Hill Pastures Research Articles

A Low-Power Postprocessed DGPS System for Logging the Locations of Sheep on Hill Pastures

Following the explosion at the Chernobyl nuclear plant, airborne cesium-137 was transported into Sweden, the United Kingdom, Iceland, Greenland, and even the northeastern United States. Rainfall washed the radioactive material into the soil, where it was absorbed by the roots of plants. Sheep eating the affected plants threatened to transfer the radiation into the human food chain. Research into the correlation between levels of radioactivity and grass types has led to the need for an instrument that can monitor the positions of sheep at 1 min intervals, with an accuracy of 5 m. An unusual approach to postprocessed differential GPS (DGPS) has been shown to provide the optimal solution to the requirement. The design of the sheep-borne unit has been optimized for minimal power consumption. Furthermore, a low-cost GPS receiver has been shown to serve as a satisfactory reference station, providing the required accuracy without the need for a survey-grade receiver.

Comparison of the behaviour of goats and sheep on an eroded hill pasture

In contrast to sheep, which have traditionally been farmed on New Zealand hill pastures, goats have gained a reputation as causing soil erosion. To investigate this difference a trial was conducted during spring and summer of 1991/92 observing the behaviour of cashmere-producing goats ( Capra hircus) and Romney sheep ( Ovis aries) on an eroded hill pasture. A fixed remote-controlled video camera was used to record the animals' behaviour while on the eroded area. Tapes were later viewed and time and animal activity recorded. During the spring, two observation periods, 8 weeks apart, were conducted on five does, each with twin kids at foot, and five ewes, each with twin lambs at foot. During the summer the behaviour of ten weaned kids was compared with that of ten weaned lambs. Does and kids spent significantly ( P<0.05) more time on the eroded area than ewes and lambs. The predominant activities of the does and ewes when on the erosion during spring observations were lying and standing. Lying, standing and grazing the edge of the eroded area were the main activities of the kids and lambs during all observation periods. The mean number of kids on the erosion at any one time was greater ( P<0.001) than the number of lambs in both spring and summer. It was concluded that differences in the behaviour of goats and sheep, in relation to their presence on existing surface erosion, do exist. It was apparent that the potential of goats to exacerbate existing surface erosion was greater than that of sheep, particularly when kids were at foot.

Soil microbial biomass, C and N mineralization, and enzyme-activities in a hill pasture - Influence of grazing management

Grazing and fertilizer management practices are of prime importance for maintaining summer-moist hill pastures of introduced grasses and clovers in New Zealand for sheep and cattle production. The influence of withholding grazing (a pastoral fallow) from spring to late summer on microbial biomass, C and N mineralization, and enzyme activities was investigated in a Typic Dystrochrept soil from unfertilized and fertilized (rock phosphate and elemental S) low-fertility pastures at a temperate hill site. The fallow increased pasture but not legume growth in the following year in the unfertilized treatment, but had no effect on pasture or legume growth in fertilized plots. High background levels of the biochemical propel-ties examined, and very variable rates of N mineralization, complicated data interpretation. Extractable-C concentration and CO2-C production were enhanced at the completion of the fallow. Increases in net N mineralization (14-56 days incubation), following initial immobilization, after the fallow were clearly indicated in the unfertilized treatment, but were less distinct, in the fertilized treatment. The fallow had no detectable influence on the concentrations of total C and N or microbial C and P, or on invertase, phosphodiesterase and sulfatase activities. Some small changes in microbial N and an increased proportion of bacteria in the microbial population were, however, suggested. Results are consistent with the concept of fallowing giving a short-term increase in pools of readily decomposable soil organic matter. Generally, the changes that did occur in these soil biochemical properties are, with the partial exception of increased N availability, unlikely to have had any pronounced impact on subsequent pasture performance.

Cadmium distribution in hill pastures as influenced by 20 years of phosphate fertilizer application and sheep grazing

Cadmium (Cd) accumulating in the kidneys of older grazing animals threatens the continued access of New Zealand offal products to traditional markets. Phosphatic fertilizers represent the largest input of Cd into pastoral farming systems. Little research has been conducted on the cycling of Cd in grazed pastures. To estimate the distribution of Cd in grazed pastures, soil samples were collected from self-contained farmlets which had received either high superphosphate (HF) inputs (765 kg P ha-1), low superphosphate (LF) inputs (113 kg P ha-1) or no phosphate fertilizer (UF) inputs over the previous 20 years. The average total Cd concentration in the surface soil (0-30 mm; bulk density 0.64 g cm-3) of the farmlets which had received HF inputs was 0.40 mg kg-1 soil (range 0.18-0.60 mg kg-1), whereas farmlets which had received LF or no fertilizer inputs had an average Cd concentration of 0.10 mg kg-1 (range 0.02-0.19 mg kg-1). Cadmium concentration decreased with soil depth. The concentration of Cd in mixed herbage reflected the difference in soil Cd between the HF (mean � standard error = 0.321 � 0.033 mg Cd kg(-1) dry matter) and LF (0.063 � 0.004 mg Cd kg(-1) dry matter) farmlets. Soil Cd accumulation was highest on low slopes (0-12�) and lowest on high slopes (&gt; 26�) in both LF and HF farmlets, whereas pasture Cd concentration in the HF farmlet increased with slope from 0.178 � 0.035 mg Cd kg-1 on low slopes to 0.487 � 0.053 mg Cd ha-1 on high dopes. A strong relationship was obtained between soil Cd and P in the 0-30 mm layer of the HF farmlet, demonstrating the link between phosphate fertilizer use and Cd accumulation. Zinc to Cd ratios were much lower in this layer compared with those in LF and UF sites, providing further evidence of the contribution of phosphate fertilizer to soil Cd. A model originally developed to explain the distribution of soil P in sheep-grazed fertilized hill pastures gave good predictions of present day soil Cd distribution in the HF farmlet. The model predicts Cd accumulation in soil by using the amounts of Cd applied in fertilizer per unit surface area of land and functions which calculate the redistribution of Cd by animal grazing and camping behaviour. The model on an average overpredicted the measured soil Cd by 17% in the high slope sites and by 10% in the low slope sites.

Biophysical indicators of sustainability of North Island hill pasture systems

"Sustainability" is a social construct, and is difficult to define in precise value-free terms. It has ecological (biophysical) and socio-economic dimensions. Biophysical indicators are tools that can be used to define resource status. They cannot directly measure sustainability, but are useful for comparing present resource status with defined limits set within a socio-economic framework. We measured vegetation and soil variables in 4 areas of grazed North Island hill country with different management (fertiliser application/stocking rate) histories (1973 to 1994) and sub-divided into 36 paddocks. Nineteen vegetation (including herbage production); soil chemical, physical and biological; and soil water variables were selected as potentially useful biophysical indicators. Analysis of the results for these variables suggested that pasture botanical composition (especially content of high-fertility responsive grasses and of herbaceous weed species) and earthworm mass/unit area explained most of the variance of the data matrix. These variables were also highly correlated with herbage production, an indicator of likely economic performance. Development of the most suitable indicators requires good understanding of agro-ecosystem function, and is hampered by our lack of understanding of critical processes. Keywords: biophysical indicators, hill country, pasture, soil, sustainability

Sheep Grazing Efficiency and Selectivity on Oregon Hill Pasture

Grazing trials were conducted during early and late spring of 1988 and 1989 to evaluate the impact of sheep grazing duration and stocking density on grazing efficiency and forage selectivity in tall fescue (Festuca arundinacea Schreb.)-subclover (Trifolium subterranum L.) hill pastures near Corvallis, Ore. Grazing treatments were 2, 6, and 10 days duration with corresponding stocking densities 380,130, 78, and 1,390, 460, and 280 ewes/ha during early and late spring trials each year, respectively. Grazing efficiency was generally greater (P < 0.05) for the low density/longer duration (10-day) than for higher density/shorter duration (2-day) treatments. Greater grazing efficiency as duration increased largely reflected higher rates of intake rather than lower levels of non-consumptive forage destruction. Stocking density within a constant grazing duration (2 days) had little effect on grazing efficiency. Within the 10 day grazing treatment, grazing efficiency was highest during the last 4 days and lowest during the first 2 days (P < 0.05). Although short duration/high density grazing is considered to be non-selective, sheep were equally or more selective under very short duration/very high density compared to longer duration/lower density treatments in this study. These results suggest that the very short duration with very high stocking density was not an attractive management option since grazing efficiency was low and sheep were more selective.

The effects of extensification of sheep farming on the semi-natural vegetation of hill pastures

The effects of extensification of sheep farming on the semi-natural vegetation of hill pastures

Distribution of diploid and tetraploidLotus pedunculatusplants in moist, North Island hill country

Abstract The proportions of diploid (2n) and tetraploid (4n) Lotus pedunculatus lines were determined at different hill country sites in southern North Island hill pastures by stomatal cell length measurements and by counting chromosome numbers. The area had been oversown 10–15 years earlier with both diploid G4703 (now ‘Grasslands Sunrise’) lotus and tetraploid ‘Grasslands Maku’ lotus seed. There was a greater frequency of diploid than tetraploid plants in the 506 plants sampled from different slope, aspect, and fertility classes. Tetraploid plants were more common on steeper slopes and north-facing aspects but the proportion of diploid:tetraploid plants was not affected by fertiliser treatments. These data are consistent with the hypothesis that plants with a large DNA content per cell nucleus and large cell size have a superior ability to grow in seasonally dry sites.

Mineralisation and fate of soil sulphur and nitrogen in hill pastures

Abstract A field experiment was conducted for 7 months using mini-lysimeters with ion exchange resin traps to study the amounts of sulphur (S) and nitrogen (N) mineralised from soil organic matter, taken up by pasture and lost by leaching. Four sites were selected on the basis of contrasting fertiliser history and land slope. The fertiliser histories since 1981 for the sites were 125 (LF) or 375 (HF) kg/ha per year single superphosphate (SSP) and the two slope positions were low (LS, 0–12°) and medium (MS, 13–26°). Pasture production at the HF site (8360 ± 250 kg DM/ha) was twice that at the LF site (4986 ± 278 kg DM/ha) and S leaching losses were 7 times greater at the HF site (HF, 15.3 ± 2.9 kg S/ha, LF, 2.1 ± 0.25 kg S/ha). Over the 7 months of measurement, the amounts of S and N mineralised were also greater at the HF site (27.5 ± 4.3 kg S/ha and 251 ± 15.2 kg N/ha, respectively) than the LF site (12 ± 2.1 kg S/ha and 119 ± 8.0 kg N/ha, respectively). Despite the fact that approximately 10 times more ...

Sulphur cycling in New Zealand hill country pastures. I. Laboratory sulphur, nitrogen and carbon mineralization studies

SUMMARYLarge leaching losses of sulphate contribute to the inefficient use of sulphur (S) fertilizer in some grazed hill country pastures in New Zealand. Laboratory mineralization studies were conducted to measure S, nitrogen (N) and carbon (C) mineralization rates and the potential for S leaching from surface soils of low (LS, 0–12°) and medium (MS, 13–25°) slope positions on hill country pastures. The soils differed in C, N and S contents as a result of different fertilizer histories and the uneven redistribution of nutrients by the grazing animal. Soils were incubated in columns for 140 d and leached periodically with 0.01 M KCl to remove mineralized sulphate, nitrate and ammonium. The net amounts of N and S mineralized were greater in soils on low slopes than medium slopes and in soils from pastures which had received fertilizer continuously, compared with those hill pastures that had not received single superphosphate fertilizer in the previous 7 years. In both cases more mineralization was associated with smaller soil C:nutrient ratios. However, the amounts of C mineralized were greater in soils from medium slopes where C:nutrient ratios were larger. In general, the ratio of N:S mineralized was smaller than the N:S ratio of the soil organic matter, suggesting that N is conserved while S remains in the soil solution susceptible to leaching. It is suggested that the extent of S leaching loss under field conditions will reflect S mineralization potential.

Revegetation of erosion scars in Wairarapa hill country

revegetation of erosion scars, 3 fertiliser and 3 seeding treatments were applied to plots on 8 recent scars in the Wairarapa, half each on northerly or southerly aspects. Four scars were grazed, and 4 were not grazed for the first 2% years. Fertiliser treatments were no fertiliser, superphosphate, and superphosphate plus nitrogen. Seedin.g treatments were no seed, a slowestablishing mixture, and a fast-establishing mixture. Changes in vegetative cover were monitored during years 0 to 2l/, and pasture production during years 3% to 5%. Conclusions include: rate of recovery of pastures can be greatly increased by not grazing for 2-3 years and sowing white clover and Lotus pedunculatus; spaceplanting hill slopes with suitable tree species could be accomplished at the same time; if slips are not spelled from grazing, rate of slip revegetation and subsequent productivity from oversowing white clover can be reduced. Keywords: erosion, fencing, fertiliser, hill pastures, oversowing, production, revegetation, slips

Plant Uptake of Radiocaesium on Heather Moorland Grazed by Sheep

A hill pasture on an iron podzol in north-east Scotland comprising areas of heather-dominated vegetation and Deschampsia flexuosa grassland was grazed by sheep from May to early October in 1989 and 1990. In each vegetation type small quadrats were artificially contaminated with 134 Cs by soil injection, and seasonal changes in 134 Cs concentrations within these quadrats were recorded for the main botanical components. Calluna vulgaris accumulated more 134 Cs than any other species. Current and previous years' shoots of C. vulgaris showed consistently higher 134 Cs concentrations than wood and dead shoots. Within the herbs 134 Cs concentrations increased significantly in the order: fine-leaved grasses < broad-leaved grasses < Carex pilulifera < Galium saxatile (...)

Response of southern North Island hill pasture to nitrogen, molybdenum and lime

of molybdenum (MO), lime and nitrogen on steep (&gt;30°) north-facing hill pasture on the Massey University Hill Farm, "Tuapaka". Treatments included application of molybdenum, lime (L), nitrogen (N) alone and together with MO and lime. MO and lime werre applied in mid May at 0.05 kg/ ha and 2000 kg/ha separately, and N fertiliser was applied as urea in August and October at 60 and 20 kg N/ha respectively. Herbage and soil responses were measured over spring and summer 1992/93. Nitrogen fertiliser increased herbage mass accumulation from 3 to 41 kg DM/kg N applied, and the response was increased by the addition of lime or MO. Ryegrass content increased in the sward and the low-fertility-tolerant grass species content decreased. MO application increased the white clover content in the sward and subsequently resulted in the increase in herbage mass accumulation by 0.4% to 32%. The effect of MO application was larger than that of liming but less than that of N alone application. Liming increased soil pH by 0.24-0.3 pH units per 2000 kg lime applied and soil moisture was increased from 2% to 26% over spring/summer, and the potential mineral nitrogen was increased by 94% in November. These resulted in the increase in herbage mass accumulation from 4.4% to 15%. These results indicate that MO and lime applications would be beneficial on these hill soils. Keywords: herbage mass accumulation, hill country, lime, molybdenum, nitrogen, Trifolium repens

Response to re-application of phosphate fertilisers on hill pasture where fertiliser had been withheld for seven years

A field experiment at the AgResearch Te Kuiti Research Area examined effects of re-application of phosphorus (P) fertilisers on production and composition of hill pastures (1520% slope) which had received no P for 7 years. Treatments were 0, 20, 40 and 80 kg P/ha/year as single superphosphate (SSP) or North Carolina reactive phosphate rock (RPR). The soil was a yellowbrown earth/yellow-brown loam intergrade with Olsen P 9. Re-application of P produced a rapid and large increase in pasture production of up to 42 and 61% in years 1 and 2, respectively, and brought production up to 95% of that measured in neighbouring regularly fertilised paddocks. The pasture response to RPR was less (PcO.01) than that to SSP in both years, particularly at the highest rate. This indicated that RPR was less suitable for capital application. The P response was due almost entirely to an increase in white clover growth, and N, fixation was estimated to increase from 30 to 130 kg N/ha/year. In year 2, there was an increase in ryegrass content of pasture receiving the high P rate and this was attributed to increased nitrogen availability due to increased N, fixation. Keywords: hill country, phosphorus, reactive phosphate rock, superphosphate

Effects of cultivar introduction and fertiliser on characteristics of white clover (Trifolium repensL.) plants and populations in a hill pasture

Abstract Pastures based on the white clover cultivars Grasslands Tahora and Grasslands Huia were established by oversowing into unimproved hill country at Ballantrae in May–June 1986. Each pasture type occupied 2.2 ha, and a further 2.2 ha of unamended pasture containing the resident clover ecotype was also included. From August 1988, four fertiliser treatments (control, receiving no fertiliser; reactive phosphate rock; partially acidulated phosphate rock; and a superphosphate/phosphate rock blend, the latter three applied at 35 kg P/ha per year) were superimposed upon pasture types. Emphasis was placed on identifying the population and plant characteristics which responded to treatment, and defining the relative benefits to pasture performance resulting from the two approaches to pasture improvement (cultivars versus fertiliser). Based on measurements of the frequency of occurrence of cyanogenic plants in populations nearly 4 years after sowing, 58% of white clover plants in the Tahora-sown pastures and ...

Effects of pre-sowing herbicide and subsequent sward mass on survival, development, and production of autumn oversown Wana cocksfoot and Tahora white clover seedlings

Abstract Although oversowing new grass and legume cultivars offers potential for development of hill country, the success of this technique is variable. The objective of this experiment was to assess the effect of pre-sowing herbicide and subsequent grazing management on autumn oversowing into dense, hill country pastures. Three herbicide treatments (paraquat, glyphosate, and unsprayed) and four spring grazing treatments (average cover of 500,1000,2000, and 3000 kg DM/ ha) were compared. In general, ‘Grasslands Wana’ cocksfoot (Dactylis glomerata L.) and ‘Grasslands Tahora’ white clover (Trifolium repens L.) seedlings were more numerous (490 Wana /m2 and 90 Tahora /m2 versus 35 Wana/m2 and 40 Tahora /m2), larger (6–12 tillers or stolons/plant versus 1 tiller or stolon/plant), and more productive in herbicidetreated than unsprayed swards. Lax grazing ( about 3000 kg DM/ha) did not influence the survival of seedlings during spring, but resulted in smaller cocksfoot and clover seedlings. Rapid growth of these seedlings occurred after uniform grazing (release from competition) and resulted in few subsequent differences in plant size and contribution of Wana to pasture production. Once established, Wana and Tahora seedlings were tolerant of a range of grazing conditions, but with the high fertiliser input in this trial, did not appear to benefit annual production.

Influence of sheep rxcreta on pasture uptake and leaching losses of sulfur, nitrogen and potassium from grazed pastures

In situ mini-lysimeters with ion exchange resin traps were used to measure the effect of dung and urine return on pasture growth and pasture uptake and leaching losses of sulfur (S), nitrogen (N) and potassium (K) in hill pastures grazed by sheep.Single dung or urine events in winter boosted pasture production by 37% and pasture uptake of S, N and K by up to 35%, 55% and 57%, respectively, during the following year. Whereas the late summer single superphosphate application increased late spring and mid summer pasture growth of the following year only, dung or urine return increased pasture growth in every season of the following year. Despite the addition of 11.5, 4.7 and 376 kg of readily available S, N and K ha-1 in a single dung event and 14.5, 28.5 and 146 kg of S, N and K ha-1 in a urine event, accelerated leaching of S, N and K did not occur from dung or urine affected soil. Less than 3 kg S, 0.5 kg N and 2 kg K ha-1 were lost by leaching from dung or urine affected soil. The majority of S, N and K from excreta remained in the soil, either immobilized in soil organic matter and/or adsorbed on to soil sesquioxide surfaces and cation exchange sites with the equivalent of only 1.6% of S, 4.4% of N and 9.0% of K from dung and 29% of S, 18.7% of N and 31% of K from urine being recovered in increased pasture uptake over a period of one year. Under the climatic conditions that prevailed after the winter deposition of excreta, immediate loss of excreta-derived nutrients was negligible but urine deposition markedly accelerated the leaching losses of native soil calcium and magnesium (8 kg Ca and 2.9 kg Mg ha-1 from urine and 6.4 kg Ca and 2.4 kg Mg from dung, respectively). Quantitative information of this kind is important for determining the long-term sustainability of soil fertility in grazed pastures before a comprehensive understanding of pasture nutrient cycles is complete.

Pasture legume establishment from oversowing in drought-prone hill country

Plant and environmental factors that affect pasture legume establishment from oversowing were examined in a series of experiments at Poukawa Research Station near Hastings. A combination of 2 sowing seasons and 2 soil conditions gave cool/ dry, cool/wet, warm/dry and warm/wet. The rainfall in the trial year (1992) was 933 mm compared with the mean of 771 mm. Eleven species (5 annual and 6 perennial legumes) from Lotus, Medicago and Tr$olium genera were used. Establishment was poor, less than 10% of total herbage yield (6 and 8 months after oversowing for the cool and warm seasons, respectively) being contributed by any of the legume species. The major cause of poor establishment was poor germination. Eighty percent of sown seed failed to produce a seedling. Although germination was worse under cool (8°C) conditions, particularly for subterranean clover, the major cause of poor germination was not identified. The usefulness of new legume species in dryland hill pastures will depend on the species being suited to establishment from oversowing and a better definition of the factors that affect successful oversowing. Keywords: drought, herbage yield, hill country, Lotus, Medicago, moisture, oversowing, pasture establishment, plant density, temperature, Trifolium

The effect of the diet on the digestive organ size of reindeer

The development of the digestive tract of ruminants is known to depend closely on the pysical form of the diet, but the evolution of the digestive tract in the reindeer calf has been poorly studied. The absolute and relative sizes of the stomachs of a young ruminant can be markedly affected by the amount and nature of the solid food eaten, and this effect is independent of the age and weight of the animal (Hodgson, 1971). Also the caecocolic volume can be adjusted like that of the rumen in response to variations in food quality and availability (Hofmann, 1984). Our objective was to determine the development of digestive tract in reindeer calves maintained on natural pasture or fed with concentrates until six months of age. The digestive tracts of 49 reindeer calves were examined at slaughter in December 1988. Altogether 37 calves were grazing on mountain hill pasture from birth until the slaughter (6 months). Six calves grazed on mountain hill range from birth until 3.5 months of age and 2.5 months prior the slaughter they were maintained on an ad libitum diet of concentrates (partly concentrate fed reindeer). Six calves were fed concentrates ad libitum without access to pasture from birth until the slaughter (6 months) (all concentrate fed reindeer). A l l calves followed their mothers during the experiment. The concentrate ration was based on rapeseed meal (25% of fresh weight), cereals (21%) and grass meal (25%). The concentrates contained 20.7% crude protein and 13.9% crude fibre in the dry matter. The reindeer were weighed to the nearest 0.5 kg with a spring scale before the slaughter. After killing the digestive organs were removed, each section of the alimentary tract was separated and weighed to the nearest 0.5 g with contents. After emptying and cleaning the organ tissues carefully the empty tissue weight of each digestive organ was determined. The small intestines and colons were weighed with contents. The natural summer food of reindeer contains about 15% crude protein and 22% crude fibre in dry matter (Nieminen and Heiskari, 1989). Because of more nutritious food and better feed availability the all concentrate fed reindeer gained more body weight during summer and autumn and were significantly (P< 0.001) heavier than the freely grazing and the partly concentrate fed reindeer at slaughter. The absolute weights of the digestive organs with contents, except small intestine and caecum, were also heavier in the all concentrate fed reindeer, but only the reticulo-rumen and abomasum were significantly heavier (Table 1). In spite of

Effects of Fluidized Bed Combustion Residue on the Health and Performance of Sheep Grazing Hill Pastures

AbstractThe effect of application of fluidized bed combustion residue (FBCR), a product resulting from the removal of S from high‐S coals, was compared with application of dolomitic limestone, or no treatment, on the performance of ewes (Ovis aries) grazing hill pastures over a 3‐yr period. Pastures were treated with FBCR and limestone twice per annum and ewes with their lambs grazed at two stocking rates from late April to October. Herbage analysis showed increases in Ca concentration in FBCR and lime‐treated pasture vs. control, a higher level of S in FBCR vs. lime‐treated herbage, but no differences in microelement concentrations due to treatment. There were no differences in weight gains of either ewes or lambs within years due to treatment, and no effect of treatment on blood hematocrit levels. Ewes were killed before and after the 3‐yr trials, and lambs were sacrificed before and after each grazing season, to determine the effect of FBCR application on mineral accumulation in the carcass or organs of the animals. There were either no differences or small differences in the concentrations of macro‐ and microelements in the carcass, liver, and kidney of ewes and lambs associated with treatment, and tissue concentrations of elements were within normal ranges. The results confirm studies with rats (Rattus rattus), hamsters (Mesocricetus auratus), and pigs (Sus scrofa) showing that treatment of agricultural soils with high levels of FBCR as a liming or fertilizing agent causes no adverse effects on composition of food crops or herbage, or on the health and productivity of animals consuming diets produced on such soils.