不同氮肥及肥料组合对芹菜生长和硝酸盐含量的影响

通过田间试验研究了氮肥品种组合及不同肥料配施对芹菜生长和硝酸盐含量的影响.结果表明氮肥中的氯化铵、硫酸铵及其配合施用有利于降低芹菜体内硝酸盐含量,减少土壤NO3--N积累;肥料组合正交试验结果表明几种肥料对芹菜产量影响的主次关系为尿素＞硫酸钾＞石灰＞油枯,对芹菜硝酸盐积累影响的主次关系为尿素＞油枯＞硫酸钾＞石灰.施用油枯和石灰,芹菜硝酸盐显著积累,但其用量水平间差异不显著.随着尿素施用量的增加,芹菜硝酸盐含量大幅度增加.钾肥能提高芹菜的产量并降低硝酸盐含量.统计分析表明油枯1125 kg/hm2,尿素495 kg/hm2,硫酸钾600 kg/hm2,石灰0 kg/hm2的配合施用在促进芹菜高产方面最为适宜.     

新疆北疆寒冷地区非烧土坯墙体材料力学性能的研究

对新疆北疆纯粘土、粘土中掺入一定量水泥、石灰和粉煤灰制成的材料试件进行试验,测试试件在不同配合比下的抗压、抗折强度及导热系数。研究不同含水率,不同掺量石灰、水泥和粉煤灰对混合材料的抗压、抗折强度、导热系数的影响。得到适合于强度高、保温性能好的非烧土坯墙体材料。     

施用氮钾肥对大葱产量和经济效益的影响

为了明确氮、钾肥对大葱产量和经济效益的影响,开展了多年施用不同数量的氮、钾肥对大葱产量和经济效益的影响试验。结果表明,增施钾肥对大葱生长发育有明显的促进作用,并能显著提高产量。白庙和黄岭地区试验在氮肥(纯N)水平为225、300 kg/hm~2时,大葱经济产量分别增加11.9%～16.8%和13.2%～21.1%,平均分别增长13.9%、16.7%,大葱产量均随钾肥施用量的加大而提高。在氮肥低用量条件下,适当增加氮肥施用量,也能有效提高大葱的经济产量,不同钾肥(K2O)用量下施氮肥大葱可增产9.9%～14.8%,平均增产12.5%;其中,白庙地区大葱产值增收26 160～41 900元/hm~2,产投比为20.22～43.21。     

玉米秸秆还田对小麦生长和土壤水分含量的影响

[目的]研究不同玉米秸秆还田量对小麦生长和砂姜黑土水分状况的影响,探讨适宜的秸秆还田量。[方法]设置0、1 500、3 000、4 500和6 000 kg/hm~2玉米干秸秆粉碎还田量,小麦主要生育期采集0~10、10~20 cm土壤样品,测定水分含量;收获期考察小麦产量结构性状。[结果]实施玉米秸秆粉碎直接还田对后季小麦生长发育具有良好的促进作用,籽粒产量增长3.49%~7.09%,平均提高4.94%,3 000 kg/hm~2的中等秸秆用量处理小麦产量最高。小麦拔节期、孕穗期和开花期0~10 cm、10~20 cm以及0~20 cm土层水分含量显著提高,减轻了土壤干旱程度。[结论]当前生产水平下,淮北平原砂姜黑土地区玉米秸秆适宜还田量为3 000 kg/hm~2。     

Response of broiler chicks to non-steam- or steam-pelleted diets containing raw,full-fat soybean meal

The objective of this study was to evaluate the effects of steam pelleting of diets containing graded levels of raw, full-fat soybean meal (RSBM) on the chemical properties and feeding values of the diets. Samples of diets with steam- or non-steam-pelleted as well as the mash containing varying levels of RSBM were subjected to detailed chemical analysis. As a result of this study, trypsin inhibitor (TI) concentrations in the diets ranged between 4,153 and 10,484 TIU/g. Amino acid concentrations were higher in the non-steam-pelleted and mash diets than the steam-pelleted diets. A 4 × 2 factorial arrangement (RSBM: zero, 10, 20 or 30%, equivalent to zero, 30, 60, and 90 g/kg of diet, respectively, and non-steam- or steam-pelleted diets) was used while feeding broiler chicks (zero to 14 d of age). Each treatment was replicated 6 times with 8 birds per replicate. As a result of this study, there was no difference (P > 0.05) in mortality of birds among the groups. Feed intake (FI) (P < 0.05) and body weight gain (BWG) (P < 0.001) decreased with increasing levels of RSBM. Birds fed on steam-pelleted diets gained less (P < 0.001) weight than birds on the non-steam-pelleted diets, but the FI was not significantly (P > 0.05) different. The FCR was negatively affected (P < 0.05) by increasing levels of RSBM. There was no interaction effect between RSBM and pelleting method on the FI, BWG, or FCR of birds. The weight of the pancreas (P < 0.001) and duodenum (P < 0.01) increased with a rise in the level of RSBM in diets. Non-steam pelleting increased (P < 0.05) the pancreatic protein content, whereas the activity of chymotrypsin was reduced (P < 0.01) when the RSBM level was increased. Birds fed with RSBM-free diets had thicker muscle, longer villi, wider villus surface area, and higher villus to crypt depth ratios than birds on the other diets, but these differences were not significant. It can be concluded that steam pelleting of diets containing RSBM is inadequate to reduce the adverse impact of TI on chicks.     

关于二灰土土质问题的商榷

通过试验表明,在石灰,粉煤灰稳定土中,砂性土比粘性稳定效果好;本文具体介绍了试验所用材料,试验配合比,通过分析得出结论。     

砂姜黑土的培肥与持续增产研究

在典型砂姜黑土上的六年定位试验证明:每年亩施圈肥2500～5000kg,可显著提高土壤有机质含量,全氮和速效氮有所增加,速效磷含量增高;在各种磷酸盐形态中,铝磷酸盐含量明显增加。施用圈肥的处理,耕层土壤容重降低,有效水含量显著提高,土壤持水曲线与对照处理有明显差别。施用氮磷化肥和无肥对照区,土壤有机质含量没有明显下降,说明砂姜黑土的土壤有机质分解速度是缓慢的。单纯施用氮磷化肥,第一年小麦增产幅度较大,以后小麦产量逐年下降。同时施用圈肥和氮磷化肥,小麦产量逐年呈上升趋势。     

Evaluation of the Lime-Cooking and Tortilla Making Properties of Quality Protein Maize Hybrids Grown in Mexico

Eleven experimental and three commercial white quality protein maize (QPM) hybrids and two regular endosperm controls were planted at Celaya, Guanajuato, Mexico with the aim of comparing grain physical characteristics, protein quality, lime-cooking and tortilla making properties. All genotypes were planted under irrigation using a density of 80,000 plants/ha and fertilized with 250 kg N-60 P-60 K per hectare. When compared with the controls these QPM genotypes had lower test (77.4 vs. 76.5 kg/hL) and 1,000 kernel weights (327 vs. 307 g), softer endosperm texture (2.5 vs. 1.8 where 1 = soft, 2 intermediate and 3 hard endosperm), lower protein (10.0 vs. 8.0%), higher nixtamal water uptake after 30 min lime-cooking (50.0 vs. 53.1% moisture) and lower pericarp removal scores. The lower thousand-kernel weight and softer endosperm texture observed in the QPM genotypes lowered the optimum lime-cooking time as estimated with regression equations. Most QPM genotypes had higher amounts of lysine, tryptophan and albumins/globulins when compared with the controls. QPMs HEC 424973, HEC 774986 and HEC 734286 had the best grain traits for nixtamalization and therefore the best potential for industrial utilization. The commercial use of these QPM hybrids should benefit Mexicans who depend on tortillas as the main staple.     

土壤的石灰反应强度估测CaCO_3含量和pH研究——以山西省黄土性母质土壤为例

pH和CaCO_3含量是土壤常规分析的两个测定指标,但其室内测定均需借助相应的仪器设备完成,耗时费力。以山西省土系调查采集的110个典型土壤剖面的426个发生层土样的野外测定的石灰反应强度和实验室测定的土壤pH、CaCO_3含量、交换性钠饱和度(Exchangeable Sodium Percentage,ESP)数据为基础,尝试建立石灰反应强度与pH、CaCO_3含量之间的定量关系模型。结果表明:北方黄土性母质土壤,当pH9.0时,CaCO_3含量是影响土壤pH的重要因素,二者的回归拟合最优关系符合幂函数曲线;当pH9.0时,CaCO_3与pH之间无明显关系。石灰反应强度在一定程度上可以半定量地反映pH或CaCO_3含量,但其确定的pH或CaCO_3含量尚是一个范围,并非精确值。同时,从发生学意义角度,土壤中CaCO_3含量高低对形态学研究具有重要意义,在这种情况下,如果需要用pH或CaCO_3含量来确定准确的土壤系统分类类型(如确定土体是否为酸性、具有钙积层/钙积现象等),为慎重起见建议还是以实验室的准确测定数据为准;对于非碱化(pH9.0)、野外有泡沫反应的北方黄土性母质土壤,无论泡沫反应强弱和CaCO_3含量高低,土壤pH基本稳定在8.51±0.49,这一pH范围对作物生长基本没有制约,如果仅从pH或CaCO_3含量是否影响作物生长角度考虑,无需实验室测定pH或CaCO_3含量。     

Effects of two commercial diets and technical feed treatment on stomach lesions and immune system of fattening pigs

The impact of technical feed treatment and diet on stomach lesions and traits of the local and systemic immune system were investigated in fattening pigs. Feeding groups differed in technical feed treatment (standard ground meal vs. finely ground and pelleted feed) and diet (soya bean meal vs. rapeseed meal/DDGS/soya beans). Pigs were fattened approximately 10 weeks by ad libitum feeding and slaughtered subsequently. Gastric alterations were assessed by a macroscopic scoring system [macroscopic stomach score (MSC) 0 =  normal to 4 =  severe lesions]. For immunological investigations, lymphocytes from blood and jejunal tissues were isolated. T‐cell phenotyping was carried out by staining intestinal lymphocytes with monoclonal antibodies for CD4 and CD8 and flow cytometric measurements. MSC was higher in animals fed finely ground and pelleted feed compared with their counterparts. Significant interactions between diet and feed treatment considering the MSC were observed (p = 0.027). There was no effect of diet or technical feed treatment on T cells of blood, Lymphonodi gastrici or lamina propria (LP) and intraepithelial cells. However, technical feed treatment significantly affected subsets of CD4⁺, CD8⁺, CD8^low, CD4/CD8 double‐positive T cells, the mean fluorescence intensity of CD4⁺ T cells and the ratio of CD8^low/CD8^high T cells in Peyer's patches (PP). All named parameters were reduced in PP of animals fed finely ground and pelleted feed compared with animals fed standard ground meal. Furthermore, significant differences between T cells of lymph nodes and LP were observed between animals with middle MSC (MSC = 1–2.5) and animals with high MSC (MSC = 3–4). Significant alterations in T cells of PP were observed between animals of low (MSC = 0–0.5) and high MSC. The observed effects provide the evidence that the impact of technical feed treatment is not limited on the stomach lesions. Possible stimuli and consequences of the immune system should be studied in more detail.