Nutrient studies in potatoes (Solanum tuberosum)
Loading...
Date
1997
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
One of the biggest problems facing potato (Solanum tuberosum) production in
Kwazulu-Natal is acidic soils with high a aluminium content. Traditionally, such
soils were ameliorated using lime, thus increasing soil pH, Ca and Mg availability,
and reducing Al availability. This study aims to determine the extent to which lime
could be replaced by Calmag+B (a Ca source with little ameliorative capacity).
The Calmag+B fertiliser increases the soil's Ca content appreciably, but does not
alter soil pH and Al availability to the same extent as lime. Pot trials were carried
out to determine the effects of liming a highly acid soil, resulting in four levels of
amelioration. At each level of amelioration, three levels of Calmag+B were
applied to determine whether an optimised yield response would be attained
through these applications. Plant emergence and subsequent development was
shown to be poor, and in extreme cases absent, under highly acidic soil
conditions. Soil amelioration using lime greatly improved plant emergence,
development and tuber yield, whereas Calmag+B applications were unable to
improve plant emergence, development or tuber yield. The effect of both
applications of substantial quantities of Calmag+B to a highly acid soil, and of the
dipping of mother tubers in a nutrient solution prior to planting was investigated.
The Calmag+B soil applications were unable to improve plant emergence and
development. The dipping of the mother tubers in nutrient solution, however,
resulted in greatly increased seedling emergence and plant development. This
was due to increased nutrient uptake from the mother tuber, and not through
increased root development and subsequent nutrient uptake.
There were unsubstantiated claims by the manufacturers of Calmag+B that the
Mg, NO(3) and B components of the fertiliser would give rise to increased uptake
of the Ca component, thus enhancing the efficacy of the fertiliser. Pot trials using
a sand medium were employed to test this claim. The trial consisted of
interactions of different levels of Ca(2+), Mg(2+), NO(3-), and BO3(2-) applied to the sand
medium in the form of a nutrient solution. None of the treatments (barring Ca
itself) led to increased Ca uptake by the potato tubers. This would indicate that
the claim that the Mg, NO(3) and B components of Calmag+B fertiliser would
enhance the uptake of the Ca component are unfounded.
It has been suggested that one of the main factors limiting potato production in
Kwazulu-Natal has been inadequate mineral nutrition. Certain fertiliser
distributors claim that fertiliser application over and above the levels
recommended by the Kwazulu-Natal Department of Agriculture Fertiliser Advisory
(KDAFA) is the solution to the problem of below potential yield and tuber quality in
the province. A field trial was carried out in New Hanover (Kwazulu-Natal), using
different levels of Calmag+B and Agrifos, as well as one level of application of
KNO(3). All treatments were applied after KDAFA fertiliser recommendations had
been fulfilled. At the 95% level of significance, the treatments did not give rise to
increased yield and tuber quality. At the 80% level of significance, however, the
results indicated that applications of 100kg ha -1 of Calmag+B and KNO(3) would
give rise to increased tuber yield.
Description
Thesis (M.Sc.Agric.)-University of Natal, Pietermaritzburg, 1997.
Keywords
Potatoes--KwaZulu-Natal., Potatoes--Nutrition., Potatoes--Effect of soil acidity on., Liming of soils., Soil amendments., Theses--Crop science.