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1.
Carbon and nitrogen budgets of nematodes in arable soil 总被引：2，自引：0，他引：2
Summary The amounts of C and N that pass through the nematode biomass in four cropping systems, barley without and with N fertilization, grass ley and lucerne, has been estimated. The nematodes were sampled at the field site of a Swedish integrated research project Ecology of Arable Land: The Role of Organisms in Nitrogen Cycling. The nematode biomass was lower (200 mg dry weight m–2) in the annual (barley) than in the perennial (grass and lucerne, 350 mg dry weight m–2) crops. For respiration, the nematodes used 4–71 O2m–2 year–1 corresponding to C liberation of 1.3%–2.0% of the carbon input to the soil. A higher relative contribution by bacterial-feeding nematodes to the C and N fluxes and a higher turnover rate of the nematode biomass is an indication of more rapid nutrient circulation in the annual than in the perennial cropping systems. 相似文献
2.
《Communications in Soil Science and Plant Analysis》2012,43(2):229-243
Abstract Phytophthora root rot (PRR) is an important disease of alfalfa (Medicago sativa L.) in wet soils. Excess soil water (ESW) stress is required for the successful infection and development of PRR. The effects of P at 0, 40, and 80 μg.g‐1 soil and K at 0, 120, and 240 μg.g‐1 soil (in factorial combinations) on the severity of PRR or ESW stress was investigated on a PRR‐susceptible (Iroquois) and a resistant (Oneida) alfalfa cultivar in a greenhouse trial. P and K applications significantly increased the dry weight of tops prior to imposition of PRR or ESW stress. However, plants subjected to PRR or ESW stress did not respond significantly to P or K and there was no significant effect of P or K on the severity of PRR or ESW injury. The plants subjected to PRR or ESW stress had lower tissue P concentration than those under stress‐free conditions. Increasing P additions resulted in a significant increase in P concentration of Iroquois plants, while in Oneida the response was non‐significant. The response of K concentration in the plant to increasing K additions was dependant on P levels. 相似文献
3.
紧实土壤降雨后常由于板结而严重影响作物出苗，导致建植不良乃至失败本实验采用遮阳膜覆盖、麦秸覆盖、不覆盖、土壤稳定剂４个表面处理和快速干燥、缓慢干燥２个干燥速度处理，研究芷蓉播后模拟降水条件一出苗情况，不同的覆盖及土壤处理条件下芷蓿出苗具有显著的处理效应，处理效应主要在出苗早期形成，遮阳膜覆盖比其他出苗显著要高；干燥速度地芷蓿出苗无影响。土壤剂和麦秸对苜蓿出苗的影响需要进一步的研究。 相似文献
4.
Effect of supplementing urea-treated barley straw with lucerne or vetch hays on feed intake,digestibility and growth of Arsi Bale Sheep 总被引：1，自引：1，他引：0
The study was conducted at Sinana Agricultural Research Center, Ethiopia to assess the supplementation of graded levels of
vetch (Vicia dasycarpa `lana’) and lucerne (Medicago sativa,’ Hunter river’) hay on feed intake, digestibility and body weight (BW) change of Arsi-Bale sheep fed urea treated barley
straw (UTBS). A 7 day- digestibility and a 90 day- feed intake trials were conducted using 28 and 35 sheep, respectively.
The experimental design was a randomized complete block design with seven dietary treatments that consisted of feeding UTBS
(T1) as the control treatment, UTBS plus 150, 250 and 350 g dry matter (DM) per day of vetch for T2, T3, T4, respectively
and UTBS plus 150, 250 and 350 g DM per day of lucerne for T5, T6 and T7, respectively. Intake of UTBS was not affected (P > 0.05)
by inclusion of lucerne hay at 25–35% of daily DM intake. The supplements increased daily intake of total DM, organic matter
(OM), neutral detergent fiber (NDF), acid detergent fiber (ADF) and metabolizable energy (ME) (P < 0.001) as well as apparent
digestibility of DM, OM (P < 0.001), NDF (P < 0.01), ADF, crude protein (CP) (P < 0.05) and daily BW gain (P < 0.001). Supplementation
with lucerne than vetch hay promoted higher (P < 0.001) CP and ME intakes and daily BW gain. Feeding with the UTBS without
supplementation was enough to meet the maintenance requirements of the sheep and allow small BW gain. The results of the study
showed that urea treatment of barley straw in conjunction with supplementation of lucerne or vetch hay could serve as a useful
strategy in improving smallholder sheep production in the tropics. 相似文献
5.
Soil moisture and water use by pastures and silvopastures in a sub-humid temperate climate in New Zealand 总被引：1，自引：1，他引：0
Soil moisture content from 0 to 2 m depth was monitored under 2–6 year old radiata pine (Pinus radiata) with three understoreys of bare ground, lucerne (Medicago sativa) and ryegrass/clover (Lolium perenne/Trifolium spp.) and under adjacent open-grown lucerne and ryegrass/clover pastures. By the fifth year soil moisture depletion/recharge
pattern under the trees alone was similar to that under open pasture and under trees with pasture understoreys. Maximum plant
available moisture storage was 207–223 mm in the top meter of this Templeton silt loam soil but only 69–104 mm at 1–2 m depth
where coarse textures often predominated. Lucerne reduced soil moisture content (SMC) to lower levels during drier summers
and extracted more water from 1 to 2 m depth than ryegrass/clover. Evapotranspiration (ET) during early summer when soil moisture
was high was close to the Penman potential evapotranspiration (E
p
), but the difference increased when SMC in the top meter dropped below 200 mm. The silvopasture treatments had higher ET
in winter than pasture alone but this was still less than E
p
. Soil moisture deficits (SMD) at the end of each summer were sufficiently large to require slightly higher than normal winter
rainfall and ET < E
p
to recharge the soil to field capacity before the next summer. The soil moisture results, taken together with root and growth
data, suggest that trees and understorey pastures are complementary in the first three or four growing seasons but this balance
subsequently declines in favor of the pine trees. Management options, to extend the period that understorey pastures are productive,
include reducing tree stockings, more vigorous pruning, using competitive understoreys and changing from pines to deciduous
trees. Research on new silvopastoral combinations is suggested. 相似文献
6.
7.
澳大利亚苜蓿抗寒性研究进展 总被引：1，自引：0，他引：1
欧洲和美国的苜蓿品种在恶劣的生长环境下持久性较差,因此培育能适应澳大利亚严酷的生长条件的苜蓿品种非常关键。通过引进优良苜蓿品系和新搜集的苜蓿品系进行杂交,获得理想杂交品种,在多种不同的气候区域及土壤类型下对杂交种抗寒性进行测定,保留表现最好的杂交后代,形成前基础种子。在国内外大量研究成果基础上,结合澳大利亚苜蓿品种选育,系统阐述了苜蓿在低温胁迫下,其形态、生理、生化诸方面适应性变化以及秋眠性与抗寒性的关系,并对苜蓿抗寒基因工程研究进展作了相关报道 相似文献
8.
新疆苜蓿病害种类和分布的初步研究 总被引：15，自引：0，他引：15
文章报道了新疆天山南北８个地州人工栽培紫花苜蓿上的１９种病害,其中一种病害,类似由黑白轮枝菌（Ｖｅｒｔｉｃｉｌｌｉｕｍａｌｂｏ－ａｔｒｕｍＲｅｉｎｋｅｒｅｔＢｅｒｔｈ．）引起的苜蓿黄萎病,而由束状匍柄霉（Ｓｔｅｍｐｈｙｌｉｕｍｓａｃｉｎｉ－ｉｆｏｒｕｍ（Ｃａｖ．）Ｗｉｔｓｈ．）引起的苜蓿匍柄霉叶斑病为新疆首次指导。不同地区苜蓿地的病原群体结构呈现较大差异。 相似文献
9.
基于APSIM 模型的宁夏半干旱区苜蓿
灌溉模拟验证和应用 总被引：1，自引：0，他引：1
基于宁夏4 个试验点的试验数据和同期气象资料,对APSIM 模型进行了充分地校准和验证。结果表明,
APSIM 模型达到了较高的精度,各验证项模拟值和实测值均表现出良好的相关性,决定系数R2在0.6~1.0 之间,D 值
在0.78~0.99 之间。在此基础上,利用APSIM 模型模拟了不同灌溉情况下不同灌溉量对苜蓿（Medicago sativa L.）的
干草产量尧蒸发蒸腾量和水分利用效率的影响。认为灌溉是宁夏半干旱地区苜蓿增产的重要因素。200 mm 的灌溉
量是苜蓿干草产量由增加到减少的转折点。苜蓿不同生育阶段对水分的敏感度不同。分枝期和现蕾期最大灌水量
为50 mm,超过50 mm 会引起产量降低。蒸发蒸腾量（ET）与灌水量呈线性显著相关,决定系数R2达到0.826,P<
0.01。苜蓿水分利用效率与灌溉量不成正比,当灌溉量增加到100 mm 时,水分利用效率达到最大尧为54.2 kg/hm2窑
mm,随后逐渐降低。较大的灌溉量不利于苜蓿水分利用效率的提高。 相似文献
10.
紫花苜蓿饲喂泌乳奶牛的效果试验 总被引：2，自引：0，他引：2
选择产奶牛18头,随机分为对照组和试验组,对照组饲喂基础日粮,试验组日喂35kg鲜苜蓿草代替基础日粮中部分精料和小麦秸。结果表明,试验组产奶量和乳脂率都高于对照组差异显著(P>0.05)。 相似文献