Organic matter and nitrogen in the unharvested fractions of grass swards in relation to the potential for nitrate leaching after ploughing

Whitehead, David; Bristow, A. W.; Lockyer, D. R.

doi:10.1007/bf00009924

Cited by 68 publications

(61 citation statements)

References 16 publications

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“…However, N mineralization rates in our study were in range of data from studies where grasslands were ploughed (Aarts et al 2001;Johnston et al 1994;Vertès et al 2007;Whitehead et al 1990). Those studies report a wide range of annual N mineralization rates (100 to 400 kg N ha −1 yr −1 ) in the first year after grassland…”

Section: Nitrogen Mineralizationsupporting

confidence: 61%

“…However, it must be noted that grass growth may be limited by climatic factors and that the N yield of grassland is only an indicator for part of the N mineralization. Large amounts of N (more than 100 kg N ha −1 ; Whitehead et al 1990) needed for the establishment of roots and stubbles are not taken in account.…”

Section: Variability In Mineralization and Indicesmentioning

confidence: 99%

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Comparison of indices for the prediction of nitrogen mineralization after destruction of managed grassland

Smit

Velthof

2009

Plant Soil

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Intensively managed grasslands are occasionally chemically killed with herbicide and ploughed in order to grow an arable crop. After this management, large N mineralization rates with large losses to the environment are commonly observed. However, it remains to be determined to what extent the chemical killing contribute to increased N mineralization. In this study the potential nitrogen (N) mineralization from grasslands, that were killed with herbicides but otherwise undisturbed, was investigated in a laboratory experiment with undisturbed soil columns. Subsequently we assessed the predictive value of several laboratory indices for N mineralization after chemically killing of the grass. Mineralization rates varied from 0.5 to 3.0 g N m −2 wk −1. The contents of total N, total C, dissolved organic carbon (DOC) and hot-KCl extractable NH 4 + were best related to N mineralization rates (R 2 =50, 48, 38 and 47%, respectively). In combination with information on the N content of the roots and stubble and the age of grassland at destruction, up to 62% of the variation in N mineralization rates could be explained. Although previous studies suggested that dissolved organic nitrogen (DON) is a good indicator for mineralization rates, this was not the case after chemically killing grass in the current study.

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Section: Nitrogen Mineralizationsupporting

confidence: 61%

Section: Variability In Mineralization and Indicesmentioning

confidence: 99%

Comparison of indices for the prediction of nitrogen mineralization after destruction of managed grassland

Smit

Velthof

2009

Plant Soil

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“…Additionally, some 15 N was probably incorporated into the stubble and root mass (Whitehead et al 1990), or moved into soil layers below 15 cm, which was not accounted for in this experiment.…”

Section: Discussionmentioning

confidence: 91%

Slurry 15NH4-N recovery in herbage and soil: effects of application method and timing

et al. 2009

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The effects of slurry application method and weather conditions after application on ammonia volatilisation are well documented, however, the effect on slurry N recovery in herbage is less evident due to large variability of results. The objective of this field experiment was to determine the recovery of cattle slurry NH 4 -N in herbage and soil in the year of application as affected by application method (trailing shoe versus broadcast) and season of application (spring versus summer), using 15 N as a tracer. In 2007 and 2008, 15 N enriched slurry was applied on grassland plots. N recovery in herbage and soil during the year of application was determined. Both spring and trailing shoe application resulted in significantly higher herbage DM yields, N uptake and an increased recovery of 15 NH 4 -N in herbage. Additionally, the recovery of slurry 15 NH 4 -N in the soil at the end of the growing season was increased. Spring and trailing shoe application reduced the losses of slurry 15 NH 4 -N by on average 14 and 18 percentage points, respectively, which corresponded closely to ammonia volatilisation as predicted by the ALFAM model. It was concluded that slurry N recovery in temperate pasture systems can be increased by adjusting the slurry application method or timing.

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“…These grasslands are harvested by grazing and cutting (for making silage and hay, and for feeding zero-grazed cattle). Mean grassland yields roughly range between 6 and 14 Mg ha -1 year -1 , depending on climate, management and fertilization (Whitehead 2000). It has been often observed in practice that yields and quality of permanent grasslands decrease during ageing, because of sward deterioration following extreme weather conditions and/or bad management.…”

Section: Introductionmentioning

confidence: 99%

“…A fraction of the annual N input accumulates in stubbles, roots and microbial biomass and ends up in dead soil organic matter during ageing of grassland. In living roots, N accumulates over time to more than 200 kg N ha -1 , however the rate of N accumulation strongly levels off during ageing of grasslands (Eriksen and Jensen 2001;Whitehead et al 1990). Stubbles of less than five years contain about 40-80 kg N ha -1 and this amount does not significantly increase with ageing (Davies et al 2001;Whitehead et al 1990).…”

Section: Introductionmentioning

confidence: 99%

Method and timing of grassland renovation affects herbage yield, nitrate leaching, and nitrous oxide emission in intensively managed grasslands

Velthof

Hoving²,

Dolfing

et al. 2009

Nutr Cycl Agroecosyst

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Managed grasslands are occasionally ploughed up and reseeded in order to maintain or increase the sward productivity. It has been reported that this renovation of grassland is associated with a flush of soil organic nitrogen (N) mineralization and with a temporary increase in soil mineral N contents. Here, we report on the effects of method and time of grassland renovation on herbage yield, nitrate (NO 3 -) leaching and nitrous oxide (N 2 O) emission. Field experiments were carried out at three sites (two sandy soils and a clay soil) in the Netherlands for three years. Renovation of grassland increased the percentage of Perennial ryegrass from 48-70% up to more than 90%. However, averaged over three years, dry matter yields were higher for the reference (not reseeded) swards (on average 13.6 Mg ha -1 for the highest N application rate) than for the renovated grasslands (12.2-13.1 Mg ha -1 dry matter). Grassland renovation in April did not increase N leaching in comparison to the reference. However, renovation in September increased the risk of leaching, because mineral N contents in the 0-90 cm were in November on average 46-77 kg N ha -1 higher than in the reference. Contents of dissolved organic N (DON) in the soil were not affected by renovation. Renovation increased N 2 O emissions by a factor of 1.8-3.0 relative to the reference grassland. Emissions of N 2 O were on average higher after renovation in April (8.2 kg N 2 O-N ha -1 ) than in September (5.8 kg N 2 O-N ha -1 ). Renovation without ploughing (i.e. only chemically destruction of the sward) resulted in a lower percentage of perennial ryegrass (60-84%) than with ploughing ([90%). Moreover, N 2 O emissions were higher after renovation without ploughing than with ploughing. Clearly, farmers need better recommendations and tools for determining when grassland renovation has beneficial agronomic effects. Losses of N via leaching and N 2 O emission after renovation can probably not be avoided, but renovation in spring in stead of autumn in combination with ploughing and proper timing of fertilizer application can minimize N losses.

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Organic matter and nitrogen in the unharvested fractions of grass swards in relation to the potential for nitrate leaching after ploughing

Cited by 68 publications

References 16 publications

Comparison of indices for the prediction of nitrogen mineralization after destruction of managed grassland

Comparison of indices for the prediction of nitrogen mineralization after destruction of managed grassland

Slurry 15NH4-N recovery in herbage and soil: effects of application method and timing

Method and timing of grassland renovation affects herbage yield, nitrate leaching, and nitrous oxide emission in intensively managed grasslands

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