Describing Polygonum aviculare emergence in different tillage systems

Effects of four tillage systems (direct drill, subsoiler, chisel plough and mouldboard plough) on the dynamics of Polygonum aviculare populations were studied over three growing seasons. Cumulative emergence on a weekly basis was determined. Cumulative emergence from two years of chisel ploughing was used to develop an emergence model for P. aviculare based on hydrothermal time. Results showed that direct drilling, which had the highest seed yields of winter cereal crops every season, was the unique soil management system that lowered P. aviculare populations because of effective weed emergence reduction. The model accurately described seedling emergence in different tillage systems, although it failed in direct drilling, probably due to very low numbers of emerged seedlings. To better control this weed, direct drilling may be the best tillage option, but if this cannot be implemented, the hydrothermal time model is a practical tool that can describe the relative proportions of emergence and assist in the timing for management operations of P. aviculare in different tillage systems.     

Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils

The concept of degree of compactness (DC), referred to as field bulk density (BD) as a percentage of a reference bulk density (BD_ref), was developed to characterize compactness of soil frequently disturbed, but for undisturbed soil such as under no-tillage critical degree of compactness values have not been tested. The objective of this study was to compare methods to determine BD_ref and limits of DC and BD for plant growth under no-tillage in subtropical soils. Data from the literature and other databases were used to establish relationships between BD and clay or clay plus silt content, and between DC and macroporosity and yield of crops under no-tillage in subtropical Brazil. Data of BD_ref reached by the soil Proctor test on disturbed soil samples, by uniaxial compression with loads of 200 kPa on disturbed and undisturbed soil samples, and 400, 800 and 1600 kPa on undisturbed soil samples, were used. Also, comparisons were made with critical bulk density based on the least limiting water range (BDc LLWR) and on observed root and/or yield restriction in the field (BDc Rest). Using vertical uniaxial compression with a load of 200 kPa on disturbed or undisturbed samples generates low BD_ref and high DC-values. The standard Proctor test generates higher BD_ref-values, which are similar to those in a uniaxial test with a load of 1600 kPa for soils with low clay content but lower for soils with high clay content. The BDc LLWR does not necessarily restrict root growth or crop yield under no-tillage, since field investigations led to higher BDc Rest-values. A uniaxial load greater than 800 kPa is promising to determine BD_ref for no-tillage soils. The BD_ref is highly correlated to the clay content and thus pedotransfer functions may be established to estimate the former based on the latter. Soil ecological properties are affected before compaction restricts plant growth and yield. The DC is an efficient parameter to identify soil compaction affecting crops. The effect of compaction on ecological properties must also be further considered.     

小麦垄作高效节水技术应用与探讨

结合当地光热资源实际,应用小麦垄作高效节水技术设计了小麦垄作套种玉米栽培试验,旨在为高产高效栽培提供新途径。试验结果表明,小麦垄作套种玉米栽培条件下,单产提高33.0%～35.8%,水分利用效率提高9kg/mm·hm^2,肥料利用效率提高4.60%～4.94%。     

玉米喷施大民先锋生物肥肥效试验

研究了玉米不同生育期叶面喷施大民先锋生物肥,对玉米全生育期、主要经济性状和产量的影响。结果表明：喷施生物肥可延长玉米全生育期,改善玉米主要经济性状和提高产量 相同施肥量条件下,在幼苗期、大喇叭口期和抽雄期各喷施1次的效果最好。     

晋中晚熟冬小麦“窄行稀条播”的群体质量和产量效应

针对晋中晚熟冬小麦群体质量不高、水肥利用率低等问题,以大穗型品种山农9-1和多穗型品种山农9801为材料,在不改变播量和水肥投入的情况下,探讨了窄行稀条播种植模式(行距10 cm)对冬小麦群体和产量的影响。结果表明,与常规条播种植(行距20 cm)相比,窄行稀条播极显著提高了小麦产量,其中山农9801增产幅度大于山农9-1;山农9-1增产原因是穗粒数、千粒重、成穗数都显著提高,而山农9801是成穗数和穗粒数分别极显著和显著提高。窄行稀条播增加了各个生育阶段的群体数量,提高了分蘖成穗率和叶面积系数,而且延长了叶片功能期。说明窄行稀条播种植模能改善晋中晚熟冬小麦群体数量和质量,进而起到增产作用。     

液压进给型数控钻床排孔钻削研究

针对主轴为液压进给型的数控平面钻床不能调用系统自带的排孔钻削循环(G81、G83)的问题,通过编制宏程序,解决了排孔钻削难题。同时,结合钢结构产品中连接板的加工特点,通过引入参数化编程和内置坐标变换指令,使钻孔零件仅需给机床系统参数赋值后,执行预存的宏程序,即可完成零件的钻孔加工。     

空间喷孔单回转钻模研究

通过对国产长型喷油嘴加工现状的思考研究和对Zck01-02喷油嘴针阀体球头部及其位置的剖析,研究出单回转钻模的设计新方案,并对该方案在喷油嘴针阀体上喷孔加工的可行性进行详细论证,从而实现单回转钻模替代国外进口设备,达到节约投资的目的。     

麻类产业体系栽培与耕作功能研究室“十二·五”发展规划研讨会在中科院亚热带所召开

本文以习惯全层施肥为对照,借助机械精量穴直播定位深施肥机具,研究了超级杂交早稻机械精量穴直播与缓释肥一次性定位深施技术配套对超级杂交早稻生长、产量和氮肥利用效果的影响。结果表明:水稻在精量穴直播条件下,缓释复合肥机械定位深施肥有利于保持水稻生长后期的养分稳定供应,缓释复合肥机械定位深施肥比习惯全层施肥(对照)处理增产630kg/hm2-924.75kg/hm2,增幅10.3%-16.5%,增产效果明显,氮肥农学利用率提高4.2￣7.9 kg/kg N,增幅29.0%￣51.2%;氮素利用率绝对值提高17.3%,增幅42.6%;氮收获指数增加9.0%。     

MJS水泥土的试桩成桩效果分析

以南京地铁7号线中胜站全断面承压含水砂层MJS加固下穿既有运营10号线车站工程为背景,基于试桩芯样对MJS水泥土试桩成桩效果进行研究,研究不同桩型、不同水泥掺入比、不同地层下各部位MJS水泥土试桩的成桩效果(加固范围、成桩质量、抗压强度、弹性模量、水泥含量),并与室内MJS水泥土强度数据比较.结果表明:全圆桩整体成桩效...