Table 1: Available organic and inorganic nutrients (kg/ha) and value (R/ha) in a soil under
warm season cover crops
Cost
R / Kg Nutrient Nutrient value
(kg/ha) Total Organic Inorganic
17 Nitrogen 23.3 R 396 R 133 R 263
40 Phosphorous 42.5 R 1 700 R 72 R 1 628
15 Potassium 209.7 R 3 146 R 0 R 3 146
R 5 242 R 205 R 5 037
Saving
Table 2: Available organic and inorganic nutrients (kg/ha) and value (R/ha) in soils under
cool season crops
Price
R / Kg Nutrient Nutrient value
(kg/ha) Total Organic Inorganic
17 Nitrogen 19.9 R 339 R 156 R 183
40 Phospho-
rous 54.6 R 2 185 R 84 R 2 101
15 Potassium 285.6 R 4 284 R 0 R 4 284
R 6 808 R 240 R 6 568
Saving
Table 3: Salient analytical data for the degraded soil taken during the growing season of a
summer cover crop mix
Soil pH (H2O) 7,3
Soluble Salts mmho / cm 0,3
Excess lime rating 1
Soil Organic Matter (SOM), LOI % 0,8
Calcium ppm 187
Aluminium extractable ppm 651,6
Phosphorous Saturation % 4,6
Iron extractable ppm 378
Table 3 shows that phosphorous saturation is below 5% which indicate that additional inorganic
phosphorous fertiliser is needed. With less than 1% SOM the soil can be seen as highly degraded
due to a long period of continuous tillage
practices. The establishment of a multi-specie
CC system are seen and applied as the start
of a process to build-up the degraded soil,
which could take up to 7 years or more,
depending on the situation and the quality
of CA application, the soil type and the
climate. However, it is anticipated that this
type of CC system, rotated every second year
by a cash crop producing high amounts of
residues (such as maize), could quickly restore
soil ecosystem functions and decrease the
rehabilitation or transformation period to 3 or
4 years.
AgriKultuur |AgriCulture
In a high temperature, low rainfall
environment such as Ottosdal, the high
amounts of CC residue would almost
immediately have had a positive effect on the
soil water content with much higher infiltration
rates and much less water loss through
evaporation. During the following few years,
the presence of a diversity of plant roots in
the soil will most probably have a positive
impact on soil microbial diversity and activity,
including mycorrhizas, which are highly
dependent on a host and living roots.
These effects are currently being measured
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