The single heterogeneous paddock approach to modelling the effects of urine patches on production and leaching in grazed pastures

2009 ◽  
Vol 60 (7) ◽  
pp. 691 ◽  
Author(s):  
V. O. Snow ◽  
I. R. Johnson ◽  
A. J. Parsons
Keyword(s):  
Primary Source ◽  
Simulation Models ◽  
N Leaching ◽  
N Fixation ◽  
Spatial Averaging ◽  
Pastoral Systems ◽  
Time Duration ◽  
Pasture Production ◽  
Software Complexity ◽  
Parameter Values

Despite the fact that urine patches within grazed paddocks are the primary source of N leaching, virtually all pastoral simulation models assume a uniform spatial return of urinary-N to the soil. This simple spatial averaging might not be appropriate if the aim of the modelling is to explore leaching losses because of the non-linearity caused by the high N concentration in urine patches. Here we describe the single heterogeneous paddock (SHP) approach to modelling the dynamics of N in pastoral systems. We also examine the potential for manipulating rate parameters in a simpler uniform-return model (URM) to compensate for the lack of explicit description of urine patches. Comparison of simulation results from the URM and SHP showed some differences in the patterns of production and a substantial difference in leaching. Depending on soil and climate simulated, there was 5–30% higher pasture production in the URM because simulated leaching in the URM was 5–85% of that simulated by the SHP. Examination of the ratio of the outputs from the two models revealed that the differences in pasture production and N fixation in the URM could probably be corrected with a change in parameter values. This was not true of leaching where there was considerable variation and skew in the ratios, so at the very least, any correction factor would be highly soil and climate specific. We suggest that models of grazed grass–legume systems can probably adequately simulate production with a simple URM but that the simulation of leaching requires an explicit representation of the heterogeneous urine return. The SHP approach is one methodology for this but this has implications for model and software complexity and for model run-time duration.

scholarly journals Residual effect of clover-rich leys on soil nitrogen and successive grain crops

2008 ◽  
Vol 17 (1) ◽  
pp. 73 ◽  
Author(s):  
A. NYKÄNEN ◽  
A. GRANSTEDT ◽  
L. JAUHIAINEN
Keyword(s):  
Field Experiments ◽  
Clayey Soil ◽  
N Uptake ◽  
Residual Effect ◽  
Red Clover ◽  
N Leaching ◽  
N Fixation ◽  
Mineral N ◽  
Total N ◽  
Biological N Fixation

Legume-based leys form the basis for crop rotations in organic farming as they fix nitrogen (N) from the atmosphere for the succeeding crops. The age, yield, C:N, biological N fixation (BNF) and total N of red clover-grass leys were studied for their influence on yields, N uptake and N use efficiency (NUE) of the two sequential cereal crops planted after the leys. Mineral N in deeper soil (30-90 cm) was measured to determine N leaching risk. Altogether, four field experiments were carried out in 1994-1998 at two sites. The age of the ley had no significant effect on the yields and N uptake of the two subsequent cereals. Surprisingly, the residual effect of the leys was negligible, at 0–20 kg N ha-1yr-1. On the other hand, the yield and C:N of previous red clover-grass leys, as well as BNF-N and total-N incorporated into the soil influenced subsequent cereals. NUEs of cereals after ley incorporation were rather high, varying from 30% to 80%. This might indicate that other factors, such as competition from weeds, prevented maximal growth of cereals. The mineral N content deeper in the soil was mostly below 10 kg ha-1 in the sandy soil of Juva, but was 5-25 kg ha-1 in clayey soil of Mietoinen.;

Dryland legumes: perspectives and problems

2003 ◽  
Vol 11 ◽  
pp. 27-36
Author(s):  
D. Scott
Keyword(s):  
Root Nodule ◽  
Fine Root ◽  
Animal Feed ◽  
Environmental Gradients ◽  
N Fixation ◽  
Indigenous Species ◽  
Nodule Bacteria ◽  
Pastoral Systems ◽  
Fertility Gradient

The different perspectives or concepts involved in developing legumes for dryland pastoral systems is commented on in relation to: N-fixation versus animal feed; root nodule bacteria requirements; large introduced legume flora compared with indigenous; species niche in relation to environmental gradients of moisture, temperature, fertility, and grazing; species adaptation along the decreasing fertility gradient from fine-root nutrient scavenging grasses, N-fixers, mycorrhiza, and proteoid roots; interaction of N- fixation with soil organic matter; establishment; determinants of pastures legume composition; and the possible role of allelopathy. Key words: dryland, environmental gradients, legumes, N-fixation, pasture composition

Updating Existing Travel Simulation Models with Small-Sample Survey Data Using Parameter Scaling Methods

1997 ◽  
Vol 1607 (1) ◽  
pp. 55-61
Author(s):  
W. Thomas Walker ◽  
Scott H. Brady ◽  
Charles Taylor
Keyword(s):  
Survey Data ◽  
Primary Source ◽  
Simulation Models ◽  
Small Sample ◽  
Sample Survey ◽  
Secondary Source ◽  
Sample Surveys ◽  
Large Sample ◽  
Scaling Methods ◽  
Home Interview

The travel simulation models for many metropolitan areas were originally developed and calibrated with older large-sample travel surveys that can no longer be undertaken given today’s funding constraints. Small-sample travel surveys have been collected as part of model update activities required by the Intermodal Surface Transportation Efficiency Act and the Clean Air Act Amendments. Although providing useful information, these surveys are inadequate for calibrating elaborate simulation models by traditional techniques. Parameter transfer scaling based on small-sample surveys and other secondary source data can be a cost-effective alternative to large-sample surveys when existing models are being updated, particularly when the models tend to be robust and the required changes are relatively small. The use of parameter scaling methods to update the Delaware Valley Planning Commission’s existing travel simulation models is demonstrated. All available sources of data are incorporated into the update process including current survey data, census work trips from the Census Transportation Planning Package (CTPP), transit ridership checks, highway screenline counts, and Highway Performance Monitoring System travel estimates. A synopsis of experience with parameter scaling techniques including the model changes and resulting accuracy is provided. Overall, small-sample-based parameter scaling techniques were judged to be effective. The census CTPP data were evaluated versus the home interview and were found to be useful in the model recalibration effort as a source of small-area employment data by place of work and as a supplement to home interview data for model validation. However, a home interview survey is required as the primary source of travel data for both work and nonwork trips.

A farm-scale framework to assess potential farm- and regional-scale implications of removing palm-kernel expeller as a supplementary feed for dairy cows

2017 ◽  
Vol 57 (7) ◽  
pp. 1336 ◽  
Author(s):  
Ronaldo Vibart ◽  
Alec Mackay ◽  
Andrew Wall ◽  
Iris Vogeler ◽  
Josef Beautrais ◽  
...  
Keyword(s):  
Production Systems ◽  
Regional Scale ◽  
Palm Kernel ◽  
Dairy Farms ◽  
Barley Grain ◽  
N Leaching ◽  
Pasture Production ◽  
Farm Scale ◽  
Supplementary Feed ◽  
The Impact

Farm-scale models were integrated with spatially discrete estimates of pasture production to examine the potential farm and regional implications of removing palm-kernel expeller (PKE) as a supplementary feed from dairy farms in Southland, New Zealand. The following two farm-production systems representing the majority of dairy farms in the region were modelled: a System 3 farm (D3; mid-intensification, with 10–20% of imported feed) and a System 4 farm (D4; mid- to high intensification, with 20–30% of imported feed). Within each system, the impact of the following four PKE options was explored: (1) a control with PKE (Baseline); (2) no PKE, with fewer cows producing the same amount of milk per cow as in Baseline; (3) no PKE, with the same number of cows producing less milk per cow than in Baseline; and (4) PKE replaced with barley grain. Barley grain provides for similar flexibility (timing of purchase and feeding), and can be sourced locally. Faced with the need to remove PKE as a dietary ingredient, farmers would benefit from adopting the second PKE option (no PKE, with fewer cows producing the same amount of milk per cow as in Baseline); farm-operating profits were reduced by only 3% (compared with 30% of System 4 farms adopting the third PKE option, i.e. no PKE, with the same number of cows producing less milk per cow than in Baseline) relative to the Baseline farms. The narrow range of mean annual nitrate-nitrogen (nitrate-N) leaching losses (estimates ranged from 30 to 33 kg N/ha) reflects similar estimates of N intake and N excreted in urine across the modelled options. Substantial amounts of barley grain would need to be transported into the region or produced locally to replace PKE.

Forecasting Manufacturing Quality and Optimizing Product Robustness Using Process Capability Data

Manufacturing ◽  
2003 ◽  
Author(s):  
Daniel Kern ◽  
Xiaoping Du ◽  
Agus Sudjianto
Keyword(s):  
Probabilistic Approach ◽  
Process Capability ◽  
Simulation Models ◽  
Design Parameters ◽  
Set Design ◽  
Manufacturing Quality ◽  
Design Engineers ◽  
Parameter Values ◽  
Manufacturing Variation

A company’s success is highly dependent on its ability to manufacture quality products. Designing products that can be manufactured to meet customer needs with an acceptable level of variation is challenging because design engineers are often unfamiliar with the company’s manufacturing capability or are unable to effectively use the capability data to improve a design. The authors present an approach to forecast the manufacturing quality of a product and optimize its robustness while it is being designed. The system comprises a database that stores process capability data and simulation models to simulate process capability data when actual, appropriate data are nonexistent. These data and tools are used with a new probabilistic approach through the inverse reliability strategy to optimize the robustness of a design by locating values of design parameters that enhance the performance of the design and are insensitive to manufacturing variation. Design engineers can use this approach to set design parameter values that will improve the functionality of the product while ensuring it can be produced with high capability. This approach is demonstrated with a design example of an engine valvetrain.

Nitrate leaching and pasture production from different nitrogen sources on a shallow stoney soil under flood-irrigated dairy pasture

Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 317 ◽  
Author(s):  
H. J. Di ◽  
K. C. Cameron
Keyword(s):  
Nitrate Leaching ◽  
Production Systems ◽  
Environmental Concern ◽  
Nitrogen Sources ◽  
N Leaching ◽  
Pasture Production ◽  
Dairy Effluent ◽  
Leaching Losses ◽  
Rooting Zone ◽  
Leaching Loss

The leaching of nitrate (NO3–) in intensive agricultural production systems, e.g. dairy pastures, is a major environmental concern in many countries. In this lysimeter study we determined the amount of NO3– leached following the application of urea, dairy effluent, urine returns, and pasture renovation to a freedraining Lismore stony silt loam (Udic Haplustept loamy skeletal) growing a mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) pasture. The study showed that NO3–-N leaching losses ranged from 112 to 162 kg N/ha per year, depending on the amount and forms of N applied and pasture conditions. Nitrate leaching under the urine patches was the main contributor to the N leaching loss in a grazed paddock. Nitrate leaching losses were lower for urine applied in the spring (29% of N applied) than for urine applied in the autumn (38–58%). The application of urea or dairy effluent only contributed a small proportion to the total NO3– leaching loss in a grazed paddock. Pasture renovation by direct-drilling may also have caused an increase in NO3– leaching (c. 31 kg N/ha) in the first year. Modelled annual average NO3–-N concentrations in the mixed recharge water in the acquifer were significantly lower than those measured under the rooting zone due to dilution effects by recharge water from other sources (3.9 v. 13–27 mg N/L). Herbage nitrogen offtake and dry matter yield were higher in the urine treatments than in the non-urine treatments. groundwater, denitrification, mineralisation, grazing, forage.

Comparison of a herbal ley with a ryegrass-white clover pasture and pure ryegrass sward receiving fertiliser nitrogen

1991 ◽  
pp. 225-230 ◽  
Author(s):  
B.E. Ruz-Jerez ◽  
P.Roger Ball ◽  
R.E. White ◽  
P.E.H. Gregg
Keyword(s):  
White Clover ◽  
Symbiotic Nitrogen Fixation ◽  
Total Yield ◽  
Red Clover ◽  
N Fixation ◽  
Botanical Composition ◽  
Forage Legumes ◽  
Pasture Production ◽  
Intensively Managed ◽  
Intensive System

This paper compares a herbal ley (of particular interest to farmers involved in the 'organic' branch of agriculture) with a conventional pasture (ryegrass-white clover) and a more intensive system (pure ryegrass receiving 400 kg fertiliser N/ha/yr) in a study lasting 2 years. The herbal ley seeds mixture was prepared following the pioneering ideas of Robert Elliot in his "Clifton ~~ ~~~~~Park"mixture,-whichbasically-included~a-group of 'non-aggressive' grasses, forage legumes and herbs. Pasture production (average of 2 years) from Herbal ley was 15 t DM/ha/yr, representing approximately 90% of the yield from the intensively managed pure ryegrass pasture receiving 400 kg N/ ha&r and some 2530% more than from ryegrassclover. A major feature of the herbal ley was substantialproductionduringlate.springandsummer, when chicory (the most dominant herb), and red clover and white clover made a major contribution to herbage yield. In winter the total yield was similar tothatI?omthegrass-cloverpasture.L.egumecontent was 23 and 3 1% (averaged over the year) for Grassclover and Herbal ley pastures respectively. In spite of this difference, symbiotic N fixation was similar. So fixation efficiency on a legume yield basis was 50.3 and 3 1.6 kg N fixed/t legume DM harvested, respectively. These results could reflect a different pattern of utilisation of soil N, as a consequence of the different botanical composition of the swards. In summary, the performance of the herbal ley offers the promise of an alternative, 'specialist' pasture and would be highly beneficial if quality feed is required in summer. Keywords herbal ley, biological fertility, nitrogen, symbiotic nitrogen fixation, pasture mixtures

Simple versus diverse pastures: opportunities and challenges in dairy systems

2015 ◽  
Vol 55 (7) ◽  
pp. 893 ◽  
Author(s):  
Keith G. Pembleton ◽  
Katherine N. Tozer ◽  
Grant R. Edwards ◽  
Joe L. Jacobs ◽  
Lydia R. Turner
Keyword(s):  
New Zealand ◽  
Low Cost ◽  
Primary Source ◽  
Optimum Level ◽  
Forage Production ◽  
Additional Species ◽  
Pasture Production ◽  
Consistent Finding ◽  
Nitrogen Fertiliser ◽  
Dairy Systems

For Australian and New Zealand dairy farms, the primary source of home-grown feed comes from grazed perennial pastures. The high utilisation of perennial pasture is a key factor in the low cost of production of Australian and New Zealand dairy systems and, hence, in their ability to maintain international competiveness. The major pasture species used are perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.), normally grown in a simple binary mixture. As pasture production has been further driven by increasing use of nitrogen fertiliser and irrigation, farms are getting closer to their economic optimum level of pasture utilisation. Increasing inputs and intensification have also increased scrutiny on the environmental footprint of dairy production. Increasing the diversity of pasture species within dairy swards presents opportunities to further increase pasture utilisation through additional forage production, extending the growing season, improving forage nutritive characteristics and, ultimately, increasing milk production per cow and/or per hectare. Diverse pastures also present an opportunity to mitigate some of the environmental consequences associated with intensive pasture-based dairy systems. A consistent finding of experiments investigating diverse pastures is that their benefits are due to the attributes of the additional species, rather than increasing the number of species per se. Therefore, the species that are best suited for inclusion into dairy pastures will be situation specific. Furthermore, the presence of additional species will generally require modification to the management of dairy pastures, particularly around nitrogen fertiliser and grazing, to ensure that the additional species remain productive and persistent.

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

1993 ◽  
pp. 67-71
Author(s):  
S.F. Ledgard ◽  
G.J. Brier
Keyword(s):  
Phosphate Rock ◽  
Nitrogen Availability ◽  
Research Area ◽  
N Fixation ◽  
Single Superphosphate ◽  
Pasture Production ◽  
Hill Country ◽  
Reactive Phosphate ◽  
Reactive Phosphate Rock ◽  
P Rate

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

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