Effect of combined use of organic manure and nitrogen fertilizer on the performance of rice under flood-prone lowland conditions

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1 Journal of Agricultural Science, Cambridge (1999), 132, Cambridge University Press Printed in the United Kingdom 461 Effect of combined use of organic manure and nitrogen fertilizer on the performance of rice under flood-prone lowland conditions A. GHOSH * AND A. R. SHARMA Division of Agronomy, Central Rice Research Institute, Cuttack , Orissa, India Division of Agronomy, Central Soil Water Conservation Research and Training Institute, 218, Kaulagarh Road, Dehradun , Uttar Pradesh, India (Revised MS received 17 November 1998) SUMMARY Field experiments were conducted during the wet seasons of 1995 and 1996 at the Central Rice Research Institute, Cuttack, Orissa, India using two rice cultivars, Matangini (improved) and Champaisali (local) to study the advantages of organic manuring in conjunction with inorganic fertilizer with the objective of enhancing rice productivity under semi-deep (0 65 cm) lowland conditions. In 1995, application of 10 t FYM ha increased grain yield compared with no FYM. The yield produced with FYM alone was similar to the yield following the application of N fertilizer at 20 and 40 kg ha. There was no significant difference in grain yield due to the application of 20 and 40 kg N ha in plots treated with FYM. Nitrogen fertilization was effective only when FYM was not applied. In 1996, FYM application alone or in combination with N fertilizer had a beneficial effect on crop growth and grain yield. This was contrary to the results obtained in 1995 when N fertilization at kg ha did not prove beneficial in plots where FYM was applied. The yield due to application of FYM alone was similar to that from the application of 40 kg N ha as urea. However, the maximum yield was produced when FYM application was supplemented with 40 kg N ha. There was a significant interaction between N application rate and cultivar. Cultivar Matangini outyielded Champaisali in both years. INTRODUCTION Rainfed lowland rice cultivation (c. 38 million ha), representing nearly a quarter of the world s total rice area produces 17% of the global rice supply (Klaus 1992). One-third of south and south-east Asian rice lands belong to this ecosystem. This lowland also constitutes more than 100 million ha of uncultivable land both in Latin America and Africa. Excess water stress due to flooding of varying depth and duration may adversely affect the rice crops grown in these lowlands, particularly in the catchment and coastal areas. Despite the use of tall cultivars, rice crops are prone to complete or partial submergence, causing poor establishment (Ram et al. 1994). Early flooding causes seedling mortality as well as the death of young plants, while flooding at later stages results in restricted tillering and suppression of dry matter production. Consequently rice yields remain low and * Corresponding author, crri crri.ori.nic.in Present address. unstable. Appropriate cultural practices need to be adopted, paying particular attention to efficient fertilizer management, which can be difficult, due to uncontrolled water accumulation, resulting in low (30 40%) recovery of applied N (Sharma et al. 1995). A better understanding of the circumstances which cause poor N utilization needs to involve a consideration of these cultural practices which may increase N-use efficiency. Initial plant vigour and tillering pattern is improved by basal N fertilization, while N fertilizer applied at later growth stages helps to restore flood affected crops compensating for the damage caused by early submergence (Puckridge et al. 1991). However, basal N application can hardly improve the later crop growth due to its uncontrolled loss encountered in different dimensions under waterlogged conditions. Top dressing of N fertilizer is not practicable with high water levels at the later stage of crop growth. So, N availability may be restricted to the crop during this period unless a feasible alternative exists which ensures its sustained availability despite having been applied basally. A possible procedure lies

2 462 A. GHOSH AND A. R. SHARMA in the practice of organic manuring instead of applying N fertilizer alone. Balanced fertilization through the combined use of organic and inorganic sources of N is therefore considered an important means of sustaining N availability. With these objectives, an experiment was planned to study the effect of organic manuring in conjunction with inorganic N fertilizer for improving rice productivity under semi-deep (0 65 cm) lowland conditions. MATERIALS AND METHODS Field experiments were conducted during the wet seasons of 1995 and 1996 at the Central Rice Research Institute, Cuttack, using two tall ( cm), longduration ( days), photosensitive rice cultivars, Matangini (improved) and Champaisali (local). The soil was a sandy clay loam (aric, heplaquept) of the Mahanadi Delta having a ph of 7 8, organic carbon 0 83%, total N 0 09%, available phosphorus 22 kg ha and available potassium 128 kg ha. In 1995, the crop was dibble-sown in saturated soil on 10 June at cm spacing in plots measured 4 m 3 m. In 1996, fertilized nursery-grown seedlings were transplanted on 1 July at a similar spacing and plot size to those in Well decomposed organic manure (farm yard manure (FYM) 50% moisture, 0 63% N) was incorporated at 0 and 10 t ha and mixed thoroughly into the soil during puddling. Nitrogen fertilizer was applied at 0, 20 and 40 kg ha as prilled urea at sowing in 1995 and at 0 and 40 kg ha as urea supergranules after transplanting in A single application of 8 7 kgp ha and 16 7 kgk ha was applied basally in both years. Treatment combinations (12 in 1995 and 8 in 1996) were arranged in a split-plot design with cultivars and FYM in the main plots, and N rates in the sub-plots with three replications. Yield attributes were recorded at the harvest of the crop from a unit sample area of 1 m in each plot; while plant height was averaged on 10 plants randomly selected from each plot. RESULTS AND DISCUSSION Flooding patterns and initial crop establishment The intensity and frequency of rainfall coupled with drainage congestion in the adjoining Mahanadi river caused considerable variations in the period and pattern of water accumulation in the field during the experiment (Fig. 1). In 1995, unusually heavy rains (603 mm) from 10 to 17 May resulted in water accumulation in the field up to 30 cm in depth. This unusual situation prevented the normal practice of sowing rice in relatively dry soil conditions. However, no heavy rains occurred during the next month. Consequently, the water had receded completely by the beginning of June. Sowing was done in saturated soil by placing the seeds on the soil surface. Subsequently, the saturated soil helped the quick emergence of seedlings due to adequate moisture enabling rapid germination. Water started accumulating in the field from June (20 days after sowing, DAS), and increased abruptly to a depth of 46 cm within 13 days and was 58 cm deep at 46 DAS. Stand establishment was affected adversely due to this initial excess water stress. Water level at the early growth stage has been found to be critical for establishment and the subsequent tolerance of the crop to flooding (Reddy et al. 1987). The water level increased to a maximum depth of 65 cm in the second week of November and fluctuated between 40 and 55 cm during most of the crop growth period. Tiller production was reduced due to the excess water stress during the vegetative stage. Severe flooding (up to 70 cm) occurring at the later stages around flowering, reduced the number of effective tillers. The water depth (15 20 cm) during the ripening stage impaired grain-filling and led to a considerable reduction in grain yield. Water level started receding by mid November and crop was harvested at the end of December. In 1996, heavy rains during April May coupled with drainage congestion caused water accumulation in the field. Nursery-grown seedlings were transplanted in July into 12 cm of water. Water rose abruptly to a depth of 52 cm at 25 days after transplanting (DAT), resulting in poor stand establishment. Water level reached a maximum of cm at 60 and 100 DAT, and fluctuated between 35 to 55 cm during most of the crop growth period. Thus, the adverse effect of excess water stress was less pronounced in this year due to generally shallower water depth than in It allowed greater dry matter accumulation ensuring good plant stand and profuse tiller production. Moreover, the gradual recession of water from the end of October was conducive to the production of higher numbers of effective tillers at maturity. The water level started to recede from the first week of October, thus hastening the date of harvesting compared with that in Growth and yield attributes Overall growth and crop vigour were better in 1996 than in 1995 (Table 1). The application of FYM and N fertilization improved initial crop growth as demonstrated by taller and healthier rice plants compared with the control. This initial crop vigour is considered important for increasing tolerance to the onset of submergence (Chaturvedi et al. 1993). The mean plant height was greater but the number of tillers m was less in 1995 than in This was attributed to a higher water level experienced during the vegetative period in 1995, which enhanced stem elongation but restricted tiller production. Such a

3 Organic manure and nitrogen fertilizer on lowland rice Water depth (cm) Sowing Transplanting Flowering Chmpaisali Matangini Harvesting Harvesting 0 Jun Jul Aug Sep Oct Nov Dec Jan Month Fig. 1. Daily variation in flooding patterns during growth period of rice at CRRI, Cuttack during 1995 ( ) and 1996 ( ). Table 1. Effect of FYM and N fertilizer on yield attributes and grain yield of two rice cultivars under unfavourable lowland situations during 1995 and 1996 Plant height at maturity (cm) Panicle m Panicle weight (g) Grain yield (t ha) Straw yield (t ha) Treatment Cultivar Matangini (17 6)* 133 (14 2) Champaisali (17 0) 109 (13 7) Organic manuring No FYM (14 8) 112 (14 0) t FYM ha (18 1) 129 (14 0) N management (kg ha) (19 1) 114 (17 97) (22 3) (20 3) 128 (17 08) S.E. Cultivar (D.F. 6) Organic manuring (D.F. 6) N management (D.F. 16 (1995), 8 (1996)) * Figures in parentheses indicate the percentage white ear head. negative correlation between plant height and tiller number m under unfavourable lowland conditions agreed with the observations of Sharma & Reddy (1992). This was due to differential utilization of stored dry matter within the crop under flooded environment. Virtually, dry matter content determines the magnitude of the crop survivability during flooding. The stored dry matter which ensures more tiller production under unflooded conditions, can inspire faster stem elongation enabling them to escape from complete submergence (Chaudhary & Zaman, 1970). The cultivar Matangini was taller than Champaisali in both years; although, no significant difference (P 0 05) in height was found to be due to the application of FYM. However, the plants grown with either 20 or 40 kg N ha were significantly taller than the plants grown without any nitrogen (control). The total number of tillers m produced by Matangini was more than Champaisali. Significantly (P 0 05) more tillers m were obtained with FYM application

4 464 A. GHOSH AND A. R. SHARMA Table 2. Interaction between rice cultivar and N-fertilizer on grain yield (t ha) Treatment N management (kg ha) Matangini Champaisali Matangini Champaisali Mean S.E D.F N means at each V V means at each N in 1996 while N fertilized crop produced significantly (P 0 05) more tillers m in both years. Similarly, the incidence of stem borer infestation as judged by white ear head was substantially more during The white ear head count did not show any considerable difference between FYM or N treated plots compared with control plots and also between the two cultivars (Sharma & Ghosh 1998). The numbers of panicles m at maturity was more in 1996 than in Significant differences (P 0 05) in panicle weight due to different application rates of FYM and N were recorded in both years. Grain and straw yield Grain and straw yield was greater in 1996 than in The shallower water depth experienced during the crop growth period in 1996 was found to be beneficial for better initial crop stand and subsequent vigour. The crop was able to withstand the extent of submergence resulting in greater survival of tillers (Chaturvedi et al. 1993). Moreover, unlike 1995, the lower water depth during the ripening period facilitated the more efficient translocation of stored dry matter ensuring adequate grain-filling and earlier crop maturity (Pande et al. 1979). Cultivar Matangini outyielded Champaisali in both years. The application of 10 t FYM ha significantly (P 0 05) increased grain yield compared with no FYM in both years. In 1995, the grain yield produced with FYM alone was comparable with the application of N fertilizer at 20 and 40 kg ha. However, no significant difference (P 0 05) in grain yield due to the application of 20 and 40 kg N ha was found in crops treated with FYM. Therefore, N fertilization was not beneficial when crops were grown with FYM application. This may indicate the complementary effects of FYM and N fertilizer in meeting the nutritional requirements of rice plants. While in 1996, there was a significant improvement following the applications of FYM either alone or in combination with N fertilizations on the grain yield. The grain yield due to the application of FYM alone was comparable with the application of 40 kg N ha. Importantly, the maximum grain yield was achieved following the application of FYM supplemented with 40 kg N ha as urea supergranule. Therefore, the application of N fertilizer in conjunction with FYM showed contrasting results in the successive years. This may be due to the different schedules and forms of urea fertilization. Application of urea at sowing, as happened in 1995, that too in saturated soil, may encounter considerable N losses because the root may not be sufficiently developed at its initial seedling stage to absorb any nutrient applied therein. In addition, urea supergranule, as applied in 1996, releases N at a rate slower than prilled urea, as applied in 1995, and consequently, it can prolong the N availability to the crop ensuring better N utilization. Interaction between cultivar and N rate was found to be significant on grain yield in both years (Table 2). Both cultivars produced higher grain yield due to the application of 40 kg ha than to 20 kg N ha; however, cv. Champaisali produced similar grain yields with either 20 or 40 kg N ha in Relationship between production factors Regression analysis indicated a positive correlation between cultivars, and rates of N and FYM application. Y X 0 03 X, r 0 98 Y X 0 02 X, r 0 98 where, Y and Y indicate grain yields (t ha) of Matangini and Champaisali, respectively, and X and X indicate rates of nitrogen and FYM respectively. Grain yield increased with increase in FYM or N. It is evident that variation in either of the rates of N and FYM brings proportionate changes in the grain yield. However, yield estimation by virtue of respective regression analysis relates differently to the dependable factors (N FYM). The regression equation for

5 Organic manure and nitrogen fertilizer on lowland rice 465 cv. Matangini estimates higher value of the intercept and regression coefficient of X as compared with cv. Champaisali. Obviously, similar variation in N and FYM in both equations results in higher grain yield of cv. Matangini as compared with cv. Champaisali. It establishes the superiority of cv. Matangini over Champaisali under identical lowland conditions. The results indicate the beneficial effect of FYM application in increasing the grain yield of rice. FYM and N fertilizer may be complementary in meeting the N requirements of rice plants. The study also suggests a feasible alternative fertilizer management practice either by the basal application of 40 kg N ha alone or a combination of 10 t FYM ha supplemented with 20 kg N ha for augmenting rainfed lowland rice productivity under excess water conditions. CHAUDHARY, M. A.& ZAMAN, S. M. H. (1970). Deep water rice of east Pakistan. In Proceedings of the 13th International Rice Communication Working Party on Rice Production and Protection, 9 14 December, Tehran, Iran (Working paper VII 6,20 p). CHATURVEDI, G. S., MISRA, C. H., SINGH, O. N., PANDEY, C. B., YADAV, V. P., SINGH, A. K., DWIVEDI, J. L., SINGH, B. B. & SINGH, R. K. (1993). Physiological basis and screening for tolerance for flash flooding. In Rainfed Lowland Rice Agricultural Research for High Risk Environments (Ed. K. T. Ingram), pp Los Banos, Philippines: International Rice Research Institute. KLAUS, L. (Ed.) (1992). Challenges and Opportunities in a Less Favorable Ecosystem: Rainfed Lowland Rice. IRRI information series, No. 1. Manila, Philippines: International Rice Research Institute. PANDE, H. K., MITTRA, B.N.&GHOSH, B. C. (1979). Flood susceptibility of sowing dwarf rices and their suitability for low-lying areas. In Proceedings of the 1978 International Deepwater Rice Workshop, pp Los Banos, Philippines: International Rice Research Institute. PUCKRIDGE, D. W., WIENGWEERA, A., THANGBANI, P., SANGTONG, P., SATTARASARAT, A., KONGCHUM, M. & RUTAN, S. (1991). Nitrogen uptake by deepwater rice during the pre-flood and flooded phases in relation to dry matter and grain production. Field Crops Research 27, REFERENCES RAM, P. C., SINGH, B. B., SINGH, A. K., SINGH, V. K., SINGH, O. N., SETTER, T. L., SINGH, R.K.&SINGH, V. P. (1994). Environmental and plant measurement requirements for the assessment of drought, flood and salinity tolerance in rice. In Proceedings of the International Conferences on Stress Physiology of Rice NDUAT, (Eds V. P. Singh, R. K. Singh, B. B. Singh, B. B. Singh & R. S. Zeigler), pp Los Banos, Philippines: International Rice Research Institute. REDDY, B. B., GHOSH, B. C.& REDDY, M. D. (1987). Effect of transplanting date and seedling age on stand establishment and grain yield of rice in rainfed lowland (intermediate) conditions. Experimental Agriculture 23, SHARMA, A.R.&REDDY, M. D. (1992). Effect of method of sowing and weed control practices on performance of rice (Oryza sativa) under intermediate deepwater conditions. Indian Journal of Agricultural Sciences 62, SHARMA, A. R., MOORTHY, B. T. S., RAO, K. S. & VENKATESWARLU, B. (1995). Improvement of rice production technology in the conventional areas of eastern India. In Sustaining Crop and Animal Productivity The Challenge of the Decade (Ed. D. L. Deb), pp New Delhi: Associated Publishing Company. SHARMA, A. R.& GHOSH, A. (1998). Optimum seed rate and nitrogen fertilizer requirement of rice under semideepwater ecosystem. Journal of Agronomy and Crop Science 181,