Physical Sciences and Mathematics Commons^™

Constraints To Production Of Annual Medic (Medicago Spp.) Pastures In Southern Australia, M D. Denton, W D. Bellotti, C R. Hill, S P. Taylor

IGC Proceedings (1997-2023)

A field experiment was used to determine the effects of the root lesion nematode (Pratylenchus neglectus) and phospate and zinc nutrition on the production of annual medic pastures. Elimination of nematodes (nematicide increased shoot and seed production significantly and zinc and nematicide in combination significantly reduced numbers of nematodes present in roots.

Changes In Soil Fertility And Plant Nutrient Contents In Degraded Tropical Pasture After Renovation, M C. Macedo, V.P. B. Euclides

IGC Proceedings (1997-2023)

A grazing experiment was conducted on an Oxisol testing five degraded tropical grasses renovated with two levels of fertilizer with the objective to study seasonal changes in plant nutrient contents and soil fertility. Total dry matter availability, green and dead matter availabilities, nutrient concentration in leaf tissue and soil fertility were the parameters measured. Availability of forage and leaf nutrients was significantly dependent on seasonal changes with green matter on offer decreasing over years. Soil fertility increased after renovation and declined thereafter. Soil available-P decreased and it was related to sustainability of green matter on offer. Soil organic matter mineralization …

Brachiaria Brizantha Response To Phosphorus Rates In The Nutrient Solution, F A. Monteiro, R A. Martim, W T. Mattos

IGC Proceedings (1997-2023)

Seven phosphorus rates in the nutrient solution were studied in a greenhouse experiment for Brachiaria brizantha (Hochst) Stapf. Plants had 54 days of growth and 49 days of regrowth. Significant responses in forage yield, tiller number and root dry weight were found. Plant tops were divided into four parts and phosphorus concentration in each one significantly changed with phosphorus rates. Sampling of the young leaf blades and analyzing for phosphorus is proposed for diagnostic purposes. A critical phosphorus concentration of 1.2 g kg-1 is suggested as the critical level in the young leaf blades.

Effects Of Different Phosphate Fertilizers On Pasture Nutrition And Soil Phosphorus In Canterbury, New Zealand, L M. Condron, K M. Goh

IGC Proceedings (1997-2023)

A field trial was conducted over 6 years to assess the relative performance of three phosphate (P) fertilisers of differing solubility (single superphosphate, ‘longlife’ superphosphate, ‘reactive’ phosphate rock) on a permanent pasture at Methven in Canterbury, New Zealand. Plant P uptake data showed that while the overall relative effectiveness of the fertilisers was closely related to their water-soluble P content (single superphosphate > ‘longlife’ superphosphate > ‘reactive’ phosphate rock), the agronomic efficiency of the sparingly soluble phosphate rock fertiliser improved markedly with time. Soil P analysis demonstrated that significant dissolution of phosphate rock had occurred in the soil, and the findings of …

Increased Phosphorus Supply Enhances Water Uptake And Water Use Efficiency In White Clover Under Dry Conditions, D K. Singh, P.W. G. Sale

IGC Proceedings (1997-2023)

A glasshouse experiment was carried out to determine how increasing rates of P supply (0, 33, 100 and 300 kg P ha-1) influenced the water use efficiency of white clover grown in a P-deficient soil under dry conditions. Increasing the P supply enhanced both shoot dry matter yield and water use by the clover plants. The relatively greater dry matter response meant that water use efficiency also increased with added P. High rates of water extraction by these high-P clover plants resulted in a marked drying of soil. Despite these dry soil conditions there was no adverse effect on growth …

The Effect Of Fertiliser History On Nutrient Accumulation And Plant-Available Nutrient Supply In Legume-Based Pasture Soils, J L. Moir, M J. Hedley, A D. Mackay, R W. Tillman

IGC Proceedings (1997-2023)

Animal production in New Zealand is dependent on pastoral legumes to build soil nitrogen fertility, which otherwise limits the growth of the major sward component, grass. Traditionally, in order to sustain legume vigour, single superphosphate has been applied to elevate soil phosphorus and sulphur levels. Rarely have either the agronomic or nutrient efficiencies of these systems been assessed. Fourteen hill country pasture sites in three broad rainfall regimes were chosen to assess the effect of contrasting fertiliser histories on soil fertility, in particular nitrogen availability. At each site soil fertility indices and pasture production for the 1993/94 growing season were …

Long Term Effects Of Liming A Basalt-Derived Soil, On Lucerene And Phalaris Production, K.M. F. Reed, J F. Chin

IGC Proceedings (1997-2023)

Lime incorporated into a basalt-derived clay loam lowered exchangeable aluminium in soil. Soil pH was still elevated, 9 years after 2 t/ha of lime was incorporated. With lower rates of lime the density of lucerne plants declined. Lucerne yield more than doubled with lime. After six years, the area was sown to a phalaris-clover pasture. A 15% increase in the yield of phalaris was recorded from limed plots over the next three years. Despite this, 11 years after liming, herbage P concentrations increased with lime, from 0.28% to 0.35%.

Phosphorus Availability, Defoliation Tolerance, And Genetic Differentiation In White Clover, D F. Chapman

IGC Proceedings (1997-2023)

The genetic composition of mixed populations of white clover growing in low fertility, grass-dominant hill pastures was estimated four and eight years after populations were established. Populations were based on an adapted ('Grasslands Tahora') or poorly adapted ('Grasslands Huia') cultivar, and received either no fertiliser, or 35kg P /ha /year. The P response curve of surviving plants was also determined, and compared with plants grown from 'standard' seedlines of the respective cultivars. Between years 4 and 8, the proportion of the populations constituted by plants true-to-type for the sown cultivar remained steady at 56 - 58% for Tahora, but fell …

Phosphorus Use Efficiency For Biomass Production Of Legume Species, A T. Ayala Torales, V A. Deregibus, P R. Moauro

IGC Proceedings (1997-2023)

The objective of the experiment was to identify traits associated with the production of plant biomass, and hence with P utilization efficiency, when legume species were fertilized. Red clover (Trifolium pratense) and narrowleaf birdsfoot trefoil (Lotus tenuis) were compared in a greenhouse experiment using phosphorus deficient soils. Three plants grew in pots fertilized with 0, 2, 4, 8, 15, 20, 30 and 40 ppm in soil, in a randomized experimental design. Harvest was made at 60 days from the sowing date. Leaf areas, shoot and root biomass, and tissue phosphorus contents were measured. Results showed that …

Seasonality In The Response Of Perennial Grass-Clover Pastures To Phosphorus Fertiliser, A K. Metherell, A C. Mckenzie

IGC Proceedings (1997-2023)

Pasture dry matter yields from individual cuts of multi-year phosphorus (P) fertilizer field trials were analyzed for evidence of consistent seasonal trends in the response to P. The relative response to P was greatest in the late autumn - winter period, with the seasonal variation in relative yield being greater where soil fertility and mean annual relative yields were lowest.

Phosphorus Requirements In Legumes: Calibration Of A Rapid And Simple Tissue Test, A Moron

IGC Proceedings (1997-2023)

The objective of this research was to adjust and calibrate a phosphorus (P) tissue test to diagnose in a simple and rapid manner the nutritional status of commonly used legumes in Uruguay. Field experiments conducted during 1993-94 with four legumes, showed a significant yield response to increasing P fertilizer rates. A colorimetric sap analysis was used to determine P status in legumes. A strong relationship was found between P sap analysis and relative yields. A critical level of 90-100 μg P/ml in sap to attain 90% of the maximum yield was obtained.

Partitioning Of Phosphorus In White Clover Populations With Different Nodulation Patterns, J R. Crush

IGC Proceedings (1997-2023)

The objective of this study was to see if a white clover (Trifolium repens L.) population selected for development of relatively few, but large nodules, differed in the way it used absorbed phosphorus, compared to a white clover population selected for many small nodules. Plants of both populations were grown in minus-nitrogen sand culture and the dry weights and phosphorus contents of shoots, roots and nodules were measured. There were no differences in growth or partitioning of dry matter or phosphorus between the clover lines.

Research Programme To Improve The Utilization Of Home-Grown Forages In The Netherlands, A.M. Van Vuuren, A H. Bosma, G J. Kaspers, J.J. M.H. Ketelaars, E.N. Van Loo, H J.P. Marvin, H Valk, G.W.J. Van De Ven

IGC Proceedings (1997-2023)

In The Netherlands a research programme has been initiated by the Ministry of Agriculture, Nature Management and Fisheries to increase the proportion of high-quality home-grown forage in rations for dairy cows. This should result in a more sustainable dairy husbandry by improving the efficiency of utilization of nitrogen and phosphorus from home-grown forages (mainly grass and maize) on farm level. Research disciplines involved are plant breeding, forage harvesting and conservation and nutrition.

Maize-Alfalfa Intercropping Promote Ecosystem Services Than Fertilized Single Crops, D. X. Tao, Y. Z. Gao

IGC Proceedings (1997-2023)

Phosphorus is a non-renewable source of fertilization, which will challenge the future of food production and cropland sustainability worldwide. Crop diversity is known to promote food production, yet its capacity to alleviate the dependence of multiple ecosystem services on non-renewable fertilization remains virtually unknown. Here, we conducted a field experiment to quantify the contribution of maize-alfalfa intercropping to support multiple ecosystem services under contrasting levels of phosphorus fertilization. We showed that unfertilized intercropping systems can support larger levels of multiple ecosystem services such as soil microbial habitat, plant-soil mutualism, nutrient cycling, and soil carbon storage compared with phosphorus-fertilized single crops. …

Could Formononetin Of Red Clover (Trifolium Pratense L.) Be Enhanced By Phosphorus And Arbuscular Mycorrhizal Fungi Management?, Fernando Ortega-Klose, Andrés Quiroz, L. Bardehle, P. Aguilera

IGC Proceedings (1997-2023)

Red clover is a forage legume of importance in the world with limited persistency; in Chile this is due mainly to the root borer (Hylastinus obscurus Marsham) infestation. Our previous studies have shown that there is a strong relationship between the root borer and the formononetin content in roots of the plants; therefore, studying factors that enhance the concentration of formononetin in the plant could help to decrease the negative effect of the root borer. The purpose of this research was to assess the relationship between phosphorus availability (P) in the soil interacting with arbuscular mycorrhizal fungi (AMF) over …

Phosphorus Transfer To River Water From Grassland Catchments In Ireland, H. Tunney, P. Jordan, G. Kiely, R. Moles, G. Morgan, P. Byrne, W. Menary, K. Daly

IGC Proceedings (1997-2023)

In Ireland it is estimated that at least half of phosphorus (P) loss to water is from agricultural sources and National and European Union policy and legislation aim at reducing phosphorus (P) loss to water in order to reduce eutrophication. In Ireland, the average soil test P (STP) levels increased ten-fold, from less than 1 to over 8 mg Morgan P per l soil over the past 50 years, reflecting increased P inputs in fertiliser and animal feed. One of the main objectives of this three-year research programme, started in 2001, was to investigate P loss to water in grassland …

Grazing Management Impacts On The Riparian Zone And Water Quality, S. R. Aarons, A. Melland, C. J. P. Gourley

IGC Proceedings (1997-2023)

Inappropriate farm management activities such as stock access to creeks, and poor fertiliser and effluent management can negatively impact riparian zones and waterways, contributing to increased in-stream nutrient, sediment and microbiological loads and loss of riparian biodiversity, amongst other impacts. Nutrient budgets for dairy systems indicate that on-farm nutrient accumulation and redistribution is common (Gourley 2004), which in large part is due to the uneven distribution of dairy cow dung and the nutrients they contain (Aarons et al., 2004). The 'Gippsland Dairy Riparian Project Environmental Monitoring module' was established in Jan. 2003 to monitor the impact of …

Influence Of P Fertility And Grazing On Plant Species In A Temperate Australian Pasture, Jacqueline O. Hill, R. J. Simpson, A. D. Moore, J. T. Wood, D. F. Chapman

IGC Proceedings (1997-2023)

Graziers in temperate Australia are increasing their use of P fertiliser so they can run more stock and maintain profitability. However, intensification changes grassland botanical composition and perennial grass cover can be reduced. Perennial grasses are important because they improve production stability, reduce deep drainage and slow the rate of soil acidification. This study examined how P fertility and grazing affected the botanical composition of pasture based on Phalaris aquatica, a key perennial grass in south-eastern Australia.

Mechanical Aeration And Liquid Dairy Manure: Application Impacts On Grassland Runoff Water Quality And Yield, T. J. Basden, S. B. Shah, J. L. Miller

IGC Proceedings (1997-2023)

Wet weather on heavy soils reduces oxygen availability in the root zone and reduces forage yields. Mechanical aeration can improve forage yield in these soil conditions. Research has shown that under certain conditions, mechanical aeration can increase yield by improving drainage and aeration (Davies et al., 1989); aeration can also increase depression, storage and infiltration thus reducing surface runoff and improving nutrient distribution in the root zone. Aeration on sloping, fertilised grassland can provide environmental (Douglas et al., 1995) and agronomic benefits. The objectives of this study were to evaluate the runoff water quality and agronomic impacts of …

Grazing Effects On Some Soil Characteristics In Lar Rangelands, S. A. Javadi, M. Jafari, Gh. Zahedi

IGC Proceedings (1997-2023)

Heavy grazing pressures jeopardise the sustainability of the ecosystem by reducing soil fertility (Dormaar et al., 1998). Different results have been reported of grazing intensities on soil chemical properties, which stem from climate, soil, vegetation, management and kind of animal (Dormaar et al., 1998; Javadi, 2003; Sanadgool, 2002).

Leaf Dry Matter Content Of Native Grassland Species Under Contrasting N And P Supply, P. Cruz, C. Jouany, Jérome M. Enjalbert, Michael Duru

IGC Proceedings (1997-2023)

The management of native grasslands - herbaceous vegetation with a broad diversity of flora and a large range of uses - must meet the requirements of environmental conservation and improvement of the quality of agricultural production. For this purpose we need tools for diagnosing the state of the vegetation in order to design, evaluate, and apply management practices to attain these objectives. These tools must be simple and quick to use and should not require botanical skills. Leaf dry matter content (LDMC) has been proposed as a good indicator of both fertility gradients and species preference for habitats (Cruz et …

Potentialities Of Near Infrared Spectroscopy To Assess Nitrogen, Phosphorus And Potassium Nutrient Status Of Grasslands In The Reunion Island, Philippe Lecomte, Vincent Blanfort, Michael Duru, P. Thomas, P. Grimaud

IGC Proceedings (1997-2023)

Controlled mineral fertilisation practices are an important component for sustainable management of grasslands. The assessment of available nutrients for plants and the general recommendations on the level of phosphorus and potassium to apply to grasslands are classically based on classical soil analysis and average regional levels. For nitrogen, mid or long term recommendations cannot easily be derived solely from soil composition, because it may be rapidly leached from the soil. Recent approaches tended to show that herbage plant N (Lemaire & Gastal, 1997), P, K (Duru & Huché, 1997) mineral analyses associated with actual biomass measurement could be useful for …

Heterogeneous Nutrient Distribution Across Dairy Grazing Systems In Southeastern Australia, C. J. P. Gourley, I. Awty, P. A. Durling, J. Collins, A. Melland, S. R. Aarons

IGC Proceedings (1997-2023)

The Australian dairy industry is largely based on a grazed pasture system, although most cows also consume substantial amounts of imported feed (Fulkerson & Doyle 2001). This trend is expected to increase as the Australian dairy industry continues to intensify. Fertiliser inputs of nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) are still viewed as necessary to maintain adequate pasture and milk production despite the fact that most dairy farms are in net positive balance for all of these nutrients (Reuter 2001). Nutrient losses from dairy farming regions and eutrophication of waterways has gained strong public and political attention …

Reasons For The Premature Decline In Astragalus Adsurgens Stands In Kerqin Sandy Land, Qizhong Sun, Z. L. Wang, J. G. Han, Y. W. Wang, G. R. Liu

IGC Proceedings (1997-2023)

Diseases partly account for reductions in Astragalus adsurgens stand longevity. The effect of some cultural practices on the control of pests and diseases have been reported (Hou, 1986; Nan, 1996), but few reports have detailed the relationship among soil fertiliser status, diseases and premature stand decline. This study was conducted to investigate these relationships in order to extend the longevity of Astragalus adsurgens stands.

Heterogeneous Nutrient Distribution Across Dairy Grazing Systems In Southeastern Australia, C. J. P. Gourley, I. Awty, P. A. Durling, J. Collins, A. Melland, S. R. Aarons

IGC Proceedings (1997-2023)

The Australian dairy industry is largely based on a grazed pasture system, although most cows also consume substantial amounts of imported feed (Fulkerson & Doyle 2001). This trend is expected to increase as the Australian dairy industry continues to intensify. Fertiliser inputs of nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) are still viewed as necessary to maintain adequate pasture and milk production despite the fact that most dairy farms are in net positive balance for all of these nutrients (Reuter 2001). Nutrient losses from dairy farming regions and eutrophication of waterways has gained strong public and political attention …

Reasons For The Premature Decline In Astragalus Adsurgens Stands In Kerqin Sandy Land, Qizhong Sun, Z. L. Wang, J. G. Han, Y. W. Wang, G. R. Liu

IGC Proceedings (1997-2023)

Diseases partly account for reductions in Astragalus adsurgens stand longevity. The effect of some cultural practices on the control of pests and diseases have been reported (Hou, 1986; Nan, 1996), but few reports have detailed the relationship among soil fertiliser status, diseases and premature stand decline. This study was conducted to investigate these relationships in order to extend the longevity of Astragalus adsurgens stands.

Breeding Milestones Correspond With Changes To Wheat Rhizosphere Biogeochemistry That Affect P Acquisition, Rebecca Kay Mcgrail, David A. Van Sanford, David H. Mcnear Jr.

Plant and Soil Sciences Faculty Publications

Breeding wheat (Triticum aestivum L.) has resulted in small gains in improved nutrient acquisition and use as numerous traits are involved. In this study, we evaluated the impact of breeding on P-acquisition and identified both plant and soil variables that could be used to inform the selection of germplasm with increased P acquisition efficiency. We previously screened a historic panel of winter wheat cultivars for root system architecture and root tip organic acid content when grown in P-deficient solution/agar and used these characteristics together with breeding history to develop a predicted P extraction potential (PEP). We tested the validity …

Better Dairy Farm Management Increases The Economic Return From Phosphorus, J. D. Morton

IGC Proceedings (1997-2023)

Some 60% of New Zealand dairy farms on allophanic and sedimentary soils have soil Olsen phosphorus (P) levels to 75 mm depth above the target range for near-maximum pasture production of 20-30 µg/ml (Roberts & Morton 1999). For an economic response in milksolids (MS) production from high Olsen P, the pasture needs to be capable of high production, and the extra pasture grown be converted to milk. This paper seeks to justify this contention and outline some of the farm management practices required to achieve it.

Grassland Productivity And Water Quality: A 21st Century Issue, David M. Nash, P. M. Haygarth

IGC Proceedings (1997-2023)

1. Irrigation and other changes to the hydrological cycle can increase soil and water salinity.
2. Primary salinisation is a natural process that affects much of Europe, Asia, Africa, the Americas and Australia. Secondary salinisation is caused by human activities such as irrigation and land clearing that mobilise salt stored in the soil.
3. The critical water contaminants exported from grasslands are nitrogen, phosphorus, potential pathogens and sediment.
4. The mechanisms responsible for diffuse pollution from grasslands and mitigation strategies are most effectively investigated using a ‘source-mobilisation-transport’ framework.
5. There is a lack of coherent interaction across discipline boundaries that links pollutant sources to impact. …

Reasons For The Premature Decline In Astragalus Adsurgens Stands In Kerqin Sandy Land, Q. Zh. Sun, Z. L. Wang, J. G. Han, Y. W. Wang, G. R. Liu

IGC Proceedings (1997-2023)

Diseases partly account for reductions in Astragalus adsurgens, stand longevity. The effect of some cultural practices on the control of pests and diseases have been reported (Hou, 1986; Nan, 1996), but few reports have detailed the relationship among soil fertiliser status, diseases and premature stand decline. This study was conducted to investigate these relationships in order to extend the longevity of Astragalus adsurgens stands.