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Articles 211 - 240 of 2248
Full-Text Articles in Agronomy and Crop Sciences
Direct Drilling Forage Maize Into Dairy Pastures In South-Eastern Australia, K E. Pritchard
Direct Drilling Forage Maize Into Dairy Pastures In South-Eastern Australia, K E. Pritchard
IGC Proceedings (1977-2023)
Forage maize (Zea mays) was planted directly into uncultivated dairy pastures after desiccation. A planter specially developed for this purpose, which used coulters, tynes and narrow rotary hoes to place fertiliser and seed precisely, achieved excellent crop establishment in dense redbrown earth soils. Yields were up to 22.7 t of dry matter/ha, similar to that of cultivated seedbeds with flood irrigation and 10% less than with furrow irrigation. Key agronomic requirements for success were a specialised planter, good surface drainage, adequate pre- and postplanting weed control and a requirement for early application of irrigation water and nitrogen fertiliser. …
Breeding To Reduce Susceptibility To Bloat In Dairy Cattle, C A. Morris, R J. Wilkins
Breeding To Reduce Susceptibility To Bloat In Dairy Cattle, C A. Morris, R J. Wilkins
IGC Proceedings (1977-2023)
An experiment with Friesian x Jersey cross cattle was established in 1972 at Ruakura, in order to select in 2 closed herds for high (HS) or low (LS) susceptibility to pasture bloat. By the 1990 calf crop, there was a difference in adjusted bloat score between herds of 0.94 units (1.93 genetic standard deviations). The repeatability and heritability of a single bloat score were 0.13+0.02, and 0.12+0.06, with a heritability of 0.52+0.22 for mean bloat score. Annual death rates from bloat have averaged 2.6% in the HS herd and 0.8% in the LS herd (0% in the LS herd for …
Mixed Herb Ley No Advantage Over Ryegrass-White Clover Pasture For Early Lamb Growth, I Popay, W Stiefel
Mixed Herb Ley No Advantage Over Ryegrass-White Clover Pasture For Early Lamb Growth, I Popay, W Stiefel
IGC Proceedings (1977-2023)
The performance of lambs at 2 stocking rates, on either ryegrasswhite clover (Lolium perenne- Trifolium repens) pasture or on a mixed herb ley, were compared under a system which precluded use of pesticides (including drenches) and highly soluble fertilisers. The mixed herb ley included 8 grasses, 5 legumes and 3 herbs: chicory (Cichorium lntybus), sheep's burnet (Sangulsorba minor ssp. muricata) and narrow-leaved plantain (Plantago lanceolata). In the first grazing cycle, there were no significant differences in lamb growth rates, nor in faecal egg counts, between the two pasture types, although in the …
Use Of Italian Ryegrass To Increase Feed Production From Dairy Pastures In Northern New Zealand, E R. Thom, R A. Prestidge
Use Of Italian Ryegrass To Increase Feed Production From Dairy Pastures In Northern New Zealand, E R. Thom, R A. Prestidge
IGC Proceedings (1977-2023)
The effect on pasture production In late winter-early spring was examined by direct drilling Italian ryegrass (Lolilum multiflorum Lam. cv, Concord) into plots previously sprayed with glyphosate or undersowing into existing pasture in autumn 1989 and 1990. Nitrogen fertiliser (25 kg N/ha) was applied to half the area of each plot on 3 occasions during winter. Concord ryegrass was also direct drilled after spraying wilh glyphosate in late summer (February) and autumn (March) in a third experiment in 1991. All plots were rotationally grazed by cows. On average for late winter-early spring 1989 and 1990, direct-drilled and undersown plots …
Effect Of A Reduction In Concentrate Price On Feed Costs And Its Implication For Grass Silage In The Diet Of Lactating Dairy Cows, S Fitzgerald
IGC Proceedings (1977-2023)
The proposed reduction in the price of cereals (29%) under the EC price reform proposals for agricultural produce will have n large effect on feed costs and on the balance between grass silage and concentrates in the diet of lactating dairy cows while indoors. The effect of n reduction in the price of dairy concentrates with varying silage production costs on the daily feed costs for a 525 kg cow yielding 25 kg milk/day in early lactation, while losing 0.5 kg/day body weight, was calculated when given a mixed diet of grass silage and concentrates to provide an MB intake …
Development Of A Genotype For Out-Of-Season Lambing, J F. Smith, D L. Johnson, T C. Reid
Development Of A Genotype For Out-Of-Season Lambing, J F. Smith, D L. Johnson, T C. Reid
IGC Proceedings (1977-2023)
A flock derived from Polled Dorset x Romney sheep has been selected for advanced lambing date for 20 years. After 15 years over 90% of selected ewes displayed the ability to lamb in autumn, Genetic parameters have been analysed and high heritability (0.23) and repeatability (0.36) estimated. Current research is aimed at selection of divergent flocks based on use of breeding values for date of lambing and the elucidation of what has altered in the physiological and endocrinological mechanisms controlling the onset of breeding season and also the identification of early indicator traits in the male and female progeny, Preliminary …
United States Forage Exports To Japan And Korea, William P. Ford
United States Forage Exports To Japan And Korea, William P. Ford
IGC Proceedings (1977-2023)
Bxports are becoming an important market for the western USA forage producer. Forage products exported are: lucerne hay and cubes, timothy hay, oat hay, sudangrass hay, and perennial ryegrass and Kentucky bluegrass straw, Demand for forage products from Japan is now playing an increasing role on West Coast markets. In 1991, Japan Imported 720 214 t of lucerne hay cubes, The USA supplies approximately 77% of these lucerne cubes and Canada about 21 %, Baled hay imports for Japan totalled 1 038 297 t in 1991. 87% of these hay products came from the USA. Total hay and cube imports …
Intensive Lucerne Production In Washington, William P. Ford, Dayid W. Evans
Intensive Lucerne Production In Washington, William P. Ford, Dayid W. Evans
IGC Proceedings (1977-2023)
Hay is the sixth valuable agricultural commoditing in the state of Washington in the USA. Lucerne (Medicago sativa L.) was grown on 190350 ha and represents 74% of all hay, 36% of the state's lucerne acreage and 48% of its production was found in two counties. Three to 5 harvests per year can be made in Central Washington. Lucerne farms under intensive management can yield as much as 22.4 Mg of 12% moisture hay/ha. A balance between stand maintenance, high yields and good quality hay can be obtained by cutting lucerne at the bud stage of growth. In 1991, over …
Use Of Irrigated Lucerne At Different Growth Stages Ii. Utilization For Milk Production, Ernesto John, Agustin Vidal, Fernando Baez, Patricio Soto
Use Of Irrigated Lucerne At Different Growth Stages Ii. Utilization For Milk Production, Ernesto John, Agustin Vidal, Fernando Baez, Patricio Soto
IGC Proceedings (1977-2023)
Lactating cows were assigned in a random block design to 6 treatments in a 3x2 factorial arrangement: 3 growth stages pre-bud (PB), 10% flower ( I OPP) and 50% flower (50PF), leaving 2 post-grazing residuals, high (HR) and low (LR).· Treatments were evaluated in 2 seasons, November-January (Sl) and January-March (S2). Forty-eight cows were used in each of the two seasons. During Sl milk production per cow (kg/day) was 20.0, 18,9 and 17.2 for PB, IOPF and 50PF for low residuals and 19.5; 19.8 and 20.3 for high residuals, respectively. For S2 milk production was lower but followed similar trends. …
Role Of Pasture Composition And Grazing Management In Affecting The Incidence Of Bloat On Farms, V R. Carruthers, G J. Brier, H V. Henderson, J.A S. Lancaster, D A. Mccallum
Role Of Pasture Composition And Grazing Management In Affecting The Incidence Of Bloat On Farms, V R. Carruthers, G J. Brier, H V. Henderson, J.A S. Lancaster, D A. Mccallum
IGC Proceedings (1977-2023)
Farm operations, pasture composition and pre- and post-grazing association with herbage mass were monitored from May 1990 to November 1991 on 16 pairs of dairy farms. Each pair included one farm with a history of bloat despite routine use of chemical preventatives (bloat-prone) and one farm which did not routinely use chemicals to prevent bloat rarely observed bloat (bloat-free). The incidence of bloat during spring was low in both years. From August to November bloat-free farms had less ryegrass (Lolium) (58%, v. 66%) and more other grass species (25% v. 17%) in pasture, and higher pre- and post-grazing …
Digestion And Rumen Metabolism Of Forages By Red Deer, Goats And Sheep, T N. Barry, B M.F Dominngue, D O. Freudenberger
Digestion And Rumen Metabolism Of Forages By Red Deer, Goats And Sheep, T N. Barry, B M.F Dominngue, D O. Freudenberger
IGC Proceedings (1977-2023)
Digestive efficiency was compared in Red deer, goats and sheep fed chaffed lucerne hay (Experiment 1), Goats digested fibre more efficiently than sheep and had the greatest rate of rumen ammonia production, Red deer showed the capacity to increase VFI from winter (W) to summer (S) without depressing apparent digestibility, through slowing the rate of rumen particulate outflow. Fractional outflow rate (FOR) of water from the rumen and the ratio FOR water/ FOR particulate matter were both considerably greater for deer than for sheep and goats. It was concluded that this would enable deer to digest soluble ration components more …
Development Of Specialist Forage Systems For Deer Production, T N. Barry, J H. Niezen, G Semiadi, J Hodgson, P R. Wilson, A M. Ataja
Development Of Specialist Forage Systems For Deer Production, T N. Barry, J H. Niezen, G Semiadi, J Hodgson, P R. Wilson, A M. Ataja
IGC Proceedings (1977-2023)
Red clover (RC) (Trlfolium pratense L.) and chicory (C) (Cichorium intybus L.) were evaluated in 3 experiments as alternative forages to perennial ryegrass (Lolium perenne L.) (0.85)-white clover (Trifolium repens L.) (0.15) pasture (PRG) for deer production. During lactation (summer), fawns grazed with their hinds on RC grew faster (410-433 g/day) than their contemporaries reared on PRO (322/g/day). Fawns reared on C during lactation were intermediate, From weaning to 12 months of age, young deer were consistently heavier when grazing RC than PRG, with the advantage at 12 months being 7 kg for stags and 3 …
Influence Of Renovation Of Old Fescue Pasture On Beef Production, J A. Josifovich
Influence Of Renovation Of Old Fescue Pasture On Beef Production, J A. Josifovich
IGC Proceedings (1977-2023)
The influence of renovation by interseeding of a 30-year-old fescue (Festuca arundinacea Schreb.) pasture, naturally invaded with dallisgrass (Paspalum dilatatum Poir.), was evaluated during 3 years at the Pergamino Experiment Station. The renovation was done by minimum tillage equipment using a spring-toothed cultivator, The mixture sown was brome (Bromus 1mioloides H.B.K.) cv. Martfn Fierro MAG, chicory (Cichoriumorium intybus L.) cv. San Pedro INTA, red clover (Trifolium pratense L.) cv. El Surefto INTA, white clover (Trifolium repens L,) cv. El Lucero MAG, and Persian clover (Trifolium resupinatum L.) cv. La yapalNTA. There were 2 treatments: …
Some Effects Of Sole Pasture Diets On Reproductive Performance Of Lactating Cows In Seasonal Dairy Herds, K L. Macmillan, S Mcdougall
Some Effects Of Sole Pasture Diets On Reproductive Performance Of Lactating Cows In Seasonal Dairy Herds, K L. Macmillan, S Mcdougall
IGC Proceedings (1977-2023)
The reproductive performance of 631 dairy cows in 5 herds which had a single concentrated calving programme in late winter was monitored through the post-partum period and the breeding programme. The cows in ench herd were of high genetic merit and received a sole ration of pasture grazed in situ. Anoestrous animals which had failed to ovulate since calving were identified before the start of the breeding programme. The average post-partum interval to first oestrus was 48.5 days, but ranged from 35.7 to 58,5 days in individual herds. It was 86.6 days in the anoestrous cows which represented 18.7% of …
Maximizing Red Deer Venison Production Through High Quality Pasture, W F. Hunt
Maximizing Red Deer Venison Production Through High Quality Pasture, W F. Hunt
IGC Proceedings (1977-2023)
A novel pasture system emphasizing pasture quality was tested for the ability to finish young Red deer stock at 11-12 months. This enables 1 year's crop of fawns to be sold before the next arrives, and hence overcomes carrying capacity problems. The species tested had previously been identified as of high quality and being highly preferred by red deer. Grasslands Colenso red clover (Trifolium pratense L,) or Grasslands Puna chicory (Chichorium intybus) were tested for supplying high quality summer forage during the lactation phase. Grasslands Tama weslerwolds ryegrass (Lolium multiflorum Lam.) provided high quality post-weaning forage during …
Berseem Clover: A New Forage For Dairying In Mexico, Hector M. Quiroga-Garza, Jose S. Cueto-Wong, Julio Jimenez-Aceves
Berseem Clover: A New Forage For Dairying In Mexico, Hector M. Quiroga-Garza, Jose S. Cueto-Wong, Julio Jimenez-Aceves
IGC Proceedings (1977-2023)
The Comarca Lagunaera is the most important dairying region in Mexico. It is located in the semi-arid north central zone (26°N, 103°W): altitude 1100 m as!, mean annual rainfall of 220 mm, mild winters with some frosts (-4 to -6°C). The winter forages used are Italian ryegrasses and oats. Since I 985, a new forage crop, berseem clover (Trifolium alexandrinum), has been studied. Berseem clover is an annual winter legume with a high nitrogen {N) fixation capacity and yield of high quality forage. During 2 consecutive years in field experiments comparing pure stands of berseem and ryegrass ( …
Alpaca Fibre Production, Fibre Growth Seasonality And Fibre Characteristics Variation In A Cool-Temperate Environment Of New Zealand, Tumen Wuliji
IGC Proceedings (1977-2023)
Live weight, fleece weight and fibre diameter of alpacas imported from South America were recorded. Seasonal fibre growth rate was estimated by a defined mid-side patch clipping. Fleece weights were 2.27 kg and 2.21 kg for Tara Hills and i.owburn properties, respectively, markedly higher than that of South American alpacas. Fibre diameter was coarsened by 4.6 µm (P<0.01) in 1990 and a further 1.2 µm (P<0.05) in the 1991 shearing for adult herds compared with the first test at importation, The fibre growth rate estimated by mid-side patch sampling coincided with seasonal changes, being highest in summer and declining in the order of autumn, winter and spring (0.45, 0.42, 0.41 and 0.35 mg/day/cm 1, respectively). Similarly, the diameter of fibre on the mid-side patch was affected but to a lesser extent. The fibre growth rate and fibre diameter was lowest in the period late winter/early spring. Males grew significantly more (42-59%) and coarser fibres (0.8-2. l 11m) than females.
Experience With Grazing Geese On Pasture, G Nacy, S Mihok
Experience With Grazing Geese On Pasture, G Nacy, S Mihok
IGC Proceedings (1977-2023)
Under large field and model experimental conditions large flocks of geese were grazed. Rotational grazing was utilised in order to avoid sward damage by overgrazing and environmental pollution by too much goose droppings on the grazed area. Observations included grazing habits of geese, selection of grasses and herbs by geese, rotational grazing and use of electric fences, effect of goose droppings on grass and the necessity of grain supplementation for meat geese grazed on pasture. Our experiences show that the geese grazed deeper into the sward canopy than any other grazing domestic animal in Hungary. The geese did not select …
Opportunities And Constraints For Production Of Marketable Products From Temperate Grassland Systems With Minimal Financial Inputs, Pedro O. Gomez, Ernesto John
Opportunities And Constraints For Production Of Marketable Products From Temperate Grassland Systems With Minimal Financial Inputs, Pedro O. Gomez, Ernesto John
IGC Proceedings (1977-2023)
Grassland and fodder crops in temperate areas of the world are the main feed resources for milk and beef production. In general, grassland systems in industrialised countries have high financial inputs. The systems in which financial inputs are minimal are those that produce mainly under all-year grazing, with minimal or no inputs such as supplementary feeding, herbicides, insecticides, fungicides, fertilisers, antibiotics, and growth promoters; in general they are located in temperate zones of non-industrialised countries. For this reason the products obtained from these systems (e.g., meat, milk) have at present a good opportunity in international markets where the demand for …
Trends In Intensive Temperate Grassland Systems, J D. Leaver, F Weissbach
Trends In Intensive Temperate Grassland Systems, J D. Leaver, F Weissbach
IGC Proceedings (1977-2023)
Intensification of grassland in temperate zones has been successful in substantially increasing output of animal products per unit area of land. This trend is unlikely to continue, however, where intensification has been supported by large subsidies, as in EC countries. The high costs of both subsidising the production systems and the export of surplus products is not sustainable. The distortion in world trade caused by such policies combined with concerns over the environmental implications of intensification has already led to CAP reforms in Europe to de-intensify ruminant. livestock systems. Liberalisation of world trade through GA TT could lend to further …
Studies On Soil Biochemical Activities Of Sub-Coryphile Meadow In Qing-Tibet Plateau, Liu Shigui, Long Zhangfu, Zeng Ying, Wu Yong
Studies On Soil Biochemical Activities Of Sub-Coryphile Meadow In Qing-Tibet Plateau, Liu Shigui, Long Zhangfu, Zeng Ying, Wu Yong
IGC Proceedings (1977-2023)
The micro-organism activities and enzymatic activities were studied in the soil of 3 degenerative grasslands (Kobresia pygmaea meadow, Festuca sinensis meadow and Dasiphora fruticosa shrub) near Ruoergai Grassland Station in Sichuan, China, Main results show that soil biochemical activities have been decreasing as the grassland degenerates, especially cellulose decomposition, nitrogen fixation, phenol decomposition, protease, cellulase and sucrase.
The New Zealand Fertilizer Industry- A Vital Cog In The Pasture Production Cycle, M J. Hickey, T Johnston
The New Zealand Fertilizer Industry- A Vital Cog In The Pasture Production Cycle, M J. Hickey, T Johnston
IGC Proceedings (1977-2023)
The New Zealand fertiliser industry is geared mainly to meet domestic demand, The main fertiliser applied is single superphosphate supplying both sulphur and phosphorus, These elements are required on most New Zealand soils. White clover (Trifolium repens L.) provides most of the nitrogen requirements by symbiotic production. Fertiliser applications are currently 1.S-1.6 million t, of which 9091, is used for livestock production, supporting SB million sheep, 4.6 million beef cattle and 3.S million dairy stock. Fertiliser sales peaked at 2.S million t in 1979 and have fallen as economic conditions deteriorated in the 1980s, coupled with removal of all …
Behavior Of Goats And Sheep On An Eroded Hill Country Pasture In Winter, L A. Greaves, M E. Wedderburn
Behavior Of Goats And Sheep On An Eroded Hill Country Pasture In Winter, L A. Greaves, M E. Wedderburn
IGC Proceedings (1977-2023)
The behaviour of cashmere-producing does was compared with that of Romney ewes on an area of surface erosion in pasture-dominated hill country during winter. Five ewes and 5 does were monitored. Each group was observed for 4 days, during June-July, from dawn to dusk. A fixed, remote video camera was used to record the animals' behaviour. Tapes were later analysed, noting animal activity, position and time. Bwes spent 13% of their day on the eroded surfaces compared to 2% for the does, Does were observed on the erosion mainly in the afternoon, whereas the ewes were present at all stages …
Effects Of Lime And Phosphate Applications On Growth And Nitrogen Fixation Of Alfalfa In Acid Soils, Chun Woo-Bock, Ki-Chun Choi, Jung-Chul Kim, Kwang-Hyun Kim, Dong-Hoo Kim
Effects Of Lime And Phosphate Applications On Growth And Nitrogen Fixation Of Alfalfa In Acid Soils, Chun Woo-Bock, Ki-Chun Choi, Jung-Chul Kim, Kwang-Hyun Kim, Dong-Hoo Kim
IGC Proceedings (1977-2023)
The effects of applications of various levels of lime (0, 250, 500 and 1000 kg/10 a) and phosphate (0, 17, and 34 kg/10 a) on growth and on nitrogen fixation of alfalfa (Medicago sativa L.) were studied. Effects of lime and phosphate applications were significantly different on dry mailer (DM) weight of each part and on acetylene reduction activity (ARA) of alfalfa al 9 weeks after sowing (P<0.05). The effect of lime on DM of shoot and root was not significantly different at 14 weeks after sowing (early bloom) but that of phosphate was significantly greater as levels increased (P<0.0 1). The effects of lime and phosphate on ARA were significantly increased (P<0.05), Nine weeks after sowing, application of lime and phosphate decreased total N content of each part of alfalfa compared with no application (P<0,05). At 14 weeks after sowing lime application increased total N content and phosphate decreased total N content, compared with not application (P<0.05).
Effects Of Subsoiling On A Northern Podzol Soil, M A. Richardson, C R. Edwards
Effects Of Subsoiling On A Northern Podzol Soil, M A. Richardson, C R. Edwards
IGC Proceedings (1977-2023)
Subsoiling is a method of mechanical loosening that can improve water movement through soil. It has been evaluated on a poorly drained northern podzol soil in paddock scale trials over three years. Subsoiling with a tractor drawn implement at 500 mm depth resulted in consistent reductions in surface water contents and lowered water tables. Pasture production was significantly increased in two of the three years and favourable pasture composition changes occurred, Root distribution in winter was also affected, with significant increases in root density between· JOO and 300 mm depth. Recompaction occurred during winter grazing and paddocks required re-subsoiling each …
Predicting The Leaching Of Sulphur Fertilizer On Yellow-Brown Pumice Soils, B S. Thorrold, K C. Cameron
Predicting The Leaching Of Sulphur Fertilizer On Yellow-Brown Pumice Soils, B S. Thorrold, K C. Cameron
IGC Proceedings (1977-2023)
Leaching of sulphate can have a major influence on pasture yield and fertiliser efficiency on the yellow-brown pumice soils of New Zealand. This study aimed to measure and predict sulphur (S) leaching on these soils. The Rose model (an approximate analytical method based on the convective-dispersive equation) accurately simulated S leaching data from intact cores when a retardation factor was included to allow for sulphate adsorption, The model was then used to predict the leaching of sulphate or elemental S fertilisers applied in spring or autumn. Predicted amounts leached below 260 mm depth after 12 months were 91, 71, 38 …
Quantification Of Oxidation Of Elemental Sulphur In Pastoral Soils Of New Zealand, A Ghani, A Lee, J H. Watkinson, C Boswell, B S. Thorrold, J D. Moryon, M P. Upsdell
Quantification Of Oxidation Of Elemental Sulphur In Pastoral Soils Of New Zealand, A Ghani, A Lee, J H. Watkinson, C Boswell, B S. Thorrold, J D. Moryon, M P. Upsdell
IGC Proceedings (1977-2023)
A cubic model to describe elemental sulphur (S) oxidation as proposed by Watkinson (1989) was tested under field conditions. Trials were conducted throughout New Zealand to examine the effects of climate, particle size and frequency of application on the rate of S oxidation. Elemental S (75-1S0 mm size) was added to duplicate plots at a rate of 30 kg/ha. Soil samples (0-38 mm) were collected regularly for determining the amounts of added elemental S remaining in the soil. The results showed that the oxidation of elemental S could be adequately described by the cubic model, Por most sites it explained …
Effectiveness Of Sulphate And Elemental Sulphur Fertilizers Applied To Pastures In Autumn Or Spring, S F. Ledgard, B S. Thorrold, M S. Sprosen, M F. Hawke
Effectiveness Of Sulphate And Elemental Sulphur Fertilizers Applied To Pastures In Autumn Or Spring, S F. Ledgard, B S. Thorrold, M S. Sprosen, M F. Hawke
IGC Proceedings (1977-2023)
Uptake of elemental sulphur {S, 50% 75-150 µm and 50% 150-250 µm diameter) or sulphate (applied as gypsum) by pasture in the field was examined using 3 rates of application in autumn or spring on 2 low Sretentive soils; u free-draining pumice soil and a slow-draining gley soil. About 90% of the el��mental S was oxidised to plant-available sulphate during I year after application. On the pumice soil, the apparent recovery of added S was greatest from autumn-applied elemental S. Leaching appeared to reduce the effectiveness of sulphate fertiliser. On the gley soil, sulphate was more effective in enhancing pasture …
Lysimeter Study Of The Fate Of Nitrogen In Animal Urine Applied To Flood-Irrigated Pasture, K C. Cameron, P M. Fraser
Lysimeter Study Of The Fate Of Nitrogen In Animal Urine Applied To Flood-Irrigated Pasture, K C. Cameron, P M. Fraser
IGC Proceedings (1977-2023)
The fate of nitrogen (N) in animal urine returns to flood irrigated pasture was studied using large soil monolith lysimeters (800 nun diameter x 1200 mm deep). Over a period of I year, the largest fraction of applied 15N (44%) was recovered by the pasture plants. The total amount (42 kg N/ha) and average peak concentration of N, in the leachate (42 µgN/ml) were less than values reported for many: other agricultural situations (e.g., ploughed pasture). The amount of N lost by denitrification was high (28% of applied 15N) and attributed to the wet soil conditions which prevailed. The amount …
Estimating Fertilizer Substitution Values From The Dissolution Rates Of Reactive Phosphate Rocks In New Zealand Pastoral Soils, J H. Watkinson, K W. Perrott
Estimating Fertilizer Substitution Values From The Dissolution Rates Of Reactive Phosphate Rocks In New Zealand Pastoral Soils, J H. Watkinson, K W. Perrott
IGC Proceedings (1977-2023)
A relationship is developed between the substitution value of reactive phosphate rock (RPR) relative to triple superphosphate (TSP), both applied annually to pasture, and the dissolution rate of the RPR. The residual effect of dissolved phosphate is included. Residual RPR is calculated from the dissolution rate of the RPR in the soil, while residual phosphate from TSP or dissolved RPR is taken as a constant fraction of the value in the previous year. Calculations including the residual effect of dissolved fertiliser produce smaller substitution values and longer lag times for RPR than when the effect is omitted. The relationship derived …