New Zealand Journal of Agricultural Research abstracts
Pasture yield responses to phosphorus, sulphur, and potassium applications on
North Otago soils, New Zealand
J. D. MORTON
L. C. SMITH
AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel, New Zealand
A. K. METHERELL
AgResearch
c/- Soil Science Department
Lincoln University
P.O. Box 84
Lincoln, New Zealand
Abstract Pasture yield responses to phosphorus (P), sulphur
(S), and potassium (K) were measured over four to eight years on different
yellow-grey earth (pallic) soils at three non-irrigated (Timaru, Kauru, and
Claremont soils) and one irrigated (Otiake soil) sites in North Otago. Large
pasture yield responses to P at application rates up to 80 kg ha-1
yr-1 occurred on three sites with initial soil Olsen P levels
of 6-11 ug ml-1, but only a small response up to this rate was
measured on the Timaru soil with a higher initial soil Olsen P level (16 ug
ml-1). The relationship between soil Olsen P and relative annual
pasture yield was similar and moderate (r2 = 0.57) for the
average of the three most responsive sites. The highest pasture yield response
to S was measured at application rates up to 80 kg ha-1
yr-1 on an Otiake soil with an initial soil sulphate S level
of 3 ug g-1. Smaller pasture yield responses at rates up to 40 kg S
ha-1 yr-1 occurred on Kauru and Timaru soils with initial
soil sulphate S levels of 8 and 4 ug g-1, respectively. In four of
the eight years there was a pasture yield response up to 10 kg S
ha-1 yr-1 on the Claremont soil with an initial soil
sulphate S level of 9 ug g-1. Soil sulphate S only accounted for a
small proportion (27%) of the average variation in relative yield. Three of the
four sites had medium to high initial soil quick test (QT) K levels (9-19) and
the fourth (Otiake soil) had a low level (4). Over four to eight years, the
soil QT K in the nil K treatments declined to 2-7, but there was a pasture
yield response only in the last four years at the lowest level, on the Otiake
soil. Soil potassium tetra-phenyl boron levels were increased by K application
and showed a lower decline than for no K. There was a moderate to strong
relationship measured between relative yield (% of maximum yield) and %P
(r2 = 0.58) and %S (r2 = 0.83) in mixed
herbage on the Otiake soil but not at the other sites. %P was related to Olsen
P (r2 = 0.52-0.69) on the Claremont and Otiake soils and %S
was related to soil sulphate S (r2 = 0.51) for the mean
of all four sites. Overall, the results show that North Otago yellow-grey earth
soils can be responsive to P, S, and K, and the size of the pasture yield
response can be predicted with a reasonable degree of accuracy by the level of
available soil P, S, and K, the amount of soil reserve K, and the P, K, and S
concentration in mixed herbage.
Keywords pasture yield response; phosphorus; sulphur;
potassium; soil Olsen P; sulphate S; K quick test; pasture analysis
New Zealand Journal of Agricultural Research, 1999, Vol. 42: 133-146
0028-8233/99/4202-0133 $7.00/0 (c) The Royal Society of New
Zealand 1999
PDF file of entire paper: medium quality (881K); (scanned from paper original: notes about this process)
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