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The effect of pre‐grazing herbage mass (HM) on herbage intake and milk production of strip‐grazing dairy cows is usually studied at the same herbage allowance (HA). In the literature, the effect of HM seems to be affected by the cutting height above which HA is estimated. The aim of this 2 × 3 factorial study was to determine whether the effect of HM (low vs high HM) on herbage intake, milk production and grazing behaviour of dairy cows is affected by the HA estimation height (ground level vs 2·5 vs 5 cm). Two HMs were compared in three different ways: at same HA above ground level (SHA0), at same HA above 2·5 cm (SHA2) and at same HA above 5 cm (SHA5). During two consecutive years, twenty‐four Holstein‐Friesian dairy cows in mid‐lactation were assigned to one estimation height in an incomplete switchback design, with two 14‐d periods. There was an interaction between HM and estimation height for herbage intake and milk production. The effect of HM on herbage intake was positive, null and negative when HMs were compared at SHA0, SHA2 and SHA5, respectively. This study may have practical implications on future research for studying, directly or indirectly, the effect of pre‐grazing HM under strip‐ or rotational‐grazing management, and on modelling herbage intake at grazing. 相似文献
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Are soil‐adjusted vegetation indices better than soil‐unadjusted vegetation indices for above‐ground green biomass estimation in arid and semi‐arid grasslands? 
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下载免费PDF全文 Accurate estimation of grassland biomass has been a central focus due to its importance in ecosystem processes and carbon cycles. This study aimed to examine whether the performance of soil‐adjusted vegetation indices for estimating above‐ground green biomass was better than that of soil‐unadjusted vegetation indices in arid and semi‐arid grasslands. Above‐ground green biomass in desert steppe of Inner Mongolia and corresponding moderate‐resolution imaging spectroradiometer (MODIS) surface reflectance 8‐day composite MOD09Q1 data were collected during late September of 2013. Results showed that soil‐adjusted SAVI (soil‐adjusted vegetation index), MSAVI (modified soil‐adjusted vegetation index), OSAVI (optimized soil‐adjusted vegetation index), TSAVI (transformed soil‐adjusted vegetation index), ATSAVI (adjusted transformed soil‐adjusted vegetation index) and PVI (perpendicular vegetation index) did not improve estimation accuracy over soil‐unadjusted simple ratio (SR) and normalized difference vegetation index (NDVI), due to low green vegetation cover (<30%) in the study area. Our results suggest that these soil‐adjusted vegetation indices may be not suitable for describing green vegetation information in arid and semi‐arid grasslands with low green vegetation cover (<30%). 相似文献
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Grazing lands in warm‐temperate and subtropical North America have become less diverse. Pastures are typically grass monocultures, while rangelands are generally managed for the grass components. Overstocking, selective herbicides, fire exclusion and heavy rates of nitrogen fertilizer have contributed to near exclusion of native, warm‐season legumes. The simplicity of managing grass monocultures, pasture production responses to nitrogen fertilizer and profitability of grass‐only systems have limited interest in legume‐based approaches. Changing economics and ecological concerns with ecosystem accumulation of industrial inputs contribute to an increasing interest in legumes. Unlike the development of temperate pasture legumes and recent research in the tropics, legumes tolerant of both freezing temperatures and hot weather have received less attention. Poor establishment, limited persistence and potential invasiveness limit currently available introduced species. Native, herbaceous, warm‐season legume species occur throughout warm‐temperate North America, but little attention has been directed to these plants as potential forage species. Some success with a few native legume species, primarily in the genus Desmanthus, suggests potential for expanded assessment of forage value of the many species available. Current assessments of native legumes, primarily for conservation purposes, provide an opportunity to expand evaluations of these species for pasture and rangeland potential while economics of livestock production and public interest in ecosystem health are supportive. Experiences with legumes of warm‐temperate origin in North America, along with results with temperate and tropical pasture legumes globally, provide a starting point for future efforts at incorporating greater legume diversity in pastures and rangelands of subtropical and warm‐temperate regions around the world. 相似文献
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Thorsten Reinsch Carsten Malisch Ralf Loges Friedhelm Taube 《Grass and Forage Science》2020,75(4):372-384
Grassland renovation by cultivation and reseeding has been shown to increase short-term emissions of N2O, but there is uncertainty about long-term effects, despite the potential impacts of reseeding on sward composition and soil functions. A field experiment was therefore carried out to determine how N2O emissions from previously renovated grasslands varied in the intermediate to long-term, compared with an undisturbed permanent grassland (PG). Plots on the PG site were renovated, either two (G2) or five (G5) years prior to the two experimental years. In each sward age and experimental year, annual N2O-measurements were conducted on a weekly basis and compared with the undisturbed PG. Plots were either unfertilized or were fertilized with slurry (240 kg N ha−1 year−1). On average, annual N2O emissions were 0.39 kg N/ha for the unfertilized swards, and 0.91 kg N/ha for slurry-fertilized swards. Sward age had no effect on N2O emissions. With increasing sward age the proportion of legumes in the sward was reduced, but a minimum biological nitrogen fixation (BNF) of 88 kg N/ha was maintained even in the fertilized PG. Both sward age and BNF were of limited importance for the annual N2O emissions compared with the effects of soil carbon content and nitrogen surplus levels. However, measured N2O emissions were low in all sward age treatments, with a low risk of additional N2O emissions when BNF is taken into account in fertilizer planning. 相似文献
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实践证明,棉农是国家实施棉花良种补贴的最大受益者，实现了棉花良种补贴的主要目的。有人对棉花良种补贴持有不同的态度，是因为棉农、种子企业和基层农技推广部门等相对独立的利益主体，均以从项目实施中获利多少来评价政策的优劣。棉种市场混乱是制约项目实施的关键因素,要提高项目实施水平，必须采取综合措施，重点是整治棉种市场，简化补贴操作程序。 相似文献
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中国2010年上海世界博览会是世界博览会有史以来规模最大、参观人数最多的盛会,吸引了无数中国游客汇聚上海。在此,排队进馆几乎可以看作是一场竞赛,而获得城市名片册敲章以换取预约券就是比赛的一个关键环节。 相似文献
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山东棉花生产“十一五”回顾及“十二五” 发展对策建议 总被引：3，自引：2，他引：1
回顾了“十一五”期间山东棉花生产现状,分析了种植面积稳定、单产提高、总产增加的主要原因。在此基础上,展望了“十二五”期间山东棉花生产面临的形势,提出了稳定发展的对策建议。 相似文献
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High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence? 下载免费PDF全文
下载免费PDF全文 J. M. Lee E. R. Thom K. Wynn D. Waugh L. Rossi D. F. Chapman 《Grass and Forage Science》2017,72(3):382-400
Failure of perennial ryegrass swards to persist is a key issue on dairy farms in many areas of the world. This study describes an experiment conducted to test the hypothesis that high ryegrass seeding rates (>18 kg seed ha?1) reduce plant size and physical survival during the first year after sowing, with negative implications for population persistence. Four cultivars representing four functional types of perennial ryegrass were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed ha?1) with white clover in three dairying regions of New Zealand. Plant establishment rates, size and survival were measured for the first 13 months after sowing. Herbage accumulation, botanical composition and perennial ryegrass tiller density were also monitored. Increasing seeding rate reduced plant survival in the seven weeks after sowing, reflecting likely differences in germination and very early mortality of small seedlings. Thereafter, plant survival was relatively high and consistent across seeding rates at two sites but was consistently greater in the 6 kg ha?1 treatment compared with the 24 and 30 kg ha?1 treatments at one site. Higher seeding rates also increased ryegrass tiller density and the contribution of ryegrass towards total herbage biomass but reduced the contribution of white clover. Very few cultivar × seeding rate interactions were detected for any of the measured variables. Many of the seeding rate effects dissipated by the end of the first year after sowing, indicating that high seeding rates did not predispose swards to poor persistence in the longer term, irrespective of ryegrass functional type. 相似文献
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新疆兵团一四七团属次宜棉区,地处欧亚大陆腹地,属大陆性干旱气候,为荒漠绿洲生态农业.与全国其它产棉区相比,干旱少雨,昼夜温差大,光照充足,水源稳定,为棉花生产提供了充足的自然资源;但是土壤盐碱重,无霜期较短,春季低温风大多雨,秋季气温迅速下降,对棉花生产十分不利.
1"十一五"棉花生产回顾
1.1棉花生产对比分析."十一五"期间,一四七团棉花生产有了较大发展,植棉面积、棉花单产、总产明显提高,总体形势良好(表1).其中2010年春季降水量仅为99.8 mm,播种期比历年推迟15d左右,但子棉总产量达51300 t,创造了一四七团历史最好水平. 相似文献
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茶也进入了IT时代,这是潮流,与日俱增的对茶叶知识感兴趣的消费者中的大多数,就是通过互联网了解茶的.茶叶公司至今仍未放弃电视、广播、印刷品和直销等传统营销手段,但他们也在与时俱进,对一些新兴的营销方式不断尝试,诸如网站、博客、Facebook、Myspace、Twitter和iPhone. 相似文献
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2010年中国茶叶博物馆大事记 总被引：1，自引：0，他引：1
中国茶中博物馆办公室 《茶叶》2011,37(1):56-60
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《来自中国的茶、艺术、茶具展》荣获＂2009年浙江省陈列展览精品评选最佳宣传推广奖＂。《黑白之美———磁州窑茶具展》荣获＂2009年浙江省陈列展览精品评选最佳综合效益奖＂。 相似文献
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The present study investigated how the abundance and sexual reproduction of herbs and grasses relates to the presence of shrubs of Rosa dumalis in three semi‐natural pastures in Sweden. Shrubs may affect grassland plants negatively by competition, positively by serving as grazing refuge, or neutrally. At different distances from shrubs of R. dumalis, data were collected on plant abundance, frequency of reproductive shoots, vegetation height and litter depth. In one grassland, data were collected on seedling density and frequency of reproductive shoots in the presence and absence of grazing. The shrubs functioned as grazing refuges with taller vegetation, deeper litter and higher probability of reproduction by plants. The overall number of plant species remained the same at all distances from shrubs. Most species showed a neutral relationship with shrubs. Proportionately, 0·08–0·26 of the species showed a negative pattern to shrubs and 0·14–0·30 a positive pattern. Seedling density was negatively correlated with litter depth and peaked at 60–90 cm from shrubs. Establishment of seedlings of small‐seeded species was negatively related to shrubs probably because of thicker litter layer close to shrubs. The observed patterns were compared with different functional traits, such as Ellenberg values, plant height, growth form and Raunkiaer life form. Plant height from data in the literature was the trait that best explained the relationship of plant species to shrubs because tall species were more common in proximity to shrubs. It was concluded that shrubs increase the heterogeneity in grasslands and that intensive shrub‐clearing may negatively affect biodiversity. 相似文献
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近年来,三十团加大新技术的推广应用力度,种植业按照十大主体技术和六项精准农业的要求,大力推广加压滴灌、双膜覆盖、杂交棉、大棚育苗等农业技术.2007年,全团棉花平均每公顷产皮棉3150 kg,实现国民生产总值1.75亿元,增长12%;全团职工均收入14418元,增长8%.2008年,三十团在往年的基础上,又利用国家土地整改项目和团场投资结合的办法,新增加压滴灌733 hm2,推广应用双大膜覆盖棉花种植技术,面积达667 hm2.这些技术在晚春播生产中成为亮点.特别是双大膜覆盖棉花种植技术,成为承包户争抢采用的"香饽饽". 相似文献
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江西省瑞金市万田乡地处偏僻山区,远离城市中心,交通不便,信息不灵,长期以来没有形成任何优势产业、特色经济。村人因穷思变,纷纷外出经商、打工,造成田地、山林荒芜,集体经济＂空壳＂,村民没有脱贫。该乡万田村村民袁小林也不例外,1991年,年仅16岁的他初中毕业后,追随着滚滚打工浪潮,离开家乡南下广东闯荡。这一干就是10年,他凭着农家子弟的精明、勤快,深受用工企业的信任和器重, 相似文献
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1杀灭病菌虫卵早春破土可使底层土壤得到充分的阳光照射,紫外线可杀死隐藏在土壤中的病菌。尤其是躲在地底下越冬待醒的棉铃虫的卵,被翻出地面后,经风化、日晒,加上气温的变化,可将其杀死。2碎土蓄水保墒上年犁翻过的预留棉田,越冬期冻土坚实,坷垃多。应抓住刚刚解冻及雨后合墒期,精细耙磨,打碎坷拉,改善土壤越冬期的物理性状,将土壤坷垃整理成粉末状,使耕作层结构紧密,可减少空气光照的进透量,防止水分蒸发,提高土壤蓄水保墒的能力。据有关资料显示,开春后及早整地耙磨的预备棉田,土壤含水量比不耙磨的多3%。3活化土壤开春及早精细整地,超… 相似文献
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"禾康"是北京飞鹰绿地科技发展有限公司推出的盐碱地改良的专利产品--盐碱土壤改良剂.它通过络合增溶作用提高土壤溶液中硫酸钙、碳酸钙的溶解度,从而大量激活被固化的钙离子. 相似文献