Use of a Disk Meter to Evaluate Continuously Grazed Pastures

One of the greatest difficulties in pasture research is accurately measuring quality and quantity of the vegetation. The disk meter may be used to rapidly estimate herbage mass (DM) but its validity depends on a good relationship between disk meter height (DMH) and DM. The objective of this study was to determine the relationship between DMH and DM for continuously grazed pastures. Pastures of varied botanical composition were grazed by cows and calves from May through October. Paired data (DMH and DM clipped from under the disk) from seven cool season pastures were subjected to covariance analysis. Prediction equations were developed utilizing data from 2 years for different pastures and dates. Disk meter height accounted for a little over half the variability in DM (R² of 0.54 and 0.59 for years 1 and 2, respectively). Regression coefficients of DM on DMH differed between dates in both years and between pastures in one year. To accurately predict DM the disk meter must be calibrated for each pasture and date. However, the disk meter can be used where an estimate of herbage mass is required and resources are limiting.     

Persistence of Legumes in Hill Land Pasture Following Sod Seeding

Unimproved hill land pastures are often characterized by low production and poor forage quality. The introduction and persistence of a legume component in the sward may increase both forage quality and quantity. Persistence of red clover ( Trifolium pratense L.), birdsfoot trefoil ( Lotus corniculatus L.) and white clover ( T. repens L.) sod-seeded into a rotationally grazed hill land pasture was examined. Legumes were introduced by broadcasting by hand, sod-seeding with a zip seeder, and sod-seeding with a Power-till seeder. The effects of paraquat (1, 1-dimethyl 4–4'-bipyridinium ion), lime and P on legume persistence also were examined. The pasture was mostly Kentucky bluegrass ( Poa pratensis L.) with 5 % white clover initially. Percentage legume in the pasture followed the same trend over time irrespective of whether sod-seeded or not, or method of sod-seeding. There was 30 % legume in control plots the year after sod-seeding and 15 % at the end of 4 years. Application of lime and P resulted in an increase in legume content of at least 5 % through the 4 year period. Paraquat, legume species, and sod-seeding method had no effect on legume persistence. It is concluded that management, soil fertility and time are the most important determinants of legume persistence in hill land pastures.     

安塞黄土丘陵区人工草地生产力与土壤水分特征

摘 要 人工草地建设是半干旱黄土丘陵区生态建设与农业生产的重要组成部分,比较不同类型人工草地生产力、土壤水分差异,可为草地建设中草地类型的选择与管理提供依据。通过比较川地与山地不同类型草地生产力、土壤水分年季变化差异,表现为以下特征：川地人工草地0-100cm土壤含水量受季节降雨量影响变化较为活跃,为活跃层。100-350cm土壤含水量与根系利用有关,为次活跃层。350-500cm季节变化不大,为相对稳定层。柳枝稷与苜蓿草地350-500cm土层干燥化明显。在2004-2005年,各草地4月到9月0-200cm土壤储水量减少,9月到11月0-200cm储水量增加,200cm以下各草地间差异明显,但季节变化量接近。山坡不同类型草地0-100cm土壤含水量表现为秋末高于春季,100-500cm不同季节均未显示明显的水分亏缺现象。     

锡林郭勒草地NDVI和牧草估产产量的变化特征

为及时准确了解草地牧草生长状况,利用EOS/MODIS遥感资料结合地面同步调查数据,分析锡林郭勒草原草甸草原、典型草原和荒漠草原3种草地类型NDVI和草地生物量的月际变化特征。结果表明,利用S曲线回归估产模型测算的草地生长季逐月牧草产量能较好地反映其生长状况变化,体现了各类草地地上生物量的分布特征。其中,草甸草原牧草生长季NDVI和牧草平均估产产量变化范围分别为0.208~0.560和39.8~168.6g/m²（干重）,峰值出现在8月;典型草原牧草生长季NDVI和牧草平均估产产量变化范围分别为0.194~0.480和33.7~146.2g/m²（干重）,峰值出现在7月;荒漠化草原牧草生长季NDVI和牧草平均估产产量变化范围分别为0.130~0.185和10.0~29.8g/m²（干重）,峰值出现在7月。     

Effects of contrasting seasonal growth patterns on composition and persistence of mixed grass‐legume pastures over 5 years in a semi‐arid Australian cropping environment

Perennial grass‐based pastures are uncommon in phased cropping rotations in south‐eastern Australia, where rainfall often limits production and persistence. The high reliance on pure legume‐based pastures limits overall pasture productivity and has adverse effects on environmental parameters such as weed incursion and ground cover. A field experiment was monitored over 5 years to examine the relative productivity of the temperate perennial grasses, phalaris (Phalaris aquatica) and cocksfoot (Dactylis glomerata) and determine whether contrasting seasonal activity enhances their persistence when grown in mixtures with lucerne (Medicago sativa) and annual legumes. Phalaris swards were shown to increase cumulative aboveground biomass by up to 96% and 32%, and in year 5 reduce annual grass emergence by between sevenfold and threefold compared to annual legume and lucerne/annual legume mixed swards, respectively. Only swards that included phalaris maintained ground cover above 70% in each autumn of the experimental period. Swards based on the highly summer dormant cocksfoot cultivar, Kasbah, were generally less productive over all, despite the cocksfoot showing a high level of persistence and good recovery following drought. Grass‐based swards that included lucerne were observed to produce ~35% greater legume biomass than a sward sown only to annual legumes. Cumulative legume biomass was greatest in lucerne swards in the absence of perennial grasses. The experiment was unable to demonstrate a consistent benefit in production and persistence associated with contrasting seasonal growth patterns. However, mixtures containing a range of functional types were consistently shown to enhance productivity over the duration of the experiment compared to less diverse swards. The potential to substantially increase forage productivity and ground cover, while reducing incursion by annual grass weeds, by including well‐adapted perennial grasses in mixtures with lucerne and annual legumes should be utilized.     

中国牧草产品国际贸易格局研究及启示

为研究中国牧草产品的贸易量、贸易结构、贸易伙伴的历史趋势和变化规律,采用描述性统计以及定量计算函数关系的方法分析1996—2014年间中国牧草产品国际贸易格局。结果发现：2008年以来,中国苜蓿干草和燕麦草的进口量都呈现指数式增长趋势,进口量与中国大型奶牛场的奶牛存栏头数呈现显著正相关关系。中国牧草产品主要进口国是美国和澳大利亚。为了保障粗饲料供给安全,中国应该采取的措施是充分利用国内、国际2个市场和2种资源,有效补充对国内优质饲料的供给。燕麦草正值发展的有利时机,应该借鉴澳大利亚燕麦草产业发展经验,重视发展燕麦草产业。同时应该调动国内各种资源发展牧草产业,从而保障中国优质安全的乳制品与牛羊肉产品的供应。     

Drought and Tropical Pasture Management

Droughts are an ever-present threat to tropical crops and pastures. One of the most difficult features of managing pastures in arid and semi-arid regions has therefore been the variability in production from year to year. An understanding of the survival mechanisms of tropical pasture plants and the factors controlling grass/legume interrelations is a prerequisite to the establishment of secure bases for management recommendations. These aspects and management strategies were discussed.
For increased agricultural productivity in order to avert famine, and efficient resource use in drought-prone regions, pasture agronomists should pay attention to the characters most needing improvement in the suite of available tropical grasses and legumes that were discussed.     

覆盖秸秆和种植牧草对盐碱化草地的影响

为了分析秸秆覆盖和种植耐盐碱牧草对盐碱土壤的影响,本研究通过田间裂区试验,比较了在采取不同的改良措施下,盐碱土壤养分含量及微生物数量的变化情况。结果表明:秸秆覆盖和种植耐盐碱牧草可改变土壤养分及微生物含量,但并不是所有覆盖量以及所有耐盐碱牧草均适宜,研究发现,当覆盖量为2kg/m²时,种植一年生牧草东饲一号稗草对土壤的改良效果较好。     

施肥对玛曲高寒沙化草地地上生物量的影响

为研究施肥对玛曲高寒沙化草地地上生物量的影响,设置不施肥（CK）、施有机肥（O）、施氮肥（N）、施磷肥（P）、施氮磷肥（NP）、施有机肥和氮肥（ON）、施有机肥和磷肥（OP）及施有机肥和氮磷肥（ONP）等8个处理,采用样方法对玛曲高寒沙化草地植被盖度和地上生物量进行研究。结果表明：在2006年和2007年,3种肥料混施处理（ONP）比对照盖度增加了7%,地上生物量均为最高。2007年施肥处理的地上生物量在不同生长季均比2006年显著增加。氮、磷肥和有机肥组合的处理（ONP）对增加高寒沙化草地的地上生物量效果最显著。     

Environmental influences on optimum nitrogen fertiliser rates for temperate dairy pastures

Considerable variability in the yield response of temperate dairy pastures to the strategic use of nitrogen (N) fertiliser has been observed previously. Some of this variation could potentially be attributed to environmental effects on the available N (soil mineral N plus fertiliser N) concentration required to optimise pasture growth. Five nitrogen application rate response field experiments were undertaken in an attempt to elucidate the environmental influence on pasture mineral N requirements. A significant response to N fertiliser application rate was detected in four out of the five experiments. The absence of a significant response in one experiment can be attributed to limited water availability. Across the experiments where a significant response to N fertiliser rate was detected the available N that was required to achieve 90% of maximum yield ranged between 60 and 81 kg N/ha. It is concluded that when water availability, soil temperatures and air temperatures are conducive to pasture growth an available N level of between 60 and 81 kg N/ha should be targeted when N fertiliser is used strategically to optimise pasture growth. Soil N testing results should be interpreted in light of the prevailing climatic and edaphic conditions if they are to be used to guide N fertiliser rate decisions within intensively managed temperate pastures.     

微灌技术对环湖区退化人工草地的影响

旨在采用微灌技术对环湖区混播人工草地进行节水灌溉试验的观测研究,探索环湖区人工草地对灌溉条件响应,为环湖区混播人工草地管理和持续高效利用提供参考依据。采用光伏扬水系统进行微喷灌节水灌溉试验,调查群落结构,计算地上和地下植物量。研究表明：植物群落多样性、均匀度、生态优势度指数均为灌溉区大于对照区;水分充足条件下能促进植物茎叶的生长,而干旱有利其根部的发育;灌溉可有效提高环湖区人工草地的优良牧草产量。可见水分的增加抑制了退化草地指标种生长,有利于草地恢复,环湖区人工草地对灌溉条件具有较好响应。     

Heritability of frost-seeded red clover establishment

In the colder parts of the United States (north of 32° N latitude and east of 92° W longitude), in late winter after disappearance of snow cover, red clover (Trifolium pratense) is often broadcast seeded into forage legume-depleted grass pastures to increase pasture forage quality. This method of establishment is referred to as frost seeding. However, in an estimated 30–40% of frost seeded pastures in Wisconsin, USA the legumes fail to establish. In this study 40 red clover halfsib families from one breeding population and ten check populations were evaluated for spring frost-seeded establishment in three environments. Seedling establishment counts and plant heights were measured 3 months after frost-seeded planting. One of the three environments experienced a stand establishment failure. Narrow sense heritability estimates on a halfsib family basis for stand counts and heights were 0.07 and 0.63, respectively. Seedling counts were greatly affected by environment with micro-environmental effects contributing to low heritability. Additive by environment genetic variance was large, again leading to low seedling count heritabilities. These results, based on one population, suggest that it may be difficult to select for increased frost-seeded seedling establishment and that many test environments are needed to achieve genetic gains for this trait. In comparison, seedling height was very heritable with relatively small additive by environment genetic variances. The genetic correlation between seedling count and height using frost-seeded establishment was r _A = 0.42.     

Nitrogen Fertilization on Rye Pasture: Effect on Forage Chemical Composition, Voluntary Intake, Digestibility and Rumen Degradation

The effects of nitrogen (N) fertilization of a rye pasture (Secale cereale L.) on the chemical composition of forage and its utilization in vivo and in situ were investigated in winter (W) and early spring (S). Half of the paddock to be assayed was spread with 93 kg urea–N ha^?1 (treatment F), and the other half was not fertilized (treatment NF). Each experiment lasted for 17 days; apparent dry matter digestibility in vivo, voluntary dry matter intake (DMI) and digestible DMI were measured on nine rams per treatment. Two rumen cannulated animals per treatment were under the same feeding regime, and used to collect samples of rumen contents. The concentrations of ammonia (NH₃) and short‐chain fatty acids and pH were measured in these samples. The offered forage was also incubated in the rumen of three Holstein–Friesian steers to estimate its degradation parameters in situ. Fertilization with N increased total N and decreased dry matter (DM) and non‐structural carbohydrate concentrations in both periods. DMI was reduced by fertilization. The rumen concentrations of NH₃ were higher in F than in NF in both periods. In both periods, the effective DM degradability of forage was higher in F than in NF. N fertilization affects chemical composition, voluntary intake and rumen digestion of forage from rye pasture.     

Sward Height and a Capacitance Probe for Estimating Herbage Mass

Estimation of herbage mass is essential in pasture research and in making practical grazing management decisions. Sward height and a capacitance probe were evaluated as non-destructive measures of herbage mass at seven dates from April 16 to July 30 on continuously grazed predominantly Kentucky bluegrass ( Poa pratensis L.) pasture. Paddocks were 1 ha in size and were stocked at 3, 4 or 5 steers ha⁻¹ (average initial weight 312 kg). Four to six, sampling points were located randomly in each paddock at each date. Sward height was measured with a ruler, the vegetation in a 0.2 nr area visually designated "high" or "low" according to legume percentage, ten readings using a single capacitance probe were made and the herbage clipped. Paired data with clipped dry weight as dependent variable and height and/or the average corrected probe reading as covariates were analyzed statistically. The relationship between clipped dry weight and nondestructive measures of herbage mass was found to be linear. There was a small effect of sampling date in Spring on the relationship between destructive and non-destructive measures of herbage mass, but each of the measures, including herbage mass predicted from probe and height measurements, resulted in the same inferences being made about differences between treatments. Neither stocking rate nor small differences in percentage legume affected the relationship. Thus, sward height and capacitance probe show promise as nondestructive measures of pasture herbage mass.     

刈割期与晾晒天数对饲料油菜产量和粗蛋白含量及水分的影响

为了明确长三角地区饲料油菜适宜收获期与晾晒时间,2016-2018年连续2年开展田间试验,终花至角果期刈割5次并于田间晾晒,比较不同刈割期和晾晒天数下饲草产量、粗蛋白含量及水分变化差异。结果表明,与首次刈割（终花期）相比,终花后4到16d刈割饲草鲜重显著增加,饲草干重分别提高了31.93%、41.50%、49.14%和61.43%。随着刈割时间延迟,饲草粗蛋白含量呈下降趋势,末次刈割饲草含水量显著降低（P<0.05）。油菜终花后4d刈割,并于田间晾晒第4和5天时,其鲜草含水量由82.16%下降为71.45%和65.26%。不考虑刈割期,田间原位晾晒3d,平均鲜草含水量由81.00%下降至66.30%。晾晒期间土壤累积温度每增加10°C,鲜草含水量降低2.30%。由此,长三角地区稻茬油菜在终花后4d刈割,饲草鲜产和粗蛋白含量均能达到较优水平,刈割后田间原位晾晒4~5d,可满足青贮水分要求。     

Pasture restoration improvement methods for temperate degraded pastures and consequences of the climatic seasonality on soil–pasture complex

Short persistence of renovated pastures is a major problem for pastoral production systems. Pasture species establishment, species performance and persistency and their relationships with soil–water attributes following pasture improvement methods were evaluated over two years. Fertilised naturalised pasture (FNP), non-fertilised naturalised pasture (NFNP), Lolium perenne–Trifolium repens cultivated pasture (CP), L. perenne–T. repens direct-drilled pasture (DP), and Bromus valdivianus, Holcus lanatus, Dactylis glomerata, L. perenne and T. repens direct-drilled pasture (DDP) were established as a randomised complete block design. Pastures were limed, fertilised and sheep-grazed. Plant growth compensatory mechanisms, by decreasing tiller number and increasing tiller size, equalised pasture yield during the establishment. In both years, the improved pastures yield was greater than that of NFNP. In the second year, DDP and FNP reached the higher pasture growth rate, with a seasonality diminishment. During the second summer, soil matrix potential at 0–20 cm soil profile exceeded the permanent wilting point, resulting in the pasture growth rate of NFNP and the sown pastures ranging from 0.0 to 3.6 kg DM/ha per day, while for FNP, it was 17.8 kg DM/ha per day. Sown species, fast-growing species spontaneous colonisation and growth were all stimulated in the improved pastures over species that tolerate stress, improving agronomical and ecological pasture features.     

Genetic Diversity in Tall Fescue Ecotypes from Alabama I. Maturity, Morphological Traits, and Disease Reaction

There is a large hectarage of tall fescue in Alabama. Recognition of the deleterious effects of the endophytic fungus Acremonium coenophialum has resulted in substantial acceptance of new endophyte-free cultivars. Destruction of old pastures and the concomitant loss of potentially valuable adapted germplasm could be a valid cause for concern. The objectives of this study were to evaluate genetic variation for maturity and plant morphological traits, both among and within tall fescue cv. ‘Kentucky 31’ populations from 18 to 38 year-old pastures in Alabama. Ten populations of approximately 50 plants each were collected from old Alabama tall fescue pastures. Two pastures were sampled in each of five counties, representing the five major land use areas of the state. In 1990, spaced plants of all populations were evaluated at heading time for maturity, morphological, and disease traits at two locations in central Alabama. Endophyte infection level of the populations ranged from 2 to 100 %. Maturity was highly correlated with tiller length and flag leaf width and was used as a covariate for these traits in the analysis of variance. Leaf rust and net blotch ratings were negatively correlated. Significant variation among populations was observed for maturity and flag leaf dimensions, most variation being due to differences among source counties. Significant variation was observed within all populations for maturity and morphological traits, but only in seven populations for leaf rust. No within-population variation was detected for net blotch. The average precipitation for the month of May explained 81 % of the variation among populations for maturity. Age of the pasture sampled had a significant effect on tiller diameter (r²= 0.55), and latitude of the pasture sampled was the best individual predictor of leaf width (r²= 0.42). This study reveals that considerable genetic diversity, largely influenced by climatic conditions, exists among ‘Kentucky 31’ tall fescue ecotypes from Alabama.     

Genetic variation, heritability and progeny testing in meadow bromegrass

Meadow bromegrass is a recently introduced pasture grass in western Canada. Its leafy production and rapid regrowth have made it a major grass species for pasturing beef animals in this region. Because relatively little breeding work has been done on this species, there is little information on its breeding behaviour. The main objective of this study was to estimate genetic parameters and assess breeding methodologies for meadow bromegrass. Forty half‐sib (polycross and open‐pollinated) and full‐sib (selfed) progenies were evaluated for dry matter and seed yield, fertility index, harvest index, plant height, plant spread, crude protein, neutral detergent fibre and acid detergent fibre. Genetic variation for seed yield, harvest index, and plant height was significant in the open‐pollinated and selfed tests. Genetic variation estimates for dry matter yield were negative (polycross), not significant (open‐pollinated), or significant (selfed). Estimates of genetic variation for quality traits were not significant, except for acid detergent fibre (selfed). Correlations among characters indicated that it is possible to simultaneously improve seed and forage yield. Rankings of progenies by the half‐sib tests for forage and seed yield were not altered by the use of the synthetic parental value (SV_i), which includes information from selfed progeny. The polycross progeny test did not discriminate parents as well as the open‐pollinated and selfed tests; this may have been a result of non‐random pollination in the polycross. Correlation among the progeny tests, showed that open‐pollinated and selfed progeny tests agreed for all characters, except for harvest index, while correlation between polycross and selfed tests were significant for six characters but not dry matter yield, and acid and neutral detergent fibres. The most dissimilar tests were polycross and open‐pollinated, with significant correlations found only for fertility index, height, spread and neutral detergent fibre. It was concluded that there was significant variation and moderate heritability for most traits in the meadow bromegrass populations evaluated, and that the open‐pollinated progeny test is the method of choice for selecting parents for synthetics of this species.     

Effect of Overseeding Forages into Alfalfa on Alfalfa Weevil, Forage Yield and Quality

Many alfalfa ( Medicago sativa L.) fields are sprayed each year with insecticides to control Egyptian alfalfa weevil ( Hypera brunneipennis ) and the alfalfa weevil ( Hypera postica ). Overseeding various species of legumes and grasses into established alfalfa has been proposed as a method to mitigate weevil damage without insecticides. Established fields of alfalfa were overseeded with legumes and grasses in randomized complete block designs in three years of study in a Mediterranean climate in the Sacramento Valley of California, USA. Several overseeding practices maintained or increased yields compared with the insecticide-sprayed treatment. Overseeding increased or maintained forage yield, eliminating the need for insecticides. However, overseeding did not prevent weevil damage to alfalfa. Overseeding is best used to extend the life of alfalfa stands in the final year of production, since overseeding can thin alfalfa stands. Market acceptance for mixed-species hay and harvest management of overseeded forages are the most important limitations to overseeding practices.     

Pasture grazing intensity and presence or absence of cattle dung input and its relationships to soybean nutrition and yield in integrated crop–livestock systems under no-till

In integrated soybean–beef cattle systems, the pasture grazing intensity affects the grain crop performance in succession. In addition, the dung cattle input influences the soil nutrients distribution in the field affecting the grain crop yield. This experiment aims to evaluate the effects of winter pasture heights and cattle dung input in soybean crop performance in succession. Main soil macronutrient content, soybean plant population, dry shoot biomass, plant height, plant nutrient content, soybean yield and yield components were assessed in the 10th experimental year. The experiment was conducted in the state of Rio Grande do Sul, Southern Brazil, in a long-term integrated crop–livestock systems implemented in 2001. Treatments were arranged in a split plot design with four pasture heights (0.10, 0.20, 0.30, and 0.40 m) and two levels of dung input (with or without). For all the variables analyzed, there was no interaction between pasture heights and cattle dung input (P > 0.05). The pasture height management had only effect in soil P content, soybean dry biomass production, plant height and number of grains per pod. The increase in grazing intensity was associated to the rise in soybean plant height and dry mass production but was without effect on grain yield. The presence of grazing animals in the integrated soybean–beef cattle systems, and the resultant augmentation of dung input increased by 122% and 38% the availability of soil K and P, respectively in relation to the absence. Thus, the content of such nutrients in the plant were increased in 41% and 7%, respectively. The improvement in soybean nutrition increases the amount of pods per plant by 20%, and resulting in a 23% increase in soybean yield. These results indicate that cattle dung input resulting from grazing animals in the pasture phase increased soybean grain yield due to better plant nutrition. Although, the occurrence of cattle dung was very concentrated in some spots of the field and thus future studies should address strategies to improve spatial distribution of cattle dung input.