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31.
32.
矮香糯水稻(Oryza sativa L, )插身后生长在大气(350ppm CO2)和CO2倍增(700 ppm CO2)的开顶式培养室中,结果显示,在CO2倍增的条件下,矮香糯生长旺盛,根系发达,根系干重增加23%,株高增加12%,每穗结实率增加29%,每株籽粒干重增加41%。本文对目前有关这方面的研究现状进行了讨论。 相似文献
33.
华北平原大部分农田土壤发育在黄河冲积物母质上,矿物钾含量较高,在当前中低产农田中,尤其在有一定秸秆还田的条件下,施用化肥钾增产效果不显著,过多施钾会出现“奢侈性消耗”。在高产条件下,适当施钾对增产仍有一定作用。农田生态系统钾平衡研究对作物生产有重要意义。本文通过3年试验探讨了华北平原农田钾平衡和供钾能力。 相似文献
34.
不同施肥措施对潮土有机碳平衡及固碳潜力的影响 总被引:11,自引:0,他引:11
以中国科学院封丘农业生态实验站的长期定位施肥试验为研究平台,研究不同施肥措施对潮土有机C含量的影响,并利用Jenny模型对不同施肥措施下的潮土有机C动态进行模拟。结果表明,施肥措施明显改变了潮土有机C含量,并且有机肥处理的作用效果要明显优于化肥处理。不同施肥措施不仅改变了潮土有机C的平衡水平,也影响了有机C的分解速率,NPK、1/2OM和OM施肥处理的有机C平衡值分别为7.19、7.75和9.37g/kg,而分解速率分别为0.038、0.113和0.1451/a。在目前施肥模式不变的情况下,与试验初相比,达到平衡时CK处理的潮土将会损失C1478kg/hm2,而NPK、1/2OM和OM处理的潮土则会分别增加C7376、7790和12066kg/hm2。因此,可以认为施肥处理促进了潮土的C固定。 相似文献
35.
为了给测土配方施肥提供土壤供肥能力的参考依据,1987年至2005年在土壤肥力较一致的马肝泥田上进行了土壤供肥能力的多点田间试验。结果表明,气候对土壤供肥能力影响显著。土壤供肥能力:高温少雨年份K2O〉N〉P2O5,低温多雨年份P2O5〉K2O〉N,正常年份K2O〉P2O5〉N。土壤供肥比例(N:P2O5:K2O):高温少雨年份为1:0.23:0.58,低温多雨年份为1:0.29:0.56,正常年份为1:0.25:0.62。 相似文献
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Effects of selenium yeast on rumen fermentation, lactation performance and feed digestibilities in lactating dairy cows 总被引:2,自引:0,他引:2
C. Wang Q. Liu W.Z. Yang Q. Dong X.M. Yang D.C. He P. Zhang K.H. Dong Y.X. Huang 《Livestock Science》2009,126(1-3):239-244
The objective was to evaluate the effects of selenium-yeast (SY) supplementation on rumen fermentation, lactation performance and feed digestibilities in dairy cows. Twenty-eight multiparous (2.5 ± 0.3 parity) Holstein dairy cows, averaging 625 ± 18.2 kg of BW, 63 ± 3.0 days in milk and average daily milk production of 26.2 ± 0.5 kg/cow were used in a replicated 4 × 4 Latin square experiment. Treatments were: control, LSY, MSY and HSY with 0, 150, 300 and 450 mg selenium yeast (Sel-Plex®, 1 g/kg selenium, produced from Saccharomyces cerevisiae CNCM I-3060) per kg of diet dry matter (DM), respectively. Experimental periods were 45 days with 30 days of adaptation and 15 days of sampling. Ruminal pH was lower for MSY than for control and was linearly (P = 0.03) decreased, whereas total VFA concentration was linearly and quadratically (P ≤ 0.01) increased with increasing SY supplementation, with the least for control, followed by LSY and HSY, and the highest for MSY. Ratio of acetate to propionate was lower for LSY, MSY and HSY than for control, and was linearly and quadratically (P ≤ 0.01) decreased as SY supplementation increased due to an increase in molar proportion of propionate. Ruminal ammonia N content was lower (P ≤ 0.01) for MSY and HSY than for control and was linearly decreased (P ≤ 0.01) with increasing SY supplementation. Dry matter intake, proportions and yields of milk fat, protein and lactose were not affected (P > 0.05). Milk yields and 4% FCM were higher (P ≤ 0.05) for LSY and MSY than for HSY and control. Milk selenium content was linearly and quadratically (P ≤ 0.01) increased as increasing SY supplementation, with the least for control, followed by LSY and MSY, and the highest for HSY. Digestibilities of DM, organic matter (OM), crude protein (CP), ether extract (EE), aNDF and ADF in the total tract were higher (P < 0.01) for LSY and MSY than for control and HSY. The results indicate that supplementation of diet with SY improved rumen fermentation, milk yields, milk selenium, and feed digestion. It was suggested that the SY stimulated the digestive microorganisms or enzymes in a dose-dependent manner. In the experimental conditions of this trial, the optimum selenium-yeast dose was about 300 mg per kg diet DM. 相似文献
38.
沈阳市玉米主产区土壤有机质和有效磷含量及其与玉米产量水平之间的关系 总被引:2,自引:0,他引:2
为了解沈阳市玉米主产区土壤养分状况及其与玉米产量水平之间的关系,于2004~2005年对沈阳市不同肥力水平的玉米主要产区的土壤有机质和有效磷含量及其与玉米产量水平之间的关系进行分析。结果表明,沈阳市玉米主产区土壤有机质含量总体处于中低水平,有效磷含量总体处于较高水平;玉米的产量水平与有机质和有效磷含量之间表现出了极显著的正相关关系。由此提出增施有机肥,实行有机无机肥配施以及建立适应目前农业生产需要的土壤磷素丰缺指标是发挥玉米增产潜力的必要手段。 相似文献
39.
40.
Nitrogen fixation and beneficial effects of some grain legumes and green-manure crops on rice 总被引:6,自引:0,他引:6
Studies were conducted on paddy soils to ascertain N2 fixation, growth, and N supplying ability of some green-manure crops and grain legumes. In a 60-day pot trial, sunhemp (Crotalaria juncia) produced a significantly higher dry matter content and N yield than Sesbania sesban, S. rostrata, cowpeas (Vigna unguiculata), and blackgram (V. mungo), deriving 91% of its N content from the atmosphere. Dry matter production and N yield by the legumes were significantly correlated with the quantity of N2 fixed. In a lowland field study involving sunhemp, blackgram, cowpeas, and mungbean, the former produced the highest stover yield and the stover N content, accumulating 160–250 kg N ha-1 in 60 days, and showed great promise as a biofertilizer for rice. The grain legumes showed good adaptability to rice-based cropping systems and produced a seed yield of 1125–2080 kg ha-1, depending on the location, species, and cultivar. Significant inter- and intraspecific differences in the stover N content were evident among the grain legumes, with blackgram having the highest N (104–155 kg N ha-1). In a trial on sequential cropping, the groundnut (Arachis hypogaea) showed a significantly higher N2 fixation and residual N effect on the succeeding rice crop than cowpeas, blackgram, mungbeans (V. radiata), and pigeonpeas (Cajanus cajan). The growth and N yield of the rice crop were positively correlated with the quantity of N2 fixed by the preceding legume crop. 相似文献