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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Einfluss organischer Düngung auf Ertrag, symbiotische N2-Fixierung und Nährstoffaufnahme von Saatplatterbse (Lathyrus sativus L.), Ackerbohne (Vicia faba L.) und Rotklee (Trifolium pratense L.) sowie auf Ertrag eines nachfolgenden Winterweizens (Triticum aestivum L.)

Lux, Guido 11 February 2016 (has links)
Das Ziel der vorliegenden Arbeit war es, zu untersuchen, ob sich mit der Düngung von Stroh, Gehölzhäcksel, frischem Pferdemist und Grüngutkompost die Ertragsleistung und Nährstoffaufnahme von Leguminosen sowie der Folgefrucht Winterweizen steigern lässt. Darüber hinaus sollte die Aufnahme von düngebürtigem Kohlenstoff durch Rotklee mittels 13-C-angereichertem Stroh quantifiziert werden. Die Verfügbarkeit von Kalium, teilweise auch von Schwefel und Molybdän, wurde vor allem nach der Düngung von Grüngutkompost und von Pferdemist für die untersuchten Leguminosen verbessert, während nach der Düngung von Gehölzhäcksel und Stroh keine signifikanten Effekte auf die Nährstoffaufnahme der Pflanzen festgestellt werden konnten. Die scheinbare Ausnutzung des gedüngten Stickstoffs durch die Leguminosen lag in Abhängigkeit von der Düngung zwischen 0 und 9 % (Gehölzhäcksel < Grüngutkompost < Pferdemist < Stroh). Nur nach der Düngung von Pferdemist zu Saatplatterbse und Ackerbohne verringerte sich der Anteil an symbiotisch fixiertem Luftstickstoff am Spross-N gegenüber der Kontrolle, nicht jedoch die symbiotisch fixierte N-Menge. Der Vorrat an mineralischem Stickstoff im Boden in einer Tiefe von 0 bis 30 cm war unter Ackerbohne und Rotklee ca. 40 Tage nach der Düngung und Einarbeitung von Gehölzhäcksel gegenüber den Vergleichsvarianten und der Kontrolle deutlich vermindert. Ein Einfluss der durch die Düngung bedingten temporären N-Festlegung im Boden auf den Anteil an fixiertem Luftstickstoff am Spross-N konnte bei keiner der untersuchten Leguminosen festgestellt werden. Der nachfolgende Winterweizen reagierte in einem Jahr mit signifikant höherem Kornertrag auf die Düngung von Grüngutkompost zu Ackerbohne und erhöhtem Rohproteingehalt im Korn auf die Düngung von Pferdemist zu Saatplatterbse. Mit Hilfe von 13-C-markiertem Stroh wurde im Freiland eine Assimilation von 0,5 % der mit dem Stroh gedüngten Kohlenstoffmenge durch Rotklee ermittelt. / The aim of this study was to examine, whether the application of wheat straw, pruning, horse manure and green compost improves the yield formation and nutrient uptake of legumes and the succeeding crop winter wheat. Furthermore it should be quantified the amount of carbon in red clover derived from the organic fertilizer by carbon dioxid assimilation. An improved uptake of potassium, partially of sulphur and molybdenum for the legumes could be detected after the application of green compost and horse manure. No effects were found on plant nutrient uptake after the application of straw and pruning. The apparent utilization of the applied nitrogen by organic fertilizer was 0 to 9 %, depending on the fertilization (pruning < green compost < horse manure < straw). The proportion of symbiontically fixed nitrogen decrease in faba bean and in chick-pea after manuring with horse manure compared with the control. However the total amount of symbiotically fixed nitrogen did not decreased. The amount of mineral nitrogen in the soil (depth: 0 to 0,3 m) was significant reduced under faba bean and red clover, 40 days after application and incorporation of pruning. No effect on the symbiotic nitrogen fixation of the legumes was found because of the organic fertilizer induced temporary immobilization of nitrogen in this soil layer. An increased grain yield was determined in the succeeding winter wheat after fertilizing green compost to faba bean and a higher content of crude protein in grain of the wheat was determined after fertilizing horse manure to chick-pea. With the help of a 13C-tracer method it could be estimated, that about 0,5 % of the added carbon with straw was assimilated by red clover under field conditions.
272

Effects of alternative grass species on grazing preference of sheep for white clover

Muraki, Tomohiro January 2008 (has links)
Despite the importance of a high white clover (Trifolium repens) content in temperate pastoral systems in terms of livestock performance and nitrogen fixation, the proportion of white clover in grass-clover pastures is often low (<20%). This thesis examined in two experiments whether the white clover content of pastures could be improved by sowing white clover with alternative grass species to diploid perennial ryegrass (Lolium perenne L.). In a pasture experiment, DM production, pasture composition and morphology of grass-clover mixtures was measured over the establishment year (January 2007 to January 2008) where white clover was sown in fine mixtures with diploid perennial ryegrass, tetraploid perennial ryegrass, timothy (Phleum pratense L.) and cocksfoot (Dactylis glomerata L.). Pastures were irrigated and rotationally grazed with on-off grazing with Coopworth ewe hoggets. Total annual DM production of pasture was more than 20% higher in tetraploid (12521 kg DM ha⁻¹) and diploid (11733 kg DM ha⁻¹) perennial ryegrass than timothy (9751 kg DM ha⁻¹) and cocksfoot (9654 kg DM ha⁻¹). However, timothy (5936 kg DM ha⁻¹) and cocksfoot (5311 kg DM ha⁻¹) had more than four times higher white clover annual DM production than tetraploid (1310 kg DM ha⁻¹) and diploid (818 kg DM ha⁻¹) ryegrass. Pasture growth rate at the first three harvests in autumn was significantly greater in tetraploid and diploid ryegrass than timothy and cocksfoot. Timothy and cocksfoot had a higher proportion of white clover than tetraploid and diploid perennial ryegrass throughout the entire year. This was due to more and larger white clover plants in timothy and cocksfoot plots. In a grazing preference experiment, the partial preference of sheep for white clover offered in combination with the same grass species as in the pasture experiment was measured in five grazing tests in May, September, October, November and December 2007. Pastures were sown in January 2007. Paired plots (grass and clover both 4.2 m x 10 m) were grazed by three Coopworth ewe hoggets between 9am and 5pm, and preference was recorded by decline in pasture mass and visual scan sampling for grazing time. Grazing preference for clover was generally low throughout these tests (e.g. average apparent DM intake from clover = 47%; average grazing time from clover = 44%). Several explanations are proposed for this low preference including a high N content and intake rate of the grass relative to the clover. No significant differences were found among the grass treatments in total grass grazing time, total clover grazing time, ruminating time, the proportion of grazing time on clover, selective coefficient for clover and DM intake percentage from clover at any date. There was no significant change in overall sward surface height (SSH) decline among grass treatments throughout all the tests except December 2007 when the overall SSH decline for cocksfoot was significantly lower than the other species. The study indicated that the rapid growth rate of perennial ryegrass in the early phase of pasture establishment, rather than differences in partial preference, was the key factor limiting white clover content in the mixed swards relative to cocksfoot and timothy pastures. It is concluded that high clover-containing pastures capable of delivering high per head performance can be established through the use of slow establishing pasture species such as timothy and cocksfoot.
273

Grazing management of subterranean clover (Trifolium subterraneum L.) in South Island (New Zealand)

Ates, Serkan January 2009 (has links)
This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.
274

A management study of light land farming in Canterbury, New Zealand

Taylor, N. W. January 1967 (has links)
By far the greatest proportion of the 1,150,000 acres of light land in Canterbury is found on the Canterbury Plain. This plain, originally covered by "low tussock" and of easy contour, was enticing to the early pioneers and became one of the earliest areas in New Zealand to be settled and farmed. Over the years it has developed into one of the most intensively farmed and productive areas of New Zealand. The dominant characteristic of the light land of Canterbury is undoubtedly the climate. The rainfall is reasonably evenly distributed over the year, but because of the low humidity, high temperatures and warm winds experienced over the summer in association with a free draining soil, the effectiveness of the rainfall over this period is drastically reduced. Consequently active plant growth is severely restricted for several months over the summer, and occasionally extends into the spring and/or autumn periods. The uncertainty as to the length and severity of this restricted growth period and the associated problem of equating the variable feed supply to the stock requirements, both within and between years, is the basic problem confronting the light land farmer. In spite of the environmental difficulties the productivity of the light land has increased several fold since early settlement. The original holdings on the Canterbury Plain were large with their boundaries on the rivers so as to provide access to water. Fine wool sheep were extensively grazed. However the introduction of refrigerated shipping and the extension of the water race system in the 1880's brought about a reduction in the size of holdings and a change in the pattern of farming. Dual purpose sheep were run and by the 1930's in response to favourable crop prices the system of diversified farming was firmly established. Unfortunately this system placed excessive emphasis on cash cropping, particularly on the light soils. Soil fertility was drained, structure severely damaged and subsequent pasture establishment and survival poor. In the late 1940s and early 1950s, with declining crop yields and with more favourable prices being obtained for fat lambs and particularly wool, the emphasis shifted from cropping to livestock farming. The carrying capacity however, was restricted by the reduced soil fertility and poor quality pastures and an environment in which climatic uncertainty tended to inhibit the rapid expansion of stock numbers. The results of research work carried out at the various institutions in Canterbury over the years have undoubtedly promoted a greater understanding and appreciation of the problems confronting the farmer and the limitations of the particular environment in which he must operate. For example, pasture species more suited to the low fertility conditions and climate were introduced with spectacular results. The most significant of these was subterranean clover (introduced in the 1930s), noted for its ability to withstand the summer droughts, to regenerate in the autumn, and to provide an increased bulk of feed in the spring. Research work had shown that both lime and phosphate were necessary on the light land soils, if high pasture production and persistency was to be expected. Soil fertility increased subsequent to a reduction in the emphasis on cropping and with the higher levels of fertiliser application. High fertility pasture species (e.g. white clover and lucerne), were introduced and not only gave higher and more reliable total production but exhibited improved seasonal spread of production. Investigations into pasture diseases and stock health provided answers to specific problems. Research into flock management generally and in comparisons between the productivity of various sheep breeds indicated the most suitable type of flock and breed for the light land farmer. From this and other research work (in conjunction with the observations of leading farmers in the area), an efficient system of light land farming has gradually evolved in which many of the basic problems have been overcome and which has resulted in a raising of the carrying capacity of the light land from ¾ stock unit per acre in the 1930's to 3½-4 stock units per acre at present. A central feature of this system (particularly at high stocking rates), is the high degree of flexibility incorporated in both the stock policies and feed supplies. Where the objective function is to maximise productivity over a period of years, it is essential to utilise the available spring feed efficiently while maintaining the ability to destock when confronted with feed shortages in the spring and early summer. Because of the fluctuating feed supply, which is characteristic of light land, the need to maintain feed reserves and to incorporate a high degree of flexibility in the stock policy is evident if the feed supply and demand are to be equated. In summary, the increased productivity can be attributed to two factors: (1) The ability to grow a greatly increased quantity of herbage per acre with an improved seasonal pattern of production. (2) A more efficient utilisation of the herbage produced. Unlike his counterpart in more reliable farming districts, the light land farmer operates in an environment of uncertainty. Yield uncertainty, particularly at high stocking rates, is the major problem to be overcome and this dictates very largely the system of farming adopted. Price uncertainty is also a significant aspect of light land farming because of the reliance on a limited range of products and the inability to diversify. In an analysis of physical and financial data collected from a sample of light land farms in Canterbury (1) there was no evidence to suggest that any one particular pattern of output was superior to all others. This result was surprising, but may reflect the uncertainty inherent in the environment. (1) For a full discussion on this, see Section 3.3.2(a). Alternatively it may infer that the actual patterns of production are less important than the managerial skill with which they are implemented. These results pointed to the need to explore more fully the following facets of light land management: (1) Given a developed farm, is there any one optimal pattern of production which (a) generates increased profit under average seasonal and price conditions, and (b) is subject to only small variations in profit under changing seasonal and price conditions? (2) Given the potential for the development and expansion of light land farming, how profitable is this from the individual farmer's viewpoint? If, in an evaluation of the first problem, high levels of productivity are shown to be profitable on existing well developed farms, then a reallocation of resources to obtain the desired combination should be recommended. An optimum combination of enterprises shown by such an analysis might well serve as the goal where an undeveloped potential still exists on a farm and where a reallocation and intensification in the use of resources is necessary if productivity is to be increased. In this study of light land farming two case farms have been used and although the results refer specifically to these particular farms, some conclusions of a general nature are possible. In Chapter II the physical characteristics of the area are described. In Chapter III a review of the research into specific problems relating to the management of light land is presented. This is followed in Chapter IV by an explanation of the technical principles of light land farming which have evolved. Chapter V is devoted to the comparison of some of the production possibilities open to the light land farmer using linear programming. An analysis of light land development 1s presented in Chapter VI, while Chapter VII presents the conclusions and summary of the study.
275

A comparison of the cool season activity of two white clover cultivars

Smetham, M. L. January 1972 (has links)
Although New Zealand is fortunate in having a climate mild enough to allow some growth of pasture in winter even in the extreme south of the South Island (Duffy, 1971), growth is nevertheless considerably less than in spring and summer. O’Connor et al, (1968) point out that at Lincoln, Canterbury, winter production from a New Zealand Certified Grasslands Ruanui Perennial ryegrass (Lolium perenne c.v.) and New Zealand Certified Grasslands Huia white clover (Trifolium repens c.v.) sward is at best only 8% of the mean total annual dry matter (D.M.) production. A similar seasonal pattern is shown by irrigated pastures (Rickard, 1968), as well as pastures in the milder North Island of New Zealand (O’Connor and Vartha, pers comm.). Stocking of grazing animals is normally related to the growth rate of pastures in the spring, with conserved hay or silage, plus specially grown greenfeed or root crops being fed if necessary to offset the winter feed deficit. However on hill country too steep for tractor cultivation, cropping and conservation are not possible. Animals have to rely upon in situ grazing of native or dominant browntop (Agrostis tenuis) swards which may not have been improved by the aerial introduction of clovers. In an unimproved state, the quality and quantity of the herbage grown on such areas are low, Molloy (1966) have discussed clover introduction into native swards and the notably beneficial result this has on stock thrift, particularly during the winter period. Considerably better growth rates of stock grazing legumes rather than grasses have been noted by many authors including Ulyatt, (1971), and McLean et al (1962); this superiority being due largely to the greater digestible organic matter intake and higher ratio of soluble to insoluble carbohydrate associated with the herbage of legumes (Ulyatt, 1971). Consequently the presence of clover, and the winter activity of this, have an important influence on the productivity of steep hill country during winter. An increase of winter activity is also desirable, but not essential, in clover associated with flat or gently rolling pastures. The main pasture legume used in New Zealand has, in the past, been the white clover cultivar Huia. Whilst since 1945 selection and breeding of ryegrasses has brought about a very considerable improvement in the winter or cool season activity of these (Corkill, 1966), no legume cultivar having an increased level of cool-season activity has been released to commerce in New Zealand over the same period to date. Breeding for increased winter growth has been an objective of the Grasslands Division Plant Breeding Section for many years (Barclay, 1960). Since 1957, breeding and selection work has been proceeding with the objective of increasing the winter growth of the New Zealand Certified Grasslands white clover cultivar – Huia (henceforth to be referred to as Huia) without sacrificing the moderately good summer growth of this strain, (Barclay, 1969). Seed of a promising cultivar selected during the course of this work – New Zealand Grasslands 4700 white clover, (henceforth to be referred to as 4700) became available for testing in 1967. The investigation to be reported here aimed to measure the cool-season activity of 4700 by comparison with that of Huia, at the same time elucidating if possible the factors controlling this growth.
276

Water use efficiency of six dryland pastures in Canterbury

Tonmukayakul, Nop January 2009 (has links)
The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.
277

A management study of light land farming in Canterbury, New Zealand

Taylor, N. W. January 1967 (has links)
By far the greatest proportion of the 1,150,000 acres of light land in Canterbury is found on the Canterbury Plain. This plain, originally covered by "low tussock" and of easy contour, was enticing to the early pioneers and became one of the earliest areas in New Zealand to be settled and farmed. Over the years it has developed into one of the most intensively farmed and productive areas of New Zealand. The dominant characteristic of the light land of Canterbury is undoubtedly the climate. The rainfall is reasonably evenly distributed over the year, but because of the low humidity, high temperatures and warm winds experienced over the summer in association with a free draining soil, the effectiveness of the rainfall over this period is drastically reduced. Consequently active plant growth is severely restricted for several months over the summer, and occasionally extends into the spring and/or autumn periods. The uncertainty as to the length and severity of this restricted growth period and the associated problem of equating the variable feed supply to the stock requirements, both within and between years, is the basic problem confronting the light land farmer. In spite of the environmental difficulties the productivity of the light land has increased several fold since early settlement. The original holdings on the Canterbury Plain were large with their boundaries on the rivers so as to provide access to water. Fine wool sheep were extensively grazed. However the introduction of refrigerated shipping and the extension of the water race system in the 1880's brought about a reduction in the size of holdings and a change in the pattern of farming. Dual purpose sheep were run and by the 1930's in response to favourable crop prices the system of diversified farming was firmly established. Unfortunately this system placed excessive emphasis on cash cropping, particularly on the light soils. Soil fertility was drained, structure severely damaged and subsequent pasture establishment and survival poor. In the late 1940s and early 1950s, with declining crop yields and with more favourable prices being obtained for fat lambs and particularly wool, the emphasis shifted from cropping to livestock farming. The carrying capacity however, was restricted by the reduced soil fertility and poor quality pastures and an environment in which climatic uncertainty tended to inhibit the rapid expansion of stock numbers. The results of research work carried out at the various institutions in Canterbury over the years have undoubtedly promoted a greater understanding and appreciation of the problems confronting the farmer and the limitations of the particular environment in which he must operate. For example, pasture species more suited to the low fertility conditions and climate were introduced with spectacular results. The most significant of these was subterranean clover (introduced in the 1930s), noted for its ability to withstand the summer droughts, to regenerate in the autumn, and to provide an increased bulk of feed in the spring. Research work had shown that both lime and phosphate were necessary on the light land soils, if high pasture production and persistency was to be expected. Soil fertility increased subsequent to a reduction in the emphasis on cropping and with the higher levels of fertiliser application. High fertility pasture species (e.g. white clover and lucerne), were introduced and not only gave higher and more reliable total production but exhibited improved seasonal spread of production. Investigations into pasture diseases and stock health provided answers to specific problems. Research into flock management generally and in comparisons between the productivity of various sheep breeds indicated the most suitable type of flock and breed for the light land farmer. From this and other research work (in conjunction with the observations of leading farmers in the area), an efficient system of light land farming has gradually evolved in which many of the basic problems have been overcome and which has resulted in a raising of the carrying capacity of the light land from ¾ stock unit per acre in the 1930's to 3½-4 stock units per acre at present. A central feature of this system (particularly at high stocking rates), is the high degree of flexibility incorporated in both the stock policies and feed supplies. Where the objective function is to maximise productivity over a period of years, it is essential to utilise the available spring feed efficiently while maintaining the ability to destock when confronted with feed shortages in the spring and early summer. Because of the fluctuating feed supply, which is characteristic of light land, the need to maintain feed reserves and to incorporate a high degree of flexibility in the stock policy is evident if the feed supply and demand are to be equated. In summary, the increased productivity can be attributed to two factors: (1) The ability to grow a greatly increased quantity of herbage per acre with an improved seasonal pattern of production. (2) A more efficient utilisation of the herbage produced. Unlike his counterpart in more reliable farming districts, the light land farmer operates in an environment of uncertainty. Yield uncertainty, particularly at high stocking rates, is the major problem to be overcome and this dictates very largely the system of farming adopted. Price uncertainty is also a significant aspect of light land farming because of the reliance on a limited range of products and the inability to diversify. In an analysis of physical and financial data collected from a sample of light land farms in Canterbury (1) there was no evidence to suggest that any one particular pattern of output was superior to all others. This result was surprising, but may reflect the uncertainty inherent in the environment. (1) For a full discussion on this, see Section 3.3.2(a). Alternatively it may infer that the actual patterns of production are less important than the managerial skill with which they are implemented. These results pointed to the need to explore more fully the following facets of light land management: (1) Given a developed farm, is there any one optimal pattern of production which (a) generates increased profit under average seasonal and price conditions, and (b) is subject to only small variations in profit under changing seasonal and price conditions? (2) Given the potential for the development and expansion of light land farming, how profitable is this from the individual farmer's viewpoint? If, in an evaluation of the first problem, high levels of productivity are shown to be profitable on existing well developed farms, then a reallocation of resources to obtain the desired combination should be recommended. An optimum combination of enterprises shown by such an analysis might well serve as the goal where an undeveloped potential still exists on a farm and where a reallocation and intensification in the use of resources is necessary if productivity is to be increased. In this study of light land farming two case farms have been used and although the results refer specifically to these particular farms, some conclusions of a general nature are possible. In Chapter II the physical characteristics of the area are described. In Chapter III a review of the research into specific problems relating to the management of light land is presented. This is followed in Chapter IV by an explanation of the technical principles of light land farming which have evolved. Chapter V is devoted to the comparison of some of the production possibilities open to the light land farmer using linear programming. An analysis of light land development 1s presented in Chapter VI, while Chapter VII presents the conclusions and summary of the study.
278

Phosphordüngewirkung von Klärschlämmen aus Klärwerken mit Phosphateliminierung durch Eisensalze / Phosphate fertilization effects of sewage sludges from waste water processing plants with phosphate elimination by iron salts

Abd El-Samie, Ihab Mohamed Farid 06 February 2003 (has links)
No description available.
279

The Relationship between Biodiversity and Productivity in Permanent Grasslands and in Ley System / Die Verbindungen zwischen Diversität und Produktivität in der Grasland und in Ley-System

Assaf, Taher 14 May 2008 (has links)
No description available.

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