Table 1. Number of soil samples in each soil-S category from seven provinces in Java and Sumatra.
<30 30-50 >50 Total
Province (m S/kg)
West Java 6 3 8 17
Central Java 11 I 1 13
East Java 11 1 3 15
Lampung 4 0 0 4
South Sumatra I 0 1 2
Jambi 0 0 2 2
West Sumatra I I 2
Total 34 5 16 55
evaluation of soil-S status. Easy, rapid, and accurate methods of determination of S should be investigated, so that mOre samples could be studied.
Soil test/crop response correlation studies and field verification trials need to be conducted to verify the critical limits of sulfur in soils for upland crops.
Plant-S uvels of Upland Crops Yazawa (1985) found that of 81 soybean leaf samples collected from Java and Sumatra, 17.30/0 were deficient «0.1 %8) and 50.6% had less than 0.15%8. These data suggest that S-deficiency is a potential constraint in soybean production and will Table 2. Number of soybean leaf samples in each plant- S category from seven provinces in Java and Sumatra.
Province <0.1070 S >0.1070 S Total
West Java 2 19 21
Central Java 8 11 19
East Java 2 16 18
Lampung 2 4 6
South Sumatra 0 2 2
Jambi 0 4 4
West Sumatra 0 11 11
Total 14 67 81
be aggravated by intensified agriculture. The S-plant status in each province is presented in Thble 2.
In West Java 2 out of 21 soybean leaf samples (or 90/0) contained less than 1% S, whereas in Central and East Java the low S level in soybean leaf were found in 42070 and 11% of samples. respectively. This indicates that S-deficiency could be expected to occur more frequently in Central and East Java than those in West Java. In Sumatra only 2 out of 23 soybean leaf samples collected contained less than 0.1 % S.
These plant S data generally support the soil S data presented in Table 1.
Upland rice samples collected from several locations in Lampung province in the 1985-86 rainy season contained from 0.087 to 0.150% S and from 0.040 to 0.064% S for straw and grain, respectively.
Although the S concentrations of upland rice plant tissues were low, no S-deficiency symptoms appeared in the fields.
Research in the BORIF/ACIAR Project has found that S concentration in plant tissues can vary markedly between crops, seasons and sites (Tables 3, 4 and 5).
In the rainy season (RS) crop at Muneng the S concentration was higher in the leaf than the stem at silking and higher in the stover than grain at maturity (Table 3). The S concentrations in leaf and stem were similar in the dry season (DS) crop at silking at Muneng, but higher in stem than leaf at Pekalongan. The grain S concentration was more constant across treatments than other tissues (Table 3).
The S concentrations of upland rice samples from a field experiment at Pekaiongan in the 1987-88 rainy season where no S response was recorded were 0.058% in brown rice and 0.103% in straw.
In cow pea and Dolichos lab lab, the S concentration of the stover was found to be higher than the seed and seed-S was more sensitive than stover-S to S application.
Critical limits of S concentration of plant tissues
Table 3. 8ulfur concentration in corn plant tissues grown in different locations and seasons.
At silking At harvest
LocationlCrops
Leaf Stem Stover Cob Grain
Muneng
Corn RS 87/88 -8 0.171 0.149 0.101 0.034 0.092
+S 0.205 0.148 0.111 0.034 0.090
Corn OS 88 -S 0.093 0.085 0.054 0.028 0.081
+S 0.097 0.084 0.058 0.029 0.081
Pekalongan
Corn OS 87 -S 0.132 0.154 0.096 0.037 0.089
+S 0.134 0.161 0.093 0.037 0.095
in upland crops are still incomplete and plant analysis for S needs to be standardised.
Measurement of the S content of plant products and residues can give estimates of the longer-term consequences of differing fertilization practices. An example of S taken up by corn plants at Muneng in the 1987-88 rainy season is presented in Table 5. Total S uptake of corn plants at harvest ranged from 7.82 to 10.32 kg S/ha. The amount of S in the grain was higher than that in the stover (leaf
+
stem+
cob), at an average grain yield of 3962 kg/ha. The addition of S did not significantly increase S uptake. The S balance was negative when stover was removed or returned in the absence of fertilizer S.The relationship between grain yield and S uptake is presented in Fig. 1. Approximately 6 kg S/ha are present in the tops in a crop of 3 tlha. The amount of fertilizer S required to produce this yield will depend on the efficiency of uptake and the contribution from sources such as rain or irrigation water and plant residues, and losses via leaching and soil erosion.
Research on the S requirement of upland crops needs to be strengthened and the monitoring of S additions and removal should be expanded to enable prediction of long-term S requirements.
Plant Response to S Application Reports on plant response to S application are incomplete. Variable responses have been recorded in experiments conducted in different areas in Indonesia.
Two field experiments have been conducted at Muneng, East Java and Pekalongan, Lampung, for several seasons to test the effects of P and S application on several upland crops. The results are presented in Tables 6 and 7. Corn yields in the first
12 S uptake. -2.14 + 2.71 yield (tlha) (kg S!ha)
11 r 0.6776"
10 - 9 8 7 6 Cl
o
2_6 2_8
[J
o 0
DD o
o
o o o
0 0
'b ,,0 o :J C 0
o
3.2 3.4 3.6 (Thousands) corn yield (kg/ha)
o
o o
o
o o
4 4_2 4.4 4_6
Figure 1. Sulfur uptake as a function of corn yield at Mumeng, East Java. RS 1987-1988.
and third seasons increased with S application when no P was applied. The most significant increase in yield occurred in the last season. The response to S, however, became inconsistent when P was applied.
This may be the result of the P application increasing soil-S availability through desorption.
The response of several crops to P and S was studied in a rotation at Pekalongan, Lampung.
Generally, there was no significant difference between yields from different treatments in different crops or seasons.
No response to S was recorded in soy bean grown under glasshouse conditions on six soils taken from Table 4. Effects of S application on S concentration (070) in plant tissues of cowpea and Dolichos lab lab.
Location Treatment Seed Stover
Pekalongan
Cowpea -S 0.103 0.159
+S 0.113 0.162
Muneng
Dolichos -S 0.086 0.136
+S 0.121 0.128
Table 5. S inputs, outputs and balance (kg/ha) in a corn crop grown at Muneng, E. Java in the 1987-88 rainy season and fertilized with 32 kg P Iha and varying rates of S,
kg/ha Inputs
Fertilizer S 0 16 32
Outputs
Grain 3.75 3.99 3.96
Stover + cob 4.03 6.33 4.50
Balance
Stover removed 7.78 + 12.01 +28.04 Stover returned -3.75 + 5.68 23.54 Table 6. Corn yields as affected by P and S application in different seasons at Muneng, East Java.
P S RS85/86 RS86/87 RS87/88
(kg/ha)
0 0 3242 3767 2968
8 3578 3655 3581
32 3896 4085 4033
16 0 3406 3500 3638
8 3087 3560 3788
32 4008 3732 3666
64 0 3148 3827 3495
8 4076 3586 3995
32 3440 3492 4072
(SO- 867 772 674
a Least significant difference P = 0.05.
Table 7. The effects of P and S fertilizers and their residues on crop yields under rotation at Pekalongan, Lampung.
P S Corn Cowpea Upland Corn Cowpea Upland
RS85/86 DS86 rice DS87 DS87 rice
RS86/87 RS87/88
(kg/ha) (tlha)
0 0 3.92 0.36 2.19
8 3.86 0.22 2.12
32 4.61 0.20 2.32
16 0 4.74 0040 2.63
8 4.10 0.21 2.54
32 4.82 0.30 2.30
64 0 4042 0.14 2.66
8 3.96 0.40 2.11
32 4.91 0045 2.15
LSoa 0.76 0.33 0.65
a Least significant difference P = 0.05.
Lampung (Gunung Sugih, Jabung, Sidomulyo, Sukadana, Abung Selatan, and Pekalongan).
Another study of S responses in upland rice grown on 11 soils from West Java under glasshouse conditions showed no response to S in any soil.
Response of soybean to S application was reported from a Vertisol at Ngaie, East Java (Yazawa, 1985).
Willis variety produced 20.0 g grain/pot and 98 pods per plant if S was applied. Without S application, the grain yield and pod number produced were reduced to 11.9 g/pot and 65 pods per plant, respectively.
The large variation of response of crops to S application in Indonesia could be due to the large variation in soil conditions including soil-S status and inputs of S from other sources, crop requirement and their sensitivity to S stress, climate, and management.
Evaluation of S inputs and outputs in cropping systems is needed if better recommendations of sulfur fertilization are to be made.
Conclusion
1. A limited number of S trials on upland crops in Indonesia indicate S deficiency may occur only in several locations in Central and East Java.
0.53 0.29 1.69
0.65 0.72 2.12
0.68 0041 1.66
1.33 0049 1.96
1.07 0.36 1.73
1.22 0.34 2.16
0.96 0.57 2.09
0.89 0.26 2.32
1.71 0.65 2.02
0.59 0.30 0048
2. There is insufficient research data available to delineate S-deficient areas of upland crops.
3. The requirement for S and the utilisation of soil and fertilizer-S varies among upland crops.
4. In view of increased cropping intensity and application of S-free fertilizers, S deficiency is likely to become a limiting factor.
References
Elkins, D.M. and Ensminger, L.E. 1971. Effects of soil pH on the availability of adsorbed sui fate. Soil Science Society of America Proceedings 35, 931-934.
Ismunadji, M. and Partohardjono, S. 1986. Nutrient status of the soils of Lampung, Indonesia. Technical meeting of the Technology Development Group, Cipayung.
September 9-10, 1986. (In Indonesian).
Kamprath, E. J., Nelson, W. L. and Fitts, 1. W. 1957.
Sulphur removed from soils by field crops. Agronomy Journal 49, 289-293.
Santoso, D. 1987. Towards increasing phosphorus and sulphur fertilization efficiency for upland cropping systems on tropical acid soils. Progress report. External review of ACIAR Project in Bogor, Indonesia. July 29-31, 1987.
Yazawa, F. 1985. Physiological disorders of soybean. Expert report. The strengthening of Legumes in Relation to Cropping System Research Project (ATA 218). 71 pp.