Mineral Concentrations of Cool Season Pasture Forages in North Florida During the Winter-Spring Grazing Season: II. Trace Minerals

Trace mineral concentrations of annual cool season pasture forages grazed by growing beef cattle during late fall-winter-spring grazing season were evaluated during two experimental cool season grazing studies, each lasting two years at the North Florida Research and Education Center (NFREC), Marianna, Florida. Eight 1.32 ha fenced pastures or paddocks were divided into two groups of pasture land preparation/planting methods, four pastures for the sod seeding treatments (SS) and four for the prepared seedbed treatments (PS). Two different pasture forages, small grains, (rye/oats mix) with or without ryegrass for the first two years (Study 1); and oats with ryegrass or ryegrass only for the last two years (Study 2) were planted in these pasture lands. Each of the four forage, type, and cultivation combination treatments was assigned to two pastures each year, thereby giving two replicates per pasture treatment per year. Forage samples were collected at the start of pasture grazing and twice monthly thereafter until the end of grazing season, pooled by month, and analyzed for copper (Cu), iron (Fe), zinc (Zn), manganese (Mn), cobalt (Co), molybdenum (Mo), and selenium (Se). Liver biopsies and blood plasma samples were collected from the tester cattle only during the spring of year two of Study 2. Liver was analyzed for Cu, Fe, Mn, Co, Mo, and Se and plasma for Cu, Fe, Zn, and Se. Forage trace mineral concentrations were found to differ by month in Cu (P < 0.01), Fe and Zn (P < 0.0001) in both studies, and with Mn (P < 0.0001) in Study 2 only. Pasture forage type effects on Cu (P < 0.05), Fe and Zn (P < 0.01), and Se (P < 0.05) and forage type by month interactions on Cu and Mn (P < 0.0001), and Zn (P < 0.05) were observed in Study 2. Forage concentrations of Cu, Zn, Mn, and Mo in Study 1 and Mn, Mo, and Se in Study 2 were affected (P < 0.05) by pasture land preparation/planting methods in that these minerals were found to be lower from forages of sod-seeded treatments than from those of prepared seedbed treatments. Forage Cu concentrations were lower than the minimum requirements (10 ppm, DM) for beef cattle among months in both studies. Oats-ryegrass pastures of Study 2 had surprisingly low Fe concentrations (P < 0.01) in all months of the winter-spring grazing season. Cobalt, Mn, Mo, and Se did not vary much month to month during the winter-spring grazing months. All mean forage Se concentrations were lower than the requirements (0.10 ppm, DM) for grazing beef cattle. There were no differences (P > 0.05) in mean Se values between the two studies. Liver Cu, Fe, Co, and Se concentrations were sufficient to indicate adequate status of these minerals in tester animals from both forage types. Liver concentrations of Mn and Mo were slightly low, indicating a low status or these minerals. Plasma concentrations of Cu, Fe, Se, and Zn were all above the recommended concentrations for beef cattle. In conclusion, trace minerals deficient in North Florida during the cool season were Cu, Co, and Se, and a special consideration should be given to include adequate amounts while supplementing the mineral mixtures to growing beef cattle since forage samples reflected deficient concentrations of these minerals.     

Mineral Concentrations of Cool Season Pasture Forages in North Florida During Winter-Spring Grazing Season. I. Macrominerals and Forage Organic Constituents

Two experimental late fall-winter-spring grazing studies, each lasting two years, were conducted at the North Florida Research and Education Center (NFREC), Marianna, Florida to evaluate the organic constituents and macromineral concentrations of annual cool season pasture forages grazed by growing beef cattle. Eight 1.32 ha fenced pastures or paddocks were divided into two pasture land preparation/planting methods, four pastures for the sod seeding treatments and four for the prepared seedbed treatments. These pastures were planted with two different forage combinations: rye/oats mix with or without ryegrass for the first two years (Study 1), and oats with ryegrass or ryegrass only for the last two years (Study 2). Each of the four forage/land preparation combination treatments was assigned to two pastures each year, thereby giving two replicates per year. Forage samples were collected at the start of grazing and twice monthly thereafter until the end of grazing season for each year, pooled by month, and were analyzed for calcium (Ca), phosphorus (P), sodium (Na), potassium (K), magnesium (Mg), dry matter (DM) yield, crude protein (CP), and in vitro organic matter digestibility (IVOMD). Blood plasma samples were also collected from the tester cattle during the spring season of year 2 of Study 2 and were analyzed for Ca, P, and Mg. Month differences were observed in forage concentrations of P and K (P < 0.0001), and Mg (P < 0.05) in both studies, Ca (P < 0.01) in Study 1 only, and Na (P < 0.05) only in Study 2. Year affected P, K, and Mg concentrations in Study 1 and Ca, P, and Na concentrations in Study 2. In Study 2, forage type by month interactions on Ca, K, and Mg concentrations were noticed (P < 0.01). Forage Ca was lower (P < 0.05) than the critical level for all months from the oat plus ryegrass pastures, and for early winter months and late spring months from ryegrass only pasture. Forage Na concentrations were consistently low throughout the grazing season and unaffected by forage type or land cultivation methods used in both studies. Low Mg concentrations of both forage types in Study 2 (also with high K concentrations) were indicative of a potential risk of grass tetany (hypomagnesemia) for grazing ruminants. Forage DM yields were highly variable with fluctuations among the experimental months and were found to be highest in the spring months, with decreasing yields towards the end of the grazing season in both studies (P < 0.0001). The CP concentrations were greater than the required levels and both CP and IVOMD decreased gradually by month in both studies (P < 0.0001). Normal blood plasma concentrations of Ca and P obtained were indicative of a good overall status of these minerals in the animal's body. Plasma Mg concentrations were slightly above the critical level for cattle from both forage types. In summary, the macrominerals most likely to be deficient in North Florida during the cool season would be Ca, Na, and Mg. Special attention should be given to supplementation of Mg since forages reflected a marginal deficiency of this mineral and high K concentrations were found.     

Soil,forage, and serum nutrient changes as affected by deposition of volcanic sediments in northwestern nicaragua

Abstract

A study was carried out to determine the mineral status of grazing cattle as affected by the eruption of the Cerro Negro Volcano in northwestern Nicaragua. A total of 14 composite soil and forage samples and 30 blood samples were collected at each collection period, before (August 1991) and after (August 1992) the volcanic eruption. Higher soil levels of calcium (Ca), sodium (Na), manganese (Mn) (P<0.01), zinc (Zn) (P<0.05), and lower organic matter (OM) (P<0.01) were found after the volcanic eruption. Phosphorus (P) was the only macromineral found deficient with 93 and 71% of the samples below a critical level before and after volcanic eruption, respectively. Forage Ca, potassium (K), magnesium (Mg), P, Zn, copper (Cu), and selenium (Se) concentrations did not vary between collections. Forage crude protein (CP), in vitro organic matter digestibility [(IVOMD) P<0.05], cobalt (Co), Mn, and Na (P<0.01) were lower after the eruption. Iron (Fe) was the only mineral in forages that increased (P<0.01) after the volcanic eruption. Of the six minerals evaluated in serum only Ca and Mg concentrations were higher (P<0.05) after the volcanic eruption. The macrominerals more likely to be deficient in this area are P and Mg. Trace elements most likely to limit cattle productivity are Zn, Mn, Cu, Se, and Co. Special attention should be given to supplementation of Cu, since both plant and animal tissue samples reflected a deficiency of this mineral.     

Monthly variation of forage and soil minerals in central Florida II. trace minerals

Abstract

A two‐year study was conducted to determine the trace mineral status of cattle grazing forages (bahiagrass) and soils on a ranch in central Florida. Forage and soil samples were collected every month for two years. Month effect (P < 0.05) on soil trace mineral concentrations were observed in manganese (Mn) and zinc (Zn) in years 1 and 2, and in copper (Cu) and iron (Fe) only in year 2. All soil trace minerals studied showed higher (P < 0.05) concentrations in year 2. Month differences (P < 0.05) in forage trace mineral concentrations were found in cobalt (Co), Cu, Fe, Mn, molybdenum (Mo), selenium (Se), and Zn. The majority of forage trace minerals were higher in spring‐summer months. Year means were similar (P > 0.05) in forage trace mineral concentrations. Few and low correlation coefficients were observed between and within soil and forage trace minerals concentrations. Percentages of total forage collected with trace minerals below critical values (in parentheses) and suggestive of deficiency were as follows: in forage, Co (0.1 ppm), 93%; Cu (8 ppm), 98%; Fe (50 ppm), 75%; Mn (40 ppm), 41%; Mo (> 6 ppm), 0%; Se (0.2 ppm), 98%; and Zn (25 ppm), 84%; in soil, Cu (0.3 ppm), 77%; Fe (2.5 ppm), 7%; Mn (5 ppm), 91%; and Zn (1.5 ppm), 53%.     

Effects of pasture‐applied biosolids on forage and soil concentrations over a grazing season in north Florida. II. microminerals

Abstract

The experiment rationale was to determine forage micromineral concentrations as effected by biosolids fertilization. We determined the effects of two exceptional quality biosolids on bahiagrass trace mineral concentrations as related to beef cattle requirements. Twenty‐five 0.8‐ha pastures were divided into five blocks. Two biosolids were applied as normal and double agronomic rates. The control received NH₄NO₃. Forages were analyzed for total copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), molybdenum (Mo), cobalt (Co), and selenium (Se), and soils were analyzed for Mehlich I extractable Cu, Mn, and Zn. Some significant increases (P<0.05) in forage Co, Cu, Fe, Zn, and Se were observed at various sampling times, but the increases were generally small and biologically insignificant. Although forage Mo samples from pastures with the Tampa biosolids applied were consistently higher than the control (P<0.05), at no time did they approach levels considered toxic. Similar results were seen in forage Mn concentrations, with treatment Baltimore‐2X elevating (P<0.05) Mn concentrations as well. Deficiencies of Co, Cu, Zn, and Se are common in this Florida region and slight elevations due to biosolids treatment could be beneficial. Biosolids applied at the highest rates improved soil Cu and Zn concentrations above control soils and soil Mn was increased over the control at both sampling times for Baltimore‐2X. In relation to beef cattle requirements, the majority of forages were deficient in Co, Cu, Se, and Zn. In summary, biosolids fertilization slightly improved the micromineral status of forage and soil, without creating toxicity.     

Monthly variation of forage and soil minerals in central Florida. I. macro‐minerals

Abstract

A two‐year study was conducted to determine the macromineral status of cattle grazed forages, mostly bahiagrass, and soils in central Florida. Soil and forage samples were collected every month for two years. Month differences (P < 0.01) were observed in all forage macrominerals and in crude protein (CP) for both years. No month effect (P > 0.05) was observed in IVOMD level during year 1. Year effects (P < 0.05) were observed in calcium (Ca), sodium (Na) and CP. Concentrations below the critical level were observed in all macrominerals studied. Higher forage macro‐mineral concentrations were found during spring‐summer months. In general, higher (P < 0.05) soil aluminum (Al), Ca, magnesium (Mg), phosphorus (P), and organic matter (OM) were observed during fall‐winter months, while Na was higher in winter. Soil Ca and Mg were adequate and potassium (K), Na and P were deficient. Year 2 showed higher (P < 0.05) soil macromineral concentrations. Correlation coefficients (r >|0.5|, P < 0.05) were present between forage K and forage CP (r = 0.557) and between forage P and forage CP (r = 0.554). Low correlations were found between soil and forage macrominerals. Percentages of total forage samples with macromineral and CP concentrations below critical levels (in parentheses) and suggestive of deficiency were as follow: in forage, Ca (0.30 ppm), 21%; Mg (0.18 ppm), 34%; K (0.60 ppm), 47%; Na (0.06 ppm), 89%; P (0.25 ppm), 85%; and CP (7%), 18%.     

Mineral concentrations of forages and soils in Benue State,Nigeria. I. Macrominerals and forage in vitro organic matter digestibility and crude protein concentrations

Abstract

Macromineral composition of different forage species and soils and forage in vitro organic matter digestibility (IVOMD) and crude protein concentrations in three agricultural zones of Benue State were studied. The zones consisted of Tiv zone (Zone A), Igala zone (Zone B), and Idoma zone (Zone C), each of which was made up of three sites. Site I was Fulani cattle migration routes across the state, site II represented grazing sites within home proximity, and site III were grazing reserves. Grazing animals were followed and forages corresponding to that consumed by them, and the corresponding soil samples were collected during the peak of the dry season (December‐January) and analyzed for nutrient composition. Forage IVOMD ranged from 21% to 79%, with values obtained in grass being lowest due to pronounced overmaturity. Only 10% of forage samples (exclusively from grasses), showed protein levels below the critical value of 7%. Most forage samples, as well as their corresponding soil samples were sufficient in calcium (Ca), magnesium (Mg), and potassium (K) concentrations. Soil concentrations of Ca, Mg, and K were particularly high compared to critical requirements in all the zones studied. Approximately 94% and 76% of forages were deficient in phosphorus (P) and sodium (Na), respectively, and the deficiencies were similar in all classes of forage and sites of study for each of the zones investigated. Results of forage‐soil relationships indicated low and nonexisting correlations; therefore soil analyzes are not of great importance in the assessment of available macromineral supplies to grazing livestock. The macrominerals most needed for supplementation of grazing livestock during the dry season are P, Na, and K.     

Variation of forage and extractable soil minerals over two grazing seasons in North Florida

Abstract

A two‐year experiment was conducted at a north Florida farm to evaluate the mineral status of bahiagrass forages and soils. Forage samples were collected every 28 d throughout the grazing season, and soils evaluated twice yearly. The minerals calcium (Ca), sodium (Na), copper (Cu), cobalt (Co), selenium (Se), and zinc (Zn) were uniformly below the dietary requirements for growing beef cattle in both years. Forage magnesium (Mg), phosphorus (P), potassium (K), crude protein (CP), and manganese (Mn) were generally adequate throughout the grazing season, with the exception of low P concentration at the end of the growing season for both years. Extractable soil concentrations of Ca, P, K, Mg and Zn were adequate but low in Cu. Although CP was adequate (>7.0%) throughout the grazing season, IVOMD values were relatively low. There was a general trend for forage P, K, and IVOMD to decrease (P<0.05) with time.     

YIELD AND MINERAL CONCENTRATIONS OF SOUTHEASTERN UNITED STATES OAT CULTIVARS USED FOR FORAGE

A shift in oat (Avena sativa L.) production from grain to forage (hay and grazing) is occurring in the southeastern USA. However, most available cultivars were developed for improved grain production, rather than forage yield. We field tested several standard and new oat releases over 2 years, using repeated clippings to determine forage yield, nutrient uptake, and the potential to match plant nutrients with cattle mineral dietary needs. There were no differences in total annual forage yield among the tested cultivars within years but there was a difference between years. Forage tissue phosphorus (P), magnesium (Mg), and calcium (Ca) were sufficient, potassium (K), sulfur (S), and manganese (Mn) were excessive, and iron (Fe), copper (Cu), and zinc (Zn) were occasionally or frequently deficient to meet daily cattle dietary mineral needs. Sulfur, Cu, Fe, Zn, and Mn may be the most challenging to regulate in U.S. Coastal Plain soils at concentrations that satisfy both, oat and cattle nutritional requirements.     

Plant tolerance to nickel toxicity: II nickel effects on influx and transport of mineral nutrients in four plant species

Nickel (Ni) is an essential micronutrient for higher plants but is toxic to plants at excess levels. Plant species differ extensively for mineral uptake and accumulation, and these differences often help explain plant tolerances to mineral toxicities/deficiencies. Solution culture experiments were conducted under controlled conditions to determine the effects of Ni on influx into roots (IN) and transport from roots to shoots (TR) of zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), calcium (Ca), magnesium (Mg), phosphorus (P), and sulfur (S) in white clover (Trifolium repens L.), cabbage (ßrassica oleracea van capitata L.), ryegrass (Lolium perenne L.), and maize (Zea mays L.). Nickel decreased both IN and TR of Zn, Cu, Ca, and Mg, but only TR of Fe and Mn in white clover. Both IN and TR of Cu, Fe, Mn, Mg, and S were markedly decreased by Ni >30 μM in cabbage, whereas IN and TR of P increased with Ni treatment. For ryegrass, TR of Cu, Fe, Mn, Ca, and Mg was decreased, but IN of these elements except Mg was not affected by Ni. The IN and TR of P and S were increased in ryegrass with increasing external Ni levels. Nickel inhibited IN of Cu, Ca, and Mg, and TR of Zn, Cu, Fe, Mn, Ca, and Mg in maize. Plant species differed in response to Ni relative to IN and TR of mineral nutrients. Plant tolerance to Ni toxicity was associated with the influence of Ni on IN and TR of Cu, Fe, and Mn in white clover and cabbage but not in maize and ryegrass.     

Effects of pasture‐applied biosolids on forage and soil concentrations over a grazing season in north Florida. I. macrominerals,crude protein,and in vitro digestibility

Abstract

The rationale for this experiment was to determine forage nutrient concentrations as affected by biosolids fertilization. We studied the effects of single applications of two exceptional quality biosolids to bahiagrass (Paspalum notatum) pasture with regard to satisfying beef cattle nutrient requirements. Twenty‐five 0.8‐ha pastures were divided into five blocks. Two biosolids were applied as normal and double agronomic rates. The control plot received NH₄NO₃. Forages were analyzed for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), sodium (Na), crude protein (CP), and in vitro organic matter digestibility (IVOMD), and soils were analyzed for Mehlich I extractable Ca, P, Mg, and K. Single (agronomic or twice this) applications of biosolids to pastures had little effect on Ca, P, Na, and K forage concentrations, but forage Mg was elevated in several treatments late in the season. Crude protein concentrations were elevated above the control for all biosolids treatments late in the season, whereas only small differences were observed at early sampling times. Trends were similar for IVOMD. In general, all treatments were associated with soils with adequate Ca, P, and Mg concentrations, while soil K was uniformly low. In relation to grazing beef cattle requirements, all treatments resulted in generally adequate forage levels of Ca, P, Mg, K, CP, and IVOMD, however, Na (<0.06%) was deficient.     

A Study on Seasonal Variability of Trace Elemental Status of Forages for Grazing Ruminants

An investigation was conducted to determine the trace- mineral concentrations of forages in relation to requirements of ruminants grazing in natural pastures in the province of Punjab, Pakistan during two different seasons. Animals were closely followed during grazing and forages corresponding to those consumed by the animals were taken and analyzed for copper (Cu), iron (Fe), zinc (Zn), manganese (Mn), and cobalt (Co) concentrations. The data on the trace- mineral concentrations showed that most of these minerals varied greatly as a function of seasons and sampling periods. The forage Cu, Fe, and Zn concentrations were affected by seasonal changes but no influence of season was observed on the concentrations of forage Mn and Co concentration. Forage Zn and Co, during both seasons and at some sampling intervals, and forage Mn during summer were at marginal deficient levels, and in contrast, all other forage trace-minerals were within the required range for ruminants during both seasons. Based on these results, the supplementation of Zn, Co, and Mn would seem most important to support optimum livestock productivity.     

Mineral concentrations of forages grazed by small ruminants in the wet season in benue state,Nigeria. II. Trace minerals and forage crude protein

Abstract

A total of 71 forage samples were analyzed for trace mineral and crude protein concentrations in three Agricultural zones of Benue State, Nigeria. The zones consisted of the Northern, Eastern, and Central zones, each of which was made up of four Local Government Areas. In each Local Government Area, grazing animals were followed and forages corresponding to those consumed were collected during the peak of the wet season (June) and analyzed for the nutrient composition. Deficiencies were observed in copper (Cu) and cobalt (Co) concentrations in all classes of forage, and in forage Cu and zinc (Zn) in all Local Government Areas in the Northern zone. A higher (P<0.05) forage Cu concentration was observed in legumes compared to other classes of forage in the Eastern zone. Concentrations of iron (Fe) and manganese (Mn) were considered adequate and their contents were not affected (P>0.05) by class of forage or Local Government Areas. In the Eastern zone, the contents of selenium (Se) in grass and tree leaf hay were higher compared to leguminous forage, which in turn was higher compared to Se concentrations in crop wastes. Only about 18% of total forage samples showed protein concentrations below the critical value of 7%. Supplementation of Cu, Zn, and Co would seem to be necessary in the Northern zone, and to a lesser extent in the Eastern zone for optimum productivity of grazing animals.     

Mineral Composition and Soil-Plant Relationships for Common Guava (Psidium guajava L.) and Yellow Strawberry Guava (Psidium cattleianum var. lucidum) Tree Parts and Fruits

The mineral compositions of the fruit and tree parts of common guava, Psidium guajava L., and strawberry guava, Psidium cattleianum var. lucidum, were determined. The study occurred during three seasons at six locations in Hawaii to assess guava as feed for livestock. Guava bark contained the greatest concentrations of calcium (Ca) and ash; leaves the greatest concentrations of magnesium (Mg), sulfur (S), sodium (Na), boron (B), and manganese (Mn); and the shoots had the greatest concentrations of nitrogen (N), phosphorus (P), and potassium (K). The leaves and the shoots had the greatest concentrations of copper (Cu) and iron (Fe). Between guava and waiwi, guava had greater concentrations of most minerals except for Na in all plant parts, and Mg and ash in the leaves. Guava leaves and shoots meet the macromineral requirements for various phases of sheep, goat, and beef cattle life cycles with the exception of P and Na. Guava shoots do not meet Mn requirements for lactating cows.     

Forage nutrient composition in the wet season in Benue state,Nigeria. I. Macrominerals and in vitro organic matter digestibility

Abstract

Seventy‐one forage samples were analyzed for their macromineral composition and forage in vitro organic matter digestibility (IVOMD) in three agricultural zones of Benue State, Nigeria. The zones consisted of Northern, Eastern, and Central zones, each of which were made up of four Local Government Areas. In each Local Government Area, grazing animals were monitored and forages corresponding to those consumed were collected during the peak of the wet season (June) and analyzed for their macromineral composition and IVOMD. Fewer number of forage samples were harvested from Northern and Eastern zones due to greater agricultural activities and infra‐structural land use which limited land space for grazing animals. Forage IVOMD ranged from 32% to 78.3% across all classes of forage and from 43.5% to 62.8% in the Local Government Areas. About 18% of total samples, exclusively from the Northern zone, showed forage IVOMD concentrations below 20%, probably resulting from grazing pressures and agricultural activities in the zone. Forages from the Northern zone were deficient in phosphorus (P), potassium (K), and sodium (Na) based on their criteria of adequacy. No deficiency levels were indicated in forage calcium (Ca) or magnesium (Mg). Northern and Eastern zones were in greatest need of mineral supplementation programs.     

Effect of Harvest Timing on Yield and Mineral Nutritional Value of Kabuli Type Chickpea Seeds

Chickpea (Cicer arietinum L.) seeds are a good source of protein and mineral nutrients. However, there is no information regarding harvest timing on yield and mineral composition of chickpea seeds. The effect of harvest timing on seed yield, some yield components and mineral nutritional value of seeds of field grown chickpea plants in two different sites were studied. The mineral composition of chickpea straw depending on harvest timing was also evaluated in order to explain the variations of seed mineral concentrations in sink-source relationship manner. Yield and mineral nutritional value of chickpea were significantly affected by harvest timing. When compared to the seed yield at optimal harvest time, seed yield was 18% and 9% lower in the early harvest and 27% and 31% in the late harvest in Site 1 and Site 2, respectively. Late harvest of chickpea crops resulted in significant pod dropping and shattering. Generally, protein, phosphorus (P), calcium (Ca), magnesium (Mg), copper (Cu), zinc (Zn), and manganese (Mn) concentrations of the seeds in optimal harvest were found to be greater than in early and late harvested plants. Harvest timing also results in significant variations in straw mineral nutrient concentrations of the plants. As the results of this study, it was concluded that the harvest timing is critical for yield losses and mineral nutritional value of chickpea seeds.     

Seasonal Variation of Trace Elements in a Semiarid Veld Pasture

Abstract

A two‐seasonal study was conducted to determine the trace mineral status of goats' grazing forages and soils in southern Punjab, Pakistan. Soil and forage samples were collected fortnightly for two seasons. Sampling period effects were found in soil copper, zinc, and selenium, and all forage minerals except selenium were affected by sampling times. Seasonal effects were observed in iron, manganese, and selenium for soils and in copper, iron, zinc, manganese, and selenium for forages. All soil mineral levels except cobalt and selenium were found to be above critical levels and likely to be adequate for normal growth of plants growing therein, whereas soil cobalt and selenium were severely deficient during both seasons. The levels of iron, zinc, cobalt, and selenium in soil were higher and copper and manganese were lower during winter than during summer. Forages contained marginal to deficient levels of cobalt during the winter, copper and selenium during the summer, and moderately deficient levels of iron and severely deficient levels of zinc, manganese, and cobalt during the summer. Forage copper, iron, zinc, manganese, and selenium during winter were found to be adequate for the requirements of ruminants. Consequently grazing animals at this location need continued mineral supplementation of these elements to prevent deficiency diseases and to support optimum animal productivity.     

Differential response of two taro cultivars to aluminum: II. Plant mineral concentrations

Abstract

One proposed mechanism of aluminum (Al)‐tolerance involves the ability of plants to maintain uptake of essential mineral elements in the presence of Al. To examine this hypothesis, taro [Colocasia esculenta (L.) Schott] cultivars (cv.) Lehua maoli and Bun long were grown in hydroponic solution at six initial Al levels (0, 110, 220, 440, 890, and 1330 μM Al), and plant mineral concentrations were determined after 27 days. Increasing Al levels significantly increased Al concentrations in taro leaf blades, petioles, and roots. This increase in Al concentrations in the leaf blades as solution Al levels increased was greater for Al‐sensitive cv. Bun long compared to cv. Lehua maoli, resulting in significant interaction between Al and cultivar effects. However, no significant cultivar differences were found for Al concentrations in the petioles or roots. Increasing Al levels in solution significantly depressed concentrations of calcium (Ca), magnesium (Mg), manganese (Mn), and iron (Fe) in taro leaf blades, and significantly depressed concentrations of Ca, Mg, copper (Cu), and zinc (Zn) in taro roots. Aluminum‐induced Ca deficiency appeared to be one possible mechanism of Al phototoxicity in taro, becvasue Ca concentrations in the leaf blades and roots at the higher Al levels were within the critical deficiency range reported for taro. Significant cultivar differences were found, in which Al‐tolerant cv. Lehua maoli had significantly greater Ca and Cu concentrations in the roots, and significantly greater potassium (K) concentrations in the leaf blades across all Al levels. Our results show that Al‐tolerance in taro cultivars is associated with the ability to maintain uptake of essential mineral nutrients, particularly Ca and K, in the presence of Al.     

Annual ryegrass response to limestone and phosphorus on an ultisol 1

Decreasing winter pasture productivity in unlimed Ultisols has been associated with increased soil acidity due to fertilizer N application. The susceptibility of cool season grasses to soil acidity and associated infertility factors that result in reduced forage yield are not well understood. This field study was undertaken to evaluate the effects of factorial combinations of limestone and P applications on annual ryegrass (Lolium multiflorum Lam. ‘Marshall') dry matter production and tissue mineral concentrations on a strongly acid (pH 4.7), sandy soil. Limestone was applied to a Lilbert loamy fine sand (loamy, siliceous, thermic, arenic Plinthic Paleudult) at rates of 0, 672, or 3808 kg ha^‐1. Phosphorus was applied to split plots at rates of 0, 30, 60, 90, 120, 240, or 480 kg P ha^‐1. Over three harvest years, ryegrass yields increased 90 to 750% and 25 to 80% at the highest lime and P rates, respectively. In the second year, yield response to applied P was significantly less at the high lime rate which indicated that liming made soil P more plant available. Lime and applied P increased plant tissue P, Ca, and Mg concentrations. Yield was positively correlated with soil pH, P, Ca, and Mg and negatively related to soil K and Al. Clear relationships between individual soil test levels and leaf mineral concentrations with yield fluctuations could not be established because these variables were inextricably related to the lime and P rates. Nevertheless, excessive soil Al, coupled with inadequate P, Ca, and Mg availability, were indicated as important nutritional factors limiting annual ryegrass growth in unlimed soil.     

Areas with high concentrations of selenium in the soil and forage produce beef with enhanced concentrations of selenium

Beef provides a significant portion of human dietary selenium (Se), and it is possible that modest portions of beef produced in areas with high-Se soil and forage could provide the entire Recommended Dietary Allowance (RDA) for Se. The present study has addressed the environmental conditions that resulted in the production of high-Se beef. One hundred and thirty-eight cull cows were obtained from 21 ranches in five distinct geographic regions that, on the basis of soil parent material, reports of Se deficiency, and previous soil and forage Se surveys, were likely to have high or low Se concentrations in the soil. Grass and soil samples were taken from ranch sites, and hair, whole blood, skeletal muscle, diaphragm muscle, and liver samples were obtained from the animals. Hair and whole blood samples were taken 1 day prior to shipping. Selenium concentrations of all samples were determined by hydride generation atomic absorption spectroscopy. Geographic origin affected Se content of all samples (p < 0.05). Selenium concentrations in soil (r = 0.53; p < 0.01) and grass (r = 0.63; p < 0.01) were correlated to Se content of skeletal muscle. Selenium concentrations in whole blood, diaphragm, hair, and liver also were significantly correlated to Se content of skeletal muscle (p < 0.01). Cows that received Se in mineral supplements did not have significantly higher concentrations of Se in sampled tissues (p > 0.05). Results of this study suggest that the greatest source of variation in Se content of bovine skeletal muscle was the geographic region from which the beef originated and not production or management practices. Results also demonstrated that a 100 g serving of high-Se beef could provide 100% of the RDA for Se.