Original Pasture Research Articles

Azawad As a Self-proclaimed Tuareg State

The author was set to find out the fundamental reasons for the separatism of the Tuareg community in the Republic of Mali. The article examines the evolution of the political identity of the Tuaregs and the consolidation of scatted nomadic tribes into a community, which aims for sovereignty within their own state. It is known that the desire for state self-determination of nomads within the self-proclaimed state of Azavad is a factor that has a serious impact on the internal political situation in the country throughout its history, starting from the time of gaining independence in the early of 60s years of last century and to the present. The study showed that the confrontation between the black majority of the population of the country and in comparison with small number of “white people of the desert” (Tuaregs, Moors, Arabs) is primarily due to the parallel existence of various “life necessities cultures” in the territory of Sahel. Relatively peaceful farmers, fishermen and hunters coexist here with the warlike nomadic cattle herders. The lands cultivated by some are considered by others to be their original pasture - lands. The author substantiates the conclusion that all acute conflict situations arising in the northern territories of Mali are ultimately conditioned by the influence of this determining factor. This determines the essence of the discriminatory policy against the Tuaregs on the part of the authorities protecting the interests of the majority, Bamako’s mistakes associated with attempts to accelerate the modernization of archaic nomadic communities. The author comes to the conclusion that the situation is complicated by the reluctance of the Elysee Palace to abandon political and economic preferences in Mali and withdraw its troops from the territory of this sovereign state, from the territory that the Tuaregs consider their ancestral lands. In his opinion, in the conditions of an acute political crisis in this country, the Tuareg’s desire for state self-determination will grow.

Microbiological and structural quality of Oxisol under pasture renewal systems

ABSTRACT The central Brazilian Savanna biome, known as Cerrado, has a vast area of pastures affected by some degree of degradation, where one of the main challenges is incorporating these areas into a crop production system. This study aimed to evaluate the effect of pasture renewal systems on the microbiological and structural quality of a medium-texture Oxisol. A randomized blocks design was adopted, with four replications and eight pasture renewal systems: 1) soybean/off-season maize/soybean; 2) soybean/maize-grass intercropping/soybean; 3) grass for 10 months and then one soybean crop; 4) grass + rattlepod for 10 months and then one soybean crop; 5) grass for 13 months and then one soybean crop; 6) grass + rattlepod for 13 months and then one soybean crop; 7) one soybean crop; 8) original pasture (control). The microbiological quality was assessed based on soil microbial biomass carbon, soil microbial activity, microbial metabolic quotient - qCO2 and activity of the β-glucosidase enzyme; and the structural quality based on the soil structural quality index. The implementation of pasture renewal systems with grass as a single crop (systems 3 and 5) or intercropped with rattlepod (systems 4 and 6) improves the soil microbiological and structural quality. The pasture renewal system beginning with soybean/off-season maize succession (system 1) is not indicated for the medium-texture soil evaluated in this study.

The legacy of pasture drill rows on soil chemical characteristics and subsequent wheat production

To examine the legacy of pasture drill rows sown to various configurations of subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.) and phalaris (Phalaris aquatica L.), on soil chemical characteristics and wheat (Triticum aestivum L.) production in the year following pasture removal. A field experiment comparing 10 pasture species combination treatments conducted on a Red Kandosol soil in a semi-arid environment in south-eastern Australia was monitored from the end of the pasture phase until harvest of the first wheat crop. Quadrats were fixed to the soil surface to mark previous pasture drill rows. Soil within and between rows was sampled to 0.6 m at three times and analysed for mineral nitrogen (N), pH, total carbon (C) and available macro-nutrients, and related to wheat growth rate and yield. Significantly higher total C, mineral N and plant-available potassium (K), and lower sulphur (S) concentrations, were still evident in the original pasture drill row after grain harvest compared to the inter-row area, four years after pastures were sown. Grain yield was 11% greater in wheat growing on the original pasture drill row compared to between rows. Pure lucerne swards had less mineralised N than mixed lucerne swards associated with reduced water in the soil profile. This study establishes the enduring legacy of pasture drill rows observed up to 14 months post-removal and highlights the opportunity to improve soil fertility through manipulation of pasture sowing configurations in a cropping field in south-eastern Australia.

Short term changes on soil physical quality after different pasture renovation methods on a clayey oxidic Red Latosol

Most of Brazilian agricultural land is occupied by pastures, which often show some degree of degradation. Grazing is usually associated to damages on soil structure because of soil compaction. The aim of this work was to evaluate short term changes on soil physical quality following different pasture renovation methods, including fertilization (FERT), conventional soil tillage (TILL) and two crop-livestock system (no-till and conventional tillage, respectively COTI and CONT), on a very clayey Red Latosol (Ustox), also comparing these to the original pasture and a nearby forest fragment. Bulk density and macroporosity were significantly different on the pasture sites (averaging 1.12 g cm-3 and 0.16 cm3 cm-3 respectively) from that under the forest fragment (respectively 0.87 g cm-3 and 0.34 cm3 cm-3); however, significant differences between the renovation methods and the original pasture were not observed. The load bearing capacity model (LBCM), which relates decrease on soil precompression stress (?p) with increase on water content (U), obtained for the original pasture, ORIG (?p = 10(2.82-1.21*U)), was considered different from that obtained for the soil under natural vegetation (?p = 10(2.69-1.25*U)), with the former being more resistant to compaction. When the ordinate pairs (U, ?p) obtained from soil cores collected on the different renovation methods experimental plots were plotted on the LBCM from ORIG, an increase on soil strength could be noticed, but with small differences between renovation methods. This was because of higher stocking rates on FERT and TILL and corn harvest for silage production on COTI and CONT. Tillage failed to improve soil physical quality even on the short turn (only one growing season) and should be disregarded as a renovation method for pastures on initial stages of degradation, while soil fertility is the main limitation.

Contributions of the hair sheep breed Santa Ines as a maintenance host for Rhipicephalus ( Boophilus ) microplus (Acari: Ixodidae) in Brazil

Hair sheep breeds are a new, cost-effective option for the diversification of livestock in the Midwest region of Brazil. They are grazed extensively with cattle as well as in isolation in small areas. Hair sheep breeds are vulnerable to infestation by parasites such as the cattle tick, Rhipicephalus microplus, which causes various types of damage and can transmit diseases. In this study, Santa Inês hair sheep were naturally infested in an area contaminated by infested cattle and then monitored to determine the ability of these animals to maintain the local tick population in the absence of cattle. After engorged tick females of each generation fell off, the animals were placed in another pasture and were returned only after larvae reappeared in the original pasture. Tick counts were performed every ten days for three generations of sheep, and average infestations per animal of 34, 12 and 4 ticks were observed for each successive generation. These numbers suggest the acquisition of resistance; however, additional studies are needed to ensure resistance is achieved. The average length of the parasitic phase for each generation of ticks was 25 days. We concluded that this hair sheep breed, even if kept separate from cattle, is able to maintain tick populations for at least three generations, although a gradual decrease in the population levels of R. microplus over three generations was observed. We also detected two positive cases of Anaplasma spp. Therefore, it appears that the Santa Inês hair sheep breed contributes to the circulation of this bacterium among other ruminants.

Effect of herbage species and renewal technique on the free living stages of gastro-intestinal roundworms

This experiment assessed the effect of commonly used pasture species and their establishment technique on endoparasites on herbage in Canterbury, New Zealand. Pasture plots were artificially contaminated with lamb faeces with a known endoparasite egg count. Subsequent treatments included retaining the original pasture, replacing the pasture immediately with new pasture via cultivation or direct-drilling, replacing the pasture immediately with a brassica via cultivation or direct drilling, or replacing the pasture immediately with a barley grain crop via cultivation. Brassica and grain crops were later replaced with new pasture. Herbages were harvested and dry matter (DM) yield and numbers and species of endoparasites (L3) were determined. Pasture and brassica establishment technique had no effect on herbage production. The old pasture initially contained more L3 than all other treatments, but subsequently had a similar number to pasture renewed by direct drilling, both of which had considerably more than all other treatments. Establishing new pasture by direct drilling resulted in 12 760 L3/kg DM over 56 weeks, nearly three times more than occurred following cultivation. Brassica swards had fewer L3 than did new grass. Nematodirus L3 were disproportional to the number of eggs deposited; they represented 2% of the eggs deposited but 67% of the L3, and they were more persistent, representing 30% of the L3 present during March but 87% during October.

Fortification of silage and hay crops with trace elements

Feeding out conserved hay or silage to animals over winter or in early spring is an integral part of New Zealand pastoral farming. However, the mineral content of conserved feed is usually below that of the original pasture, and is fed to stock at a time when their mineral requirements are high. During these periods, iodine and copper concentrations in pasture are marginal or deficient, exacerbating the problem. Three trials were laid down, two in Southland and one in the Waikato, looking at the uptake of copper (Cu), cobalt (Co), selenium (Se), and iodine (I) when applied in liquid form at various times between the shutting‐up stage and harvesting of conserved silage and hay paddocks. Application times for the Southland trials were 4 weeks prior to cutting, 2 weeks prior to cutting, the same day as cutting and onto the windrow after cutting. Minerals applied and rates of application were Cu: 0, 0.5, 1 and 3 kg copper sulphate ha–1, Se: 10 g Se ha–1 as sodium selenate, I:200 g potassium iodate ha–1, and Co: 60 g cobalt sulphate ha–1. For the Waikato trials two rates of copper sulphate (1 and 2 kg ha–1) along with one rate of Co, Se and I were spray applied to silage and hay crops 4 and 7 weeks before harvesting respectively. The application of 3 kg CuSO4ha–1 as a spray to pastures 4 weeks prior to them being harvested increased the Cu status of the silage from 9 to 18 mg kg–1 and from 8 to 15 mg kg–1, and of the hay from 12 to 49 mg kg–1 and from 7 to 13 mg kg–1 at the two Southland trials respectively. However, only the increase from 12 to 49 mg kg–1 was statistically significant (P < 0.001). In the Waikato the application of 2 kg CuSO4 ha–1 lifted the Cu concentration from 7 to 11 ppm, and from 6 to 9 ppm for the silage and hay respectively (P < 0.01). In Southland the application of 0.5 kg CuSO4 ha–1 directly onto the windrow following cutting increased Cu concentrations from 8 to 31 ppm for the silage and from 12 to 63 ppm and 7 to 24 ppm for the hay (P < 0.001). It is recommended that to increase the Cu status of silage and hay sufficient to supply the animal requirements that 3 kg CuSO4 ha–1 be applied as a spray to pastures 4 weeks prior to harvest for silage or hay, or alternatively that Cu be applied to the windrow once cut at a rate no greater than 0.5 kg CuSO4 ha–1. The addition of the other trace elements, I and Co to the Cu spray further enhanced the conserved feeds’ mineral concentrations, and this is likely to be reflected in enhanced animal mineral status.

Soil properties, crop productivity and irrigation effects on five croplands of Inner Mongolia

In the Horqin Sand Land, more than half of the original pasture area has been converted to farmland over the last century. A field experiment was conducted from 2000 to 2001 on five croplands in the Horqin Sand Land of Inner Mongolia to examine differences in soil properties, crop productivity and irrigation effects across different soils in the region to assess their relative suitability for cultivation, in the face of continued pressure for conversion of these generally fragile, sandy soils to agriculture. Two irrigated croplands studied were originally sandy meadow (ISM) and sandy grassland (ISG), and three dry croplands were from sandy meadow (DSM), sandy grassland (DSG) and fixed sand dunes (DFD). Results showed that most measured properties of soils, and crop productivity, differed among the five croplands. The silt + clay fraction, bulk density, organic matter content, total N and P, available N and P, average soil moisture and temperature, plant height and aboveground biomass were as follows in the DSM|DSG|DFD soils: 51.1%|47.5%|24.3%; 1.44 g/cm 3|1.49 g/cm 3|1.58 g/cm 3; 6.3 g/kg|4.6 g/kg|3.4 g/kg; 0.55 g/kg|0.33 g/kg|0.21 g/kg; 0.21 g/kg|0.17 g/kg|0.13 g/kg; 27.0 mg/kg|13.7 mg/kg|7.7 mg/kg; 2.9 mg/kg|2.9 mg/kg|3.0 mg/kg; 9.4%|7.0%|6.2%; 21.4 °C|21.7 °C|22.0 °C; 225 cm|220 cm|181 cm; and 2116 g/m 2|1864 g/m 2|1338 g/m 2. Corresponding values for ISM|ISG soils were: 54.3%|47.9%; 1.42 g/cm 3|1.49 g/cm 3; 8.5 g/kg|6.4 g/kg; 0.58 g/kg|0.42 g/kg; 0.20 g/kg|0.19 g/kg; 29.0 mg/kg|23.3 mg/kg; 4.7 mg/kg|7.9 mg/kg; 13.0%|10.1%; 21.0 °C|21.1 °C; 266 cm|245 cm; and 2958 g/m 2|2702 g/m 2. In general, the ecological origin of a cropland was a stronger determinant of its current characteristics than was irrigation history, although irrigation was correlated with significantly increased organic matter content, some soil nutrient levels, and aboveground biomass productivity. Results indicate that fixed sand dunes should not be converted to cropland because of their very sandy and poorer soil, lower biomass productivity and greater wind-erosion risk. Although both the sandy meadow and sandy grassland may be reclaimed for farming, the cropland derived from the sandy meadow had higher resistance to wind erosion and higher crop productivity, so is somewhat more suitable than sandy grassland.

SOBRE-SEMEADURA DE FORRAGEIRAS HIBERNAIS EM PASTAGEM DEGRADADA DE PENSACOLA COM DOSES DE GLIFOSATO

O presente trabalho foi conduzido na Fazenda Capão Redondo, situada no município de Candói - PR. Foi realizado nos anos agrícolas de 2000 e 2001, com o objetivo de avaliar a participação das forrageiras sobre-semeadas em pastagem degradada de pensacola, submetida à aplicação de glifosato, bem como o efeito desta aplicação no restabelecimento e na composição botânica da pastagem de pensacola. O delineamento experimental foi o de blocos ao acaso com seis tratamentos e duas repetições. Foram sobresemeados azevém, trevo branco, trevo vermelho e cornichão, após dessecação da pastagem de pensacola com doses de glifosato (T2=zero; T3=0,5; T4=0,75; T5=1,0; T6=1,25 L.ha-1). A testemunha (T1) não recebeu herbicida, nem sobre-semeadura e adubo. Para a estimativa da participação de cada espécie na matéria seca disponível (MSd), foi utilizada a metodologia Botanal em quatro avaliações (08/12/00; 09/02/01; 06/06/01; 20/12/01). Observou-se que no tratamento sem herbicida houve excelente estabelecimento das forrageiras hibernais na época fria e restabelecimento da pensacola no verão. Concluiu-se que, nas condições em que este trabalho foi desenvolvido, não foi necessária a aplicação de glifosato para o estabelecimento das espécies em sobre-semeadura. A sobre-semeadura de espécies hibernais em pastagem naturalizada, com e sem a aplicação do herbicida glifosato, melhorou a qualidade da composição botânica da matéria seca disponível, mas influenciou negativamente a participação da pensacola no campo naturalizado. Observou-se também, que esta prática foi responsável pelo decréscimo das espécies naturais do campo, um ano após a sobre-semeadura. As diferentes dosagens de glifosato não influenciaram a participação das espécies sobre-semeadas, excetuando-se o trevo vermelho e o trevo branco, 8 meses e 18 meses após a sobre-semeadura, respectivamente. A pensacola sempre permaneceu inversamente proporcional à participação da espécies sobre-semeadas.

Tillage-induced changes to soil structure and organic carbon fractions in New Zealand soils

The effects of increasing cropping and soil compaction on aggregate stability and dry-sieved aggregate-size distribution, and their relationship to total organic C (TOC) and the major functional groups of soil organic carbon, were investigated on 5 soils of contrasting mineralogy. All soils except the allophanic soil showed a significant decline in aggregate stability under medium- to long-term cropping. Mica-rich, fine-textured mineral and humic soils showed the greatest increase in the mean weight diameter (MWD) of dry aggregates, while the oxide-rich soils, and particularly the allophanic soils, showed only a slight increase in the MWD after long-term cropping. On conversion back to pasture, the aggregate stability of the mica-rich soils increased and the MWD of the aggregate-size distribution decreased, with the humic soil showing the greatest recovery. Aggregate stability and dry aggregate-size distribution patterns show that soil resistance to structural degradation and soil resilience increased from fine-textured to coarse-textured to humic mica-rich soils to oxide-rich soils to allophanic soils. Coarse- and fine-textured mica-rich and oxide-rich soils under pasture contained medium amounts of TOC, hot-water soluble carbohydrate (WSC), and acid hydrolysable carbohydrate (AHC), all of which declined significantly under cropping. The rate of decline varied with soil type in the initial years of cropping, but was similar under medium- and long-term cropping. TOC was high in the humic mica-rich and allophanic soils, and levels did not decline appreciably under medium- and long-term cropping. 13C-nuclear magnetic resonance evidence also indicates that all major functional groups of soil organic carbon declined under cropping, with O-alkyl C and alkyl C showing the fastest and slowest rate of decline, respectively. On conversion back to pasture, both WSC and AHC returned to levels originally present under long-term pasture. TOC recovered to original pasture levels in the humic soil, but recovered only to 60–70% of original levels in the coarse- and fine-textured soils. Aggregate stability was strongly correlated to TOC, WSC, and AHC (P &lt; 0.001), while aggregate-size distribution was moderately correlated to aggregate stability (P &lt; 0.01) and weakly correlated to AHC (P &lt; 0.05). Scanning electron microscopy indicated a loss of the binding agents around aggregates under cropping. The effect of the loss of these binding agents on soil structure was more pronounced in mica-rich soils than in oxide-rich and allophanic soils. The very high aggregate stabilities of the humic soil under pasture was attributed to the presence of a protective water-repellent lattice of long-chain polymethylene compounds around the soil aggregates.

Influence of earthworms, Aporrectodea spp. (Lumbricidae), on pasture production in south-eastern Australia

Most of the earthworms now found in agricultural fields in south-eastern Australia are exotic, patchily distributed, mineral soil dwellers (endogeic species). The influence of two of the most common endogeic species, Aporrectodea caliginosa and A. trapezoides, on pasture production was compared with that of another exotic, surface-feeding, deep-burrowing (anecic) species, A. longa, which is essentially restricted in its Australian distribution to Tasmania. Comparisons were made by introducing 4 different densities of the worms in cages at 10 field sites and measuring pasture production for approximately 5 months. All 3 species increased pasture production at most of the 10 sites. Increases in pasture production were greatest where original pasture production was low. Pasture production increased with earthworm density. Averaged across sites, earthworms increased pasture production by up to 61%. Significant increases in yield were detected with ≥214 A. longa/m 2 and ≥429 A. caliginosa or A. trapezoides/m 2. A. longa is a much bigger worm than A. caliginosa and A. trapezoides. If the initial number of worms introduced to the cages was taken as the measure of earthworm ‘abundance’, then A. longa increased pasture production more than the 2 endogeic species. If the biomass of introduced worms was taken as the measure of abundance, then the reverse was the case. A. longa reduced nitrogen levels in some soils. Phosphorus levels were not affected. No residual effects on pasture production were detected when soil that had been improved by earthworms was potted and resown with ryegrass. Broad scale introduction of A. caliginosa, A. longa, or A. trapezoides to sites lacking them in south-eastern Australia is likely to improve pasture production significantly. Addition of A. longa to existing communities of endogeic species should further increase pasture yield by enhancing functional diversity.

Relationship of equine housing to large airway inflammation

Summary The pasture, as compared to stall confinement, has been considered a more desirable environment for maintaining the health of the respiratory system in the horse. This conclusion is based on reports which showed that ventilation in most barns was generally poor, and that horses bedded on straw and fed hay were exposed to many forms of respirable debris. In this study, six normal horses were evaluated for evidence of airway mucosal inflammation after being housed on pasture or stabled in a barn for one month. The response of the horses' airways was measured by assigning scores for the degree of tracheal mucosal secretions that were observed by endoscopic visualization. Cytological examination of transtracheal wash secretions was also performed, as well as histologic evaluation of tracheobronchial tissues obtained by a transendoscopic epithelial biopsy technique. Samples were collected at three time points; the initial collection occurred after the horses were housed on pasture for one month. The horses were subsequently moved to a barn for an equal length of time and samples were obtained at the end of this period. The horses were then returned to their original pasture and final sampling was performed after they were housed in this environment for two months. There were no significant changes in any of the parameters evaluated, regardless of the environment in which the horses were maintained. These findings indicate that housing horses in a barn for four weeks does not cause tracheobronchial mucosal inflammation in a manner that could be detected using the methods employed in this study.

Effect of oversown ryegrass(Lolium perenne)and white clover(Trifolium repens)on the genetic structure of New Zealand hill pastures

Abstract The botanical composition and genetic structure of North Island hill pastures were studied after oversowing. Three pre‐sowing treatments were applied: (a) no herbicide; (b) herbicide to suppress existing pasture; and (c) herbicide to kill existing pasture. Four oversowing treatments were imposed: (1) no oversowing; (2) hill country ryegrass and ‘Prop’ white clover; (3) ‘Yatsyn’ ryegrass and ‘Prop’ white clover; and (4) a mixture of hill country grass species. Five times as many ryegrass seeds were oversown than emerged from buried seed, giving the introduced material an advantage. The ryegrass content was greater at the high‐fertility sites than at the low‐fertility sites, both before and after oversowing. Killing the original pasture tended to increase ryegrass content for 16 months at the low‐fertility sites but increased the ryegrass content for less than 9 months at the high‐fertility sites. The ryegrass content was not significantly different on any of the sown and unsown plots, 16 months af...

Pasture response to fertiliser inputs under dairy grazing

Conversion of sheep and beef farms into dairy units has resulted in research on appropriate fertiliser rates and pasture species to achieve maximum productivity in minimum time. An onfarm trial involving five different mixtures of pasture species (based on fescue, prairie grass, an improved mixture, farmer mixture or original pasture), three rates of nitrogen as urea (0, 50 or 100 kg/ha of N applied half in March and half in August) and four rates of superphosphate (0, 250, 500 or 1000 kg/ha applied annually in March) was established in Canterbury on a Waimakariri sandy silt loam with border-dyke irrigation and an Olsen P of 5 pg/ml. The trial was grazed by dairy cattle as part of the general rotation; plots were not fenced individually. Pasture growth rates were measured pre- and post-grazing using a calibrated pasture probe. Botanical dissections ,were made seasonally and soil samples were taken annually. Pasture dry matter production was greatest from the prairie grass, "improved" mixture and the original pasture, involved often contain a high proportion of annual and perennial, low-producing species. Grass species, nutrient status and management have been identified as the limiting factors in dairy conversion (Kleyngeld &amp; Kleyngeld 1992). Ryegrass and white clover are still the most common species used in pasture renovation (Maloney 1991). However, short-rotation ryegrasses are favoured by some dairy farmers, and in new dairying areas such as Canterbury, optimally producing species may differ from those used in the more traditional North Island dairying areas (Charlton &amp; Belgrave 1992). Nitrogen (N) is recognised as a strategic tool for increasing grass production in winter-spring in summerdry areas (Thomsoneta/. 1991) as well as for extending the milking season for factory supply herds in Southland (Kleyngeld &amp; Kleyngeld 1992). High rates of nitrogen (217 and 324 kg/ha per year) have been found to increase annual net herbage accumulation by 23 and 27%, respectively, in the Waikato, but clover content declined significantly (Harrisetaf. 1994). Maintenance fertiliser requirements have been related to desired stocking rate in the past, based on animal production system and soil type (Computerised Fertiliser Advisory System (CFAS), reaching 13 000,ll 000 and 16 000 kg/ha in years Cornforth &amp; Sinclair 1984). Recently responses in milk one, two and three, respectively; production from yield have been recorded to very high rates (100 kg/ha- IT the fescue increased with time; the 'farmer' mix performed poorly. Nitrogen at 50 kg/ha was generally sufficient to produce maximum yield increases. Increasing superphosphate increased production; this effect decreased with time. Change in Olsen P reflected superphosphate inputs and after three years of differential superphosphate application the Olsen P status was 8, 14, 27 or 42 (corresponding to 0, 250, 500 or 1000 kg/ha superphosphate). Keywords: Bromus wildenowii, dairy conversion, dry matter production Festuca arundinacea, Loliumperenne, nitrogen, Olsen P, superphosphate

Growth and persistence of perennial ryegrass and white clover direct-drilled into a paspalum-dominant dairy pasture treated with glyphosate

Abstract Paspalum-dominant pastures suffer from poor winter/spring herbage production, which can be corrected by direct-drilling cool-season-active species such as ryegrass. The growth and persistence of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) direct-drilled into a paspalum (Paspalum dilatatum Poir.)-dominant, rotationally grazed dairy pasture, and their effects on production, were studied over 5 years. Treatments were original pasture (control) and herbicide treatment with 0, 0.72, 1.44, and 2.16 kg a.i./ha of glyphosate (Roundup® herbicide, 36% glyphosate) before direct-drilling. Observations on tagged ryegrass and white clover plants found establishment plant numbers for ryegrass were 74% higher (788 plants/m2) in herbicide-treated than in untreated areas (452 plants/m2). Half of all tagged ryegrass plants disappeared in the first year after which losses were much reduced. The establishment and survival of tagged white clover plants were poor. Paspalum gradually re-infested the herbicide-treated areas and by the end of the fourth year had reached pretreatment levels of 30–40% of dry matter (DM). Application of glyphosate before drilling produced a 38% increase in winter/spring herbage accumulation in the first year, but this advantage declined and was non-significant by the end of the fourth year.

Recolonization of methyl bromide sterilized soils under four different field conditions

The course of recovery in biological activity was assessed in the top 5 cm of undisturbed soil cores (29.7 cm diameter, 30 cm deep) that had been fumigated in the laboratory with methyl bromide. The cores were returned to their original pasture and forest sites, two with a moderate and two with a high rainfall, and untreated soils at all sites served as baselines. Sampling took place over 166 days (midsummer to midwinter). Microbial biomass (as measured by fumigation-extraction and substrate-induced respiration procedures) and dehydrogenase activity both recovered rapidly, but remained consistently lower in the fumigated than in untreated samples at both forest sites and at the moister of the two pasture sites. Bacterial numbers also recovered rapidly. Fungal hyphal lengths were, on average over 166 days, 25% lower in the fumigated soils. Levels of mineral N were initially highest in the fumigated soils, but declined with time. Fumigation generally had no detectable effects on the subsequent rates of net N mineralization and little effect on nitrification rates. Fumigation almost totally eliminated protozoa, with one to three species being recovered on day 0; the numbers recovered most rapidly in the moist forest soil and slowly in the dry pasture soil. The recoionization rate of protozoan species was similar in all soils, with species numbers on day 110 being 33 and 34 in the fumigated and untreated soils, respectively. Nematodes were eliminated by fumigation; recolonization was first detected on day 26 but by day 166, nematode numbers were still lower in fumigated than in untreated soils, the abundance being 10 and 62 g-1 soil and diversity 10 and 31 species, respectively. Overall, the results suggest that protozoan and nematode populations and diversities could provide a useful medium-term ecological index of the recovery in comprehensive soil biological activity following major soil pollution or disturbance.

The Growth, Distribution and Neighbour Relationships of Trifolium Repens in a Permanent Pasture. VI. Conditioning Effects by Neighbours

(1) Genetic diversity and phenotype plasticity within any population will allow it to adjust to changing environmental conditions. Their relative importance will depend upon the amount of spatial and temporal heterogeneity and rapidity of change as seen from the plant's-eye-view. (2) Clones of Trifolium repens were collected from patches dominated by Agrostis capillaris, Holcus lanatus and Lolium perenne in an old permanent pasture. The clones were multiplied and then subjected to three different conditioning treatments: repeated cloning in glasshouse conditions, repeated cutting (but not cloning) in boxes outdoors, and transplanting into the original pasture. The conditioning was carried out for varying lengths of time, and the pasture transplants were made into three patch types. (3) Newly collected T. repens showed significant among-grass-neighbour patterns of differentiation for five out of eight morphological characters. Clones from Holcusdominated sites were largest and those from Agrostis-dominated sites smallest. These patterns were altered by the different conditioning treatments. For clones transplanted into the pasture, shorter conditioning periods in the pasture lead to fewer amongsubpopulation differences. (4) The ecological and evolutionary consequences of life in a spatially and temporally patchy environment are discussed. Genetic diversity of the T. repens population may reflect both the avoidance of mortality through phenotype plasticity and the existence of multiple adaptive optima to which genotypes have been fitted by natural selection.

CHANGING SEASONAL GROWTH OF PASPALUM PASTURES BY OVER-DRILLING RYEGRASS AND WHITE CLOVER CLOVER

Volunteer summer-growing paspalum is often present in dairy pastures of northern New Zealand. When paspalum becomes the dominant grass winter/spring pasture production is reduced. This creates management problems on seasonal dairy farms because cow feed requirements and milkfat production are highest in winter/spring. This paper gives data from a current experiment at Ruakura Agricultural Research Station in which Roundup herbicide was used to provide a competitlon-free environment for the overdrilling of cool-season pasture species. Herbicide rates of 6, 4, 2 and 0 l/ha were applied in autumn 1965 before overdrilling a mixture of Ellett ryagrass and Grasslands Kopu white clover. A fifth treatment was the original pasture which was not sprayed or overdrilled. High rates (4-6 I/ha) of Roundup completely elimmated paspalum from the pasture and immediately reduced the white clover to a low proportion (less than 10% of dry matter). The sprayed and overdrilled pastures have remained ryegrass dominant over the duration of the experiment. In 1985 and 1966, winter/spring production from the new ryegrass dominant pastures were significantly better than from the original paspalum dominant pasture. The implications of the noticeable increase in paspalum in the renewed pastures are discussed. Keywords: pasture renewal, pasture renovation, Roundup herbicide, pasture botanical composition, seasonal pasture productlo".

Effect of land preparation and nitrogen fertilizer on yield and quality of temperate species introduced into a tropical grass sward during autumn

Five temperate pasture species (Trifolium repens cv. Ladino, Trifolium subterraneum cv. Mt Barker, Lolium multiflorum cv. Tama, Lolium perenne cv. Kangaroo Valley, and (Lolium perenne x L. multiflorum cv. Ariki) were compared singly and in combination for their winter production when introduced into an existing couch and pangola mixed pasture grown under irrigation in tropical Queensland. The effects of preparing a cultivated seedbed and applying 50 kg N/ha.month on dry matter (DM) yield and in vitro dry matter digestibility (IVDMD) were studied. Nitrogen fertilizer increased the DM yields of all pasture types, (P &lt; 0.05), but with a lesser effect on clovers and mixtures of clover and ryegrass than on ryegrass. Average DM yields for winter (April to September) were 5740, 3665 and 5238 kg/ha for nitrogen-fertilized clovers, ryegrasses, and clover and ryegrass mixtures, respectively. Corresponding DM yields without nitrogen were 4852, 874 and 4532 kg/ha, respectively. Clovers, and clover and ryegrass mixtures maintained a higher IVDMD than did the ryegrasses. Cultivation assisted early establishment of temperate pastures, though satisfactory pastures were also established after slashing and burning of the original couch and pangola mixed pasture. DM yields were higher for clover, and clover and ryegrass mixtures. Ryegrass did not persist without N fertilizer. It was concluded that clovers, ryegrasses, and clover and ryegrass mixtures could be introduced annually into existing couch and pangola mixed pastures to provide winter forage in a tropical environment.

Nutritive value for lactating dairy cows of the pressed herbage remaining after the partial extraction of leaf juice

A series of six experiments compared the production of lactating dairy cows eating either fresh herbage or the pressed herbage remaining after the partial extraction of juice. Irrigated perennial pasture and irrigated lucerne (Medicago sativa) were used in different experiments. With forage-harvested pasture, extraction removed an average of 42.1 g of protein per kg dry matter (DM) of pasture processed. An average of 85% of the DM of the original fresh pasture was left as pressed pasture. The process lowered the in vitro digestibility, total nitrogen, and cell contents of the herbage, and raised the cell wall constituents. It also reduced herbage phosphorus, potassium, magnesium and sodium, but increased herbage calcium slightly. The milk yield of cows fed an equivalent DM intake of pressed residue was, on average, 6% lower than the milk yield of cows fed fresh pasture. The responses shown by the milk constituents were inconsistent. With lucerne, extraction removed an average of 95.9 g of protein from each kg of fresh herbage and an average of 74% of the lucerne was left as pressed lucerne. This reduced the quality of the pressed residue as determined by in vitro digestibility (5%), Kjeldahl nitrogen (19%) and neutral detergent fibre (27%). However, there was no significant loss of production for cows on the pressed herbage, although there were small differences. It is concluded that lucerne would appear to have the greater potential for a leaf protein extraction industry in the irrigated areas of the Goulburn Valley of Victoria.