化肥减氮及有机肥配施对水稻产量及土壤养分含量的影响

本文旨在研究等磷、钾量条件下，化肥减氮及有机肥不同用量配施对水稻产量及土壤养分的影响，试验共设6个处理，分别为T1∶80%N+20%有机肥；T2∶80%N+40%有机肥；T3∶70%N+60%有机肥；T4∶70%N+80%有机肥；T5∶60%化肥+100%有机肥；CK：100%N+0，对水稻生育期株高、群体动态、产量、构产因子以及秋季土壤养分含量进行分析，结果表明：1化肥减氮20%时，不会对水稻造成明显减产，且当有机肥配施量为500kg·mu-2时，水稻籽粒产量最高，为775.19kg·mu-2，比CK增产17.20%；2有机肥的施用能提高水稻基本苗，对水稻穗长有显著提高效果，对空秕率影响较大，对枝梗数影响最小；3化肥减氮+有机肥配施可以提高土壤肥力，增加土壤有机质含量，提高土壤碱解氮、速效钾含量。     

河北省土壤有机质时空变化分析

采用BP神经网络和地统计方法,对1980~2009年间河北省耕地土壤有机质时空变化规律及影响因素进行对比分析。结果表明:河北省耕地土壤有机质具有西北高东南低的格局;随着时间的推移,有机质总体呈现上升趋势。1980年的低值区域到了2009年SOM上升变化明显,成为热点;北部坝上、西部太行山区及东部沿海地区到2009年SOM含量下降,成为冷点。分析表明,这种变化格局的形成与施用有机肥、实施秸秆还田等社会经济过程有关。本研究为预测有机质变化趋势、改善土壤质量、优化种植结构和耕地的可持续发展提供了一定依据。     

施肥方式对沃柑果实产量和外观品质的影响

为验证沃柑测土配方施肥的效果,推进化肥减量增效,探究有机肥、中微量元素肥料与化肥配施对沃柑果实产量和外观品质的效应,在沃柑园设置随机区组小区精确试验,试验处理包括当地习惯施肥、测土配方推荐施肥、优化施肥、优化施肥兼叶面喷施0.2%硼酸、优化施肥兼叶面喷施0.05%钼酸铵、优化施肥兼叶面喷施4%硫酸镁。结果表明,测土配方推荐施肥相较于习惯施肥增产效果显著。在同等养分施用量的情况下,用有机肥代替部分化肥处理与全化肥处理比较产量无显著差异,但前者比后者增效4.03%。在土壤交换性镁贫乏的情况下,沃柑叶面施镁可以获得极显著而稳定的增产效果。在土壤不缺硼的情况下,叶面施硼可能无效。在土壤有效钼不足时沃柑叶面施钼能够增产,但连年施用效果不稳定。由此可见,伴随果实外观品质的提升,化肥减量增效在沃柑生产上是可行的;沃柑施肥的增产潜力较大,如果配方和选材得当,可以发挥更大效益。     

不同包膜肥用量对油菜碳氮代谢产物和产量的影响

为研究包膜肥在直播早熟油菜上的应用效果,采用田间小区试验,探究不同用量包膜肥对‘湘杂油1613’碳氮代谢和籽粒产量的影响。结果表明,施肥量相同条件下,施用包膜肥油菜碳氮代谢活跃,叶绿素含量(SPAD)升高,可溶性糖和游离氨基酸总量增加,含量差异不明显;单株有效分枝数和角果数明显增加,每角果粒数和千粒重小幅提高。施用包膜肥增产效果明显,包膜肥施肥量为1500 kg/hm~2时产量最高,达到2066.9 kg/hm~2。通过拟合建模,包膜肥用量为1611.0 kg/hm~2时,产量达到最高为2164.9 kg/hm~2;而普通肥的用量为1870.5 kg/hm~2时,最高产量为1904.8 kg/hm~2,包膜肥产量增加13.6%,同时用量减少13.9%。     

农产品中白藜芦醇的高效液相色谱标准化测定方法研究

旨在建立同时测定花生衣、葡萄皮、苜蓿、虎杖、藜芦等农产品中白藜芦醇含量的高效液相色谱标准化测定方法。色谱分析条件如下:以Waters Atlantis T3-C18色谱柱(4.6×150mm,3μm)分离,柱温40℃;以乙腈:0.1%乙酸溶液(体积比为26:74)为流动相,流速1.0 mL/min;采用二极管阵列检测器,检测波长306 nm。花生衣、葡萄皮、苜蓿中白藜芦醇含量的检出限均为0.6μg/g,定量限均为2.0μg/g;虎杖、藜芦中白藜芦醇含量的检出限均为7.5μg/g,定量限均为25μg/g。方法学考察结果显示符合含量测定要求。该方法操作简便、快速,结果可靠,重现性好,可用来研究农产品中白藜芦醇的含量。     

基于霍尔效应的微小压强测量装置的设计与实现

针对化工液体的微小压强测量中所存在的测量复杂、精度低的问题，设计一种基于霍尔效应的测量流体微小压强变化的装置。该测量装置通过前端受力装置来承受液体压强的变化而产生一定的位移，并转换成霍尔电动势，经放大调理电路，最后接电压表显示相应的电压值。根据输出电压与液体压强之间的关系即可得到相应深度的压强大小。在实验中，电压表精确到1mV，最小可测量到0.792Pa的压强变化，其测量精度较高。该装置体积小、通用性强，具有较好的应用前景。     

Evaluating biodegradability of soil organic matter by its thermal stability and chemical composition

The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, and C sequestration. Hence, there is interest in developing new ways to quantify and characterise the labile and stable forms of SOM. Our objective in this study was to evaluate SOM under widely contrasting management regimes to determine whether the variation in chemical composition and resistance to pyrolysis observed for various constituent C fractions could be related to their resistance to decomposition. Samples from the same soil under permanent pasture, an arable cropping rotation, and chemical fallow were physically fractionated (sand: 2000-50 μm; silt: 50-5 μm, and clay: <5 μm). Biodegradability of the SOM in size fractions and whole soils was assessed in a laboratory mineralization study. Thermal stability was determined by analytical pyrolysis using a Rock-Eval pyrolyser, and chemical composition was characterized by X-ray absorption near-edge structure (XANES) spectroscopy at the C and N K-edges. Relative to the pasture soil, SOM in the arable and fallow soils declined by 30% and 40%, respectively. The mineralization bioassay showed that SOM in whole soil and soil fractions under fallow was less susceptible to biodegradation than that in other management practices. The SOM in the sand fraction was significantly more biodegradable than that in the silt or clay fractions. Analysis by XANES showed a proportional increase in carboxylates and a reduction in amides (protein) and aromatics in the fallow whole soil compared to the pasture and arable soils. Moreover, protein depletion was greatest in the sand fraction of the fallow soil. Sand fractions in fallow and arable soils were, however, relatively enriched in plant-derived phenols, aromatics, and carboxylates compared to the sand fraction of pasture soils. Analytical pyrolysis showed distinct differences in the thermal stability of SOM among the whole soil and their size fractions; it also showed that the loss of SOM generally involved preferential degradation of H-rich compounds. The temperature at which half of the C was pyrolyzed was strongly correlated with mineralizable C, providing good evidence for a link between the biological and thermal stability of SOM.     

Environmental stress response limits microbial necromass contributions to soil organic carbon

The majority of dead organic material enters the soil carbon pool following initial incorporation into microbial biomass. The decomposition of microbial necromass carbon (C) is, therefore, an important process governing the balance between terrestrial and atmospheric C pools. We tested how abiotic stress (drought), biotic interactions (invertebrate grazing) and physical disturbance influence the biochemistry (C:N ratio and calcium oxalate production) of living fungal cells, and the subsequent stabilization of fungal-derived C after senescence. We traced the fate of ¹³C-labeled necromass from ‘stressed’ and ‘unstressed’ fungi into living soil microbes, dissolved organic carbon (DOC), total soil carbon and respired CO₂. All stressors stimulated the production of calcium oxalate crystals and enhanced the C:N ratios of living fungal mycelia, leading to the formation of ‘recalcitrant’ necromass. Although we were unable to detect consistent effects of stress on the mineralization rates of fungal necromass, a greater proportion of the non-stressed (labile) fungal necromass C was stabilised in soil. Our finding is consistent with the emerging understanding that recalcitrant material is entirely decomposed within soil, but incorporated less efficiently into living microbial biomass and, ultimately, into stable SOC.     

44个紫花苜蓿品种的酸铝适应性与耐受性评价

为了解紫花苜蓿在贵州地区的适应性及耐酸铝胁迫机理，以44份紫花苜蓿品种为研究对象，研究紫花苜蓿处于酸铝胁迫下的生理变化，并揭示其生理变化与耐酸铝胁迫间的关系。利用基因与环境互作模型对两个地点1年的紫花苜蓿进行产量分析，筛选出阿尔冈金、新疆大叶苜蓿、Trifecta、Vernal和中牧1号苜蓿5个耐酸铝强适应品种。利用敏感型UC-1465和耐受型阿尔冈金进行酸铝胁迫试验。结果表明：相同处理下，耐受型紫花苜蓿的电导率、相对铝含量、死亡率显著低于敏感型；紫花苜蓿对酸铝胁迫的响应主要通过柠檬酸、苹果酸、乙酸、酒石酸、反丁烯二酸和草酸的显著（P<0.05）增加来体现，其中苹果酸的合成和分泌增多可能是其耐酸铝胁迫的重要原因。     

钾肥减量分期施用对莴笋产量和品质的效应研究

通过大田试验研究了紫色菜园土壤钾肥减量分期施用对莴笋产量和品质的影响。结果表明：两个试验点钾肥减量10%~30%分期施用对莴笋产量有提高作用，各处理以K2（钾肥减量10%分期等量追施）效应最好，增产最大（4.2%和4.5%）、施肥利润最高（84923元/hm²和72075元/hm²）。两个试验点莴笋叶维生素C含量均呈下降趋势，K2处理较常规施肥(CK)处理均显著降低莴笋叶维生素C含量（8.0%和8.7%）；而莴笋茎维生素C含量变化规律不一致。钾肥减量分期施用降低两个试验点莴笋叶和茎硝酸盐含量，以K4处理（钾肥减量30%分期等量追施）降低作用最大；从莴笋叶和茎糖组分的均衡性看，以K3处理最好。钾肥减量分期施用对两个试验点莴笋叶必需氨基酸含量有显著增加作用，改善叶氨基酸品质性状，但降低莴笋茎必需氨基酸含量和品质性状；莴笋氨基酸品质性状以K4处理为最优，其次是K2处理。综合考虑莴笋产量和品质，紫色菜园土壤以K2处理（钾肥减量10%分期等量追施）最优。