An evaluation of a strategic de-stocking regime for dairying to improve nitrogen efficiency and reduce nitrate leaching from dairy farms in nitrate-sensitive areas

Author(s):  
Cecile De Klein ◽  
Jim Paton ◽  
Stewart Ledgard

Strategic de-stocking in winter is a common management practice on dairy farms in Southland, New Zealand, to protect the soil against pugging damage. This paper examines whether this practice can also be used to reduce nitrate leaching losses. Model analyses and field measurements were used to estimate nitrate leaching losses and pasture production under two strategic de-stocking regimes: 3 months off-farm or 5 months on a feed pad with effluent collected and applied back to the land. The model analyses, based on the results of a long-term farmlet study under conventional grazing and on information for an average New Zealand farm, suggested that the 3- or 5-month de-stocking could reduce nitrate leaching losses by about 20% or 35-50%, respectively compared to a conventional grazing system. Field measurements on the Taieri Plain in Otago support these findings, although the results to date are confounded by drought conditions during the 1998 and 1999 seasons. The average nitrate concentration of the drainage water of a 5-month strategic de-stocking treatment was about 60% lower than under conventional grazing. Pasture production of the 5-month strategic de-stocking regime with effluent return was estimated based on data for apparent N efficiency of excreta patches versus uniformlyspread farm dairy effluent N. The results suggested that a strategic de-stocking regime could increase pasture production by about 2 to 8%. A cost/ benefit analysis of the 5-month de-stocking system using a feed pad, comparing additional capital and operational costs with additional income from a 5% increase in DM production, show a positive return on capital for an average New Zealand dairy farm. This suggests that a strategic destocking system has good potential as a management tool to reduce nitrate leaching losses in nitrate sensitive areas whilst being economically viable, particularly on farms where an effluent application system or a feed pad are already in place. Keywords: dairying, feed pads, nitrate leaching, nitrogen efficiency, productivity, strategic de-stocking

Soil Research ◽  
2014 ◽  
Vol 52 (7) ◽  
pp. 621 ◽  
Author(s):  
Lucy L. Burkitt

This paper reviews the literature on nitrate leaching and nitrogen (N) runoff under intensive dairy pasture systems in Australia and draws comparisons with research undertaken under similar climates and farming systems internationally, with the aim to inform future research in this area. An Australian nitrate-leaching study suggests that annual nitrate-leaching loads are lower (3.7–14.5 kg N ha–1 year–1 for nil N and 6–22 kg N ha–1 year–1 for 200 kg N ha–1 applied) than the range previously measured and modelled on New Zealand dairy farms (~18–110 kg N ha–1 year–1). It is likely that nitrate-leaching rates are higher in New Zealand because of the prevalence of free-draining soils and higher average stocking rates. However, this review highlights that there are insufficient Australian nitrate-leaching data, particularly following urine application, to undertake a rigorous comparison. Median N surpluses on Australian dairy farms are higher (198 kg N ha–1) than values for an average New Zealand farm (135 kg N ha–1). Given the facts that many soils used for intensive pasture production in Australia are lightly textured or free-draining clay loams receiving average rainfall of >800 mm year–1, that herd sizes have risen in the last 10 years and that water quality is a concern in some dairy catchments, nitrate leaching could be an issue for the Australian dairy industry. Australian data on surface runoff of N are more available, despite its overall contribution to N losses being low (generally <5 kg N ha–1 year–1), except under border-check flood irrigation or hump-and-hollow surface drainage (3–23 kg N ha–1 year–1). More research is needed to quantify surface N runoff and leaching following effluent application and to examine dissolved organic forms of N loss, particularly in view of the continued intensification of the Australian dairy industry.


Author(s):  
G.J. Doole ◽  
U.H. Paragahawewa

Nitrification inhibitors are an important mitigation practice for nitrate leaching since they reduce leaching loads and can potentially increase farm profit through promoting pasture production.


2014 ◽  
Vol 153 (1) ◽  
pp. 124-137 ◽  
Author(s):  
A. J. ROMERA ◽  
G. J. DOOLE ◽  
E. N. KHAEMBAH

SUMMARYChicory (Cichorium intybusL.) crops can increase milk production on New Zealand dairy farms through providing high-quality feed in late lactation. Non-linear optimization models of three Waikato dairy farms, differing in the degree to which imported supplement is used, were employed to evaluate chicory crops in this environment. At a baseline milk price of $NZ 7/kg milk solids, it was only profitable for chicory to be used on a farm where no imported supplement was fed. However, even then, only 0·04 of the farm area was planted and profit only increased by $NZ 30/ha (0·006 of baseline profit), relative to where it was not used. It was not optimal to plant any chicory on farms where imported feed was available, at the baseline milk price and cost of establishment considered here. This was evident because imported feed is more flexible than chicory for filling temporary feed gaps; also its use does not displace pasture production. Sensitivity analysis indicated that the unprofitability of chicory is robust to broad variation in calving date and the relative growth of chicory and pasture. Overall, results indicate that farmers are unlikely to receive adequate reward for the additional complexity arising from the utilization of chicory crops, especially when imported supplement provides more flexibility.


Soil Research ◽  
2002 ◽  
Vol 40 (2) ◽  
pp. 317 ◽  
Author(s):  
H. J. Di ◽  
K. C. Cameron

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&sol;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&percnt; of N applied) than for urine applied in the autumn (38–58&percnt;). 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&sol;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&sol;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.


Author(s):  
C.G. Roach ◽  
G. Stevens ◽  
D.A. Clark ◽  
P. Nicholas

encouraged by many regional councils, and the use of urea fertiliser on dairy farms has increased over recent years. A 3-year trial was started in September 1997 to investigate the effects of urea and dairy effluent applications on pastures, soils and groundwater quality. Twenty-one 0.25 ha paddocks received urea or dairy effluent at rates of 0, 100, 200, or 400 kg N/ha/yr, and were grazed by dairy cows. Increasing nitrogen application rates resulted in increased pasture production and ryegrass content, and nitrate leaching to ground water. Nitrate leaching was estimated to be 14, 18, 26 and 56 kg N/ha/yr for the 0, 100, 200 and 400 kg N/ha/yr application rates respectively. No differences in these responses were measured between urea and effluent when applied at the same rate of nitrogen. Application of dairy effluent resulted in increased average pasture potassium levels from 3.65%DM to 4.00%DM, which may have implications for animal health. Application of dairy effluent also decreased soil sulphur levels and increased soil magnesium status. Keywords: dairy effluent, groundwater, nitrate leaching, nitrogen, pasture, soil, urea


Author(s):  
M.H. Beare ◽  
F.Tabley R. Gillespie ◽  
S. Maley ◽  
T. Harrison-Kirk ◽  
J. De Ruiter

New Zealand pastoral industries have set a goal of producing 45 t DM/ha annually from supplementary feed crops. Achieving this will require high inputs of water and nutrients that may increase the risk of nitrate leaching. This research describes nitrate leaching losses from the first year of intensively managed forage crop sequences to identify mitigation options.


Author(s):  
S.F. Ledgard ◽  
J.W. Penno ◽  
M.S. Sprosen

Nitrogen (N) balances were constructed for "average" dairy farms in New Zealand, south west England and The Netherlands, and for Dairying Research Corporation (DRC) farmlets varying in stocking rate and use of N fertiliser and maize grain. N surpluses were calculated to indicate the potential impact on the environment and these were compared with measured N losses from the DRC farmlets. On the average New Zealand farm, annual N inputs of 186 kg N/ha/year (mainly from N2 fixation) resulted in N outputs in milk+meat of 55 kg N/ha/year (30% efficiency) and a N surplus of 131 kg N/ha/year. Dutch farms produced 70% more milk/ha but had N inputs of 568 kg/ha, N outputs in produce of 81 kg/ha (14% efficiency) and a N surplus of 487 kg/ha. English farms were intermediate. In the DRC farmlets, applying fertiliser N at 400 kg N/ha/year increased N surpluses and nitrate leaching by 3-4 fold, resulting in nitrate-N concentrations in drainage of 2.5× the recommended maximum for drinking water. The most efficient farm system received no N fertiliser and was highly stocked (3.3 Friesian cows/ha) for very high pasture utilisation. This resulted in similar milk production/ha to Dutch farms (with 1/3 the N inputs) and a 45% efficiency of conversion of N inputs from N2 fixation into milk and meat products. Keywords: dairy farm, nitrate leaching, nitrogen balance, nitrogen fertiliser, stocking rate


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