混合方式对泡沫砂与土壤混合均匀性的影响

通过设置常规混合+风干态泡沫砂(CK)、常规混合+水浸态泡沫砂(1T)、常规混合+泥浆态泡沫砂(2T)、分层混合+风干态泡沫砂(3T)和分层混合+水浸态泡沫砂(4T) 5个处理,研究了不同混合方式对泡沫砂和土壤混合均匀性的影响,并采用容重的标准差和变异系数表征混合均匀性。结果表明:泡沫砂形态显著影响了混合均匀性。采用常规混合时,水浸态泡沫砂显著增加了0～10 cm和0～20cm土层混合均匀性,容重的标准差比风干态泡沫砂分别降低了188%和105%,容重的变异系数分别降低了62.1%和50.1%;与风干态泡沫砂相比,泥浆态泡沫砂不仅显著降低了不同土层的混合均匀性,还显著降低了混合物内部的混合均匀性,0～10 cm土层容重的标准差和变异系数分别比10～20 cm土层显著增加68.1%和50.8%。单变量分析表明,混合方式对混合均匀性无显著性影响,混合方式和泡沫砂形态之间无交互效应,泡沫砂形态是影响泡沫砂和土壤混合均匀性的主要因素。采用水浸态泡沫砂在常规混合方式下与土壤混合,不仅提高了混合物整体以及不同土层的混合均匀性,而且还降低了不同层次之间混合均匀性的差异。因此,建议采用常规混合+水浸态泡沫砂的方式混合土壤和泡沫砂。     

生物炭和无机肥对盐碱滩涂围垦农田土壤性状的影响

在重度盐碱滩涂围垦的土地上,添加不同量的生物炭(0、3、6、9 hm~(-2)),在玉米不同生育期施加无机肥,对照CK不施肥,研究土壤在不进行作物种植下的性状变化。结果表明:自然条件下重度盐碱土地土壤物理性状变差,施用无机肥加剧了土壤的退化程度;在未种植作物条件下,生物炭添加没有对降低土壤容重起到促进作用,同时也没有提高土壤饱和含水量及田间持水量;团聚体组成分析显示生物炭用量在3 t hm~(-2)时土壤中2 mm团聚体增加最多;雨季时雨水淋洗显著降低土壤0~20 cm土层盐分,生物炭用量越大土壤盐分淋洗效果越明显;八月份和九月份时随着雨季结束,地下水位升高、太阳辐射增强加速了盐分在表层土壤的积聚,生物炭添加能有效抑制盐分在表层的积累,但无机肥添加又阻碍了这种抑制作用。     

Moisture conservation for rainfed wheat production with alternative mulches and conservation tillage in the hills of north-west India

In the hills of north–west India, maize (Zea mays L.)-wheat (Triticum aestivum L.) is the dominant cropping system. However, rainfed wheat suffers from lack of optimum moisture at sowing. Field experiments were conducted for 3 years on a silty clay loam (Typic Hapludalf) to evaluate the effectiveness of mulches and conservation tillage for rainfed wheat in mitigating this problem. The treatments were ten factorial combinations of five mulch-tillage practices and two nitrogen levels (N₆₀ and N₁₂₀ kg ha⁻¹). Mulch treatments consisted of application of 10 Mg ha⁻¹ (dry weight basis), to previous standing maize, of either wild sage (Lantana camara L.) or eupatorium (Eupatorium adenophorum Sprengel) in combination with either conventional or conservation (minium) tillage prior to wheat sowing. These alternative practices were compared to the conventional farmer practice of soil tillage after harvest of maize with no mulch. The application of these weed mulches to standing maize maintained friable soil structure owing to a five fold higher mean population of earthworms underneath mulch. Mulches resulted in 0.06–0.10 m³ m⁻³ higher moisture in the seed-zone when wheat was sown compared with the conventional farmer practice of soil tillage after maize harvest. Mulch-conservation tillage treatments favourably moderated the hydro-thermal regime for growing a wheat crop. The mean root mass density under these treatments at wheat flowering was higher by 1.27–1.40 times over the conventional farmer practice during the 3 year study. Conservation tillage holds promise because it does not require elaborate tillage and may ultimately reduce animal draught in the hilly regions. Recycling available organic materials having no fodder value coupled with conservation tillage may help enrich the soil environment in the long-term. The practice also offers gainful use of these obnoxious weeds that cause great menace in grass and forest lands in the region.     

耕层土壤颗粒表面的分形维数及其与主要土壤特性的关系

四川 1 6个耕地表层的土壤颗粒表面分形维数D为 2 80 5～ 2 942 ,其中砂土2 82 1、壤土 2 870、粘壤土 2 91 6和粘土 2 939。统计分析表明D分别与国际制粗砂粒和细砂粒含量呈极显著负相关 ,与粉粒和粘粒含量呈极显著正相关 ;它与粉粒、粘粒和有机质含量的偏相关关系达极显著水平 ,与容重的偏相关关系达显著水平     

Efficiency and energy use in puddling of lowland rice grown on Vertisols in Central India

Transplanting of rice seedling in puddled soil is one of the most widely used cultivation practices. The present research is aimed at determining what specific implements are needed to obtain optimal puddle bed for transplantating. Puddling experiments were carried out by the use of pair of bullocks with traditional country plough (T₁), pair of bullocks with lug wheel puddler (T₂), power tiller with rotary puddler (T₃), tractor with cage wheel and 9-tine cultivator (T₄) and tractor with cage wheel and rotavator (T₅). One summer ploughing was done at friable moisture condition (18.6% db) and then tilled soil was flooded to saturation (24 h) for preparation of puddled bed. Weeding efficiency, puddling depth, percentage increase in bulk density, puddling index, percolation rate and grain yield of paddy were studied for the above treatments. Puddling performance by different implements in comparison to the traditional animal drawn country plough (T₁) shows that there is a definite reduction in time requirement for field preparation. Increase in weeding efficiency, bulk density, grain yield and puddling index were also observed. The highest values of weeding efficiency and puddling index were found 98.6% and 79.3, respectively, for rotavator (T₅). The total time requirement for preparation of puddle field for treatment T₄ (tractor with cultivator) was found to be the lowest (9.4 h ha⁻¹) with 67% weeding efficiency and 62.7 puddling index as compared to all other alternatives tested. Energy requirement for preparation of puddle field was found highest (2390 MJ ha⁻¹) for rotavator (T₅) followed by T₃, T₄, T₁, and T₂ treatments.     

烘烤工艺、成熟度和取样方式对烤后烟叶多酚的影响

测定了2种烘烤工艺、3个成熟度和2种取样方式对烤烟品种翠碧1号(CB-1)中部叶烤后多酚含量的影响.结果表明,成熟度和烘烤工艺对烤后烟叶多酚含量都有极显著的影响.随着成熟度的提高,多酚含量显著加大.在取样方式上,同一处理混合样多酚含量均高于C3F,在慢烤工艺下的差异不显著,在快烤工艺下的差异极显著(P＜0.01).     

生物质能在密集烤房上应用现状和发展方向

为探究烟叶密集烘烤中经济性和实用性较强的生物质能源,笔者归纳了当前密集型烤房上使用较多的气体、液体、固体生物质能源的应用现状,在总结了3种生物质能源对烟叶烘烤质量影响和能源转化设备技术成熟度的基础上,依据经济性和实用性分析了3种生物质能在密集烤房上应用所具有的优势和局限。最后得出固体生物质颗粒燃料是当前和今后密集烤房应用前景中最好的一种生物质能,指出未来应从加强原料配方研究、持续提升颗粒燃料燃烧机技术改进、并融入大农业物联网技术以实现精准烘烤。     

热压温度和养护时间对快速固化水泥刨花板性能的影响

以定向刨花板厂的大片杨木刨花经简易粉碎设备粉碎分选得到的刨花和42.5强度等级的普通硅酸盐水泥为原料,Na2SiO3为添加剂,通过热压制板的方法,研究了热压温度和养护时间对快速固化水泥刨花板性能的影响。结果表明:①在85~95℃范围内,热压温度对厚板(20 mm)的物理力学性能无显著影响,而对薄板(12 mm)的弹性模量和吸水厚度膨胀率影响显著。②水泥刨花板卸出压机后的自然养护时间对快速固化水泥刨花板物理力学性能的影响主要取决于板在养护期间水泥的水化情况。厚板卸出压机后的含水率高,养护期间水泥水化好,养护时间对性能的影响显著;薄板卸出压机后含水率低,养护期间水泥水化不如厚板好,养护时间对性能无显著影响。表7参10     

烤烟烘烤过程中叶片膜脂过氧化特性的研究

采用温湿度自动控制电热烤烟箱，研究了烘烤过程中烟叶膜脂过氧化及其内源保护酶活性的变化。结果表明，随烘烤时间延长，叶内超氧物歧化酶（ＳＯＤ）和过氧化物酶（ＰＯＤ）活性下降，丙二醛（ＭＤＡ）含量增加。烘烤４８ｈ和７２ｈ后，两种酶先后失活，ＭＤＡ积累达最大值，证明烟叶烘烤过程中叶片膜脂过氧化水平不断提高。不同处理以高温快烤烟叶膜脂过氧化水平最高，低温慢烤最低。而且变黄温度对烟叶膜脂过氧化的作用比定色期不同升温处理的作用大。     

DSC法研究水分含量对低分子量MUF树脂固化特性的影响

  目的  探究水分含量对低分子量三聚氰胺脲醛（MUF）树脂溶液固化特性的影响,为阐明树脂浸渍材在不同干燥阶段、不同空间层位中的树脂固化特性提供数据支撑。  方法  以实验室自制的MUF树脂溶液为研究对象,将其稀释成20%、30%、40%、50%后进行升温差示扫描量热测试（DSC）,通过外推法消除升温速率对峰顶温度的影响,拟合求解其最佳固化温度,定性阐述水分含量对MUF树脂固化特性的影响,并运用Kissinger微分法和Flynn-Wall-Ozawa积分法计算20%、30%、40%、50%树脂溶液固化反应的表观活化能,定量分析水分对树脂固化特性的影响。  结果  随着MUF树脂溶液质量分数的降低,DSC曲线中峰顶温度整体上呈现向高温方向偏移的趋势,但是在升温速率15和20 ℃/min条件下,20%树脂溶液DSC曲线的峰顶温度峰位置向低温区域发生了偏移;通过外推法得到的20%、30%、40%、50% MUF树脂溶液的最佳固化温度分别为93.99、90.71、85.46和79.71 ℃;运用Kissinger微分法计算得到其表观活化能分别为92.94、82.37、65.93和50.68 kJ/mol,其结果与Flynn-Wall-Ozawa积分法验算结果相近。  结论  整体上,消除升温速率的影响后,水分对树脂固化反应起阻碍作用,并且水分越多,阻碍效应越明显;但在较高升温速率（15和20 ℃/min）条件下,20%MUF树脂溶液的DSC测试结果表明水分促进树脂固化反应,这可能是由分子运动加剧造成的。