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This green fallow with pasture ley crops serves the function of
restoring soil health after long periods of continuous cropping with
grain cash crops and provides the additional value of grazing or hay
for cattle. Grass pastures in particular have the ability to suppress
other weed species reducing the cost of chemical control.
Once this pasture ley crop has served its purpose, it can be killed
chemically followed by a no-till practice to plant cash crops. Pasture
ley crops containing a legume are extremely valuable and address
the widespread deficiency of nitrogen for both plant and animal
production.
The incorporation of legumes into grass pastures, or the solitary
use of legume pastures are valuable, because they establish eas-
ily – especially after a short crop phase. These legumes contribute
to appreciable levels of biological N in the soil and particularly to
subsequent crops.
These legume crops are also easily controlled as required in the
crop phase and they contribute to good lightweight gains in cattle
grazing systems. Prospects for widespread commercial use of ley
systems are considered as a strengthening of the economic viabi-
lity of grain cropping in various regions of South Africa.
Biological benefits
Producers urgently need to manage a number of serious environ-
mental challenges facing grain crop production systems, such
as soil health decline, soil erosion, biodiversity loss and
climate change.
Ley crop systems have the ability to stop and reverse all these
detrimental processes. It can restore critical ecosystem functions
and services by improving soil organic matter, fertility and soil s
tructure with the establishment of strong, living root systems.
The soil fertility improvements, especially the addition of nitro-
gen from legume pastures through N fixation, make the following
cropping phase more profitable. Research has shown that a good
legume pasture stand can contribute the equivalent of 10 kg to 90 kg
N/ha (Jones
et al
. 1983; McCown
et al
. 1986).
It improves water infiltration and –storage, leading to stable higher
yields of the following cash crops, even during dry periods. With
low overhead costs, a pasture ley crop can still ensure good profits
per hectare, while improving the various ecosystems such as soil
and reducing the risks.
Economic comparisons, analysis and value
When considering the alternative use of cultivated land, especially
for a forage cover crop or short or long-term pasture, it is impor-
tant to calculate the potential income and subtract the estimated
cost of production.
For example, livestock running costs and profits should be com-
pared to grain crop costs and profits. The costs of running live-
stock on the pasture ley crops can be considerable if livestock is
bought and brought onto the property, specifically to fatten them
on forage or pasture. When livestock is already on the property, at
least 50% of the transport costs are covered and the capital required
to purchase livestock does not have an immediate cash flow impact.
It should be noted that in most cases breeding cows are less profit-
able than fattening weaner calves. It is also difficult to calculate profit
from dairy cows, since pasture quality remains the determinant fac-
tor on a year-on-year basis.
Supplementing livestock on winter pastures and proposed grazing
system costs (fencing and drinking water provision) also need to be
included as a cost item on the overall farm feed budget. Addition-
ally, overhead costs of machinery, labour and administration need to
be considered.
Fortunately, pastures have much lower costs of depreciation and
labour. With changes in the labour, machinery and administration
costs, it is better to examine the income potential and costs on a
whole farm basis, rather than per hectare and over the short- or long-
term period of the pastures or forage cover crops. If there are no
major changes in the aforementioned costs, the profit per hectare is
a good starting point.
The subsequent soil health improvement from a pasture ley crop is
not easily quantified and mostly excluded from the profit calcula-
tion. It can possibly be realised in the improved profit gained from
the successive grain crop production. It is also essential that realistic
assumptions be made when introducing pasture ley crops, i.e. the
possibility of a dry year when forage yields are lower and the grazing
periods shorter.
Old cultivated lands or marginal lands could possibly have low
nitrogen levels and will require a fertiliser input that can potentially
make the system uneconomical. This scenario does provide the op-
portunity to introduce a legume which can over time contribute to
the soil nitrogen levels.
Hypothetical scenario (model prediction)
This scenario assumes that a producer has 1 000 ha of cultivated
land with 75% under cash crops (in this case maize and soybeans)
and 25% under Smuts Finger grass planted pasture (
Graph 1
on
page 71
).
In year one, 650 ha of maize are planted, 300 ha of soybeans and
50 ha of Smuts Finger grass (with no grazing in year one). In year
two the process is repeated, except that the first-year grass can be
moderately grazed.
This conversion process is repeated so that by year five, at least
25% of the cultivated land is planted to a grazing crop. It should be
stated that in an ideal CA rotation system a third crop such as sun-
flower will have to form part of the cash crop rotation.
Planting two crops for a successive 19 years is not regarded as
sustainable in CA. Ideally, annual cover crops should be included
every third year.
A practical layout is represented in
Figure 1
(on page 71), where a
1 000 ha of cultivated land are hypothetically broken down into
50 ha fields (known not to be the case, but the concept is illustrated).
The 1 000 ha are therefore broken down to 20 fields.
From this process it is illustrated that a cash crop to grass conver-
sion factor of 75%:25% is considered, fields would be planted to
grass in year one, grazed for five years and re-introduced to cash
crop production for 15 years, to then only be planted to grass again
in the 20th year.
This conversion process will have economic implications, with the
cash flow restriction probably being the most obvious one, since
the capital investment in an intensive grazing rotation is higher than
conventional cash crop production.
From
Graph 2
(on page 71
)
it is evident that the grazed Smuts
Finger pasture’s gross margin per hectare can break-even in year
three, and from there on, it has a higher return per hectare than
that of maize and soybeans.
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