Crops Respond to SULPHUR?
to applied SULPHUR were first found on second-cut silage in the early
1980s. Recently, responses have been found consistently in oilseed
rape grown on light land, especially in East Angola and the southern
In the past two years, yield increases have been found in winter wheat
and first-cut silage. Trial results go back to 1984 where responses
were monitored on wheat, rape and silage from research funded by Hydro
Last year, yield responses from first-cut silage showed an average
increase of 1.04 tons of dry material/ha, worth about L80/ha for
a cost of L3-5/ha for SULPHUR.
Leaf tissue tests can give an accurate picture of SULPHUR availability
and are best taken when crops are just coming into flower, because
it is at this stage they will have taken up all their needs.
Current advice suggest supplementation is needed in oilseed rape if
total content is below 0.4%.
For wheat, leaf samples should be taken on leaves two and three immediately
below the flag. SULPHUR deficiency is possible where the nitrogen:SULPHUR
ratio is greater than 17:1, and SULPHUR content less than 0.12% in
the dry matter of the grain or below 0.25% in leaf tissue.... total
SULPHUR is below 0.25.
to Check for SULPHUR Deficiency
Without adequate SULPHUR, crops cannot reach their
full potential in terms of yield, quality or protein content. Nor
can they make efficient use of applied nitrogen.
a sharp eye
When fed to livestock, SULPHUR deficient forages can reduce animal
With today's variety of fertilizers and application techniques,
SULPHUR deficiency is easy to prevent and correct. But it's
not always easy to identify.
To prevent unexpected losses from SULPHUR deficiency, and to get
an accurate reading of SULPHUR requirements, you'll need to check
deficiency - like shortages of other nutrients - leaves its own distinct
mark. SULPHUR - deficient crops are typically small and spindly,
with short and slender stalks. New leaves turn yellowish - green
in color, with even lighter - colored veins.
These symptoms can be easy to recognize - if SULPHUR deficiency
is the crop's only problem. Unfortunately, SULPHUR deficiency is often
accompanied by shortages of other nutrients, which can mask these
"text book" symptoms.
Other diagnostic measures will be needed to positively identify SULPHUR
deficiency, but learning to recognize its symptoms will give you an
edge and help reduce your losses.
Ask about soil
tests for SULPHUR
SULPHUR is a mobile nutrient that moves rapidly in the soil.
A soil test will therefore provide a general indication of your SULPHUR
reserves, but the information gathered should only serve as a basis
for your diagnosis.
Not all labs are equipped to test soils for SULPHUR, and those that
are may do it by special request only. Be sure to specify SULPHUR
when sending in your samples. Also, check with your soil lab
for sampling guidelines, as they may want soil from various depths.
For example, 0 - 6 inches, 6 - 12 inches, 12 - 24 inches.
on Plant Analysis
analysis, or tissue test, is regarded as the most accurate means of
measuring SULPHUR. The information is especially useful when
combined with soil-test results.
Agronomists generally recommend sampling plants early in the season
so corrective measures can be taken. Check with your testing
lab for specific sampling procedures and timing.
Tabs on N:S Ratios
shows that, for optimum performance and efficiency, plants should
contain 1 part SULPHUR(S) for every 15-20 parts Nitrogen(N).
If the results of your plant analysis show a N:S ratio greater than
15:1, your crop could benefit from SULPHUR fertilization.
Likewise, if the N:S ratio is borderline, consider what it might be
after you apply additional nitrogen - without SULPHUR. University
research shows that applying nitrogen alone can sometimes induce SULPHUR
crop respond well to applied nitrogen? If not, it could signal
SULPHUR deficiency. In one university field trial, a hay crop
had failed to respond to 150 pounds N. But when the same crop
was fertilized with 33 pounds of SULPHUR, the crop yield nearly tripled.
Similar results have occurred on wheat, corn and canola. Make
sure your SULPHUR use keeps pace with your nitrogen rates.
Protein up to Par?
plays an important role in protein synthesis. If your grains
and forages have been testing low in protein, your crops may not
be getting enough SULPHUR.
A small investment is SULPHUR could have a dramatic impact on protein
levels, while reducing your needs for expensive protein supplements.
naturally remove high levels of SULPHUR from the soil. If
you've enjoyed bumper crops in recent years, your land could be
on the verge of a SULPHUR shortage.
Scrutinize Fertilizer Records
Unlike the fertilizers used 10 - 20 years ago, today's popular,
high-analysis grades of nitrogen, phosphorus and potassium do not
contain significant amounts of SULPHUR.
If you've been fertilizing with such popular materials as urea,
anhydrous ammonia, nitrogen solutions, tripplesuper phosphate, DAP
or muriate of potash, your crops may not be getting as much SULPHUR
as they did in previous years.
- control regulations have reduced SULPHUR-dioxide pollution by
about 30 percent. That's good news for the environment, but
it also means that crops are getting less "free" SULPHUR from the
atmosphere. In high-yield situations, this can result in SULPHUR
deficiency - even on farms near industrial areas.
Does your crop still get enough "free" SULPHUR to support your production
Traditionally, soils that are coarse in texture and/or
low in organic matter are most susceptible to SULPHUR deficiency.
If your soils meet this description, the odds are good that your
crops will benefit from SULPHUR fertilization - even if there are
SULPHUR reserves beneath the sandy topsoil. Traffic pans or
soil acidity may prevent root penetration into the subsoil and reduce
Farmers with fine-textured, clay soils should also be careful, as
intensive land use makes all crops vulnerable to SULPHUR deficiency.
Don't Over look
temperatures can limit root development and reduce SULPHUR availability
- even in heavy soils with rich SULPHUR reserves.
Whether topdressing a winter crop or just getting an early start
on spring planting, always consider soil temperature and nutrient
availability. Conservation tillage situations can also produce
cooler soils. SULPHUR may be needed to stimulate early growth
and nurse the crop through this stressful period.
Gauge Your Rainfall
SULPHUR can be leached from the topsoil by heavy rains. Irrigation
can also carry SULPHUR beyond the reach of crop roots.
If your crop needs a mid-season application of nitrogen. It
also might benefit from SULPHUR.
a Test Plot
not have the time or equipment to fuss with a scientific field trial,
but leaving a check strip or putting out a few test plots will give
you a glimpse of SULPHUR's impact on crop yield, quality and protein.
Before you start, check with your local crop specialist or fertilizer
dealer about the difference between elemental and sulphate SULPHUR
materials. Using the right source at the right time will ensure