In situ net N transformations in pine,fir, and oak stands of different ages on acid sandy soil, 3 years after liming

Summary The effect of liming on in-situ N transformations was studied in two stands of different ages of each of Scots pine (Pinus sylvestris L.), Douglas fir [Pseudotsuga menziesii (Mirb.) Franco], and common oak (Quercus robur L.). The stands were located on acid sandy soils in an area with high atmospheric N input. The organic matter of the upper 10-cm layer of the soil, including the forest floor, had a relatively high N content (C: N ratio <25) in all stands. Using a sequential core technique, N transformations were measured in both control plots and plots that had been limed 3 years previously with 3 t ha^-1 of dolomitic lime. Limed plots had a higher net NO _inf3 ^sup- production and a higher potential for NO _inf3 ^sup- leaching than the controls in all stands except that of the younger oak. Net N mineralization did not differ significantly between limed and control plots in oak stands and younger coniferous stands but was significantly lower in the limed plots of the older coniferous stands. It is concluded that long-term measurements of net N mineralization in limed forest soils are needed to evaluate the effect of liming with respect to the risk of groundwater pollution.     

Influence of compost and lime on population structure and element concentrations of forest soil invertebrates

Summary We tested the effects of two organic fertilizers (composts) and lime on the soil fauna of a spruce stand. One compost was obtained from chopped wood and the other from household garbage. At the time of distribution the pH of the control plots averaged 3.2, the garbage compost had a pH of 7.5, and the wood compost of 6.2. During the experimental period the pH of the compost layers decreased. The pH of the former litter layer beneath the composts showed a steep increase after 5 months, but beneath the treatment with wood compost this effect did no persist. Liming increased the pH only slightly in the litter layer. The two types of compost, the litter layer, and lumbricids (Lumbricus rubellus) were analyzed for concentrations of essential and potentially toxic elements. The element burden was highest in the garbage compost with 7- to 11-fold concentrations of Zn, Cd, Pb, Mg, and Cu compared to the needle litter. K, Ba, and Ca were 4 times more concentrated. L. rubellus showed an increased Cu concentration after extraction from the highly contaminated sites of garbage compost. Despite the differences in Pb contamination in the needle litter and in the two compost types, all investigated individuals of L. rubellus contained similar concentrations of Pb. In contrast to Pb, Cd accumulated in this lumbricid. Seasonal fluctuations of microarthropods, their total abundance, and differences in the colonization of the compost layers were observed. Collembola abundance was significantly increased in the garbage compost plots in July 91. There were generally more Prostigmata in the control and limed plots than in the compost plots. Oribatid numbers fell under all treatments compared to the controls. Mesostigmata were identified to species level and 33 species were found in the experimental areas. Certain species, such as Arctoseius cetratus and Uropoda minima, were only found in the treated sites.     

北京地区玉米就地加代技术的初步研究

1984—1986年在北京进行早熟、中早熟玉米一年两季加代试验.试验结果表明.第一季加代采用早春(3月上旬—下旬)温室育苗,3月末至4月上旬移栽到塑料薄膜复盖的阳畦、小棚或大棚;以及3月下旬直播于铺设电热线的阳畦,大棚等增温保温措施,早熟、中早熟玉米自交系和育种材料。可于5月下旬进入抽雄、吐丝、散粉期,7月上旬末以前收获授粉后25—30天果穗,种子发芽率可达到80%以上,第二季加代采用上季25—30天嫩粒,经2%H_2O_2浸种24小时,于7月上旬播种(气温偏高年份还可适当延迟播种),在大田条件下,8月下旬可进入抽雄、吐丝、散粉期,授粉工作可进行到9月上旬末,10月底以前收获的种子,发芽率一般达80%左右,高的达90%以上.H_2O_2处理玉米种子可明显加速种子发芽,促进幼苗生长.采用了短日照处理(8—10小时日照)生育后期叶面喷磷钾肥和乙烯利等促进早熟措施,对本试验成功实现一年两季加代,均取得了一定效果。     

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。     

施氮对砂姜黑土区不同玉米品种产量构成、氮素利用及节氮潜力的影响

通过田间试验研究不同施氮水平对6个主推品种在砂姜黑土区的产量、产量构成因素、氮素利用及节氮增产潜力的影响。结果表明,施氮显著提高各玉米品种的子粒产量,对收获指数的影响相对较小;施氮显著增加行粒数、穗长和穗粗,增幅分别为22.5%~66.9%、16.8%~50.5%和9.4%~29.7%,N120与N240水平间无明显差异;各玉米品种的氮肥农学利用率和氮肥偏生产力均表现为N120显著高于N240水平,平均值分别是N240的1.89倍和1.96倍;蠡玉13和郑单958的节氮增产潜力明显高于其他品种。综合分析认为,适宜在胶东砂姜黑土区推广的玉米品种排序为蠡玉13、郑单958、浚单20、先玉335、莱农14、先锋32D22。     

马铃薯脱毒原原种高架移动苗床繁殖效益分析

为了降低种薯成本,解决水肥等资源的过度消耗的问题,本试验分析比较了高架苗床无土繁育模式和地面隔层无土繁育模式水肥投入和产出效益。结果表明：高架苗床无土繁育模式有利于结薯,直径d≤25mm原原种居多,占总结薯个数的59.49%,较地面隔层无土繁育模式增加72个/㎡.年,增幅为4.58%。节水16.4方/100㎡.年,节省肥料8kg/100㎡.年,成本降低48.58元/100㎡.年。     

周年耕作方式对砂姜黑土农田土壤养分及作物产量的影响

为探明适宜于砂姜黑土农田的周年耕作方式, 提升砂姜黑土农田地力及作物产量, 在冬小麦?夏玉米一年两熟种植制度下, 设置多年定位夏玉米季?冬小麦季免耕?旋耕(对照)、免耕?深耕、深松?旋耕、深松?免耕、免耕?免耕5种周年耕作方式田间试验, 在定位处理的第4个周年研究耕作方式对砂姜黑土农田土壤有机碳含量、土壤养分及其对作物产量的影响。结果表明, 在秸秆全量还田条件下, 与试验开始前相比, 各处理0~20 cm土层土壤有机碳、全氮、速效钾含量均有所增加。与对照相比, 其他处理均增加周年内0~20 cm土层土壤有机碳和全氮含量。免耕?深耕、深松?旋耕、免耕?免耕处理显著增加周年内0~20 cm土层土壤有效磷含量, 而深松?免耕处理显著增加冬小麦开花期和收获期0~20 cm土层土壤有效磷含量, 整个周年内对照在20~40 cm土层土壤的有效磷含量均最低。深松?免耕处理增加周年内0~20 cm土层土壤速效钾含量, 而深松?免耕、免耕?免耕处理20~40 cm土层土壤速效钾含量在夏玉米苗期、大口期、开花期和灌浆期显著高于对照处理。深松?旋耕和深松?免耕处理显著增加夏玉米?冬小麦周年籽粒产量, 增幅分别为7.67%和10.21%。综上所述, 在秸秆全量还田基础上, 深松?旋耕和深松?免耕能够改善土壤有机碳和养分状况, 显著提高周年作物产量, 可作为黄淮区砂姜黑土农田相对适宜的周年耕作方式。     

石灰和泥炭处理对超积累植物东南景天清除土壤重金属的影响

[目的]采用植物修复技术对广西崇左市某一铅锌矿区的重金属污染土壤进行治理。研究石灰和泥炭处理对东南景天和玉米的生长及积累重金属的影响。[方法]进行为期1年的大田试验,植物种植模式为单种玉米和玉米套种东南景天2种方式;土壤改良剂的处理为单施石灰和石灰+泥炭处理2种方式。[结果]大田试验证明,在土壤Zn和Cd分别达3 574 mg/kg和29 mg/kg的条件下,东南景天生长良好,其地上部Zn和Cd含量最高达21 982 mg/kg和1 013 mg/kg。施用石灰或泥炭均可促进东南景天和玉米的生长,提高2种植物对Zn的积累,抑制玉米对Cd的积累。[结论]在施用石灰+泥炭的基础上采用玉米套种东南景天的方式可以获得最大的Zn和Cd去除效果。