土壤施硅对小麦和麦蚜的影响

为明确土壤施硅对小麦蚜虫的防控效果，本研究在小麦种植前分别配施0（CK）、40、80和120 kg/hm²四个浓度的硅肥，测量施硅后小麦生育期、生物量、叶面积、株高、产量指标以及荻草谷网蚜Sitobion miscanthi和禾谷缢管蚜Rhopalosiphum padi发生量。结果表明，施硅对小麦株高和穗数无显著影响，但80 kg/hm²和120 kg/hm²浓度施硅处理后小麦叶面积分别为1 786.03 mm²和2 033.54 mm²，生物量分别为133.68 g和134.50 g，小麦穗粒数分别为35.61粒和35.92粒，小麦千粒重分别为45.34 g和45.59 g，小麦产量分别为9 684.45 kg/hm²和9 835.05 kg/hm²，均显著高于对照，且小麦成熟期较对照提前3 d；80 kg/hm²和120 kg/hm²浓度施硅处理后禾谷缢管蚜发生量分别为90头和86头，均显著低于对照；40、80和120 kg/hm²浓度施硅处理后荻草谷网蚜发生量分别为128、117和105头，均显著低于对照。因此，田间土壤施硅80 kg/hm²和120 kg/hm²可以明显改善小麦农艺性状，提高小麦产量，并能减少麦蚜发生量。     

Predicting Carbon Stocks Following Reforestation of Pastures: A Sampling Scenario‐Based Approach for Testing the Utility of Field‐Measured and Remotely Derived Variables

Reforestation of agricultural lands is an important means of restoring land and sequestering carbon (C). At large scales, the labour and costs of direct measurement of ecosystem responses can be prohibitive, making the development of models valuable. Here, we develop a new sampling scenario‐based modelling approach coupled with Bayesian model averaging to build predictive models for absolute values in mixed‐species woody plantings and differences from their adjacent pasture, for litter stocks, soil C stocks and soil C:N ratios. Modelling scenarios of increasing data availability and effort were tested. These included variables that could be derived without a site visit (e.g. location, climate and management) that were sampled in the adjacent pasture (e.g. soil C and nutrients) or were sampled in the environmental planting (e.g. vegetation, litter properties, soil C and nutrients). The predictive power of models varied considerably among C variables (litter stocks, soil C stocks and soil C:N ratios in tree plantings and their differences to their adjacent pastures) and the model scenarios used. The use of a sampling scenario‐based approach to building predictive models shows promise for monitoring changes in tree plantings, following reforestation. The approach could also be readily adapted to other contexts where sampling effort for predictor variables in models is a major potential limitation to model utilization. This study demonstrates the benefit of exploring scenarios of data availability during modelling and will be especially valuable where the sampling effort differs greatly among variables. Copyright © 2016 John Wiley & Sons, Ltd.     

Carbon Fluxes from Different Pools in a Mined Area under Reclamation in Minas Gerais State,Brazil

Despite the benefits of grass cultivation and organic fertilization in mining areas undergoing reclamation, these practices may be associated to CO₂ emissions and soil organic matter (SOM) losses by priming effect. In the present study, we evaluated the changes on SOM pools and C–CO₂ emissions in a bauxite‐mined area under reclamation fertilized with poultry litter (PL) (0, 10, 20, and 40 Mg ha⁻¹) and cultivated with Brachiaria brizantha . Increases of about 3·5 times in the soil labile C were observed 1 year after experiment establishment. High C–CO₂ fluxes and a significant positive priming effect were observed in the presence of B. brizantha , increasing native C mineralization by nearly 4·9 times. Nevertheless, no net soil C loss was detected, probably because of the C inputs derived from B. brizantha , which offset these losses. In fact, the grass increased total organic C by 45% when fertilized with 40 Mg PL ha⁻¹. The data obtained suggest that the cultivation of B. brizantha fertilized with PL can be a promising option for rapid recovery in SOM in areas under reclamation. Copyright © 2016 John Wiley & Sons, Ltd.     

土壤养分数据几种特异值处理方法的比较

利用贵州省平坝县马场镇栗木村的13项土壤养分测试数据,对比分析了3σ准则、估计邻域法、影响系数法、邻近点数据比较法4种识别与处理特异值方法的优劣。结果表明:将3σ准则与邻近点数据比较法相结合,对土壤养分测试数据进行特异值处理获得了较好的效果,对提高地质统计学研究结果的精度有积极的作用。     

Chemical composition and in sacco dry matter degradability of residue and by-products of palm fruit processing in the rumen of steers

The nutritive value of residue (palm calyx leaves (PCL)) and by-products (palm press fiber (PPF) and palm oil sludge (POS)) of palm fruit processing were studied through analysis of their chemical components and degradability of their dry matter (DM) in the rumen of steers. Chemical analysis showed that the materials have similar organic matter components (mean = 95.2%), while crude protein (CP, g/100 g) and metabolisable energy (ME, MJ/kg DM) were highest in POS (10.02 and 9.43), followed by PPF (7.02 and 8.61) and least in PCL (5.42 and 8.04). An opposite trend of CP and ME was noticed in NDF and ADF contents, being 61.53 and 49.11% in PCL, 44.84 and 32.08% in PPF and 25.35 and 20.29% in POS. Mineral contents showed that PPF and POS had the lowest and highest concentration, respectively, of Mg (0.07 vs. 0.11%), Cu (58.5 vs. 143.9 mg/kg) and Fe (1374.5 vs. 4086.0 mg/kg). Dry matter degradation characteristics and effective degradability varied significantly ( P  < 0.05) and were consistently highest in POS and least in PCL. Results have generally shown that the residue and by-products could be ranked for their potential feeding value as POS > PPF > PCL. It is concluded that POS and PPF can be harnessed directly as feed resources for ruminant animals, while PCL will require some treatments to enhance its nutritive value in ruminants.     

Complexities Surrounding China's Soil Action Plan

China's soil pollution is serious, with 16·1% of all soil samples exceeding soil quality standard according to a national soil quality survey. On 31 May 2016, the Chinese government unleashed an ambitious plan to address its soil pollution problem. The large scale and fast pace of the proposed plan pose many challenges. There are biogeochemical complexities governing the fate and transport of soil contaminants that require more thorough study. There are also human‐related complexities and dynamic feedback loops, which determine the behaviour of farmers, industrial polluters, remediation practitioners and regulators. Soil pollution prevention and remediation also have externalities and spillover effects ranging from greenhouse gas emission to social justice. Rigorous policy instruments must be developed to account for complex human behaviour, to strengthen risk management and to encourage interdisciplinary scientific research. Copyright © 2017 John Wiley & Sons, Ltd.     

水保林水源涵养与防止侵蚀效益评价信息系统

密云水库上游水源保持林水源涵养与防止土壤侵蚀效益评价信息系统是以管理信息系统理论为指导，按照信息系统的设计流程研制开发的，为水源保护林水源涵养与防止土壤侵蚀效益评价及预测的专题性系统。     

控制土壤含水量对蔬菜产量及露地菜田水分渗漏量的影响

【目的】通过揭示不同土壤含水量对蔬菜产量及蔬菜地土壤水分渗漏量的影响,为蔬菜生产中合理灌溉提供指导。【方法】通过3年田间试验,利用TDR连续监测土壤含水量,运用田间定位通量法计算土体水分渗漏量,分析不同水分处理下蔬菜产量和土体水分渗漏量之间的差异。【结果】传统水分处理下蔬菜地水分累积渗漏量为982mm,其中蔬菜生长期内累积渗漏量为748mm,占蔬菜生长期内供水量的36%;优化水分处理和充分水分处理下蔬菜地水分累积渗漏量230mm和468mm,其中蔬菜生长期内水分累积渗漏量分别144mm和293mm,占各处理下供水量的9%和17%。除2002年优化和充分水分处理下花椰菜产量高于传统水分处理下花椰菜产量并达到显著水平外,其余年份蔬菜产量并无显著差异。【结论】保持土壤含水量在蔬菜生长有效土壤含水量50%～80%的优化水分处理在蔬菜生产中有很大的推广价值。     

湘南三种典型红壤生土长期施肥对作物产量的影响

以长期定位试验为基本材料,研究了湘南3种典型红壤生土25年长期施肥对作物产量的影响。结果表明:(1)25年作物累计产量以紫色土为最高,其次是花岗岩红壤,第四纪红壤最低。(2)3种母质生土熟化过程中,对于不同处理,平衡施用氮磷钾化肥处理,均能获得较高作物产量,显著高于施用有机物料稻草处理,显著高于对照处理。施肥是加速红壤母质熟化的主要途径和方法。(3)对于不同处理方式,作物归还条件下其作物产量要高于不归还。(4)供试的3种土壤在熟化的过程中对植被的影响非常明显,在熟化的初期,许多作物在花岗岩发育的和第四纪红土发育的土壤上,都生长不好,然而在施有NPK的处理中,马唐草(Dischaemum Schreb)生长特别茂盛(覆盖度100%,高lm),明显地影响了土壤的水热状况,紫色土上马唐草生长不好。(5)种植小麦和黄豆,花岗岩、四纪红土NPK处理靠小区水泥梗边缘要好,小区中间95%部分长势差,叶片淡黄,植株矮小。(6)花岗岩红壤和第四纪红壤二种母质熟化24年后(即2005年)种植豆科作物—黄豆和禾本科作物小麦(2006年),其作物产量均表现为:0M>NPK。     

基于MGWRK的土壤有机质制图及驱动因素研究

【目的】空间预测是一种获得有机质空间局部细节的重要方法,其准确性对于农田合理管理有着重要意义。本研究通过对比不同的土壤有机质空间制图方法以获得更优的预测精度,在预测的同时揭示环境协变量的空间非平稳性特征及不同环境协变量关系的空间尺度。【方法】选取晋中盆地的7个乡镇作为研究区,对比普通克里金（OK）、回归克里金（RK）、地理加权回归克里金（GWRK）和多重尺度地理加权回归克里金（MGWRK）4种不同方法对土壤有机质的预测能力和效果,并探究影响因子在空间分布中对有机质的影响效应变化和这种影响效应的空间尺度。MGWRK是一种多重尺度地理加权回归（MGWR）与普通克里金方法相结合的方法。【结果】选取坡向、坡度、年均降水量、年平均温度、海拔、植被年总初级生产力、年蒸散量、地形湿度指数、平面曲率、汇流动力指数、地形指数、地形粗糙指数、年平均NDVI为环境协变量参与建模,在多元线性回归建模中,模型统计学意义显著,这表明模型具备统计学意义。从Radius指数来看,各模型模拟效果由好到差依次为RK、OK、GWRK、MGWRK;从制图效果来看,MGWRK与GWRK制图效果相当,从有机质的空间预测图可以看出,土壤有机质在研究区呈现东西两侧偏低、中部偏高的空间格局,其中汾河以东、昌源河流经区域土壤有机质普遍偏高。坡向、年均降水量、年平均温度、海拔、地形指数、年平均NDVI对研究区东部有机质的影响强于西部,而坡度、植被年总初级生产力、年蒸散量、平面曲率、汇流动力指数、地形粗糙指数则表现出截然相反的空间非平稳性特征,地形湿度指数对有机质的影响则体现为北部强南部弱。【结论】MGWRK方法的空间预测精度分别达到了RK方法的69%、OK方法的71.74%、GWRK方法的71.17%。MGWRK在空间非平稳性特征的解释能力和空间可视化表现良好,为有机质的预测和空间非平稳性特征的描述提供方法借鉴。