Potassium metaphosphate as a fertiliser for pastures

Hogg, D. E.; Toxopeus, M. R. J.

doi:10.1080/00288233.1970.10430521

Cited by 4 publications

(2 citation statements)

References 6 publications

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“…This data, together with data on leaching of K in the laboratory (Davies et al 1962;Hogg & Toxopeus 1970), led to the initial selection of 2 ppm for KDW for most New Zealand soils and 4 ppm for peats, sands, and yellow-brown pumice soils. The latter 3 groups of soils consistently showed much greater K leaching losses in the laboratory.…”

Section: K Concentration In Drainage Water (Kdu1mentioning

confidence: 99%

Model for calculating potassium requirements for grazed pastures

Campkin¹

1985

New Zealand Journal of Experimental Agriculture

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A model has been developed for calculating the potassium (K) requirements of grazed pastures. It assesses K losses in animal products, in transfer from the grazing area, and in drainage, using knowledge of the type of stock, stocking rate, land slope, and mean annual rainfall. Potassium supplied by the soil from residual fertiliser K and through weathering of clay minerals is then subtracted from these losses to give the fertiliser required. An adjustment can be made for those areas which lose or receive extra K in hay or silage.

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Section: K Concentration In Drainage Water (Kdu1mentioning

confidence: 99%

Model for calculating potassium requirements for grazed pastures

Campkin¹

1985

New Zealand Journal of Experimental Agriculture

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“…Potassium chloride has disadvantages as a fertiliser for grazed pasture. Not only is the potassium (K) susceptible to leaching on free-draining soils (Hogg & Cooper 1964;Hogg & Toxopeus 1970), but, following topdressing, there is rapid luxury uptake of K by pasture species (McNaught 1958;Saunders & Metson 1959;Metson & Saunders 1962). On K responsive sites, at normal rates of topdressing with KCl, the concentration of K in dry matter (DM) may rise into the range 3.…”

Section: Introductionmentioning

confidence: 99%

A comparison of slow release potassium fertilisers for pasture

Saunders¹,

Cooper²,

Campkin³

1988

New Zealand Journal of Experimental Agriculture

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Luxury uptake of potassium (K) from potassium chloride (KCl) by pasture plants is a major disadvantage in its use as a fertiliser for pastures. Luxury uptake shortens the fertiliser's effective life and causes excessively high concentrations of potassium relative to calcium, magnesium, and sodium. This can result in health problems for grazing stock. A further disadvantage is that KCl is readily leached from the soil if there is heavy rain. Coating KCl has been tried as a way of slowing the release of K and its uptake by ryegrass, and of reducing loss by leaching. Coating KCl with sulphur reduced its rate of dissolution greatly and avoided luxury uptake by the grass. On an extremely K deficient soil there was some loss of growth relative to uncoated KCl for 2 months, but over the next 4 months, the sulphur-coated KCl gave higher yields. Wax-coated KCl gave practically the same results as uncoated KCI. A leaching test was used to measure rate of solution of KCl and its results related well to the reduction of luxury uptake.

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The effect of preferential flow of dairy cow urine and simulated rainfall on movement of potassium through undisturbed topsoil cores

Williams¹,

Hedley²,

Gregg³

1990

Soil Res.

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Cores of undisturbed topsoil (15 cm in depth and diameter) were taken from a range of soil types to a controlled climate chamber. Urine from dairy cows was spiked with tritiated water (3H2O) and then applied to these cores which had moisture contents near field capacity. Liquid draining from these cores, as a direct consequence of urine application, contained up to 72% of the tritiated water, 74% of the potassium (K), 62% of the nitrogen (N) and 80% of the chloride (Cl) applied in the urine, indicating that urine could flow preferentially beyond the 15 cm depth in these soils. The activity of tritium and the concentrations of K, N and Cl in the effluent indicated that this preferential movement of urine occurred too quickly for sorption reactions to occur between the soil surface and the majority of solutes in the urine. After preferential flow had ceased, the amounts of K leached by subsequent simulated rain events were much smaller than losses immediately following the urine application. Leaching losses were particularly small (accounting for 3-15% of the applied urine K) when the majority of the rain water moved preferentially through the soil cores, thus bypassing the urine K which was in soil micropores or which had been sorbed by the soil. Overall, these results suggest that substantial movement of K (and N) through the topsoil of grazed pastures may occur following a urination event due to preferential flow of dairy cow urine through the soil profile, at least when soils are near field capacity at the time of urine deposition. The extent of this movement through topsoil will be more dependent upon soil structural characteristics rather than soil chemical characteristics.

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Potassium metaphosphate as a fertiliser for pastures

Cited by 4 publications

References 6 publications

Model for calculating potassium requirements for grazed pastures

Model for calculating potassium requirements for grazed pastures

A comparison of slow release potassium fertilisers for pasture

The effect of preferential flow of dairy cow urine and simulated rainfall on movement of potassium through undisturbed topsoil cores

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