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951.
Nitrous oxide, methane and ammonia emissions following slurry spreading on grassland 总被引:1,自引:0,他引:1
In Sweden, 90% of ammonia (NH3) emissions to the atmosphere originate from agriculture, predominantly from animal manure handling. It is well known that incorporation of manure into soil can reduce NH3 emissions after spreading. However, there is a risk of increased nitrous oxide (N2O) and methane (CH4) emissions caused by bacterial activity and limited oxygen availability under these conditions. A full‐scale injector was developed and evaluated in a field experiment on grassland. Cattle slurry was either injected in closed slots 5 cm below ground or band spread on the soil surface above the crop canopy at a rate of 25 t ha?1. In a control treatment, no slurry was applied. During a 5‐day period after application, NH3 emissions were measured using an equilibrium concentration method. Gas samples for estimating CH4 and N2O emissions were also collected during 7 weeks following slurry application. Injection in closed slots resulted in no detectable NH3 emissions. After band spreading, however, NH3 emissions corresponded to nearly 40% of the total ammoniacal nitrogen in the applied slurry. The injection of slurry gave rise to a broad peak of N2O emissions during the first 3 weeks after application. In total, for the measuring period, N2O emissions corresponded to 0.75 kg N ha?1. Band spreading resulted in only a very small N2O release of about 0.2 kg N ha?1 during the same period. Except for the first sampling occasion, the soil was predominantly a sink for CH4 in all the treatments. The use of the injector without slurry application reduced grass yield during unfavourable growing conditions. In conclusion, shallow injection in closed slots seems to be a promising technique to reduce negative environmental impacts from NH3 emissions with a limited release of N2O and CH4. 相似文献
952.
Gully development in the Moldavian Plateau of Romania 总被引:1,自引:0,他引:1
Gully erosion has been recognized as an important environmental threat in the Moldavian Plateau of Eastern Romania. The main objective of this study was to define the process-based gully development by providing quantitative information from long-term field measurements in small catchments.Three main areas of monitoring gullies were explored: aerial photographs of flights in 1960 and 1970, classical leveling and repeated survey through a particular close stakes grid after 1980. The Caesium-137 technique has been used effectively in the areas of deposition of gully sediments to obtain reliable information on dating specific levels of sediments and to provide chronological measures of gully development.Most of the discontinuous gullies exhibit both proper gullying, mainly if not exclusively by gully head advance, and aggradation of the gully basin floor. Results indicated that the mean gully head retreat was 0.92 m year− 1 and the mean areal gully growth was 17.0 m2 year− 1. Both values indicate a slow erosion rate for this area. The average annual regime of gullying is pulsatory, one that is best described by great fluctuations. Conventional measurements on sedimentation over the period 1987–1997 indicate a higher rate of aggradation in the upper half of the gully floor. Information on the Caesium-137 depth profile was used to provide estimates of a mean sedimentation rate of 4.4 cm year− 1 over the period 1963–1996 and 2.5 cm year− 1 after 1986 for the short successive discontinuous gullies. A new classification of the discontinuous gullies based on two criteria, respectively, the field patterns and the rate of aggradation within the gully basin floor was established.For continuous gullies, linear gully head retreat, areal gully growth and eroded material rates were quantified for three periods (1961–1970, 1971–1980 and 1981–1990). Results indicate that gully erosion has decreased since 1960. This gullying decline is due to the rainfall distribution, and the increased influence of soil conservation practices. The mean gully head retreat of 12.5 m year− 1 between 1961–1990 was accompanied by a mean areal gully growth of 366.8 m2 year− 1 and a mean erosion rate of 4168 t year− 1. As with discontinuous gullies, continuous gullies showed pulsatory development.The critical period for gullying over 1981–1996 covers 4 months from Mid March to Mid July in an area with mean annual precipitation around 500 mm. Another main finding of this 16-year stationary monitoring was that 57% of the total gullying occurred during the cold season, with the remainder during the warm season. Of the total gully growth, 66% results from only four years (1981, 1988, 1991 and 1996), when a greater amount of precipitation fell. 相似文献
953.
954.
优质青贮玉米新青1号的选育及其栽培技术 总被引:17,自引:4,他引:17
新青1号是新疆农科院粮作所培育的优质高产青贮玉米新品种.该品种一般生物产量67 500~82 500kg/hm2.春播生育期110 d左右,复播生育期90~100d,适宜≥10℃有效积温2400℃·d以上地区种植.全株粗蛋白含量10.07%,粗脂肪3.02%,总糖11.65%,粗纤维8.38%,无氮浸出物32.42%,干物质含量49.94%.子粒容重828g/L,子粒粗蛋白13.19%,粗脂肪5.55%,赖氨酸含量0.34%.通过适时播种、合理密植、加强田间管理和适时收获即可获得高产 相似文献
956.
[目的]探究小米米糠蛋白的提取工艺.[方法]以小米米糠为原料,先测定其营养成分,然后制备脱脂米糠,利用淀粉酶对小米米糠酶解处理进行米糠蛋白的提取,通过单因素试验对提取条件进行筛选.[结果]试验得到小米米糠蛋白的最佳提取工艺条件为:最佳料液比1∶10 g/ml,淀粉酶用量20 U/g,最佳反应时间2h,最佳反应温度60℃.[结论]研究可为小米米糠蛋白的提取提供理论依据. 相似文献
957.
958.
[目的]针对目前南方双季稻区适用型紫云英品种缺乏的现状,湖南省土壤肥料研究所选育出了适于在双季稻区种植利用的紫云英新品种湘紫2号。[方法]通过开展多点田间品种比较试验和示范,了解湘紫2号的生长特性及其高产栽培技术。[结果]湘紫2号在湖南双季稻区种植表现出极早花、适产、养分含量高、抗性好、耐迟播、适应性广等优点。其高产栽培技术要点包括及早开沟,科学施肥,施用磷钾肥以小肥换大肥,注意防治病虫害,适时翻沤。[结论]湘紫2号的推广应用对解决原有紫云英品种与双季稻种植上季节不相匹配的问题具有重要意义,有利于恢复和发展紫云英生产、培肥地力和提高土地综合生产力。 相似文献
959.
960.
黄果枸杞硬枝扦插繁殖技术研究 总被引:3,自引:0,他引:3
[目的]探讨黄果枸杞硬枝扦插繁殖对植株成活率、结果率的影响.[方法]以一年生和二年生黄果枸杞不同部位的硬枝为插穗试验材料,采用不同浓度的生根粉及赤霉素进行处理.[结果]采用生根粉2 500 mg/L药液处理的二年生基部枝条的插穗植株其平均成活率及结果率最高,分别为63.6%和71%,植株生长状况最好;其次是赤霉素50 mg/L药液处理的二年生基部枝条的插稳,其植株生长状况较好.[结论]该研究为黄果枸杞规范化栽培提供技术服务. 相似文献