Improvement of a Peat Soil for Rice Cultivation in Thailand

Transcription

1 Jpn. J. Trop. Agr. 43(2) : 91-96, 1999 Improvement of a Peat Soil for Rice Cultivation in Thailand Tasnee ATTANANDANA, Benjaporn CHAKRANON *, Kazutake KYUMA * 2 and Pojanee MONCHAROEN * 3 Department of Soil Science, Kasetsart University, Bangkok, Thailand * Phikulthong Royal Development Study Center, Narathiwat, Thailand *2 Faculty of Agriculture, Kyoto University, Kyoto, Japan (presently, School of Environmental Science, the University of Shiga Prefecture, Hikone) *3 Land Development Department, Bangkok, Thailand Abstract The effects of mineral soil dressing, liming and/or trace element application on yield and sterility of rice plants grown on a peat soil in Thailand were investigated. The results of the pot experiments showed that mineral soil dressing gave the highest grain yield and the lowest percentage of unfilled grains. Liming and trace element (Cu+B+Zn) application increased grain yield and decreased rice sterility appreciably. It was also shown that the application of a high dose of copper at a low level of lime had detrimental effects. At a high level of liming, copper addition resulted in a higher yield. Beneficial effects of mineral soil dressing and liming were also observed under the field conditions. The application of copper to the peat soil did not result in any beneficial effect in terms of grain yield, but in a beneficial effect in terms of decrease of the percentage of unfilled grains when adequate liming was applied. Key words Copper deficiency, Rice cultivation, Soil acidity, Soil dressing, Sterility, Tropical peat soil Introduction Peat soil is one of the problem soils which requires careful management for agricultural use. Due to the increase in population, most of the marginal lands are likely, sooner or later, to be disturbed and utilized for food production. Peat soils cover more than 200 million ha worldwide, of which about 32 million ha occur in the tropics. In Asia, about 22 million ha were reported3). Most of the peat lands in Thailand are located in the southern provinces. The estimated total area is about 45,336 ha2), of which more than half occurs in Narathiwat province. Deficiency of trace elements, especially copper has often been reported for crops grown on peat soils. Rice has been reported to Received July 24, 1998 Accepted Feb. 19,1999 * 2 The corresponding author. experience sterility on peat in Southeast Asia, unlike in the Japanese peat lands. Soil dressing is considered to be an effective measure to improve peat soils in Japan. Previous studies showed that trace element application, especially copper, gave a higher yield of rice grown on peat soils1,4) The objective of this study was to analyze the effect of liming, trace element application, and soil dressing on the yield of rice plants grown on a soil from a peat swamp, Bacho, Narathiwat. Proper management of liming and optimum level of copper application were tested in pot and field experiments. Three experiments were carried out, of which two in pots and the other in a field. Materials and Methods Experiment 1 The experiment was conducted using a

2 92 Jpn. J. Trop. Agr. 43 (2) 1999 randomized complete block design with 3 replications. The treatments were as follows: 1. Peat 2. Peat+lime 3. Peat+lime+NPK 4. Peat+lime+NPK+Cu 5. Peat+lime+NPK+Cu+Zn+B 6. Peat+lime+NPK+Zn+B (-Cu) 7. Peat+lime+NPK+Cu+B (-Zn) 8. Peat+lime+NPK+Cu+Zn (-B) 9. Peat+7.5 cm of mineral soils+npk (soil dressing) The soils used consisted of a peat soil from the Bacho swamp (Narathiwat series) and a mineral soil (Tak Bai series) from Narathiwat province. Eleven kg of peat soil was put into a 30 l pot. The treatments were applied as mentioned above. Lime (Ca (OH)2) was applied at a rate of 96 g for the liming treatment. The soil was incubated with lime for 3 weeks. Urea and triple superphosphate were applied at 3.8 g/pot of N and P205 and potassium chloride was applied at the rate of 2.92 g K20/pot. Copper (Cu), zinc (Zn), and boron (B) were applied as CuSO4.5H2O at the rate of 0.45 g Cu, ZnSO4 at the rate of 0.44 g Zn, and sodium tetraborate at the rate of g B per pot, respectively. For the soil dressing treatment, mineral soil was topdressed at a depth of 7.5cm on the peat soil. Three week old seedlings of a rice variety, RD23, were transplanted in November, Chemical properties of the two soils used are shown in Table 1. Table 1. Chemical and physical properties of the soils studied Experiment 2 The experiment was conducted using 3 application rates of lime and 3 application rates of Cu in a factorial randomized complete block design with 3 replications. The treatments were as follows: 1. Peat+Lo+Cuo 2. Peat+Lo+Cu1 3. Peat+Lo+Cu2 4. Peat+Ll+Cu0 5. Peat+Ll+Cu1 6. Peat+L+Cu2 7. Peat+U+Cu0 8. Peat+L2+Cu1 9. Peat+U+Cu2 The soil used was a peat soil from the Bacho swamp (Narathiwat series) in Narathiwat province. Eleven kg of a peat soil was put into a 30 l pot. The treatments were applied as described above. Lime was applied at the rate of 36 and 96 g as Ca(OH)2 for the L1 and L2 treatments. The soils were incubated with lime for 3 weeks. Copper was applied as CuSO4.5H2O at the rate of 0.45 and 0.90 g Cu per pot for the Cu1 and Cu2 treatments. Urea and triple superphosphate were applied at the rate of 3.8 g/pot of N and P205, respectively, and potassium chloride was applied at the rate of 2.92 g K2O/pot to all the pots. Three week old seedlings of a rice variety RD23 were transplanted in March, Chemical properties of the soils used are shown in Table 1. The soil solution was analyzed for the ph value as well as levels of Fe, Cu and p-hydroxybenzoic acid at the transplanting, tillering, panicle initiation, flowering and harvesting stages. The growth, yield, and nutrient uptake of the rice plants were recorded. The unfilled grains were screened out using a screening machine and the percentage of unfilled grains was calculated. Experiment 3 *Extracted with DTPA (soil: DTPA=1:5) The experiment was conducted using a completely randomized design. There were 4 replications for treatments No. 3 `5, while two replications for treatments No. 1 `2. The treatments were as follows: 1. NPK (control) 2. NPK+ soil dressing 3. NPK+ lime+cu0 4. NPK+ lime+cu1 5. NPK+ lime+cu2

3 ATTANANDANA at al.: Peat soil in Thailand 93 As in Experiments 1 and 2, the soil used was a peat soil (Narathiwat series). The plot size was 3 ~ 5 m2. Chemical fertilizer was applied as urea, triple superphosphate and potassium chloride at the rates of 62.5, 75, 62.5 kg/ha of N, P2O5 and K2O, respectively. The nitrogen fertilizer was applied in two stages, one half as basal dressing and the other half as top dressing. Lime was applied as lime dust (CaCO3) at the rate of 18 ton/ha. CuSO4. 5H2O was applied at the rates of 18 and 36 kg/ha for the Cu1 and Cu2, respectively. Takbai series, a mineral soil in South Thailand, was applied at 5 cm depth on the peat soil as soil dressing treatment. Three week old seedlings of the rice variety RD 23 were transplanted in October, Results Experiment 1 Effects of liming, NPK fertilization, trace element application and mineral soil dressing on the growth and yield of rice 1.1 Straw and grain weight The RD 23 rice plants could not grow in the Narathiwat series peat soil without amendment or in a peat soil with liming. When NPK fertilizer was applied with liming, a marked increase in straw and grain weight was obtained. An even higher increase in yield was observed when trace elements were applied. No significant difference in straw and grain weight was observed between a single addition of copper and combined application of trace elements (Cu+Zn+B). Mineral soil dressing gave the highest straw and grain yield (Table 2). 1.2 Yield components No significant difference in the number of panicles per pot was observed between the combined addition of trace elements and a single application of copper. However, a lower number of panicles per pot was observed for the treatment without copper application compared to the treatments in which Cu was applied. Mineral soil dressing gave the highest number of panicles per pot. There was no difference in the 1000 grain weight among the treatments, except for the peat alone and peat+lime treatments where rice could not grow. In relation to rice sterility, the percentage of unfilled grains decreased appreciably with copper addition. The combined application of trace elements gave similar results. Mineral soil dressing gave the lowest percentage of unfilled grains (Table 2). Experiment 2 Effects of levels of lime and copper on soil solution analysis, growth and yield of rice 2.1 Straw, grain weight and yield components Rice could not grow in the pot with peat soil alone although NPK fertilizers were added. When lime was applied at a low level, substantial yield of rice was obtained. At a low level of lime, copper application resulted in a higher straw yield but not grain yield. However, when a high level of copper (L1Cu2) was added, markedly detrimental effect was observed, i.e., a decrease in grain weight and an increase in the Table 2. Effect of liming, N P K fertilizer and trace element application on straw, grain weight and yield components of rice (Experiment 1) Note: Figures in the same column followed by the same alphabetical letter are not significantly different according to the Duncan's new multiple range test(dmrt) at the 95% level. (If there is one common letter, there is no significant difference in that comparison.)

4 94 Jpn. J. Trop. Agr. 43 (2) 1999 percentage of unfilled grains. On the other hand, when lime was applied at a higher rate, a marked increase in grain yield was obtained at a low level of Cu application. The subsequent increase in copper application did not increase the yield significantly, but the percentage of unfilled grains decreased appreciably, though not significantly (Table 3). 2.2 Nutrient uptake Liming markedly increased the calcium and copper uptake in straw. Higher NPK uptake in straw at a lower level of liming with copper addition was observed, while a relatively lower uptake of NPK in straw at a higher rate of liming with copper addition was obtained (Table 4). The toxicity level of copper in straw is reported to be about 30 ppm6). It should be noted that the copper concentration in straw in treatment L1Cu2 was about 38 ppm (Table 4), where a marked decrease in grain yield and significant increase in sterility were observed (Table 3), indicating that there is a critical balance between the application rate of copper and lime. If an insufficient amount of lime is applied at a given application rate of Cu, toxicity may occur. 2.3 Soil solution analysis Liming increased the concentration of soluble p-hydroxybenzoic acid (PHBA) in a peat soil. This phenolic acid is toxic to the rice plants. The absorption of K, P, Cu and Zn was inhibited by the phenolic acids, including PHBA, by the formation of complex compounds of phenolic acids with Cu and Zn5). It was interesting to note that Cu application resulted in a lower PHBA concentration at a low level of lime at the harvesting stage of rice growth. On Table 3. Effect of liming and application on straw, grain weight, panicle nunber, 1000 grain weight and percentage of unfilled grains (Experiment 2) Note: Figures in the same column followed by the same alphabetical letter are not significantly different according to the Duncan's new multiple range test(dmrt) at the 95% level. (If there is one common letter, there is no significant difference in that comparison.) Table 4. Nutrient uptake and copper concentration in straw (Experiment 2).

5 ATTANANDANA at al.: Peat soil in Thailand 95 the other hand, Cu application decreased the PHBA content appreciably at a high level of liming at the transplanting and panicle initiation stages of rice growth (Table 5). Experiment 3 Effects of soil dressing, liming and copper application on the growth and yield of rice Soil dressing resulted in the highest straw and grain yield of rice. Beneficial effect of copper application was not significant. However, the percentage of unfilled grains was lower with Cu application than without Cu addition (Table 6). Soil dressing treatment also gave the lowest percentage of unfilled grains. Discussion It was eventually concluded that the application of 7.5 and 5 cm layers of mineral soil dresssing on a peat soil in pot and field experiments resulted in the highest grain yield and lowest percentage of unfilled grains, presumably due to the ability of the rice plants to grow in a shallow mineral soil layer. The 7.5 or 5 cm layer of mineral soil gave enough volume for the rice roots to grow normally. Trace element (Cu+B+Zn) application increased grain yield and decreased rice sterility appreciably, this is due to the essential requirement of Cu for grain development. Hi et al.4) also reported similar observations. The effect of a single application of copper was not different in terms of grain yield compared to (Cu+B+Zn) application. The combination of lime and copper application was critical to the yield of rice. Copper application at a high level of liming (96 g Ca(OH)2 per 11 kg of peat soil) resulted in a higher grain yield. On the other hand, copper application at a low level of liming (36g Ca(OH)2 per 11 kg of peat soil) resulted in a comparatively lower grain yield and higher percentage of unfilled grains. A very high concentration of copper in straw was noted (38 ppm). A Cu content in straw above 30 ppm was considered to be toxic6). High copper application to unhealthy plants at a low level of liming could lead to the detrimental effect of copper on rice plants. In Table 5. Content of soluble p-hydroxybenzoic acid in a peat soil (Đg/ml) (Experiment 2). Table 6. Effect of liming and application on straw, grain weight, and percentage of unfilled grains of rice (Dry season, 1993 : Experiment 3). Note: Figures in the same column followed by the same alphabetical letter are not significantly different according to the Duncan's new multiple range test(dmrt) at the 95% level. (If there is one common letter, there is no significant difference in that comparison.)

6 96 Jpn. J. Trop. Agr. 43 (2) 1999 the case of a high level of liming, since healthy plants could use a higher copper concentration, a higher grain yield was obtained. The field trial in the dry season confirmed the beneficial effects of soil dressing and liming. The application of copper did not result in any appreciable increase in grain yield, but in an appreciable decrease of the percentage of unfilled grains. The optimum soil dressing still gave a lower yield than the yield of rice grown on ordinary mineral soils. Further investigations should be carried out to improve the productivity of peat soils. Acknowledgement The authors would like to express their gratitude to Dr. K. YONEBAYASHI, Professor of Kyoto Prefectural University, for the analysis of p-hydroxybenzoic acid and to Mr. Chaiwat SITTIBUSAYA, Director of Phikulthong Royal Development Study Center, for the provision of facilities for the field experiment. Thanks are also due to the Kasetsart University Research and Development Institute for the financial support to the present study. References 1. ATTANANDANA, T., B. KRISORNPORNSAN, K. KYUMA and P. MONCHAROEN 1992 Amelioration of peat soils. Thai J. Soil and Fertilizer 14 : (in Thai). 2. CHAROENPONG, S Physical property of peat in Narathiwat province. Report on development of peat swamp. pp (in Thai). 3. DRIESSEN, P. M Peat soils. In: Soils and Rice (IRRI ed.), The International Rice Research Institute, Los Bað os (Laguna) HARA, T., A. BOONSOM, P. VUARNSORN and T. TADANO 1992 The effect of the application of lime and micronutrients on the growth and occurrence of sterility of rice plants in peat soils of Southern Thailand. In: Coastal lowland ecosystems in Southern Thailand and Malaysia (K. KYUMA, P. VIJARNSORN and A. ZAKARIA eds.) Kyoto Univ. (Kyoto) TADANO, T., K. YONEBAYASHI and N. SAITO Effect of phenolic acids on the growth and occurrence of sterility in crop plants. 1. Contents of phenolic compound monomers in peat soils. In: Coastal lowland ecosystems in Southern Thailand and Malaysia (K. KYUMA, P. VUARNSORN and A. ZAKARIA eds.) Kyoto Univ. (Kyoto) YOSHIDA, S., D. A. FORNO, J. H. COCK and K. A. KOMEZ 1972 Laboratory manual for physiological studies of rice. The International Rice Research Institute. Los Bað os (Laguna) pp.70.