal bunt resistance in the validation panel. The potential of genomic selection was investigated by comparing accuracies of a model trained with all available markers and a model based solely on validated QTL information from the biparental populations. Genomic prediction accuracy, based on the two scenarios, averaged 0.43 and 0.33, respectively, suggesting that even in situations where phenotyping is difficult due to quarantine restrictions, the prospects for pre-emptive breeding against Karnal bunt are encouraging, and resources are now available that will reduce the cost burden.  相似文献   

Multifunctionality of paddy fields in Taiwan     

C. C. Huang  M. H. Tsai  W. T. Lin  Y. F. Ho  C. H. Tan 《Paddy and Water Environment》2006,4(4):199-204

Paddy rice is the staple food in Taiwan, where rice farming always plays an important role in agricultural activities. The paddy fields and irrigation activities hold diversified functions, such as production, eco-environmental and living-associated functions. This paper is to provide information regarding the potential magnitude and monetary value of seven functions of paddy fields in Taiwan, including flood mitigation, fostering water resources, preventing soil erosion, purifying water, cooling air temperature, refreshing atmosphere and recreation. For quantification of the above values, replacement cost method (RCM), contingent valuation method (CVM), and the travel cost method (TCM) are adopted. In addition, the ratio of monetary value and their rice production commodity value (R) was also estimated. The results indicated that the flood mitigation function had a monetary value of US$ 389 million each year, and the ratio to the rice production value R was estimated at 37%. Water resource fostering function was US$ 501 million and R at 47%; soil erosion reduction function was US$ 433 million and R at 41%; water quality purification function was US$ 3 million and R at 0.3%; cooling air temperature function was US$ 961 million and R at 91%; refreshing air function was US$ 196 million and R at 19%, health and recreation function was US$ 987 million and R at 93%, respectively. Due to the significant importance of these externalities, it is recommended that the government should properly take into account the multifunctionalities in policy making to ensure sustainable development of agriculture.  相似文献   

Determination of the magnitudes and values for groundwater recharge from Taiwan's paddy field     

Chen-Wuing Liu  Chih-Huang Tan  Cheng-Chang Huang 《Paddy and Water Environment》2005,3(2):121-126

Flooded paddy fields have many functions, including not only rice production, and ecological and environmental conservation. This work estimates the extent of paddy field infiltration in Taiwan by adopting a one-dimensional Darcy-based soil/water balance model SAWAH (Simulation Algorithm for Water Flow in Aquatic Habitats). A 10 cm thick plow sole layer with a hydraulic conductivity of 0.03 cm/day, coupled with the soil texture and irrigation data obtained from 15 irrigation associations, is used to estimate the volumetric amount of annual infiltration in Taiwan. Simulation results from SAWAH indicate that the plow sole layer controls the movement of infiltrated water, with a rate about 1.8 billion cubic meters annually. The estimated infiltration rate of 1.8 billion m³/yr comprises more than 40% of the annual infiltration recharge to ground water in Taiwan. Additionally, the amount of infiltration recharge to groundwater is equivalent to 20 billion Taiwan dollars NT$ (or 0.65 billion US$) while the yearly rice crop production is 35 billion NT$ (or 1.13 billion US$). It is evident that the infiltration from rice paddy is of great importance to the economy, environment, and water resources conservation in Taiwan.  相似文献   

丁酸钠对饮食诱导肥胖大鼠的作用     

朱涵  谭莎莎  杨虹  王凌 《浙江大学学报(农业与生命科学版)》2015,(2):195-200

为建立由高脂饲料诱导的肥胖易感(obesity-susceptible,OS)和肥胖抵抗(obesity-resistant,OR)大鼠模型,并探讨在高脂饲料中添加丁酸钠对二者的作用,给予SD(Sprague-Dawley)大鼠高脂饲料饲喂3周后依据其体质量增加量排序并再分组,上1/3作为OS组,下1/3作为OR组,继续给予高脂饲料喂养12周,OS大鼠体质量增加明显,体质指数、皮下脂肪、内脏脂肪和体脂肪含量以及血清总胆固醇、甘油三酯、低密度脂蛋白、瘦素与对照组比较显著增高,差异有统计学意义(P0.05),OR组各项指标与对照组比较在统计学上无显著差异(P0.05).按照此造模方法从饲喂高脂饲料第4周起,丁酸钠干预(obesity intervention with sodium butyrate,OI)组增加8 mmol/L丁酸钠生理盐水(0.9%氯化钠)溶液1 m L灌胃,1次/日;肥胖对照(obesity control,OC)组则用1 m L 0.9%氯化钠溶液灌胃,1次/日,共干预16周.结果表明:添加丁酸钠后,OI组大鼠体质量增加、体质指数、皮下脂肪、内脏脂肪和体脂肪含量以及血清总胆固醇、甘油三酯、低密度脂蛋白、瘦素与OC组比较均显著改善,差异有统计学意义(P0.05).说明SD大鼠对于高脂饲料具有不同的应答能力,可获得肥胖敏感及肥胖抵抗模型;对于高脂饮食敏感的SD大鼠,在其高脂饲料中添加丁酸盐能够改善其体质量增加与体质指数,减少体脂肪含量,降低血脂与血清瘦素水平.  相似文献