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Fertasa stempel
van goedkeuring –
gesertifiseerde geloofwaardigheid
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Fertasa
– beskerm die volhoubare
gebruik van kunsmis.
Fertasa
en sy lede is verbind tot die bevordering van volhoubare
grondvrugbaarheid en verbeterde plantvoeding.
Fertasa
-lede is
verbind tot:
• ’n Gedragskode.
• Standaarde deur ’n onafhanklike nakomingsbestuursliggaam geouditeer.
• Gehalte produkte.
• Toepaslike wetenskaplik-gebaseerde aanbevelings.
• Voortgesette onderrig en verbetering.
• Die nakoming van wetlike vereistes.
The Fertilizer Association of Southern Africa NPC
Reg. Nr. 1971/000012/08 • VAT Reg. Nr. 4830104164
Tel: +27 (0)12 349 1450, Faks: +27 (0)12 349 1463
E-pos:
general@fertasa.co.za,Webtuiste:
www.fertasa.co.zaThis longer period of plant growth sub-
stantially increases the volume of plant
biomass produced, which in turn increases
organic matter additions to the soil. It also
traps excess soluble nutrients not used
by the previous crop, prevents them from
leaching, and stores (recycles) them for re-
lease during the next growing season.
Nutrients provided by
CA and enhanced
ecosystem services
Table 1
illustrates the amount of nutri-
ents potentially available to the next crop
through CA and various soil ecosystem
processes – only N, P and K are included.
As an example, an average dry matter
(crop residue) quantity of 12 t/ha (typically
produced by a mixed summer cover crop)
was used, a soil depth of 10 cm, a soil or-
ganic matter of 2,5% and soil bulk density
of 1,3 g/cm
3
.
The nutrients available to the next crop in
the example illustrated in Table 1 are freely
supplied by the soil ecosystem functions
and services that have been influenced
by the CA system; these nutrients are val-
ued at R8 315. This value will increase as
CA practices are optimised, soil organic
matter have increased and other soil eco-
system services have improved (such as
soil microbial recycling of nutrients). To
shorten the transformation period of restor-
ing these functions (e.g. in a degraded soil),
quality CA practices are needed that will
speed-up the biological process and time. In
wetter areas with clay soils this could take
three to five years, but in warmer areas with
sandy soils, it could take longer.
In Part II of this article (on page 26) a case
study from Ottosdal, North West Province
will be discussed.
References
Jones, C. 2017.
Light farming: Five principles for soil
sequestration
. Keynote address at the 5
th
Annual No-
till Conference: Victoria, Australia.
Jones, DL, Nguyen C and Finlay, RD. 2009.
Carbon
flow in the rhizosphere: Carbon trading at the soil-
root interface
. Plant Soil 321, 5 - 33.
Drinkwater, LE and Snapp, SS. 2007.
Nutrients in
agroecosystems: Rethinking the management para-
digm
. Advances in Agronomy 92, 163 - 186.
Hoorman, J and Islam, R. 2010.
Understanding soil
microbes and nutrient recycling
. Fact Sheet SAG-16 -
10, Ohio State University.