Desmodium Intortum Cv Research Articles

Human exposure to organochlorine pesticides in vegetables from major cities in south-south Nigeria.

Contamination of vegetables with organochlorine pesticides (OCPs) during cultivation could affect their nutritional value and also results in adverse health effects to consumers. Thus, this study evaluates human exposure to OCPs in vegetables from major cities in south-south Nigeria. A total of eighty vegetables consisting of Vernonia amygdalina, Telfairia occidentalis, Desmodium intortum cv and Talinum triangulare obtained from four major cities (Warri, Benin, Yenagoa and Port-Harcourt) in south-south Nigeria were analysed for OCPs using a gas chromatograph coupled with a mass selective detector. The results showed that the mean concentration of ∑20 OCPs in the vegetables ranged from 11.6 to 37.7ngg-1 fresh wt for Vernonia amygdalina, 2.48-37.0ngg-1 fresh wt for Telfairia occidentalis, 7.63-54.2ngg-1 fresh wt for Desmodium intortum cv and 27.3-57.3ngg-1 fresh wt for Talinum triangulare. The concentrations of OCPs were generally lower than their respective Maximum Residue Limits (MRLs). The EDI values of the ∑20 OCPs in the vegetables ranged from 141 to 464ngkg-1 bw day-1 for children and 26.5-87.0ngkg-1 bw day-1 for adults. The EDI of ∑Drins, ∑Chlordanes and ∑DDTs for the vegetables were below their respective acceptable EDI values set by FAO/WHO Joint Meeting on Pesticide Residue. The hazard index values for children and adults were generally <1 suggesting that there is no potential non-carcinogenic risk for children and adults consuming the vegetables. The total cancer risk values were above 1×10-6 and indicated that children and adults have moderate and low carcinogenic risks respectively from ingestion of these vegetables. The isomeric ratios and principal component analysis result showed that OCPs in these vegetables originated from both historical and recent usage in vegetable cultivation.

Condensed tannins from Sesbania sesban and Desmodium intortum as a means of Haemonchus contortus control in goats

Two experiments were conducted to determine whether the proanthocyanidin (condensed tannin)-containing forage legumes Desmodium intortum cv Greenleaf and Sesbania sesban (accession 15019) could be integrated into a feeding management strategy as a means of Haemonchus contortus control in goats. The anthelmintic effects of condensed tannin extracts from the two legumes on H. contortus L(3) larvae were studied in an in vitro larval migration inhibition system. The extracts inhibited larval migration in a dose-dependent manner, and at concentrations from 1,000 μg/ml condensed tannin, the extract from D. intortum caused a significantly higher inhibition of larval migration than did the corresponding concentrations of the S. sesban extract (P < 0.01). Prolonged feeding of tanniniferous forage legumes showed that animals receiving D. intortum had the lowest total worm burden, the lowest female to male parasite ratio, the lowest number of eggs in the uterus of each female worm and the lowest per capita fecundity (P < 0.01). However, there was no change in the performance (weight gain) of parasite-infected goats probably due to incomplete removal of the parasite or prolonged confinement of goats in small pens, which calls for further investigation. However, since there is no single efficient method in control of parasites, based on the obtained data from this experiment, integrated feeding of D. intortum with other suitable method of parasite control is thus suggested.

Alleviating Soil Acidity With Crop Residues

Abstract Soil acidity, which is characterized by mainly aluminum (Al) toxicity and often calcium (Ca) deficiency, is a serious constraint for crop production. To separate these two factors and to alleviate the acidity problem using organic materials instead of lime, a greenhouse experiment was conducted on two acid soils of Hawaii. Eight treatments were established: (i) unamended (control); (ii) 4 cmolc/kg as Ca(OH)2; (iii) 4 cmolc/kg as MgO; (iv) 4 cmolc/kg as CaSO4 · 2H2O; (v) 10 g/kg ground fresh cowpea (Vigna unguiculata) leaves; (vi) 10 g ground, dried, fresh cowpea leaves ashed at 350°C for 4 h and then added to 1 kg soil; (vii) 10 g/kg ground fresh pineapple (Ananas comosus) crowns; and (viii) ashed pineapple at rate equivalent to (vii). Desmodium intortum cv. greenleaf, which is a tropical forage legume highly sensitive to soil acidity, was used as the test plant. The results indicated that treatments 1 to 4 could distinguish Al toxicity from Ca deficiency in acid soils and that crop residues could be used to alleviate soil acidity; the fresh cowpea amendment was most effective. More specifically, soil pH was raised moderately by crop-residue amendments, yet exchangeable Al was lowered substantially. Furthermore, soil-solution Al was complexed substantially by dissolved oxidizable carbon, particularly by organic acids produced by the crop residues. There was a good correlation between plant growth and the activity of total monomeric hydrolytic species of Al (Σ{Al}). Significant growth reduction would be expected when Σ{Al} > 12.0 μM.

Prediction of feed intake, digestibility and growth rate of sheep fed basal diets of maize stover supplemented with Desmodium intortum hay from dry matter degradability of the diets

The in sacco dry matter (DM) degradability of diets based on maize stover harvested at three stages of maturity and supplemented with graded levels of desmodium ( Desmodium intortum cv. Greenleaf) hay were estimated from degradability of the individual feeds and their corresponding DM intake. The estimated DM degradability of the diets was used for prediction of DM intake (DMI), digestible DM intake (DDMI), DM digestibility (DMD) and growth rate of sheep feeding on the diets. The desmodium hay had significantly higher ( P<0.05) DM disappearance than the maize stovers after 4, 8, 16, 24 and 48 h of incubation, as well as higher washing loss ( A), degradation rate ( c value) and effective DM degradability (ED) than the maize stovers. The washing loss was lowest in maize stover harvested at stage III and, as a consequence, the washing loss of the diets showed a significant decrease ( P<0.05) with increasing stage of maturity of the stovers. The DM disappearance after 48 h incubation, washing loss and degradation rate showed a significant increase whereas the insoluble, but potentially degradable, fraction ( B) showed a significant decrease ( P<0.05) with increasing level of supplementation. The DM disappearance after 24 and 48 h of incubation, washing loss, ED and degradation rate showed strong positive correlation whereas the insoluble, but potentially degradable, fraction showed a negative correlation with DMI, DMD, DDMI and growth rate. On the other hand, the DM disappearance after 96 h of incubation, potential degradability and the lag phase showed very low correlation with these parameters. In general, the washing loss, ED and the DM disappearance after 24 and 48 h of incubation were found to be simple and reliable predictors of DMI, DDMI, DMD and growth rate. However, the use of the A, B and c values simultaneously in a multiple regression gave a more precise prediction of feed intake, digestibility and growth rate.

Supplementation of graded levels of Desmodium intortum hay to sheep feeding on maize stover harvested at three stages of maturity : 2. Rumen fermentation and nitrogen metabolism

The utilisation of cereal crop residues as animal feed is limited by deficiencies of protein, fermentable energy and other nutrients. In this study, rumen fermentation and nitrogen metabolism of lambs fed basal diets of maize stover harvested at three stages of maturity and supplemented with graded levels (0, 150, 300 and 450 g per head per day) of desmodium ( Desmodium intortum cv Greenleaf) hay were investigated. The maize stovers were harvested at 30, 22 and 12% grain moisture content which were designated as stages I, II and III, respectively. Rumen ammonia and volatile fatty acids (VFA), nitrogen (N) balance and microbial N supply, based on urinary excretion of purine derivatives, were determined. The concentration of ammonia-N in rumen fluid was significantly lower ( P<0.05) in sheep fed maize stover harvested at stage III than at stages I and II and increased significantly ( P<0.001) with increasing level of supplementation. The total VFA concentration and the molar proportions of acetate and butyrate in rumen fluid were not significantly influenced ( P>0.05) by the stage of maturity of the stover. The total VFA content increased with increasing level of supplementation and varied from 64.1 to 113.6 mmol/l of rumen fluid. The N intake, N absorbed and N retained decreased with increasing stage of maturity of the stover and showed a significant linear increase ( P<0.05) with increasing level of supplementation. However, use of maize stover as a sole diet resulted in negative N balance at all stages of maturity due to the low N content of the stover. Microbial N supply was not affected by stage of maturity of the stover while microbial efficiency (g/kg digestible organic matter fermented in the rumen) was significantly lower ( P<0.05) in sheep fed maize stover harvested at stage III than at stages I and II. The microbial N supply increased with increasing level of supplementation, presumably due to improved degradation of the diet and increased supply of N, fermentable carbohydrates, sulphur and probably other essential nutrients.

Supplementation of graded levels of Desmodium intortum hay to sheep feeding on maize stover harvested at three stages of maturity : 1. Feed intake, digestibility and body weight change

Feed intake, digestibility and body weight change of lambs fed basal diets of maize stover harvested at three stages of maturity and supplemented with graded levels (0, 150, 300 and 450 g per head per day) of desmodium ( Desmodium intortum cv. Greenleaf) hay were studied. The maize stovers were harvested at 30, 22 and 12% grain moisture content which were designated as stages I, II and III, respectively. The crude protein (CP) content of the stovers showed a decreasing trend whereas the fibre contents showed an increase from stages I to III. The desmodium hay had higher CP, phenolic compounds, calcium, sulphur and manganese contents and lower fibre (neutral and acid detergent fibres, cellulose and hemicellulose) contents than the stovers. Maize stover, total dry matter (DM) and organic matter (OM) intake showed a decreasing trend ( p>0.05) with increasing stage of maturity of the stover. The CP intake was significantly higher ( p<0.05) in sheep fed maize stover harvested at stage I than at stages II and III. Total DM, OM and CP intake increased whereas maize stover DM intake showed a significant decrease ( p<0.05) with increasing level of supplementation. Desmodium hay constituted about 28, 47 and 66% of the total DM intake and, on average, there was a substitution of about 12, 21 and 37% of the stover by the desmodium hay at 150, 300 and 450 g of supplementation, respectively. Dry matter, OM and neutral detergent fibre (NDF) digestibilities showed a decreasing trend ( p>0.05) with increasing stage of maturity. Crude protein digestibility and the intakes of digestible OM and metabolizable energy (ME) were significantly higher ( p<0.05) in sheep feeding on maize stover harvested at stage I than stage III and showed a general declining trend with increasing stage of maturity of the stover. Supplementation resulted in improved digestibility of the diet. There was a significant increase ( p<0.05) in CP digestibility, digestible OM intake, digestible organic matter in the DM (DOMD), ME concentration of the diet and ME intake with increasing level of supplementation. The body weight gain showed a significant increase ( p<0.05) with increasing level of supplementation whereas all sheep without supplement lost body weight. The weight loss increased with increasing stage of maturity of the stover. Considering DM intake and digestibility, 300 g of desmodium hay appears to be an optimum level of supplementation, under similar conditions to the current study.

Competitiveness of indigenous strains of Bradyrhizobium on Desmodium intortum CV Greenleaf in three soils of South East Queensland

Six spontaneous antibiotic (streptomycin + rifampicin) resistant strains of B radyrhizobium were tested for rhizosphere and nodulating competitiveness on Desmodium intortum. The resistant strains were obtained from parental strains that were selected from indigenous soil populations nodulating D. intortum in south east Queensland. The parental strains represented five dominant groups of isolates obtained using intrinsic antiboditic resistance and serological typing techniques. The sixth parental strain CB627 was that recommended for D. intortum. Test strains were reintroduced into their soil of origin and into two other soils in numbers approximately equal to the populations in the original soils. The number of each test strain in the soil and rhizosphere and the proportion of nodules formed by these strains were assessed for two sowing occasions. All strains colonized the soil and rhizosphere. There was an overriding effect of soil type on numbers of bradyrhizobia in the soil and the rhizosphere and only a small interaction effect between soil and strain. There were markedly different responses in the proportion of nodules formed by the test strains. A strain from Beerwah soil (CB3098) failed to form nodules in Tumbulgum soil in the first sowing, but all strains formed nodules in Beerwah and Samford soils. Strain CB3097, from Tumbulgum soil, was the most competitive of all strains throughout the experiment and in all soil types tested. There was no relationship between number of bradyrhizobia in either the soil or in the rhizophere and the proportion of nodules formed by a strain. Strain CB3097 has potential as a new inoculum strain for D. intortum.

Growth, competitiveness and effectiveness of spontaneous antibiotic resistant strains of Bradyrhizobium for Desmodium intortum CV greenleaf

Spontaneous antibiotic-resistant strains of Bradyrhizobium, from six parent strains isolated from Desmodium intortum, were compared with their parents for changes in ecologically-important characteristics. Strains resistant to 30 μ g rifampicin ml −1 and 500 μg streptomycin ml −1 were serologically homologous with their parents in gel-immunodiffusion tests against antisera for the parent strains. They had similar growth and rhizosphere colonizing abilities, but were not equally effective in N 2 fixation or equally competitive for nodule formation on D. intortum. Such variation suggests, firstly that a single colony isolate should not be used to represent a parent strain. Secondly, if single colony isolates are used they should be considered as strains for their individual characteristics.

Toward a Stable Low-Input Highland Agricultural System: Ley Farming in Imperata cylindrica Grasslands of Northern Thailand

This paper considers popular misconceptions concerning Imperata cylindrica grassland areas and Imperata succession in Northern Thailand. It provides a description of a suggested ley farming system (alternation of pastures and crops). Only 2.5 percent of 2,500 km2 of Northern Thailand is covered by I. cylindrica, nearly all between 1,000-2,000 m and in the western part of the north. There is little evidence that watershed characteristics of I. cylindrica grassland are inferior to those of forested areas; it is readily grazed and is a poor competitor under grazing; it is also relatively easy to establish improved pasture; and grazing quickly results in sown legume dominance to the almost total exclusion of I. cylindrica. I. cylindrica is found mainly in maize/opium areas and is absent from the Karen integral swiddening areas. Establishment of I. cylindrica can be attributed to the removal of shade in the seed and seedling phase; this is a consequence of the intensive weeding practised in the maize/opium swidden systems. Preliminary experiments indicate the benefit of a previously fertilized sown legume pasture to a subsequent upland crop. I. cylindrica grassland should be oversown with Desmodium intortum cv. greenleaf pastures and grazed for 2-3 years, and then dibbled and cultivated with upland crops for two years. Management details are presented. Major constraints to the adoption of ley farming in the Northern Thailand highlands include entrenched traditional tribal attitudes, lack of expertise and interest by official personnel and organiza- tions, and the current high price for opium coupled with the ease of growing and selling it.

Growth and N Fixation of Some Tropical Forage Legumes as Influenced by Solar Radiation Regimes1

AbstractDecreased solar radiation due to cloud cover or shading by plantation crops or associated grass can severely limit the production of tropical forage legumes. We therefore evaluated the response of six legumes (three replicated and three not replicated) to four radiation regimes (100, 70,45, and 27% of unshaded solar radiation, hereafter termed “full sun”) with polypropylene netting in the field.The three replicated legumes had significant yield reductions at 27% full sun, with intermediate reductions at 70 and 45%. Dry matter (DM) yields at full sun [metric tons (mt) ha,−1yr−1 and proportional yields at 27%] were: Desmodium intortum cv. Greenleaf (20.0, 46%); Centrosema pubescens ‘centro’ (13.7, 44%); and Macroptilium atropurpureum cv. Siratro (12.9, 20%). Greenleaf was relatively tolerantof moderate shading; proportional yields at 70 and 45% of full sun were 93 and 75%, respectively. Centro and Siratro yields declined linearly as shortwave radiation (hereafter termed “radiation”) decreased, but Siratro yields declined significantly more than centro. Marked seasonal differences were noted in the response of the legumes to shade, and this was attributed to differences in the ability of the legumes to utilize solar radiation during periods of cool temperatures. The three non‐replicated legumes were evaluated similarly, except that yields were adjusted for replication effects. Dry matter yields and proportional yields at 27% full sun were: Leucaena Ieucocephala cv. Hawaiian Giant (23.5, 40%); Stylosanthes guianensis cv. Schofield (17.0, 17%); and Desmodium canum ‘kaimi clover’ (12.2, 32%). Hawaiian Giant and Greenleaf yielded similarly at 45 and 27% full sun. Kaimi clover DM yield tended to be slightly higher (13.8) at 70% full sun, but thereafter yields declined linearly with reduced radiation. Schofield stylo was the most sensitive to shading.Dry matter and N concentrations were not significantly elevated by reduced radiation or cool weather except that N increased during the cool season. Concentrations of N differed among species being highest for centro and Hawaiian Giant (3.4%) and lowest for kaimi clover (2.6%). Total N yields were associated with DM yields. Nitrogen yields (kg N ha−1yr−1) of replicated legumes at full sun and proportional yields at 27% full sun were: Greenleaf (540, 45%), centro (461,44%), and Siratro (362,27%); and for the non‐replicated legumes, Hawaiian Giant (751,38%), Schofield (496, 18%), and kaimi clover [340 (361 at 70% full sun), 38%]. Acetylene reduction rates by nodules in soil cores were highly correlated with radiation regimes (r = 0.92‐0.995; except for centro, r = 0.71.) Correlation of acetylene reduction rates with DM yields ranged from 0.80 to 0.996.The higher yielding legumes, Greenleaf, centro, and Hawaiian Giant (plus kaimi clover for ≈70 % full sun only) appear well‐suited for areas of low solar radiation because they have relatively constant concentrations of DM and N and fixed significant quantities of N even under dense shade.

Critical phosphorus concentrations in parts of Macroptilium atropurpureum cv. Siratro and Desmodium intortum cv. Greenleaf as affected by plant age

Critical phosphorus concentrations were determined for different parts of Macroptilium atropurpureum cv. Siratro and Desmodium intortum cv. Greenleaf at several plant ages in order to establish an appropriate sampling technique for chemical analysis of phosphorus status. Critical phosphorus concentrations were derived by using a non-rectangular hyperbola functional relationship which allowed calculation of variance associated with critical values. When expressed relative to tissue dry weight, critical phosphorus concentrations in whole shoots declined from 0.30�0,03% (95% confidence limits) at 41 days from sowing to 0.09� 0.01 % at 77 days for Siratro and from 0.33 � 0.14 % at 45 days to 0.16 � 0.03 % at 73 days for Greenleaf. Similar declines in critical phosphorus concentration with plant age were measured for combinations of all parts of the upper shoot back to the fourth expanded leaf. Thus plant age effects and variability associated with each determination of critical phosphorus concentration would limit the practicability of phosphorus analysis in detecting marginal phosphorus deficiency. This especially applies to plants growing as perennials in pastures where identification of plant age is not possible. Plant age effects can be lessened to some extent when critical phosphorus concentrations are calculated relative to tissue water, but it is suggested that less empirical techniques of plant analysis are required if plant age effects on critical phosphorus concentrations are to be overcome.

The Influence of Rate and Form of Mineral Nitrogen on Seedling Growth, Symbiotic Nitrogen Fixation, and Mineral Nitrogen Assimilation in Desmodium intortum cv. Greenleaf

The Influence of Rate and Form of Mineral Nitrogen on Seedling Growth, Symbiotic Nitrogen Fixation, and Mineral Nitrogen Assimilation in Desmodium intortum cv. Greenleaf

Prediction of yield responses to phosphorus by established Greenleaf desmodium/grass pastures in south-east Queensland using chemical tests

Phosphorus topdressing experiments (rates to 60 kg P ha-1) on 18 commercial Desmodium intortum cv. Greenleaf/grass pastures were conducted over a 4-year period in south-east Queensland. The aim was to determine whether yield responses, which occurred only in the Greenleaf component at six sites, could be predicted using soil or plant chemical tests. Acid-(0.005 M H2SO4) and bicarbonate-(0.5 M NaHCO3) extractable tests of phosphorus status in 0-10 cm soil samples each explained about 60% of the variance in Greenleaf relative yields. The residual variance was not significantly reduced by the inclusion of terms for total soil nitrogen, total soil phosphorus, exchangeable calcium and pH into the independent variable. These empirical soil phosphorus tests had higher predictive value than plant tests based on phosphorus concentrations in tops and diagnostic samples of Greenleaf. With both acid- and bicarbonate-extractable phosphorus, yield responses are likely in the Greenleaf component when phosphorus levels in most soils are below 22 ppm. Above 29 ppm, no response would be expected

Beef production potential ofdesmodium intortumcv. Greenleaf in the coastal belt to the north of east London

The beef production potential of Desmodium intortum cv. Greenleaf pasture is extremely promising. Friesland type steers grazing on pastures in the Komga district had an average daily gain of 0, 91 kg. During the five year period of the investigation and average livemass gain of 544 kg/ha was recorded. The gross margin/ha calculated on current income and expenditure data is approximately R172/ha Keywords: average daily gain; beef production; daily gain; desmodium intortum; east london; eastern cape; expenditure; grazing; komga; live mass gain; pasture; pastures; production; production potential; south africa

Small-plot studies ofDesmodium intortum(Mill.) Urb. cv. ‘Greenleaf’,D. uncinatum(Jacq.) DC. cv. ‘Silverleaf’, andLotononis bainesiiBaker cv. ‘Miles’, in Northland, New Zealand

Abstract Establishment and subsequent dry matter productivity of three subtropical legume species Desmodium intortum cv. ‘Greenleaf’, D. uncinatum cv. ‘Silverleaf’, and Lotononis bainesii cv. ‘Miles’ were compared with that of Lotus pendunculatus cv. ‘Commercial’ at two sites in Northland from 1971–74. Late December sowings resulted in successful establishment of both Desmodium species at the two sites. The establishment of Lotononis and Lotus was variable between sites and generally less than that of the Desmodiums. D. uncinatum yielded most at the northern site over the growing season, although D. intortum was higher yielding at the Southern site. Maximum growth rates for D. uncinatum were 45 kg DM/ha/day, although yields appeared to be limited by moisture stress and low minimum temperatures over the growing season at both sites. D. uncinatum, more so than D. intortum, was higher yielding when cut at 42-day intervals than when cut at 21-day intervals at the Northern site. Cutting interval had little effect on yields of Lotononis or Lotus at either site or on Desmodium yields at the Southern site. It is concluded that Lotononis, because of lack of persistence, has little potential as a pasture legume, and that although both Desmodium species were equal to or better than Lotus, their potential is likely to be limited by summer-autumn moisture stress, low minimum temperatures, and special management requirements over the growing season in Northland.

Effect of plant age on element concentrations in parts of Desmodium intortum cv. Greenleaf

Abstract The distribution of some nutrient elements in parts of Desmodium intortum cv. Greenleaf plants of different age was studied in order to determine the most appropriate sampling technique for chemical analysis of nutrient status. When expressed on a dry weight basis, concentrations of N, P, K, S, Ca, Mg, Al, B and Mn in plant parts of similar physiological age declined with plant age, thus necessitating a standardized plant age for sampling. Only Zn concentrations remained stable with plant age. When expressed relative to tissue water, concentrations of P, S, Mg, Al, B and Mn changed little with plant age because percentage dry matter in all plant parts increased with plant age. On a tissue water basis, K concentrations still decreased with plant age. Concentrations of N and Ca were most stable with plant age when expressed relative to tissue fresh weight.

In vitro digestibility and chemical composition of three tropical pasture legumes, Desmodium intortum cv. Greenleaf, D. tortuosum and Macroptilium atropurpureum cv. Siratro

Leaflets and petioles of Desmodium intortum cv. Greenleaf and Desmodium tortuosum (Florida beggarweed) and leaflets of Macroptilium atropurpureum (Siratro) were analysed for nitrogen: sodium, potassium, phosphorus, carbohydrates (monosaccharides, cyclitols and polysaccharides), organic acids, lignin and polyphenols. The major cyclitol, D(+)-pinitol, was isolated and characterized, along with D-glucose, D-galactose and myo-inositol. The major organid acid was malonic acid, and small amounts of oxalic and succinic acids were also present. The major chemical difference between the legumes appeared in the polyphenols. D. intortum leaflets containqi large amounts of proanthocyanidins (20% catechin equivalent), such polyphenols being undetected in the other legumes. The proanthocyanidins gave three anthocyanidins, two of which were identified (delphinidin and cyanidin). The polyphenols of D. intortum, because of their ability to complex with protein, appeared to be the major cause of the resistance of this legume to bacterial decomposition. However, they did not fully explain the low in vitro digestibility of this legume, since there w'as no significant inhibition of bacterial or pepsin activities, up to 70% of the total crude protein in D. intortum leaflet being liberated with pepsin treatment. The major resistance to in vitro digestion occurred, in the cell wall, where it is possible that some proanthocyanidins were complexed with either cellulose or protein, protecting linkages from cleavage.

Limitations of the electronic capacitance meter in measuring yields of grazed tropical pastures

AbstractRelationships between readings of the electronic (capacitance) pasture meter and descriptions of pasture yield were examined over the yearly growth cycle in grazed pastures of Setaria anceps cv. Nandi, with or without Macroptilium atropurpurem cv. Siratro and Desmodium intortum cv. Greenleaf. There was a poor relationship between meter reading and pasture dry matter yield (r =+0.574 pooled over pastures and seasons) but this relationship was improved to r=+0.750 by inclusion of other regressors describing pasture height and proportion of inert material. Meter reading was more closely related to fresh pasture yield (r =+0.830), water yield (r =+0.885) or dried green yield (r =+0.830), although inclusion of a pasture height term still improved the relationship slightly. Suggestions are made about using the meter to estimate dried green yield rather than total dry matter yield, and taking more consideration of the proportion of inert material when relating the meter reading to total dry matter yield.Visual estimation was also compared with actual pasture yield measured by cutting. Even though prior training for yield estimation was inadequate, the relationships between visually estimated and actual yield were as good as those from the pasture meter. It is concluded that the pasture meter will not find a regular use as a sampling tool in most grazed tropical pastures.

Yield, nitrogen uptake and liveweight gains from irrigated grass-legume pasture on a Queensland tropical highland

The growth and nitrogen uptake of grazed irrigated mixed pastures based on eleven legumes and Brachiaria mutica (Para grass) was measured over four years. Four of these legumes were also used in two short grazing trials to estimate the fattening potential of irrigated grass-legume pastures. Glycine wightii cv. Tinaroo and Desmodium intortum cv. Greenleaf were the most persistent legumes, had winter growth rates twice that of other legumes, and formed the most stable pastures. Apparent nitrogen fixation was linearly related to legume dry matter yield and became a more efficient process with time. In the final two years each 1000 kg legume DM resulted in an extra 33 kg N in the system. Nitrogen in Macroptilium atropurpureum cv. Siratro pastures was transferred twice as efficiently as in other pastures. G. wightii- B. mutica pastures produced the most rapid liveweight gains of up to 0.61 kg day-1 over a full year, and produced the highest liveweight gain per hectare (860 kg year -1). Increasing stocking rate from 3.4 steers ha-1 to 5.1 steers h-la depressed pasture legume contents and rate of liveweight gain per animal but generally did not increase liveweight gain per hectare.

The residual effect of molybdenum fertilizer on growth of tropical pasture legumes in a sub-tropical environment

The response of several tropical legumes, grown with Panicum maximum cv. Gatton, to an initial application of molybdenum as molybdenum trioxide was studied over a five year period at six sites in south-eastern Queensland. The most responsive legumes were Glycine wightii cv. Tinaroo and Desmodium intortum cv. Greenleaf, followed by Macroptilium atropurpureum cv. Siratro and Medicago sativa cv. Hunter River, with Lotononis bainesiicv. Miles and Stylosanthesguianensis cv. Cook being least responsive. Sites differed markedly in magnitude of legume response. For example, the most responsive site required 200 g ha-1 molybdenum over five years for maximum growth of Siratro whereas there was no response of Siratro to molybdenum application at another site. There was no difference between surface-applied molybdenum trioxide, molybdenum trioxide applied to the seed pellet and surface-applied sodium molybdate in their residual effects on legume growth. Response of the grass to molybdenum treatment was generally similar to legume response and nitrogen concentrations in legume and grass increased with yield.