The efficiency of nitrogen in cattle manures when applied to a double‐annual forage cropping system

The use of cattle manure (CM) for fertilization presents challenges for optimizing nitrogen (N) use. Our work aimed to assess N efficiencies, in a 6‐year experiment with three biennial rotations of four crops: oat–sorghum (first year) and ryegrass–maize (second year) in a rainfed humid Mediterranean area of Spain. Fertilization treatments included the following: control (no N), 250 kg mineral N ha^?1 year^?1 (250MN), three CM rates (supplying 170, 250 and 500 kg N ha^?1 year^?1) and four treatments where the two lowest CM rates were complemented with either 80 or 160 kg mineral N ha^?1 year^?1. Treatments were distributed randomly in each of three blocks. Maximum dry‐matter yield (~44–49 t ha^?1 rotation^?1) was achieved in the third rotation, and only the control and the 170CM yielded significantly less. Within the limitations of the EU Nitrate Directive, the N steady state supply of 170CM always requires a complement of mineral N (80 kg N ha^?1) to maximize N agronomic efficiency. The maximum N‐fertilizer replacement value (250CM vs. 250MN) was 0·67, without significant differences between the two treatments in other N‐related efficiency indexes, which indicates that plants took advantage of residual‐N effects. Nitrogen losses by leaching in the 250CM treatment were around 5–7% of the N applied. This reinforces the sustainability of manure recycling in long cropping seasons.     

湿热处理制备马铃薯抗性淀粉工艺优化

为获得湿热处理制备马铃薯抗性淀粉的最适工艺参数，以抗性淀粉得率为考察指标，研究淀粉含水量、湿热处理温度和湿热处理时间对抗性淀粉得率的影响。在单因素试验的基础上进行正交优化，确定了制备马铃薯抗性淀粉的最佳工艺条件为：淀粉含水量30%，湿热处理温度90 ℃，热处理时间90 min。在此条件下制得的抗性淀粉得率为26.63%。淀粉经过湿热处理后仍然保持偏光十字，为颗粒型抗性淀粉。     

亏缺灌溉对南疆棉花生长和水分利用的影响

针对南疆地区水资源短缺、作物水分利用效率低等问题,以棉花为试验材料进行田间小区试验,在棉花现蕾期、开花期以及结铃期分别设置3个亏缺灌溉水平(W₁:50%ET_c,W₂:65%ET_c,W₃:80%ET_c,ET_c为作物蒸发蒸腾量),以全生育期100%ET_c灌溉处理为对照(CK),研究膜下滴灌条件下,不同生育期亏缺灌溉对棉花生长、产量、氮素吸收和水分利用效率的影响.结果表明:现蕾期亏水对棉花株高、叶面积指数、地上干物质生长、氮素吸收和产量有不同程度的抑制效应,但复水后补偿效应显著,其中轻度亏水(W₃)在籽棉产量减少3.48%的条件下,WUE高达1.57 kg/m³,显著高于CK的1.48 kg/m³;开花期亏水,棉花的各项生长指标均有显著降低,复水后补偿效应不显著,不利于棉花生长发育;结铃期亏水对棉花地上干物质累积、氮素吸收和产量均有显著的抑制效应,但在W₂和W₃水平下,WUE均达1.51 kg/m³.综合考虑在保证棉花产量的同时达到节水增产的目的,可在棉花蕾期进行80%ET_c灌水,其他生育阶段实施充分灌溉,来控制营养生长,促进生殖生长,获得更高的水分利用效率.     

富锗酵母培养物对下笼蛋鸡肉品质、肠道菌群及结构的影响

本试验旨在研究富锗酵母培养物对下笼蛋鸡肉品质及肠道的影响。选取505日龄健康的海兰褐壳蛋鸡480只,随机分为4组,每组5个重复,每个重复24只鸡。对照组饲喂基础日粮,试验组在基础日粮中分别添加12、16、20 mg/kg的富锗酵母菌培养物。预试期7 d,正试期为42 d。结果表明:与对照组相比,12、16、20 mg/kg组腿肉的蒸煮损失分别降低45.2%、33.6%、39.7%(P<0.01),pH均高于对照组(P<0.01);16mg/kg组腿肌的亮度(L~*)低于对照组(P<0.05);12、16、20 mg/kg组腿肌的剪切力分别比对照组低44.13%、56.07%、50.60%(P<0.01);各试验组胸肌pH均高于对照组(P<0.01),16mg/kg组的pH高于12、20mg/kg组(P<0.05);与对照组相比,16mg/kg组乳酸菌数量升高(P<0.05);空肠中,各试验组的绒毛长度高于对照组(P<0.01);16、20 mg/kg组绒毛长度/隐窝深度高于对照组(P<0.01)。结果显示,日粮中添加富锗酵母培养物可以改善下笼蛋鸡小肠的形态结构和肠道菌群平衡,提高鸡肉品质,建议添加量为16 mg/kg。     

不同施氮量下覆膜滴灌玉米相对根长密度模型研究

为探明施氮量对宁夏引黄灌区覆膜滴灌玉米根长密度(RLD)的影响,设置5个施氮水平和1个对照(CK,不施氮与不覆膜)进行试验,测定玉米RLD,建立不同施氮量下相对根长密度(NRLD)模型,并加以检验。结果表明:不同施氮处理的玉米RLD分布区域均随土层深度的增加而减小,且大部分集中在0～20 cm土层;随着施氮量的增加,RLD分布区域明显扩大; NRLD分布满足三阶多项式函数模型,模拟曲线的决定系数R2为0.951,模型检验结果R2为0.845,均方根误差(RMSE)为0.248,拟合效果好,但该多项式模型不能保证NRLD在相对取样深度Zr为1时达到0,故对玉米NRLD分布多项式模型进行优化。优化模型验证结果显示,各施氮处理RMSE不大于0.308,CK、N0、N1、N2、N3和N4处理的标准化均方根误差分别为0.242、0.193、0.184、0.226、0.208和0.273,R2分别为0.903、0.953、0.920、0.944、0.962和0.898,具有较高的拟合度,解决了NRLD在Zr=1时达到0的问题。本研究可为宁夏引黄灌区膜下滴灌玉米NRLD分布拟合、根系养分吸收和施肥管理提供理论参考。     

长期施肥处理对双季晚稻叶绿素荧光特征及籽粒产量的影响

研究施肥模式对水稻叶绿素含量及荧光参数的调节作用,对提高水稻光能利用效率及籽粒产量具有重要意义。本研究以水稻品种赣929为试验材料,比较长期定位施磷钾肥(PK)、施氮磷钾肥(NPK)、等养分条件下70%氮磷钾肥配合施用30%有机肥(70F+30M)、50%氮磷钾肥配合施用50%有机肥(50F+50M)、30%氮磷钾肥配合施用70%有机肥(30F+70M)条件下水稻叶绿素荧光参数和产量变化特征。结果表明,水稻旗叶叶绿素含量从齐穗期到成熟期呈下降趋势,且表现为30F+70M50F+50M70F+30MNPKPK。水稻叶绿素荧光参数Fv/Fm随水稻生育期的推进呈降低趋势,其中PK处理Fv/Fm值最低,而施氮处理比不施氮处理Fv/Fm值增加了2.85%～4.18%。叶绿素荧光参数qL、ΦPSII在NPK处理中表现为齐穗期较高, 20 d之后显著降低;在50F+50M、30F+70M处理中表现为齐穗期较低, 20 d以后显著增加;在PK处理、70F+30M处理中一直处于较高水平。NPQ变化趋势与qL基本相反。ETR-PAR光响应曲线拟合结果表明, 70F+30M处理ETRmax、?和Ek值在齐穗期和20 d后值均最高。综合看来,等养分条件下配施30%有机肥具有最优的叶绿素荧光指标组合及籽粒产量;而配施超过50%有机肥由于前期热耗散增大使得用于光合作用的光能份额减少,而施用氮磷钾肥处理则由于后期的衰老使得光能利用效率下降。     

极端暴雨条件下黄土丘陵沟壑区土壤蓄水能力和入渗规律

黄土高原退耕还林还草工程实施后,下垫面环境条件的变化可能对流域水文过程、水文通量、水量平衡以及生态系统产生十分重要的影响。研究极端暴雨条件下剖面土壤蓄水能力和入渗规律,对于阐明流域产汇流过程和影响机制具有重要的科学价值。采用土壤墒情仪对陕北"7·26"特大暴雨事件下黄土丘陵沟壑区草地剖面土壤水分进行了实时动态监测,分析了极端暴雨条件下剖面土壤水分的动态变化和蓄水过程,利用Horton入渗模型模拟了剖面土壤水分湿润锋的运动过程,揭示了极端暴雨条件下剖面土壤水分的入渗规律。结果表明:(1)极端暴雨条件下,黄土丘陵沟壑区坡面草地不同深度层次土壤水分与降雨过程的响应不同,具有层次性和明显的滞后效应,其中,0～140 cm是影响该地区土壤水文过程的关键层次;(2)土壤水分再分配结束时,湿润锋最深深度达140 cm,土壤蓄水量达225.99 mm,较降雨前95.37 mm增加了1.37倍;(3)极端暴雨过程中湿润锋的运动随时间呈对数递减关系,其稳渗速率随容重增加而减小,呈指数函数递减;(4)极端降雨过程中该地区坡面草地的产流机制仍以超渗产流为主,对于揭示流域的产汇流机制和完善水文预报模型具有重要的科学意义。     

Sorghum extrusion process combined with biofortified sweet potato contributed for high iron bioavailability in Wistar rats

This study aimed to evaluate the effect of sorghum and sweet potato on the bioavailability of iron, gene expression of proteins involved in iron metabolism and the plasma antioxidant capacity in animals fed with whole sorghum grains processed by dry heat or extrusion, combined or not with sweet potato flour with high content of carotenoids. Five experimental groups were tested (n = 7): dry heat sorghum flour (DS); extruded sorghum flour (ES); whole sorghum flour + sweet potato flour (DS + SP); extruded sorghum flour + sweet potato flour (ES + SP) and positive control (FS). The evaluations included: hemoglobin gain, hemoglobin regeneration efficiency, gene expression of divalente metal transporter 1 (DMT-1), duodenal citochroma B (DcytB), ferroportin, hephaestin, transferrin and ferritin and total plasma antioxidant capacity (TAC). The ES + SP group showed higher (p < 0.05) expression of DcytB, ferroportin and hephaestin when compared to the control group. The DS group showed high (p < 0.05) expression of DMT-1 and the ES showed high mRNA expression of transferrin and ferritin. The changes in the sorghum physicochemical properties from extrusion process reduced the iron and phytate content, and increased the gene expression of proteins involved in iron metabolism, improving iron bioavailability. The combination of sweet potato and sorghum flour (dry or extruded) improved the iron capture and total antioxidant capacity, probably due to the presence of β-carotene and antioxidant compounds.     

新型蕨麻佐餐藏羊肉酱配方研究

以藏羊肉和蕨麻为主要原料进行新型复合型蕨麻佐餐藏羊肉酱的制作,在单因素试验基础上采用感官品评和正交试验分析,对复合酱配比、植物油添加量、藏羊肉添加量、蕨麻添加量以及复合酱添加量5个因素进行正交试验,依据感官评分表进行感官品评,确定蕨麻佐餐藏羊肉酱加工的最佳配方。结果表明,对蕨麻佐餐藏羊肉酱品质影响的因素依次为复合酱配比>复合酱添加量>植物油添加量>蕨麻添加量>藏羊肉添加量;并确定最终配方为植物油20.7%、羊肉17.2%、蕨麻3.4%、辣椒酱13.8%、甜面酱5.2%、花生酱5.2%、牛肉精膏0.3%、葱沫8.6%、蒜沫8.6%、盐1.0%、鸡精2.0%、味精1.7%、白糖3.1%、生姜粉0.3%、海天酱油3.1%、白芝麻1%、瓜子仁1%、辣椒粉3.4%。     

Measuring trail users’ perception of crowding in a peri-urban nature park: A best-worst scaling experiment

This paper evaluates the perception of crowding, its determinants and relationship with trail users’ experience in a peri-urban nature park. Existing crowding surveys rely heavily on a single-item 9-point crowding scale which was originally developed for backcountry areas. Receiver operating characteristic (ROC) analysis was used to test the validity and reliability of this measure in detecting crowding issues and formulating visitor capacity limits. Low validity and reliability raised concerns about the applicability of this scale in similar frontcountry areas. Inability of this simple crowding measure to detect a visitor threshold brings to the fore its another important limitation – ignorance of the complexity of crowding phenomenon. The perception of crowding varies with various social, psychological and situational factors, and a best-worst scaling (BWS) experiment was designed to simultaneously evaluate different aspects of crowding in the Medvednica Nature Park, a peri-urban nature park near Zagreb, Croatia. The findings of BWS experiment revealed that occupancy of mountain huts, number of other hikers on the trail and amount of litter along the trail on average contributed most to the trail users’ sense of crowding. A latent class analysis identified a large heterogeneity in the perception of crowding; while one group of trail users (63%) was more disturbed by the direct social impacts, the others (37%) were more disturbed by the secondary impacts of other visitors, especially by the negative externalities from road traffic in the park. Older visitors had a greater tendency to primarily associate crowding with the environmental conditions. A higher impact of trail use level in the perception of crowding, younger age and more frequent use were associated with a more negative evaluation of crowding. The park management should closely monitor road traffic in the park and visitor activity on highly used trails, especially on those popular among younger trail users.