刈割次数、施肥量及混播比例对牛鞭草和白三叶混播草地牧草品质的影响

在不同刈割频率、施肥量和混播比例下,对混播草地牛鞭草Hemarthria compressa和白三叶Triflium re-pen不同种群产量、地下生物量及分蘖数进行了研究。试验表明,刈割4次牧草蛋白质的收获量与刈割5次的差异不显著(P>0.05),而酸性洗涤纤维的收获量各处理间差异极显著(P<0.01),其中以刈割4次的最高,为1 135.1 g/m2。当刈割次数适当时,牛鞭草粗蛋白的收获量随着施肥量和禾草混播比例的增加而提高。     

天然草场助推式间歇排种器的设计、分析与试验

为解决禾本科草种细长,千粒质量小,流动性差,易缠绕等造成的禾本科草种排种困难的问题,设计助推式间歇排种器。该排种器主要由种箱、种盒、护种轮、种刷、推种板、连杆和曲柄构成。工作时,通过曲柄转动,驱动推种板往复移动实现充种、清种、护种的排种过程。排种过程为主动排种,改变以往依靠种子自身重力和流动性实现被动排种的情况。根据排种器设计要求,确定影响工作性能的相关参数,并进行排种量稳定性试验。试验结果表明:排种器单次排种量为0.137 5g,满足禾本科草种排种量要求;试验过程中,排种器充种顺利,无草种堵塞和架空现象;排种器排种量稳定性变异系数为5.5,符合GB/T 25421—2010要求。     

Digestible energy content of pasture species in growing European wild boar (Sus scrofa L.)

The objectives were to determine the apparent energy digestibility of six pasture species frequently grazed by European wild boar (Sus scrofa L.) and to estimate the digestible energy (DE) consumption from pasture by grazing wild boar. Seven diets were prepared; a base diet (BD) which did not contain any pasture species, diets D1 to D5 which included 75% of the BD and 25% of the dried pasture species Lolium perenne (D1), Festuca arundinacea (D2), Agrostis capillaris (D3), Bromus staminius (D4) or Trifolium repens (D5) and D6 which contained 85% BD and 15% dried Plantago lanceolata. Seven purebred European wild boar (initial liveweight 24.4 ± 0.8 kg, average ± SEM) were given access to the diets following a Latin Square design. The animals received each diet for eight days, with faecal sampling on days 6, 7 and 8. The total apparent DE consumption from pasture by grazing wild boar was estimated using previously collected pasture consumption data from wild boar. The digestibility coefficients and DE contents of the pasture species ranged from 0.29 to 0.65, and 5.8 to 12.6 MJ/kg DM respectively, with L. perenne and P. lanceolata having the greatest digestibility coefficients and DE contents. The wild boar were estimated to satisfy between 52% and 142% of their maintenance energy requirements through pasture consumption. Grazing wild boar are able to utilise an important proportion of the energy present in pasture species.     

放牧对黑麦草＋白三叶混播草地植被构成的作用

通过4个放牧强度（轻牧、适牧、重牧和过牧,牧后草层高度分别为7.5、5.5、3.5和<2.0 cm）的轮牧试验,对黑麦草(Lolium perenne)、白三叶(Trifolium repens)混播草地土壤化学特性;黑麦草分蘖和白三叶匍匐茎、叶片数及其茎叶构成,牧草高度、生物量与植被构成进行系统研究。结果表明,土壤速效养分含量对放牧强度响应较大,稳定性较弱。随放牧强度的增加,黑麦草分蘖密度和叶片生物量显著增加,黑麦草分蘖质量和白三叶匍匐茎密度及牧草高度和生物量显著下降;黑麦草叶片数,白三叶叶片数、茎叶比和匍匐茎质量在放牧强度间无显著变化。放牧强度在降低黑麦草和白三叶生长特性整齐度的同时,增加其可塑性生长;黑麦草对放牧强度的响应比白三叶敏感,但白三叶的可塑性生长比黑麦草的高。鸭茅（Dactylis glomerata）和非播种植物种的生长特性在放牧强度内变异系数较大。综合分析认为,放牧对草地植被的作用体现于植物个体、种群和群落3个水平,播种的低组分禾草（鸭茅）和非播种禾草是混播草地植被构成变化的关键种。     

A mail survey of factors affecting performance in 627 selected sheep flocks in south-eastern Norway

Abstract

Factors influencing rate of barren ewes, number of lambs born per pregnant ewe, and autumn live weight of the lambs were studied in 627 Norwegian sheep flocks based on herd level data from the Norwegian Sheep Recording System and a mailed questionnaire to the sheep farmers. The following factors were significantly associated (P<0.05) with rate of barren ewes: breed, herd average lambing date, type of production/age of farmer, routines for treatments for parasites, and housing type. Number of lambs born per pregnant ewe was significantly associated with rate of barren ewes, herd average lambing date, breed, percentage grass silage of total roughage, and no separation of gimmers during the housing period. Corrected autumn live weight of the lambs was significantly associated with breed, flock size, lambs born per pregnant ewe, no separation of gimmers during the housing period, and type of summer pasture.     

Two perennial legumes (Astragalus adsurgens Pall. and Lespedeza davurica S.) adapted to semiarid environments are not as productive as lucerne (Medicago sativa L.), but use less water

Perennial forage legumes, particularly lucerne (Medicago sativa L.), play a significant role in crop/livestock mixed farming systems in the semiarid region of the Loess Plateau of China as stock feed and a source of nitrogen for subsequent crops. However, there is evidence that lucerne reduces soil water deep in the soil profile, thereby reducing subsequent crop productivity. From 2004 to 2010, this study evaluated the forage productivity and water use of two locally adapted perennial legume species, milk vetch (Astragalus adsurgens Pall.) and bush clover (Lespedeza davurica S.), compared with lucerne. The 7‐year total and average annual forage yield of milk vetch were 56 and 8 t ha^?1 and bush clover was 42 and 6 t ha^?1, respectively, significantly lower than lucerne at 91 and 13 t ha^?1. However, despite lower water‐use efficiencies (16 and 12 kg ha^?1 mm^?1 for milk vetch and bush clover, respectively, compared to 22 kg ha^?1 mm^?1 for lucerne), the total 7‐year water use in milk vetch and bush clover was 3500 mm and 3490 mm, respectively, which was 135–140 mm less than lucerne. After 7 years, lucerne had extracted water from the upper 5 m soil, whereas bush clover used water mainly from the upper 2 m of the soil profile and milk vetch still had some water available below 3 m. We conclude that while the locally adapted forage legumes were not as productive as lucerne as a source of fodder in mixed cropping/livestock system in this region, they use less water, which may be advantageous in drier regions.     

Proximal sensing of the seasonal variability of pasture nutritive value using multispectral radiometry

The nutritive value of pasture is an important determinant of the performance of grazing livestock. Proximal sensing of in situ pasture is a potential technique for rapid prediction of nutritive value. In this study, multispectral radiometry was used to obtain pasture spectral reflectance during different seasons (autumn, spring and summer) in 2009–2010 from commercial farms throughout New Zealand. The analytical data set (n = 420) was analysed to develop season‐specific and combined models for predicting pasture nutritive‐value parameters. The predicted parameters included crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF), ash, lignin, lipid, metabolizable energy (ME) and organic matter digestibility (OMD) using a partial least squares regression analysis. The calibration models were tested by internal and external validation. The results suggested that the global models can predict the pasture nutritive value parameters (CP, ADF, NDF, lignin, ME and OMD) with moderate accuracy (0·64 ≤ r² ≤ 0·70) while ash and lipid are poorly predicted (0·33 ≤ r² ≤ 0·40). However, the season‐specific models improved the prediction accuracy, in autumn (0·73 ≤ r² ≤ 0·83) for CP, ADF, NDF and lignin; in spring (0·61 ≤ r² ≤ 0·78) for CP and ash; in summer (0·77 ≤ r² ≤ 0·80) for CP and ash, indicating a seasonal impact on spectral response.     

Benefits of Re-Integrating Livestock and Forages in Crop Production Systems

SUMMARY

Specialization is the foundation of contemporary agriculture, yet until the early decades of the 20th century, enterprise diversity was the norm. As agriculture has become more specialized in the intervening years, yields have increased dramatically, but so too have a range of economic, environmental, and health problems. This contribution presents evidence that specialization is an ecologically dysfunctional design for food production, a thesis which is supported by the predominance of problem-solving research in the contemporary literature. As demonstrated by Louis Bromfield in the 1940s and by organic and sustainable farmers today, the strategic integration of crops and livestock/ forage enterprises avoids many of the problems of specialization, while also capturing economic and ecological synergies denied to specialist producers. In addition to providing human foodstuffs, forage-based livestock production also offers a range of novel opportunities to channel natural processes to the service of humanity, from carbon sequestration and site remediation to non-chemical vegetation management.     

Collective management on communal grazing lands: Its impact on vegetation attributes and soil erosion in the upper Blue Nile basin,northwestern Ethiopia

Collective action, on communal grazing land, has evolved in the highlands of northwestern Ethiopia to mitigate the problems of feed shortage and land degradation due to overgrazing. The exercise is liked by farmers for improving the availability of natural pasture during the long dry season when other feed sources get depleted. However, large portions of the communal grazing lands are still managed under free grazing throughout the year. This study was undertaken in Maynet village in the upper Blue Nile basin, northwestern Ethiopia, to assess the impacts of three different types of grazing land management (GLM) and two slope gradients (<10%; 15–25%) on aboveground herbaceous biomass yield, ground cover, species richness, runoff, soil loss and soil bulk density of grazing lands. The GLMs include (a) freely open communal GLM, (b) restricted communal GLM – collective management of communal grazing land locally named as ‘yebere sar’ and (c) private holding GLM. Stocking density was more than carrying capacity of grazing lands across all GLMs. However, the extent of overstocking problem was exceptionally severe in freely open communal GLM. The interaction between GLM and slope was significant (P<0.05) for runoff, soil loss and runoff coefficient. The average runoff coefficient was close to 50% in freely open communal GLM on steeper slopes (15–25%). Freely open communal GLM on steeper slopes resulted in consistently highest cumulative runoff and soil loss amounting to 491 mm and 32 t/ha per year, respectively. Polynomial regression analysis showed that quadratic relationship (r²=0.87) existed between soil loss and runoff. But, soil loss was close to nil when runoff did not exceed 2 mm per rainfall event. As expected, restricted communal GLM appeared to reduce surface runoff by more than 40% and curb the rate of soil erosion by more than 50% compared to freely open communal GLM. Its vegetation cover persisted above 70% throughout the year, meeting the threshold level recommended to keep surface runoff and soil loss to minimum. Reducing the problem of overstocking and pasture resting in August–November are important components to improve ground cover and aboveground herbaceous biomass yield, which in turn reduce land degradation on grazing lands.     

Land‐use changes influence the sporulation and survival of Phytophthora agathidicida,a lethal pathogen of New Zealand kauri (Agathis australis)

Phytophthora agathidicida is the accepted causal agent of dieback in remnant stands of long‐lived indigenous New Zealand kauri (Agathis australis) and poses a significant threat to the long‐term survival of this species. Little is known about the effect of key soil physicochemical characteristics on the growth of P. agathidicida. In this study, we investigated the growth of P. agathidicida in soils collected from adjacent areas under original kauri forest, short rotation pine (Pinus radiata) plantation forest and grazed pastures. A growth response assay was used to quantify asexual (sporangia) and sexual (oospore) spore counts over 8 days in soils sampled from each land‐use. Significantly higher numbers of sporangia (p < 0.001) and oospores (p < 0.01) were found in pasture and pine forest soil within 2 days of the growth assay trials, suggesting these soils may favour asexual/sexual reproduction in the early stages of P. agathidicida establishment compared to kauri forest soils. Additionally, oospore production significantly increased over 8 days in pine forest soil, suggesting that with an increase in inoculum loads, these soils potentially act as pathogen reservoirs. The soil physicochemical properties (e.g., pH, C and N, phosphorus content and electrical conductivity) investigated in this study did not significantly correspond to spore count data between land‐uses, suggesting that differences in growth response are driven by other edaphic factors not explored in the present study.