Field Research Brief No. 17
September, 1985


Title : Sulfur Responses and Reactions in Soils of Sumatera

Researchers: E.J. Kamprath,' M.K. Wade, and Heryadi

Justification: Little information is available on the sulfur (S)
status and response to S fertilization on highly weathered soils
in Sumatra. Sulfur deficiencies and responses to S fertilization
have been reported for soils in Java, as well for soils in
Sulawesi. The likelihood of S becoming a limiting nutrient in
these soils is quite high, once correction of N,P,K and lime
deficiencies has occurred, since none of the major sources of
fertilizers used in the area contain significant quantities of S.
Development of sound fertilizer management systems must include a
knowledge of the S status of soils in the area.

Objectives.

1. To determine sulfate and total S levels in Sitiung soils
cultivated for some time (5+ years) and in those recently
cleared.

2. To examine the response of grain and legume crops to S
fertilization on both recently cleared soils and soils which have
been cultivated for more than 5 years.

Soils: 1. The recently cleared soil is a clayey, kaolinitic,
isohyperthermic orthoxic tropudult on the new CSR
e-xperiment station. The experimental site was cleared
in August, 1984 by hand.

2. The soil which has been cultivated is a clayey,
kaolinitic isohyperthemic typic haplorthox near
SSitiung II E. It was cleared by bulldozers in 1978
and has been cropped'with upland rice each year
Since then.


Data for both soils is shown in appendix 1.

Treatments : This experiment, a randomized complete block design
with three replications, examines rates of S applied both
initially only and to each crop which is grown. For the
first crop (corn), the rates applied initially only are the
same as those applied per crop : 0, 10, 20 and 40 kg S /ha
applied as CaS04. The mung beans to follow will be grown
with S rate applied to them (per crop application), as well
as with the residual S rate applied to the corn. The corn
crop, however, had rates of S applied prior to planting as
the only factor.







Tmt Code


A
B
C
D
E
F
G


CROP HISTORY:


S rates
(kg/ha)


Application time


First crop only

Each crop
Each crop
11
I1


Cargill C1 hybrid corn was planted in December,
1984, at a spacing of 25 X 75 cm. Base
fertilizers applied (kg/ha) included 300 urea,
100 KC1, 750 TSP, 25 MgO, 20 ZnSO4*7H20 and 10
H3B04. The crop was harvested in April, 1985.


Data to be collected:
1. Height, stover and grain yield.
2. Stover and grain nutrient analysis.
3. Soil analysis for 0-15, 15-30 and 30-45 cm depth.

Results: A strong drought during flowering and grain fill
severely decreased yields at both locations, but stress was more
severe at the cultivated (Sitiung II E) site. Data for both
locations are shown in Tables 1 and 2. No significant treatment
effects were observed with the crop response data, although
there was some response to S at the cultivated site, and in both
locations there was a tendency for grain:stover ratio to go up
with S rates. It is hoped that soil analysis data currently being
processed will give a better understanding of what the S status
of these soils is. Although soybeans were planned as the second
crop in the rotation due to the impending dry season, mung beans
were planted instead. It is hoped that this crop will give more
information about S management in the area, since this time the
experiment not only has rates of S, but also residual rates of S.


Table 1. Effect of rates of S on corn height, stover and grain
yield and grain:stove ratio on a newly cleared udult.


Height
(cm)

238
238
238
244


stover
(t/ha)

6.11
6.91
6.91
5.26


grain
(kg/ha)

1408
1738
1672
1656


grain: stover
ratio

.23
.25
.33
.31


S rate
(kg/ha)

0
10
20
40










Effects of rates of S on corn height, stover and grain
yield and grain:stover ratio on a soil cultivated for
some time.


S Rate
Kg/ha

0
10
20
40


Appendix


Height
cm

183
178
188
178


Stover
t/ha

3.56
3.47
3.62
3.21


Grain
kg/ha

407
618-
966
700


1. Soil characteristics at the
cultivated sites.


Grain Stonerr
ratio

.12
.18
.27
.22


newly cleared and


Soil Depth pH A1+H Ca+Mg K P Acid Sat.

cm meq/100 ml ppm
--------------------------------------------------------------
Newly cleared 0-15 4.1 2.17 0.3 0.16 7.0 83
15-30 4.2 1.74 0.3 0.11 4.0 81
30-45 4.3 1.36 0.3 0.07 4.0 83

Cultivated 0-15 4.3 2.24 1.0 0.07 9.0 68
15-30 4.3 2.32 0.5 0.06 0.7 81
30-45 4.3 1.80 0.4 0.06 0.0 80
--------------------------------------------------------------


Table 2.