Chapter 3
Fertilizer use studies in Indonesia

Fertilizer use

Numerous studies have been carried out on fertilizer use in Indonesia. At the International Conference on Nutrient Management for Sustainable Food Production in Asia held in Bali, Indonesia, in December 1996 Karama et al. (1996) and Santoso (1996) concluded that Indonesia had become self sufficient in rice thanks to fertilizer use. Today only a small increment of rice production can be expected from the shrinking area of lowland rice. The main challenge is to develop productive agricultural systems in the underdeveloped, rainfed uplands, which are currently poorly fertilized.

The official fertilizer recommendations date from 1984. Some overall estimates of fertilizer use by crop in Indonesia are given in the publication Fertilizer use by crop, FAO et al. (2002). According to this publication, 52 percent of the fertilizers consumed in Indonesia are applied to rice, 12 percent to maize, 13 percent to oil-palm, 5 percent to vegetables and 4 percent to fruits, the remaining 14 percent to various other crops. Information on the quantities of fertilizer used by each crop in each province and island is not available. In the absence of reliable information on fertilizer use on crops and up-to-date recommendations, it is not possible to assess reliably the relationships between fertilizer use and development of crop production.

Lowland rice

There was a substantial increase in the productivity of lowland rice in Indonesia between 1960 and 1990. The development of the planted area and yields of lowland rice since the beginning of the intensification programmes in the early 1960s are presented in Table 2. During the period between 1960 and 1975, the area of lowland rice increased from 6.5 to 8.5 million ha and the yield increased by 26 percent, an average annual increase of 1.7 percent per year. Between 1975 and 1990, the planted area increased from 8.5 to 10.5 million ha and the average yield increased by 56.4 percent, an average increase of 3.8 percent per year. These large increases were due to consistent governmental support of increased national food production by means of a good supply of agricultural inputs (i.e. fertilizers, pesticides), capital and guaranteed prices, accompanied by extension efforts to encourage the implementation of improved technologies.

TABLE 2
Development of the planted area, production and yield of lowland rice

Source: IFPA, 2004.

Between 1975 and 2002 fertilizer consumption increased more than nine-fold (Figure 2), from 635 to 5 931 thousand tonnes, an average increase of 49.6 percent per year (IFPA, 2004).

Between 1990 and 2002, the rice area increased only slightly, from 10.5 to 11.5 million ha. The yield increased by a total of four percent, an average increase of just 0.3 percent per year. This small increase in rice yields coincided with a falling trend in fertilizer consumption, apart from urea that still increased at an average annual rate of 0.9 percent. It has been suggested that the decreases in fertilizer consumption were due to the following factors (IFPA, 2004):

1. Removal of fertilizer subsidies i.e. for potassium chloride in October 1991, TSP/SP-36 in October 1994 and urea in December 1998.

2. A policy to reduce phosphorus fertilization on Java Island due to the accumulation of residual phosphorus.

3. A reduction in the extension services.

4. The low purchasing power of farmers.

Upland crops

Unlike fertilizer use for lowland rice, that increased considerably in the period of 1960-1990, fertilizers remain underused on upland crops. For example, 67 percent of the more than 1.1 million tonnes of TSP consumed in 1985 was used in Java, mainly for lowland rice, while Java accounts for only 16 percent of the total cultivated land area of Indonesia. A reasonable strategy for future agricultural development is therefore the development of upland areas. The upland areas in the humid tropics of Indonesia are capable of producing high yields of a wide range of food crops, including root and tuber crops, pulses, and beans. The integration of livestock into this productive system of upland farming would make it more viable and sustainable (Santoso, 1996).

Soil fertility status and fertilizer recommendations

Phosphorus buildup on lowland rice soils

TABLE 3
Phosphorus deficient lowland rice soils in Java in the early 1970s

Source: Santoso and Sudjadi, 1974.

In the early 1970s, it was estimated that as much as one-third of the lowland rice soils on Java were deficient in phosphorus (Table 3).

However, the phosphorus status of lowland rice soils has increased considerably as a result of the seasonal (twice in a year) application of about 100 kg TSP/ha since the mid-1960s, in the context of the rice production programme of the Mass Guidance Program (Bimbingan Masal, BIMAS). As a result, in the early 2000s it was estimated that only about 15 percent of the rice soils in Java were deficient in phosphorus (Table 4), despite the fact that the lowland rice area had expanded from 2.65 million ha in the early 1970s to 3.65 million ha in the early 2000s.

TABLE 4
Phosphorus status of lowland rice soils in the early 2000s

¹ Does not include the whole West and East Nusa Tenggara Provinces.
² Does not include West, Central and East Kalimantan Provinces.
Source: Setyorini et al., 2004.

Figure 3 provides an illustration of Table 4 for West Java Province.

Soil potassium status

A study of the potassium status of lowland rice soils in Indonesia was carried out together with the study of the phosphorus status. It was estimated that out of the 7.5 million ha of lowland rice, about 0.9 million ha (12 percent) were deficient in K (Table 5).

TABLE 5
Soil potassium (K) status of lowland rice soils in the early 2000s

¹ Does not include the whole West and East Nusa Tenggara Provinces.
² Does not include West, Central and East Kalimantan Provinces.
Source: Setyorini et al., 2004.

Figure 4 illustrates Table 5 for West Java Province.

Fertilizer use recommendations

There are three major crop sectors (food, horticultural and plantation sectors), each with a number of economically important crops. In this report, 34 crops are selected. The wide variations in soil characteristics existing in the country, each with different nutrient imbalances and deficiencies, combined with the large number of crops, presents a challenge for the development of fertilizer recommendations for each specific soil and crop combination. Much research has been carried out to study crops' responses to fertilization. One of the latest reviews is the study by Hanson et al. (1994).

The fertilizer use recommendations have not been changed for the past 20 years and should be considered as general guidelines (Tables 6, 7 and 8). In practice, farmers tend to apply fertilizers mainly according to their own experience and financial means.

New, up-to-date recommendations, incorporating more recent information on crop responses and soil nutrient status, are greatly required.

TABLE 6
Range of fertilizer rates recommended for food and horticultural crops

* Total of provinces surveyed/analyzed
Source: Anonymous, 1984.

TABLE 7
Range of fertilizer rates recommended for perennial crops

Source: Anonymous, 1984.

TABLE 8
Estimates of fertilizer practices