Obervations on the depth of removal of soil potassium and magnesium by permanent grass/clover pasture

Weeda, W. C.

doi:10.1080/03015521.1978.10426297

Cited by 6 publications

(8 citation statements)

References 4 publications

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“…It arises in the context of this discussion only as an attempt to explain the large variability in K pasture production functions Uptake of K from below 75 mm depth A further explanation for the lack of pasture responses to fertiliser K at low soil QTK levels (0Á75 mm) is the possibility that pasture plants take up considerable amounts of K from below the soil sampling depth. This has been The diagnosis and correction of potassium deficiency in New Zealand pastoral soils 163 suggested by many authors (Weeda 1978;During & Campkin 1980;Williams et al 1990;Carey & Metherell 2003b), essentially to explain the results of K balance studies. This plant-available K below 75 mm depth may be from natural sources*the result of weathering*or it could be from past and indeed current (see next section) fertiliser applications.…”

Section: Temporal Effectsmentioning

confidence: 99%

“…It is possible that for this set of soils, applied fertiliser K is readily leached beyond the soil sampling depth of 0Á75 mm within the time frame of the experiment, from where it could still be utilised by the plant. Weeda (1978) and During & Campkin (1980) showed that pasture plants could extract K from down to 30 cm. Ozanne et al (1965) showed this explicitly using radioactive K, and found that plant K uptake at various depths was related to the quantity of roots present.…”

Section: Movement Of Fertiliser Kmentioning

confidence: 99%

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The diagnosis and correction of potassium deficiency in New Zealand pastoral soils: a review

Edmeades

Morton²,

Waller

et al. 2010

New Zealand Journal of Agricultural Research

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Field-trial data from a database comprising records of 804 potassium (K) fertiliser trials were used to define the production functions relating exchangeable soil K (quick test K (QTK) 0Á75 mm) to the relative response to fertiliser K applications, for the major soil groups in New Zealand. For all soil groups for which there were sufficient data, the production functions were generally flat in the range QTK 5Á10, and thus the estimated relative pasture production at QTK 5 and QTK 10 were similar. The critical QTK levels to achieve 97% maximum production were relatively well defined, being 6 (5Á8) for sedimentary soils (brown and pallic) and brown soils, and 7 (5Á10) for pumice soils. The data for the allophanic soils were unstable and the best estimate was 6 (5Á10). For the remaining soils groups (podzols and raw soils, organic, recent and gley soils) for which there was much less data, the relationships were essentially flat over the range QTK 2Á10. The probability of pasture responses to applied K increased as soil QTK decreased from 10. For the sedimentary and volcanic soils (including both allophanic and pumice) the probability was about 70Á80% at soil QTK B2. The comparable probabilities were 50Á60% for the recent and gley soils, and 30Á43% for the podzols and raw soils. A feature of the response functions was that some trials were not responsive to fertiliser K despite having low soil QTK. In most cases this could not be attributed to soil K reserves as measured by the soil TBK test (sodium tetra-phenol-boron extractable which measures exchangeable K plus plant-available but non-exchangeable K). Other possible reasons for this feature in the data are discussed, including uptake of K from below the soil sampling depth and the temporal effects of clover responses to applied K. Soil K buffer capacities*the amount of fertiliser K over and above maintenance required to increase soil QTK by 1 unit (DK)*ranged from 50 to 150 kg K ha (1 (average 124) for sedimentary soils. For some soils (developed organic soils, gleyed soils and podzols), fertiliser K had very little effect on QTK (0Á75 mm). It is not clear whether these differences are due to differences in leaching of K from the sampling depth, differences between soils in their ability to absorb and retain applied K or indeed the result of errors in the measurement of this parameter. Estimated maintenance K requirements (i.e. the amount of applied K required to maintain soil QTK levels) increased with increasing soil QTK from 4 to 10, from 0Á150 kg K ha(1 yr (1 to 100Á300 kg K ha (1 yr (1 in situations where losses of K were extreme due to the removal of all harvested clippings. Given the uncertainties in predicting K responses and the amount of fertiliser K required to correct K deficiency, practical suggestions are offered as to how best to diagnose and manage soil K deficiency. Areas for future research to improve the prediction of pasture responses to fertiliser K are also included.

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Section: Temporal Effectsmentioning

confidence: 99%

Section: Movement Of Fertiliser Kmentioning

confidence: 99%

The diagnosis and correction of potassium deficiency in New Zealand pastoral soils: a review

Edmeades

Morton²,

Waller

et al. 2010

New Zealand Journal of Agricultural Research

View full text Add to dashboard Cite

show abstract

“…Presumably exchangeable-K, even at these depths, is more accessible for plant uptake than from nonexchangeable-K sources in surface layers. Other authors have also shown that volumes of soil used by pasture species for K uptake will extend to depths of 300 mm or greater (Ozanne et al 1964;Weeda 1978). This needs to be considered in any budget of K losses or gains when monitoring the sustainability of soil K reserves.…”

Section: Unaccounted-k In North Otago and Woodlands Trialsmentioning

confidence: 99%

Monitoring long‐term changes in reserve potassium in some New Zealand soils using a modified sodium tetraphenyl‐boron method

Carey

Metherell

2003

New Zealand Journal of Agricultural Research

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“…In contrast, all the K.:.levels were lower than the topsoil and showed little variation between the sites. It has been shown by Weeda (1978) and During & Campkin (1980) that pasture plants can extract K from soil down to 30 cm below the surface. Uptake of both exchangeable and reserve K can occur (During & Campkin 1980), so the large pool of reserve K found at some of these sites at 15-30 cm may have contributed K to the plants.…”

Section: Soil Analysismentioning

confidence: 99%

Chemical soil test prediction of pasture responses to potassium on recent soils of the South Island west coast

Williams

Morton²,

Jackson³

1986

New Zealand Journal of Experimental Agriculture

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Obervations on the depth of removal of soil potassium and magnesium by permanent grass/clover pasture

Cited by 6 publications

References 4 publications

The diagnosis and correction of potassium deficiency in New Zealand pastoral soils: a review

The diagnosis and correction of potassium deficiency in New Zealand pastoral soils: a review

Monitoring long‐term changes in reserve potassium in some New Zealand soils using a modified sodium tetraphenyl‐boron method

Chemical soil test prediction of pasture responses to potassium on recent soils of the South Island west coast

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