TITLE:
Feasibility of a New Granular Rapid Release Elemental S Fertilizer in Preventing S Deficiency of Canola on a S-Deficient Soil
AUTHORS:
Sukhdev S. Malhi, Cecil L. Vera, Stewart A. Brandt
KEYWORDS:
Canola, Elemental S, N Uptake, Oil, Protein, Seed Yield, Sulphate-S, S-Deficiency, S Uptake
JOURNAL NAME:
Agricultural Sciences,
Vol.5 No.11,
September
26,
2014
ABSTRACT: Our previous research has indicated that granular elemental S (ES)
fertilizers are not effective in the year of application and also are not
consistently as effective as sulphate-S in increasing seed yield of canola in
subsequent years, especially when applied at seeding in spring, because of slow
dispersion of elemental S particles from granules for subsequent oxidation of
ES to sulphate-S. A field experiment was established in autumn 2010 to determine the relative effectiveness of a new rapid release elemental S
(RRES, now called Vitasul) fertilizer, in comparison to sulphate-S fertilizer, with
various combinations of application times
and placement methods (applied at 20 kg·S·ha-1) on seed yield, straw yield, oil and protein concentration in seed, N and
S uptake, partial factor productivity (PFP—kg·seed·kg-1 applied N·ha-1—blanket application of 120 kg·N·ha-1), S use efficiency (SUE—increase in kg·seed·kg-1 applied S·ha-1) and percent recovery of applied S in seed + straw
(%) of canola in 2011, 2012 and 2013 growing seasons on a S-deficient Gray Luvisol loam soil at Star City, Saskatchewan. The
11 treatments included two granular S sources (RRES and potassium sulphate) and
five application time/placement method combinations (broadcast in autumn and
incorporated in spring, broadcast in spring pre-tillage [broadcast and
incorporated], broadcast in spring pre-emergence, sideband in spring and
seedrow-placed in spring), plus a zero-S control. There was a significant response of seed yield of canola to applied S in
all 3 years, but the responses varied with S source and with application
time-placement combinations in different years. Seed yield increased
considerably with all sulphate-S treatments compared to the zero-S control,
although seed yield tended to be slightly lower in some spring and/or autumn
broadcast treatments than the other sulphate-S treatments. Compared to the
zero-S control, seed yield also increased significantly with all RRES
treatments, but the increase was greater with autumn applied RRES than the
spring applied RRES in many cases. Autumn applied RRES produced only slightly
lower seed yield but spring applied RRES produced much lower seed yield than
the highest yielding spring applied sulphate-S treatments. In 2011, straw
yields increased significantly with applied S in some S treatments, but there
was no significant effect of S fertilization on straw yield in 2012 and 2013.
Oil concentration in canola seed increased only with sulphate-S fertilizer
treatments in 2011, and it increased with both sulphate-S and ES sources in
2012 and 2013. There was no effect of any S treatment on the protein
concentration in canola seed. The response trends of total N uptake and PFP
were usually similar to seed yield for both S sources, but total S uptake, SUE
and % recovery of applied S were lower with RRES than sulphate-S in many/most
cases. In conclusion, the findings suggested the potential of spring broadcast
pre-emergence RRES or autumn broadcast RRES in preventing S deficiency in
hybrid canola, although seed yields were still slightly lower than the ideal
highest yielding spring broadcast/incorporated sulphate-S treatment.