Investigation on Nutritional Factors Limiting Crop Growth in the Red-Yellow Podzolic Soils Distributed in the Province of Lampung, Indonesia

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1 Investigation on Nutritional Factors Limiting Crop Growth in the Red-Yellow Podzolic Soils Distributed in the Province of Lampung, Indonesia I. Nutritional Factors of the Soils Limiting the Growth of Main Cereal Crops Toshiaki TADANO*, Midori NINAKI**, Kazuhiro OYA***, Tomio YOSHIDA****, J. LUMBANRAJA*****, M. UT0M0***** and A. D. SITORUS***** *Faculty of Agriculture, Hokkaido University, Sapporo 060, **Faculty of Agriculture, Tokyo University of Agriculture, Setagaya-ku, Tokyo 156, ***College of Agriculture, University of the Ryukyus, Nishihara, Okinawa ,****Institute of Applied Biochemistry, the University of Tsukuba, Sakura, Ibaraki 305, *****Faculty of Agriculture, University of Lampung,Tanjungkarang, Lampung, Indonesia Abstract Red-yellow podzolic soils distributed in the province of Lampung, Indonesia are low in ph, phosphorus content as well as base supplying and rataining power. The most important nutritional factor limiting the growth of the main cereal crops on the red-yellow podzolic soils is the low phosphorus supply of the soils, followed by the low nitrogen supply. The low ph becomes an important limiting factor when the tolerance of crop species to low ph or high Al is weak. Thus, application of phosphorus and nitrogen is essential in order to increase crop production in the red-yellow podzolic soils and liming is required where crops sensitive to the low ph conditions of the soil are cultivated. Iron toxicity becomes a factor limiting the growth of lowland rice under ill-drained conditions. In addition, it is assumed that the low supply of potassium will also become a limiting factor in future. Introduction Red-yellow podzolic soils, latosols, brown podzolic soils, andosols, regosols and alluvial soils are distributed in the province of Lampung, Indonesia as indicated in Fig. 1. Red-yellow podzolic soils account for the largest distribution area, followed by latosols. Annual crops such as lowland rice, upland rice, maize, cassava, soybean etc. are cultivated mainly on the redyellow podzolic soils while perennial crops such as rubber tree, oil palm, coffee, tea etc. on the latosols. But the crop productivity of the redyellow podzolic soils is low. This type of soils is distributed widely in Indonesia, especially in Sumatra, Kalimantan and other island and is often included in the Ultisols order in the soil classification of U. S. D. A.1) The purpose of the present investigation was to analyse the nutritional factors of the redyellow podzolic soils limiting the growth of main Received 24 July cereal crops such as lowland rice, upland rice Fig. 1 Soils distributed in the province of Lampung, Indonesia and sites where soils and crop plants were collected. (Soil map was supplied by the Ministry of Agriculture, Indonesia)

2 68 and maize in order to identify a method to improve the low crop productivity of the soils. Materials and Methds Survey 1: Surface soils, 15 cm in depth, were sampled from f ourty, four and twetve fields with crops cultivated on red-yellow podzolic soil, alluvial soils and latosols areas, respectively (Fig. 1). Alluvial soils and latosols were collected for comparison. The alluvial soils were located around the lower reaches of a river flowing through a red-yellow podzolic soil area. Lowland rice, upland rice, maize and cassava were cultivated on the red-yellow podzolic soils from which the soil samples had been collected, lowland rice and cassava on the alluvial soils while pepper, coffee, banana, coconut, clove in addition to lowland rice, upland rice and maize were cultivated on the latosols. The soils were air-dried, passed through a sieve, 2 mm in diameter and analysed for the chemical properties. The ph was determined with a glass electrode, exchange acidity was determined by the titration method, available phosphorus by the Truog method,10) cation exchange capacity and exchangeable cations by the method of Schollenberger with a modified procedure2) and total carbon by the Tyurin method. Survey 2: The tops of young seedlings of lowland rice, upland rice and maize 10 to 30 days after germination or transplanting were collected in farmer's fields in December in The plant samples were dried at 80 Ž, ground and analysed for the contents in N, P, K, Ca, Mg, Fe, Mn, Zn and B. Experiment 1: A sample of redyellow podzolic soil was collected in Adi jaya, Terbanggibesar, Lampung and a pot experiment was conducted in a greenhouse of the University of Lampung in order to analyse soil nutritional factors limiting the growth of lowland rice, upland rice and maize. Ten Kg of soil was added to a 101 pot and the following ten treatments were applied, - NPK (-F), -N, -P, - K and + NPK with and without lime for each crop. Amount of fertilizer was 2 g N as urea, 2 g P2O5 as triple superphosphate and 1 g K2O as K2SO4 per pot. Ca(OH)2 required for the soil to reach ph 6.0 was added to the treatments with lime. The treatments were triplicated. Four seedlings of lowland rice (variety, G. H. 32). were transplanted to each pot and eight or four seeds of upland rice (variety, Bicol) or maize (variety, Arjuna) were sown on Jan. 5, All the varieties were improved ones. When upland rice and maize were germinated, some of the seedlings were eliminated and four and one plants per pot, respectively, remained. A suitable amount of tap water was added to each pot everyday during the growth. Survey 3: Rice plants from the maximum tillering to the starchy stage were collected from ten lowland fields in three sites differing in drainage and supply of irrigation water in August 1981 and the nutritional status of the plants was investigated. Conditions of water supply and drainage, amount of fertilizer applied, variety of rice plants cultivated and growth stages in the respective fields are indicated in Table 1. The lowland fields in Terbanggibesar were well-drained and equipped with an artificial irrigation system but the fields were not irrigated continuously since the amount of water used for irrigation was limited. Those in Metro were also equipped with an artificial irrigation system. Of these, water supply and drainage in field No. 6 were more or less similar to those in Terbanggibesar while fields No. 7 and 8 were ill drained and swamplike fields since they were located at the bottom of the area topographically. The soils in Terbanggibesar and Metro were redyellow podzolic soils. Soils in Seputih Surabaya were alluvial soils distributed around the lower reaches of a river running through a red-yellow podzolic area. These fields were located in a lower ill drained area with abundant water supplied from a stream and were always submerged. Eighty to 92 kg/ha of N as urea and 18 to 50 kg/ha of P2O5 as triple superphosphate were applied to fields No. 1, 6 and 7. Dung of chicken or cow, though the amount was unknown, applied to fields No. 2, 3, 4 and 5. Only 15 kg/ha of P2O5 as triple superphosphate was applied to fields No. 9 and 10 while no fertilizer was applied to field No. 8. Potassium

3 TADANO et al.: Growth Limiting Factors in Red-Yellow Podzolic Soils 69 Table 1 Characteristics of the lowland fields from which the rice plants had been collected in Survey 3. * N: Urea, P2O5: Triple superphosphate was not applied in any of the fields. Varieties of the rice plants cultivated were IR-36 in fields No. 1, 6, 7 and 8, Pelita I/1 in fields No. 2, 3 and 4 and C4-63 in No. 5. These were improved varieties. On the other hand, Nyampah, a local variety, was cultivated in fields No. 9 and 10. Results and DiscussionI. Chemical properties of red-yellow podzolic soils. Mean value and the standard deviation of each chemical property are indicated in Table 2. The mean values of ph, available phosphorus (Truog P), cation exchange capacity, exchangeable cations and base saturation were low in the redyellow podzolic soils studied. These were much lower than the mean values of 410 soils collected in all the tropical Asian countries by Kawaguchi and Kyuma5'. Thus, it is considered that the chemical properties of the red-yellow podzolic soils are characterized by low ph, available phosphrus content, cation exchange capacity, exchangeable cation amount and degree of base saturation. The content of N-KCl soluble Al was not particularly high and the degree of Al saturation was relatively low. The ph, available phosphorus amount, exchangeable cation values and degree of base saturation were somewhat higher in the lowland rice soils than in the upland soils belonging to the red-yellow podzolic soil group. In Indonesia, although urea and triple superphosphate are used as fertilizer, fertilization is limited to a part of lowland rice fields in most areas. In this survey, kg/ha of N as urea and kg/ha of P205 as triple superphosphate were applied to approximately 60 percent of the lowland rice fields while no fertilizer was applied to the upland fields. Therefore, it appears that the somewhat larger amount of available phosphorus in the lowland rice soils than in the upland soils may be due to the application of phosphate fertilizer to the lowland rice soils. However the level of available phosphorus in the lowland soils is still too low for normal rice growth. On the other hand, the larger amount of exchangeable cations in the lowland soils is as-

4 70 Table 2 Chemical properties of red-yellow podzolic soils, alluviasoils and latosols Numeral in parenthesis indicates the number of soils analysed. sumed to be due to the supply of cations from irrigation water. No difference in the chemical properties of soils cultivated with cassava and those with other upland crops was recognized. However, soils of the fields where were invaded by alang alang (Imperata cylindrica) after crop cultivation was stopped and which were maintained as grasslands for more than four years, showed a higher ph and higher values of exchangeable cations, degree of base saturation and total carbon content than soils cultivated with crop plants. Alluvial soils located near an area with redyellow podzolic soil were principally similar but inferior in the chemical properties to the redyellow podzolic soils. On the other hand, latosols showed a higher ph and higher values of cation exchange capacity, exchangeable cations and degree of base saturation than the red-yellow podzolic soils. The higher crop productivity of the latosols than that of the red-yellow podzolic soils can be ascribed primarily to these characteristics of the soils. However, the level of the available phosphorus is still too low for normal crop growth even in latosols.ii. Nutritional status of young seedlings of main crops cultivated in farmer's fields. Phosphorus contents of lowland rice, upland rice and maize cultivated in all the soils were low (Table 3). There were several fields where distinct phosphorus deficiency symptoms were observed. Phosphorus content required for the normal growth of rice plant and maize at the early stages of growth has been reported to be approximately 0.20 percent7). Thus, most young seedlings of these crops were considered to be deficient in phosphorus. There were some redyellow podzolic and alluvial soils where Zn contents of crop plants were very low. Furthermore, Fe contents of lowland rice plants were sometimes considerably high irrespective of the kind of soil on which they were cultivated. The critical Zn content of rice plant for deficiency has been reported to range from 10 to 15 ppm3,4) and the Fe content for toxicity from 300 to 550 PPm 6,9)

5 III TADANO et al.: Growth Limiting Factors in Red-Yellow Podzolic Soils 71 Table 3 Element content in the top of main cereal crops at early growth stage. Effect o f application o f nitrogen, phosphorus, potassium and lime on the growth of main cereal crops. The ph of the soil used for the experiment was 4, 90 and the nutrient status was somewhat lower (Table 4) than the mean value for the red-yellow podzolic soils indicated in Table 2. Dry weights of lowland rice, upland rice and maize were the lowest in the -P treatment, followed by the - N treatment. The - K treatment resulted in normal growth for upland rice and maize, but to some extent poorer growth for lowland rice than the + NPK treatment (Fig. 2). Liming had no effect on the growth of lowland rice and upland rice while a large effect on the grain yield of maize in the + NPK and the - K treatments. Tolerance of rice plant to the low ph and high A l condition of soil has been reported to be very strong whereas that of maize weaker than that of the rice plant.8) Thus, it is considered that the most important nutritional factor of the red-yellow podzolic soil limiting the growth of these crops is the low phosphorus supply of the soil, followed by the low nitrogen supply and that the low ph becomes an importent factor when the tolerance Fig. 2 Effect of nitrogen, phosphorus, potassium and lime application on the dry weight of lowland rice, upland rice and maize at harvest (Amount of fertilizer ; N: 2, P2O5: 2, K2O: 1 g/pot)

6 72 Table 4 Chemical properties of the red-yellow podzolic soil used for the pot experiment * N-CH3000NH4 soluble of cultivated crop to low ph and high Al condition of the soil is weak. In addition, the low supply of potassium of the soil may become a factor limiting crop growth in future. IV. Nutritional status of lowland rice plants grown on red-yellow podzolic soils with different conditions of drainage and supply of irrigation water. Top dry weight of rice plants in Terbanggibesar more or less reflected the growth stages, and was lower in plants at the maximum tillering or the early booting stage which were cultivated on fields No 4, 5-1 and 5-2 than that of the plants which were at the booting stage in the other three fields (Table 5). N content of the shoot was low in plants in fields No. 3 and 5-2. P content was lower in plants in fields No. 4, 5-1 and 5-2 than in those in the other three fields in spite of the younger growth stages of the former than of the latter. K content was low in plants in fields No. 2 and 3. Content of other elements was normal. The rice plants of fields 5-1 and 5-2 which were collected from the same field showed a difference in the leaf color that was green in the former while yellowish in the latter. Since the leveling of the field was uneven, the surface level of the soil where the rice plants of field 5-2 were planted was higher than that of field 5-1. Furthermore, the field was irrigated once a week. Thus, it is suggested that denitrification occurred significantly in the soil of field 5-2 and, as a result, the rice plants became deficient in nitrogen. The leaf color of plants in field No. 3 was also yellowish and the N content was lower than the critical value for deficiency at this growth stage. Therefore, it is assumed that the rice plants in fields No. 3 and 5-2 were deficient in nitrogen, those in fields No. 4, 5-1 and 5-2 moderately deficient in phosphorus and those in fields No. 2 and 3 deficient in potassium. The rice plants in Metro were at the starchy Table 5 Top dry weight and element content of the shoot of rice plants collected in Survey 3

7 TADANO et al.: Growth Limiting Factors in Red-Yellow Podzolic Soils 73 stage and the growth was considerably poorer in fields No. 7 and 8 than in field No. 6. Iron toxicity symptoms were observed and Fe content of the shoots was very high in fields No. 7 and 8. Therefore, it is considered that the rice plants of these fields were suffering from iron toxicity. Although contents of N and P in the plants in field No. 6 were low, they were not too low in taking into account the contents in rice plants growing normally at the starchy stage. Contents of P of plants in field No. 8 and Mg in field No. 7 were low. Thus, the growth of the rice plants might be adversely affected by phosphorus or magnesium deficiency along with iron toxicity. The rice plants in Seputih Surabaya were at the booting stage and the dry weight was lower in field No. 10 than in No. 9 (Table 5). Contents of N, P and K of the shoot were low for rice plant at the booting stage and contents of N and K were considerably lower in field No. 10 than in field No. 9. Furthermore, Fe content was rather high in the rice plant of both fields. Thus, the low supply of N, P and K coupled with the high concentration of Fe in the soil solution caused by strong soil reduction was responsible for the limitation of the growth of the rice plants in these f eilds and the adverse effects were more conspicuous in plant growing in field No. 10 than in field No. 9. From the results described above, it appears that iron toxicity becomes a factor limiting the growth of lowland rice under ill-drained soil conditions. Thus, soil amelioration and suitable water management are required to avert strong soil reduction and iron toxicity when lowland rice is cultivated on ill-drained soils. In addition, it is considered that denitrif ication may become an important adverse factor for rice growth where the soils are well-drained and irrigated irregularly. Summary Several surveys and experiments were con ducted in order to identify the nutritional factors limiting the growth of main cereal crops culti vated on the red-yellow podzolic soils distributed in the province of Lampung, Indonesia. The results obtained are summarized as follows. 1. Red-yellow podzolic soils distributed in the province of Lampung, Indonesia were low in ph, available phosphorus content as well as base supplying and retaining power. 2. The most important nutritional factor limiting the growth of main cereal crops on the red-yellow podzolic soils was the low phosphorus supply of the soil, followed by the low nitrogen supply and the low ph became an important factor when the tolerance of crop species to low ph or high Al was weak. 3. Thus, it is concidered that application of phosphorus and nitrogen is essential in order to increase crop production on the red-yellow podzolic soils and that liming is required where crops sensitive to low ph conditions of the soil are cultivated. 4. Iron toxicity became a factor limiting the growth of lowland rice under ill-drained con ditions. Therefore, when lowland rice is culti vated on ill-drained soils, soil amelioration and suitable water management are necessary to avert strong soil reduction and iron toxicity. 5. It is postulated that the low supply of potassium of the soil may become a factor limit ing the growth of cereal crops in future. Literature Cited 1. BUOL, S. W., F. D. HOLE and R. J. MCCRACKEN 1973 Soil genesis and classification. The Iowa State University Press, Ames. 2. Committee for Soil Nutrient Detemination 1980 Analytical procedures of soil nutrients. (in Japanese) Yokendo Co., Tokyo. 3. FORNO, D. A., C. J. ASHER and S. YOSHIDA 1975 Zinc deficiency in rice. II. Studies on two varieties differing in susceptibility to zinc deficiency. Plant Soil. 42 : Ishizuka, Y. and A.TANAKA 1962 Inorganic nutrition of rice plant. 7. Effect of boron, zinc and molybdenum level in culture solution on yield and chemical composition of the plant. (in Japanese) J. Sci. Soil Manure, Jpn. 33 : KAWAGUCHI, K. and K. KYUMA 1977 Paddy

8 74 soils in tropical Asia, their material nature and fertility. Monograph of the Center for Southeast Asian Studies, Kyoto University, The University Press of Hawaii, Honolulu. 6. Tadano, T Studies on the iron nutrition of the rice plant. 5. Changes of the susceptibility to iron toxicity during growth. (in Japanese) J. Sci. Soil Manure, Jpn. 45 : TADANO, T. and A. TANAKA 1980 Difference among crop plants in effect of low phosphate con centrations in the growth media on the growth at early stage. (in Japanese) J. Sci. Soil Manure, Jpn. 51: TANAKA, A. and Y. HAYAKAWA 1975 Compar ison of tolerance to soil acidity among crop plants. 3. Tolerance to soil acidity. J. Sci. Soil Manure, Jpn. 46 : TANAKA, A., R. LOE and A. NAVASERO 1966 Some mechanisms involved in the development of iron toxicity symptoms in the rice plant. Soil Sci. Plant Nutr. 12: TRUOG, E The determination of the readily available phosphorus of soils. J. Amer. Soc. Agron., 22 :