Incidental S Inputs in Rainfall and Irrigation Water

burning of organic matter and fossil fuel, which is almost entirely controlled by man's activity.

Proximity to tbe coast

The effect of distance from the coast can be seen from data collected over a 12-month period along a transect from the Australian east coast city of Coffs Harbour to the town of Bourke, about 700 km inland (Fig. I). The first three sites, all within 40 km of the coast, have very similar rainfall of over 2000 mm and yet the accession of S drops from over 22 kg SI ha at the coast to less than 7 kg S/ha within 13 km of the coast.

Weather conditions

The effect of the prevailing weather conditions can be seen from the S accession maps for Peninsular Malaysia (Fig.2). Figure 2b is for the period when the most active storms of the N.E. monsoon affect the east coast. The effect is an increase in S accession along the east coast and for much of the rest of the country, excluding the Cameron Highlands. Figure 2a is for the S-W monsoon period, which produces much less violent storms, due largely to the protection afforded by Sumatra. Figure 2c is later in the N-E monsoon season when, although the accession on the east coast is much lower than in the previous period, it is still evident that the monsoon is having an effect.

An experiment to investigate the S reponse of lowland rice on the east coast of Malaysia was set up in October 1988. One month after transplanting there was clear evidence of a response to S. At maturity, however, there was no evidence of the response. The rainfall accession data allowed us to estimate that between 5 and ID kg S/ha had been deposited in the rain during the life of this crop and this appears to have been sufficient to overcome the low S status of the light textured soil in which the experiment was carried out.

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Figure 1. The accession of S (kg/ha) (solid line) and the rainfall (broken line) on a transect from eoffs Harbour to Bourke, NSW.

Fossil fuel burning

The effect of the urbanised and industrialised inputs from Kuala Lumpur/Petaling laya and 10hore BarulSingapore can be clearly seen in Figure 2, particularly Figure 2c. The effect of other agro- industrial inputs, such as from the burning of

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rich oil palm residues cannot be specifically identified, due to its diverse distribution, but it is thought that this may be an important source of atmospheric S.

Indonesian data

A set of rainfall collectors was established at meteorological stations and experimental sites in December 1988. Results from the first 2-month collection period are shown in Table 1. The accession of S ranged from less than 0.1 kg S/ha to over 2.5 kg SI ha with a rainfall range of 300-1300 mm. From these two data sets it is possible to calculate that there was a very large range in the concentration of S in the rain, from 0.005-0.37 ppm.

In interpreting this data it must be remembered that much of Indonesia, being around latitude 0°, does not have the violent seas that are experienced on the east coast of Malaysia. As such, the heavy rain

<1kg Slhalcolleclion period 1-2kg Slhalcolleclion period 2-4kg Slhalcollection period 4

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Figure 2. Spatial analysis of S inputs in Malaysia for the periods (a) 101711986-10/9/1986; (b) 10/9/1986-10/1111986;

and (c) 1112/1986-311111987.

Table 1. Accession of S in rainfall in Indonesia over a two-month period, from December 1988 to February 1989.

Site Sampali Sincinin Kubang Ujo Tanjung Karang Ciledug Cilacap Klaten Ngawi Banyuwangi Denpasar Karangasem Bima Kupang Genyem Manado Palu

Ujung Pandang Tarakan Palangkaraya Pontianak

Province Sumatera Utara Sumatera Barat Jambi Lampung Jakarta Selatan Jawa Tengah Jawa Tengah Jawa Timur Jawa Timur Bali Bali

Nusa Tenggara Barat Nusa Tengarra Timur Irian Jaya

Sulawesi Utara Sulawesi Tengah Sulawesi Selatan Kalimantan Timur Kalimantan Tengah Kalimantan Barat in Ujung Pandang is not associated with high accessions of S due to the calmer seas; this is likely to be true for much of the country.

In the more populated areas, such as in Java, it is likely that the higher S accessions are as a result of the greater anthropogenic inputs from the burning of organic matter and fossil fuel and from industry.

Inputs from volcanoes will also have a significant effect in specific areas of the country. As more periods are sampled and more sites are established, so the major geographical, seasonal and year-by-year variations in S accession in rainfall across the Indonesian archipelago will become evident.

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S concentration in irrigation wale, (ppm)

Figure 3. Relationship between total S in soil and S concentration of irrigation water.

Rainfall S

(mm) (kg/ha)

302 0.42

683 1.51

519 1.58

728 0.92

588 1.67

700 2.62

714 2.25

684 1.45

608 1.68

801 1.56

779 1.34

n.a. 0.21

518 0.92

784 0.52

982 1.26

348 0.26

1333 0.10

528 0.55

803 0.04

500 0.44

From this preliminary data it appears that some areas of Indonesia receive substantial amounts of S in rainfall, which must contribute significantly to the S nutrition of crops, while other areas receive only very minor amounts.

Irrigation water

Unlike the situation with the experiment in east coast Malaysia, where the amount of S in rain during the rice crop was sufficient to provide enough S for the crop, one lowland rice site in Thailand showed no response to S or P for three years and yet had a

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Figure 4. Relationship between available S in soil and the concentration of S in irrigation water.

negative S balance in each year. While this may have been because the crops were growing on the soil S reserves, it may also be that not all inputs were being taken into account. It is possible that there was enough S in the irrigation water to sustain the crop's growth.

There is little data on the extent to which irrigation water can provide a crop's S requirements (Yoshida and Chaudry 1979). Estimates for the concentration of S in irrigation water required for adequate growth range from 1.7 ppm (Ishizuka and Tanaka 1959 cited in Freney et al. 1982) to 6.4 (Wang 1979). Despite this lack of precise information, it is clear that the S in irrigation water must be of importance, either directly to the plant or as an input to the soil reserves.

Work in Indonesia has investigated the relationship between the concentration of S in irrigation water and the levels of total and available S in soils collected at the same sites (lsmunadji and Zulkarnaini 1978).

There was no relationship between the total S levels and the irrigation water concentration (Fig. 3).

However, although a limited data set of only 9 there appears to be a relationship between the level of available S and the irrigation water concentration (Fig. 4).

The S concentration of irrigation water varies widely. In a survey of 192 sites in Java the concentrations measured ranged from less than 0.5 ppm to more than 200 ppm. However, over 55070 were found to be less than 3 ppm and less than 10% were found to be greater than 20 ppm (see Ismunadji, these Proceedings) .

Conclusion

While further work could be carried out to assess the relative contribution of S in rain and in irrigation water under a range of water management regimes

and for a range of soil types, a reasonable estimate of the potential S accession from these sources can probably be made from current knowledge. The rainfall distribution, the water catchment structure, the water management regime,the prevailing weather conditions and proximity to the sea and other sources of S, can all be used to estimate S accessions. Further collection of rainfall accession data and irrigation water concentrations will only improve these estimates.

The use of estimates of the accession of S in rain and irrigation water, along with knowledge of the fertilizer and residue S inputs, the crop offtake and the soil chemical and physical characteristics should allow those areas and cropping systems which are likely to require S fertilizers to be identified and appropriate fertilizer programs designed. It is apparent from preliminary data on the accession of S in rainfall for Indonesia that this is a significant source of S in parts of the country, such as Java, but is of little consequence in other parts of the country, such as Sulawesi.

References

Freney. J.R. Jacq, V.A. and Baldensterger, El. 1982. The significance of the biological sui fur cycle in rice production. In: Dommergues, Y.R. and Diem, H.G. (ed.) Microbiology of tropical soils and plant productivity.

Developments in Plant and Soil Science V. The Hague, Martinus Nijhoff. 271-317.

Ismunadji, M. and Zulkarnaini, I. 1978. Sulfur deficiency of lowland rice in Indonesia. Sulphur in Agriculture 2, 17-19.

Wang, CH. 1979. Sulphur fertilization of rice - diagnostic techniques. Sulphur in Agriculture 3, 12-15.

Yoshida, S. and Chaudry, M. R. 1979. S nutrition of rice.

Soil Science Plant Nutrition 25, 121-134.

Dalam dokumen This document is discoverable and free to researchers across the globe due to the work of AgEcon Search (Halaman 100-104)

Incidental S Inputs in Rainfall and Irrigation Water

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